Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2018	Aug. 03, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	BankUnited, Inc.
Entity Central Index Key	0001504008
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock Shares Outstanding		105,352,328
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash and due from banks:
Non-interest bearing	$ 10,937	$ 35,246
Interest bearing	368,319	159,336
Cash and cash equivalents	379,256	194,582
Investment securities (including securities recorded at fair value of $7,093,068 and $6,680,832)	7,103,068	6,690,832
Non-marketable equity securities	278,739	265,989
Loans held for sale	46,829	34,097
Loans (including covered loans of $451,350 and $503,118)	21,869,723	21,416,504
Allowance for loan and lease losses	(134,971)	(144,795)
Loans, net	21,734,752	21,271,709
FDIC indemnification asset	200,783	295,635
Bank owned life insurance	261,758	252,462
Equipment under operating lease, net	591,267	599,502
Goodwill and other intangible assets	77,740	77,796
Other assets	675,379	664,382
Total assets	31,349,571	30,346,986
Demand deposits:
Non-interest bearing	3,315,550	3,071,032
Interest bearing	1,621,940	1,757,581
Savings and money market	10,590,438	10,715,024
Time Deposits	6,650,022	6,334,842
Total deposits	22,177,950	21,878,479
Federal Home Loan Bank advances	5,071,000	4,771,000
Notes and other borrowings	402,799	402,830
Other liabilities	598,389	268,615
Total liabilities	28,250,138	27,320,924
Commitments and contingencies
Stockholders' equity:
Common stock, par value $0.01 per share, 400,000,000 shares authorized; 106,241,116 and 106,848,185 shares issued and outstanding	1,062	1,068
Paid-in capital	1,455,554	1,498,227
Retained earnings	1,592,157	1,471,781
Accumulated other comprehensive income	50,660	54,986
Total stockholders' equity	3,099,433	3,026,062
Total liabilities and stockholders' equity	$ 31,349,571	$ 30,346,986

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Investments, Fair Value Disclosure	$ 7,093,068	$ 6,680,832
ASSETS
Covered loans net of premiums, discounts and deferred fees and costs	$ 451,350,000	$ 503,118,000
Stockholders' equity:
Common stock, par value (in Dollars per Share)	$ 0.01	$ 0.01
Common stock, shares authorized (in Shares)	400,000,000	400,000,000
Common stock, shares issued (in Shares)	106,241,116	106,848,185
Common stock, shares outstanding (in Shares)	106,241,116	106,848,185

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income:
Loans	$ 288,264	$ 249,409	$ 562,264	$ 485,771
Investment Securities	56,092	46,054	106,077	89,773
Other	4,499	3,372	8,290	6,829
Total interest income	348,855	298,835	676,631	582,373
Interest expense:
Deposits	65,298	39,514	121,659	74,242
Borrowings	28,294	19,732	51,900	37,949
Total interest expense	93,592	59,246	173,559	112,191
Net interest income before provision for loan losses	255,263	239,589	503,072	470,182
Provision for loan losses	8,995	13,619	12,142	25,719
Net interest income after provision for loan losses	246,268	225,970	490,930	444,463
Non-interest income:
Income from resolution of covered assets, net	4,238	8,361	7,555	15,666
Net loss on FDIC indemnification	(1,400)	(2,588)	(5,015)	(9,336)
Deposit service charges and fees	3,510	3,252	6,997	6,455
Gain on sale of loans, net	768	(404)	4,269	4,154
Gain on investment securities, net	2,142	627	2,506	2,263
Lease financing	17,492	13,141	31,594	26,780
Other non-interest income	5,223	7,504	12,053	12,055
Total non-interest income	31,973	29,893	59,959	58,037
Non-interest expense:
Employee compensation and benefits	65,537	60,388	132,573	120,059
Occupancy and equipment	18,985	19,251	37,817	37,860
Amortization of FDIC indemnification asset	44,250	45,663	84,597	90,126
Deposit insurance expense	4,623	5,588	9,435	11,063
Professional fees	2,657	4,785	5,532	9,825
Telecommunications and data processing	3,900	3,745	7,585	7,029
Depreciation of equipment under operating lease	9,476	8,733	18,792	16,750
Other non-interest expense	11,819	12,282	26,733	24,280
Total non-interest expense	161,247	160,435	323,064	316,992
Income before income taxes	116,994	95,428	227,825	185,508
Provision for income taxes	27,094	29,021	52,690	56,808
Net income	$ 89,900	$ 66,407	$ 175,135	$ 128,700
Earnings Per Share, Basic	$ 0.82	$ 0.60	$ 1.60	$ 1.18
Earnings Per Share, Diluted	0.82	0.60	1.59	1.17
Cash dividends declared per common share (in Dollars per Share)	$ 0.21	$ 0.21	$ 0.42	$ 0.42

CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Provision for loan losses	$ 8,995	$ 13,619	$ 12,142	$ 25,719
Non-interest income:
Gain on sale of loans, net	768	(404)	4,269	4,154
Covered [Member]
Provision for loan losses	294	1,653	567	2,432
Non-interest income:
Gain on sale of loans, net	$ (2,002)	$ (3,447)	$ (298)	$ (1,565)

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 89,900	$ 66,407	$ 175,135	$ 128,700
Unrealized gains on investment securities available for sale:
Net unrealized holding gain (loss) arising during the period	(13,106)	8,092	(40,430)	24,269
Reclassification adjustment for net securities gains realized in income	(1,875)	(379)	(2,592)	(1,369)
Net change in unrealized gains on securities available for sale	(14,981)	7,713	(43,022)	22,900
Unrealized gains on derivative instruments:
Net unrealized holding gain (loss) arising during the period	9,846	(8,598)	29,639	(8,167)
Reclassification adjustment for net losses realized in income	(535)	1,556	155	3,305
Net change in unrealized gains on derivative instruments	9,311	(7,042)	29,794	(4,862)
Other comprehensive income (loss)	(5,670)	671	(13,228)	18,038
Comprehensive income	$ 84,230	$ 67,078	$ 161,907	$ 146,738

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 175,135	$ 128,700
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization and accretion, net	(69,157)	(49,408)
Provision for loan losses	12,142	25,719
Income from resolution of covered assets, net	(7,555)	(15,666)
Net loss on FDIC indemnification	5,015	9,336
Gain on sale of loans, net	(4,269)	(4,154)
Gain on investment securities, net	(2,506)	(2,263)
Equity based compensation	12,272	9,705
Depreciation and amortization	31,391	29,837
Deferred income taxes	24,074	24,983
Proceeds from sale of loans held for sale	86,118	92,660
Loans originated for sale, net of repayments	(73,633)	(71,499)
Other:
Decrease in other assets	15,625	9,022
Increase (decrease) in other liabilities	25,242	(58,035)
Net cash provided by operating activities	229,894	128,937
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchase of investment securities	(1,730,173)	(1,658,461)
Proceeds from repayments and calls of investment securities	691,220	608,060
Proceeds from sale of investment securities	836,317	427,923
Purchase of non-marketable equity securities	(166,813)	(99,238)
Proceeds from redemption of non-marketable equity securities	154,063	111,563
Purchases of loans	(604,278)	(636,876)
Loan originations, repayments and resolutions, net	152,848	(167,525)
Proceeds from sale of loans, net	115,560	98,421
Proceeds from sale of equipment under operating lease	49,892	2,269
Acquisition of equipment under operating lease	(56,132)	(52,180)
Other investing activities	(16,404)	(8,727)
Net cash used in investing activities	(573,900)	(1,374,771)
Cash flows from financing activities:
Net increase in deposits	299,471	1,286,950
Additions to Federal Home Loan Bank advances	2,201,000	2,820,000
Repayments of Federal Home Loan Bank advances	(1,901,000)	(3,110,000)
Dividends paid	(45,996)	(45,549)
Exercise of stock options	7,727	61,519
Repurchase of common stock	(54,399)	0
Other financing activities	21,877	12,961
Net cash provided by financing activities	528,680	1,025,881
Net increase (decrease) in cash and cash equivalents	184,674	(219,953)
Cash and cash equivalents, beginning of period	194,582	448,313
Cash and cash equivalents, end of period	379,256	228,360
Supplemental Cash Flow Information [Abstract]
Interest paid	171,379	108,036
Income taxes paid, net	18,677	41,298
Supplemental schedule of non-cash investing and financing activities:
Transfers from loans to other real estate owned and other repossessed assets	7,574	3,602
Transfers from loans to loans held for sale	22,094	5,190
Dividends declared, not paid	22,916	23,034
Unsettled purchases of investment securities	$ 272,500	$ 0

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income
Balance (in Shares) at Dec. 31, 2016		104,166,945
Balance at Dec. 31, 2016	$ 2,418,429	$ 1,042	$ 1,426,459	$ 949,681	$ 41,247
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	146,738			128,700	18,038
Dividends	(46,073)			(46,073)
Equity based compensation (in Shares)		591,999
Equity based compensation	7,386	$ 6	7,380
Forfeiture of unvested shares (in Shares)		(262,080)
Forfeiture of unvested shares and shares surrendered for tax withholding obligations	$ (7,179)	$ (3)	(7,176)
Exercise of stock options (in Shares)	2,304,108	2,304,108
Exercise of stock options	$ 61,519	$ 23	61,496
Balance (in Shares) at Jun. 30, 2017		106,800,972
Balance at Jun. 30, 2017	2,580,820	$ 1,068	1,488,159	1,032,308	59,285
Cumulative Effect of New Accounting Principle in Period of Adoption				(8,902)	8,902
Balance (in Shares) at Dec. 31, 2017		106,848,185
Balance at Dec. 31, 2017	3,026,062	$ 1,068	1,498,227	1,471,781	54,986
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	161,907			175,135	(13,228)
Dividends	(45,857)			(45,857)
Equity based compensation (in Shares)		654,420
Equity based compensation	10,342	$ 6	10,336
Forfeiture of unvested shares (in Shares)		(207,720)
Forfeiture of unvested shares and shares surrendered for tax withholding obligations	$ (6,349)	$ (2)	(6,347)
Exercise of stock options (in Shares)	291,689	291,689
Exercise of stock options	$ 7,727	$ 3	7,724
Stock Repurchased During Period, Shares		(1,345,458)
Stock Repurchased During Period, Value	54,399	$ (13)	(54,386)
Balance (in Shares) at Jun. 30, 2018		106,241,116
Balance at Jun. 30, 2018	$ 3,099,433	$ 1,062	$ 1,455,554	$ 1,592,157	$ 50,660

Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation (Notes)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Note 1 Basis of Presentation and Summary of Significant Accounting Policies BankUnited, Inc. is a national bank holding company with one wholly-owned subsidiary, BankUnited, collectively, the Company. BankUnited, a national banking association headquartered in Miami Lakes, Florida, provides a full range of banking and related services to individual and corporate customers through 87 banking centers located in 15 Florida counties and 5 banking centers located in the New York metropolitan area at June 30, 2018. The Bank also offers certain commercial lending and deposit products through national platforms. In connection with the FSB Acquisition, BankUnited entered into two loss sharing agreements with the FDIC. The Loss Sharing Agreements consisted of the Single Family Shared-Loss Agreement and the Commercial Shared-Loss Agreement. Assets covered by the Loss Sharing Agreements are referred to as covered assets or, in certain cases, covered loans. The Single Family Shared-Loss Agreement provides for FDIC loss sharing and the Bank’s reimbursement for recoveries to the FDIC through May 21, 2019 for single family residential loans and OREO. Loss sharing under the Commercial Shared-Loss Agreement terminated on May 21, 2014. The Commercial Shared-Loss Agreement continued to provide for the Bank’s reimbursement of recoveries to the FDIC through June 30, 2017 for all other covered assets, including commercial real estate, commercial and industrial and consumer loans, certain investment securities and commercial OREO. Pursuant to the terms of the Loss Sharing Agreements, the covered assets are subject to a stated loss threshold whereby the FDIC will reimburse BankUnited for 80% of losses related to the covered assets up to $4.0 billion and 95% of losses in excess of this amount, beginning with the first dollar of loss incurred. The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X of the SEC. Accordingly, these do not include all of the information and footnotes required for a fair presentation of financial position, results of operations and cash flows in conformity with GAAP and should be read in conjunction with the Company’s consolidated financial statements and the notes thereto appearing in BKU’s Annual Report on Form 10-K for the year ended December 31, 2017 filed with the SEC. In the opinion of management, all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation have been included. Operating results for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected in future periods. Certain amounts presented for prior periods have been reclassified to conform to the current period presentation. Accounting Estimates In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and disclosures of contingent assets and liabilities. Actual results could differ significantly from these estimates. Significant estimates include the ALLL, the amount and timing of expected cash flows from covered assets and the FDIC indemnification asset, and the fair values of investment securities and other financial instruments. Management has used information provided by third party valuation specialists to assist in the determination of the fair values of investment securities. New Accounting Pronouncements Adopted ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), superseded the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific revenue recognition guidance throughout the Accounting Standards Codification. The amendments in this update affect any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets unless those contracts are within the scope of other standards. The amendments establish a core principle requiring the recognition of revenue to depict the transfer of goods or services to customers in an amount reflecting the consideration to which the entity expects to be entitled in exchange for such goods or services and require expanded disclosure about revenue from contracts with customers that are within the scope of the standard. Revenue from financial instruments and lease contracts are generally outside the scope of Topic 606 as are revenues that are in the scope of ASC 860 "Transfers and Servicing", ASC 460 "Guarantees" and ASC 815 "Derivatives and Hedging". The Company adopted this standard in the first quarter of 2018 with respect to contracts not completed on the date of adoption using the modified retrospective transition method. Substantially all of the Company's revenues are generated from activities outside the scope of Topic 606; existing revenue recognition policies for contracts with customers that are within the scope of the standard are consistent with the principles in Topic 606. Therefore, there was no impact at adoption to the Company's consolidated financial position, results of operations, or cash flows. ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The amendments in the ASU addressed certain aspects of recognition, measurement, presentation and disclosure of certain financial instruments. The main provisions of this ASU that are applicable to the Company are to (1) eliminate the available for sale classification for equity securities and require investments in equity securities (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income, provided that equity investments that do not have readily determinable fair values may be re-measured at fair value upon occurrence of an observable price change or recognition of impairment, (2) eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet, and (3) require public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. The amendments also clarified that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity's other deferred tax assets, which is consistent with the Company's previous practice. The Company adopted this ASU in the first quarter of 2018 using the modified retrospective transition method. The cumulative effect adjustment to reclassify unrealized gains on equity securities from AOCI to retained earnings totaled $2.2 million, net of tax, at adoption. Unrealized losses on equity securities recognized in earnings totaled $0.4 million and $1.0 million, respectively, for the three and six months ended June 30, 2018. ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This amendment provided guidance on eight specific cash flow classification issues where there had been diversity in practice. The provisions of this ASU that are expected to be applicable to the Company include requirements to: (1) classify cash payments for debt prepayment or extinguishment costs to be classified as cash outflows for financing activities, (2) classify proceeds from settlement of insurance claims on the basis of the nature of the loss and (3) require cash payments from settlement of bank-owned life insurance policies to be classified as cash flows from investing activities. The Company adopted this ASU for the first quarter of 2018; the provisions of the ASU were generally consistent with the Company's existing practice, therefore, adoption did not have an impact on the Company's consolidated cash flows. ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this ASU allowed a reclassification from AOCI to retained earnings of stranded tax effects in AOCI resulting from enactment of the TCJA that reduced the statutory federal tax rate from 35 percent to 21 percent. The Company’s existing accounting policy was to release stranded tax effects only when the entire portfolio of the type of item that created them is liquidated. This ASU was early adopted effective January 1, 2018 and a cumulative-effect adjustment was recorded to reclassify stranded tax effects totaling $11.1 million from AOCI to retained earnings. Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The amendments in this ASU require a lessee to recognize in the statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for leases with terms longer than one year. Accounting applied by lessors is largely unchanged by this ASU. The ASU also will require both qualitative and quantitative disclosures that provide additional information about the amounts recorded in the consolidated financial statements. The amendments in this ASU are effective for the Company for interim and annual periods in fiscal years beginning after December 15, 2018. Early adoption is permitted; however, the Company does not intend to early adopt this ASU. The most significant impact of adoption is expected to be the recognition, as lessee, of new right-of-use assets and lease liabilities on the Consolidated Balance Sheet for real estate leases currently classified as operating leases. Under a package of practical expedients that the Company plans to elect, the Company will not be required to (i) re-assess whether expired or existing contracts contain leases, (ii) re-assess the classification of expired or existing leases, (iii) re-evaluate initial direct costs for existing leases or (iv) separate lease components of certain contracts from non-lease components. The Company also plans to elect the transition method that allows entities the option of applying the provisions of the ASU at the effective date without adjusting the comparative periods presented. Management is in the process of finalizing its evaluation of the impact of adoption of this ASU on its processes and controls. The Company has substantially completed its review of contractual arrangements for embedded leases. The Company has acquired and implemented software to facilitate calculation and reporting of the lease liability and right-of-use asset. Certain accounting policy decisions have been made including use of the incremental borrowing rate to determine the discount rate and assumptions around inclusion of renewals in lease terms. Based on the population of lease contracts existing at June 30, 2018 and an incremental borrowing rate determined as of that date, the Company estimates that a lease liability and related right-of-use asset of approximately $100 million and $90 million, respectively, will be recognized on adoption at January 1, 2019. The amounts actually recognized will be based on terms of contracts in place and an incremental borrowing rate determined at the date of adoption. The Company does not expect the impact of adoption to be material to its consolidated results of operations or cash flows. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326); Measurement of Credit Losses on Financial Instruments. The ASU introduces new guidance which makes substantive changes to the accounting for credit losses. The ASU introduces the CECL model which applies to financial assets subject to credit losses and measured at amortized cost, as well as certain off-balance sheet credit exposures. This includes loans, loan commitments, standby letters of credit, net investments in leases recognized by a lessor and HTM debt securities. The CECL model requires an entity to estimate credit losses expected over the life of an exposure, considering information about historical events, current conditions and reasonable and supportable forecasts, and is generally expected to result in earlier recognition of credit losses. The ASU also modifies certain provisions of the current OTTI model for AFS debt securities. Credit losses on AFS debt securities will be limited to the difference between the security's amortized cost basis and its fair value, and will be recognized through an allowance for credit losses rather than as a direct reduction in amortized cost basis. The ASU also provides for a simplified accounting model for purchased financial assets with more than insignificant credit deterioration since their origination. The ASU requires expanded disclosures including, but not limited to, (i) information about the methods and assumptions used to estimate expected credit losses, including changes in the factors that influenced management's estimate and the reasons for those changes, (ii) for financing receivables and net investment in leases measured at amortized cost, further disaggregation of information about the credit quality of those assets and (iii) a rollforward of the allowance for credit losses for AFS and HTM securities. The amendments in this ASU are effective for the Company for interim and annual periods in fiscal years beginning after December 15, 2019. Early adoption is permitted; however, the Company does not intend to early adopt this ASU. Management is in the process of evaluating the impact of adoption of this ASU on its consolidated financial statements, processes and controls and is not currently able to reasonably estimate the impact of adoption on the Company's consolidated financial position, results of operations or cash flows; however, adoption is likely to lead to significant changes in accounting policies related to, and the methods employed in estimating, the ALLL. It is possible that the impact will be material to the Company's consolidated financial position and results of operations. To date, the Company has completed a gap analysis, adopted and is in the process of executing a detailed implementation plan, established a formal governance structure, selected and implemented credit loss models for key portfolio segments, chosen loss estimation methodologies for key portfolio segments, and selected a software solution to serve as its CECL platform. Revenue From Contracts with Customers Revenue from contracts with customers within the scope of Topic 606 "Revenue from Contracts with Customers", is recognized in an amount that reflects the consideration the Company expects to be entitled to receive in exchange for those goods or services as the related performance obligations are satisfied. The majority of our revenues, including revenues from loans, leases, investment securities, derivative instruments and letters of credit and from transfers and servicing of financial assets, are excluded from the scope of Topic 606. Deposit service charges and fees is the most significant category of revenue within the scope of the standard. These service charges and fees consist primarily of monthly maintenance fees and other transaction based fees. Revenue is recognized when our performance obligations are complete, generally monthly for account maintenance fees or when a transaction, such as a wire transfer, is completed. Payment is typically received at the time the performance obligation is satisfied. The aggregate amount of revenue that is within the scope of Topic 606 from sources other than deposit service charges and fees is not material. Investment Securities Investment securities include debt securities and marketable equity securities. Debt securities that the Company has the positive intent and ability to hold to maturity are classified as held to maturity and reported at amortized cost. Debt securities that the Company may not have the intent to hold to maturity are classified as available for sale at the time of acquisition and carried at fair value with unrealized gains and losses, net of tax, excluded from earnings and reported in AOCI. Marketable equity securities with readily determinable fair values are reported at fair value with unrealized gains and losses included in earnings. Equity securities that do not have readily determinable fair values are reported at cost and re-measured at fair value upon occurrence of an observable price change or recognition of impairment.

Earnings Per Common Share

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Earnings Per Common Share

The computation of basic and diluted earnings per common share is presented below for the periods indicated (in thousands, except share and per share data):



	Three Months Ended June 30,						Six Months Ended June 30,
c	2018			2017			2018			2017
Basic earnings per common share:
Numerator:
Net income	$	89,900		$	66,407		$	175,135		$	128,700
Distributed and undistributed earnings allocated to participating securities	(3,463		)	(2,483		)	(6,676		)	(4,805		)
Income allocated to common stockholders for basic earnings per common share	$	86,437		$	63,924		$	168,459		$	123,895
Denominator:
Weighted average common shares outstanding	106,170,834			106,827,077			106,347,378			106,325,244
Less average unvested stock awards	(1,222,436		)	(1,144,135		)	(1,165,750		)	(1,102,836		)
Weighted average shares for basic earnings per common share	104,948,398			105,682,942			105,181,628			105,222,408
Basic earnings per common share	$	0.82		$	0.60		$	1.60		$	1.18
Diluted earnings per common share:
Numerator:
Income allocated to common stockholders for basic earnings per common share	$	86,437		$	63,924		$	168,459		$	123,895
Adjustment for earnings reallocated from participating securities	12			7			23			15
Income used in calculating diluted earnings per common share	$	86,449		$	63,931		$	168,482		$	123,910
Denominator:
Weighted average shares for basic earnings per common share	104,948,398			105,682,942			105,181,628			105,222,408
Dilutive effect of stock options and executive share-based awards	522,997			455,135			519,598			537,491
Weighted average shares for diluted earnings per common share	105,471,395			106,138,077			105,701,226			105,759,899
Diluted earnings per common share	$	0.82		$	0.60		$	1.59		$	1.17

Included in participating securities above are unvested shares and 3,023,314 dividend equivalent rights outstanding at June 30, 2018 that were issued in conjunction with the IPO of the Company's common stock. These dividend equivalent rights expire in 2021 and participate in dividends on a one-for-one basis.

The following potentially dilutive securities were outstanding at June 30, 2018 and 2017, but excluded from the calculation of diluted earnings per common share for the periods indicated because their inclusion would have been anti-dilutive:



	Three Months Ended June 30,		Six Months Ended June 30,
	2018	2017	2018	2017
Unvested shares and share units	1,644,336	1,521,817	1,644,336	1,521,817
Stock options and warrants	1,850,279	1,850,279	1,850,279	1,850,279

Investment Securities

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Investment Securities

Investment securities include investment securities available for sale, marketable equity securities, and investment securities held to maturity. The investment securities available for sale portfolio consisted of the following at the dates indicated (in thousands):



	June 30, 2018
	Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value
Investment securities available for sale:
U.S. Treasury securities	$	34,769	$	7	$	(18	)	$	34,758
U.S. Government agency and sponsored enterprise residential MBS	1,802,758		22,052		(3,548		)	1,821,262
U.S. Government agency and sponsored enterprise commercial MBS	240,835		820		(1,736		)	239,919
Private label residential MBS and CMOs	882,864		11,133		(14,739		)	879,258
Private label commercial MBS	1,093,409		7,146		(4,518		)	1,096,037
Single family rental real estate-backed securities	578,314		1,090		(3,490		)	575,914
Collateralized loan obligations	1,242,541		2,422		(148		)	1,244,815
Non-mortgage asset-backed securities	198,818		1,911		(1,722		)	199,007
State and municipal obligations	463,995		5,388		(3,510		)	465,873
SBA securities	459,876		8,854		(540		)	468,190
Other debt securities	1,552		4,029		—			5,581
	$	6,999,731	$	64,852	$	(33,969	)	$	7,030,614



	December 31, 2017
	Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value
Investment securities available for sale:
U.S. Treasury securities	$	24,981	$	—	$	(28	)	$	24,953
U.S. Government agency and sponsored enterprise residential MBS	2,043,373		16,094		(1,440		)	2,058,027
U.S. Government agency and sponsored enterprise commercial MBS	233,522		1,330		(344		)	234,508
Private label residential MBS and CMOs	613,732		16,473		(1,958		)	628,247
Private label commercial MBS	1,033,022		13,651		(258		)	1,046,415
Single family rental real estate-backed securities	559,741		3,823		(858		)	562,706
Collateralized loan obligations	720,429		3,252		—			723,681
Non-mortgage asset-backed securities	119,939		1,808		—			121,747
Marketable equity securities	59,912		3,631		—			63,543
State and municipal obligations	640,511		17,606		(914		)	657,203
SBA securities	534,534		16,208		(60		)	550,682
Other debt securities	4,090		5,030		—			9,120
	$	6,587,786	$	98,906	$	(5,860	)	$	6,680,832

Marketable equity securities, recorded at fair value, totaled $62.5 million and $63.5 million, at June 30, 2018 and December 31, 2017, respectively. Investment securities held to maturity at June 30, 2018 and December 31, 2017 consisted of one State of Israel bond with a carrying value of $10 million maturing in 2024. Fair value approximated carrying value at June 30, 2018 and December 31, 2017.

At June 30, 2018, contractual maturities of investment securities available for sale, adjusted for anticipated prepayments of mortgage-backed and other pass-through securities, were as follows (in thousands):



	Amortized Cost		Fair Value
Due in one year or less	$	735,040	$	740,310
Due after one year through five years	3,512,471		3,524,379
Due after five years through ten years	2,374,418		2,384,147
Due after ten years	377,802		381,778
	$	6,999,731	$	7,030,614

Based on the Company’s assumptions, the estimated weighted average life of the investment portfolio as of June 30, 2018 was 4.8 years. The effective duration of the investment portfolio as of June 30, 2018 was 1.5 years. The model results are based on assumptions that may differ from actual results.

The carrying value of securities pledged as collateral for FHLB advances, public deposits, interest rate swaps and to secure borrowing capacity at the FRB totaled $2.2 billion and $2.6 billion at June 30, 2018 and December 31, 2017, respectively.

The following table provides information about gains and losses on investment securities for the periods indicated (in thousands):



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Proceeds from sale of investment securities available for sale	$	569,387		$	166,368		$	836,317		$	427,923

Gross realized gains:
Investment securities available for sale	$	2,554		$	656		$	6,041		$	2,292
Gross realized losses:
Investment securities available for sale	(4		)	(29		)	(2,514		)	(29		)
Net realized gain	2,550			627			3,527			2,263

Net unrealized losses on marketable equity securities recognized in earnings	(408		)	—			(1,021		)	—

Gain on investment securities, net	$	2,142		$	627		$	2,506		$	2,263

The following tables present the aggregate fair value and the aggregate amount by which amortized cost exceeded fair value for investment securities available for sale in unrealized loss positions, aggregated by investment category and length of time that individual securities had been in continuous unrealized loss positions at the dates indicated (in thousands):



	June 30, 2018
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities	$	14,838	$	(18	)	$	—	$	—		$	14,838	$	(18	)
U.S. Government agency and sponsored enterprise residential MBS	334,733		(2,869		)	12,361		(679		)	347,094		(3,548		)
U.S. Government agency and sponsored enterprise commercial MBS	97,975		(1,736		)	—		—			97,975		(1,736		)
Private label residential MBS and CMOs	721,684		(14,544		)	4,178		(195		)	725,862		(14,739		)
Private label commercial MBS	277,920		(4,518		)	—		—			277,920		(4,518		)
Single family rental real estate-backed securities	295,632		(3,490		)	—		—			295,632		(3,490		)
Collateralized loan obligations	364,004		(148		)	—		—			364,004		(148		)
Non-mortgage asset-backed securities	125,669		(1,722		)	—		—			125,669		(1,722		)
State and municipal obligations	242,677		(3,179		)	16,367		(331		)	259,044		(3,510		)
SBA securities	105,816		(505		)	13,797		(35		)	119,613		(540		)
	$	2,580,948	$	(32,729	)	$	46,703	$	(1,240	)	$	2,627,651	$	(33,969	)



	December 31, 2017
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities	$	24,953	$	(28	)	$	—	$	—		$	24,953	$	(28	)
U.S. Government agency and sponsored enterprise residential MBS	471,120		(1,141		)	13,028		(299		)	484,148		(1,440		)
U.S. Government agency and sponsored enterprise commercial MBS	26,265		(344		)	—		—			26,265		(344		)
Private label residential MBS and CMOs	330,068		(1,858		)	5,083		(100		)	335,151		(1,958		)
Private label commercial MBS	81,322		(258		)	—		—			81,322		(258		)
Single family rental real estate-backed securities	94,750		(858		)	—		—			94,750		(858		)
State and municipal obligations	30,715		(49		)	60,982		(865		)	91,697		(914		)
SBA securities	21,300		(10		)	15,427		(50		)	36,727		(60		)
	$	1,080,493	$	(4,546	)	$	94,520	$	(1,314	)	$	1,175,013	$	(5,860	)

The Company monitors its investment securities available for sale for OTTI on an individual security basis. No securities were determined to be other-than-temporarily impaired during the six months ended June 30, 2018 or 2017. The Company does not intend to sell securities that are in significant unrealized loss positions at June 30, 2018 and it is not more likely than not that the Company will be required to sell these securities before recovery of the amortized cost basis, which may be at maturity. At June 30, 2018, 147 securities were in unrealized loss positions. The amount of impairment related to 32 of these securities was considered insignificant both individually and in the aggregate, totaling approximately $313 thousand and no further analysis with respect to these securities was considered necessary. The basis for concluding that impairment of the remaining securities was not other-than-temporary is further described below:

U.S. Government agency and sponsored enterprise residential and commercial MBS

At June 30, 2018, thirty-two U.S. Government agency and sponsored enterprise residential MBS and six U.S. Government agency and sponsored enterprise commercial MBS were in unrealized loss positions. Impairment of these securities was primarily attributable to increases in market interest rates subsequent to the date of acquisition. The timely payment of principal and interest on these securities is explicitly or implicitly guaranteed by the U.S. Government. Given the expectation of timely payment of principal and interest the impairments were considered to be temporary.

Private label residential MBS and CMOs

At June 30, 2018, twenty-eight private label residential MBS and CMOs were in unrealized loss positions, primarily as a result of an increase in medium and long-term market interest rates subsequent to acquisition. These securities were assessed for OTTI using credit and prepayment behavioral models that incorporate CUSIP level constant default rates, voluntary prepayment rates and loss severity and delinquency assumptions. The results of these assessments were not indicative of credit losses related to any of these securities as of June 30, 2018. Given the expectation of timely recovery of outstanding principal the impairments were considered to be temporary.

Private label commercial MBS

At June 30, 2018, fourteen private label commercial MBS were in unrealized loss positions, primarily as a result of an increase in market interest rates. These securities were assessed for OTTI using credit and prepayment behavioral models incorporating assumptions consistent with the collateral characteristics of each security. The results of this analysis were not indicative of expected credit losses. Given the expectation of timely recovery of outstanding principal the impairments were considered to be temporary.

Single family rental real estate-backed securities

At June 30, 2018, ten single family rental real estate-backed securities were in unrealized loss positions. The unrealized losses were primarily due to increases in market interest rates since the purchase of the securities. Management's analysis of the credit characteristics, including loan-to-value and debt service coverage ratios, and levels of subordination for each of the securities is not indicative of projected credit losses. Given the absence of projected credit losses the impairments were considered to be temporary.

Collateralized loan obligations:

At June 30, 2018, two collateralized loan obligations were in unrealized loss positions. The amount of impairment of each of the individual securities was less than 1% of amortized cost. These securities were assessed for OTTI using credit and prepayment behavioral models incorporating assumptions consistent with the collateral characteristics of each security. The results of this analysis were not indicative of expected credit losses. Given the limited severity of impairment and the expectation of timely recovery of outstanding principal, the impairments were considered to be temporary.

Non-mortgage asset-backed securities

At June 30, 2018, four non-mortgage asset-backed securities were in unrealized loss positions, due primarily to increases in market interest rates subsequent to the date of acquisition. The amount of impairment each of the individual securities was 2% or less of amortized cost. These securities were assessed for OTTI using credit and prepayment behavioral models incorporating assumptions consistent with the collateral characteristics of each security. The results of this analysis were not indicative of expected credit losses. Given the limited severity of impairment and the expectation of timely recovery of outstanding principal, the impairment were considered to be temporary.

State and municipal obligations

At June 30, 2018, fifteen state and municipal obligations were in unrealized loss positions. The impairments are primarily attributable to increases in market interest rates and changes in statutory tax rates. All of the securities are rated investment grade by nationally recognized statistical ratings organizations. Management's evaluation of these securities for OTTI also encompassed the review of credit scores and analysis provided by a third party firm specializing in the analysis and credit review of municipal securities. Given the absence of expected credit losses, the impairments were considered to be temporary.

SBA Securities

At June 30, 2018, four SBA securities were in unrealized loss positions. The amount of impairment of each of these securities was less than 1% of amortized cost. These securities were purchased at a premium and the impairment was attributable primarily to increased prepayment speeds. The timely payment of principal and interest on these securities is guaranteed by this U.S. Government agency. Given the limited severity of impairment and the expectation of timely payment of principal and interest, the impairments were considered to be temporary.

Loans and Allowance for Loan and Lease Losses

6 Months Ended

Jun. 30, 2018

Receivables [Abstract]

Loans and Allowance for Loan and Lease Losses

The Company segregates its loan portfolio between covered and non-covered loans. Non-covered loans include loans originated since the FSB acquisition and commercial and consumer loans acquired in the FSB acquisition for which loss share coverage has terminated. Covered loans are further segregated between ACI and non-ACI loans.

Loans consisted of the following at the dates indicated (dollars in thousands):



	June 30, 2018
				Covered Loans								Percent of Total
	Non-Covered Loans			ACI		Non-ACI			Total			Percent of Total
Residential and other consumer:
1-4 single family residential	$	4,257,026		$	431,413	$	23,166		$	4,711,605		21.6	%
Government insured residential	111,761			—		—			111,761			0.5	%
Home equity loans and lines of credit	1,855			—		331			2,186			—	%
Other consumer loans	18,600			—		—			18,600			0.1	%
	4,389,242			431,413		23,497			4,844,152			22.2	%
Commercial:
Multi-family	2,859,179			—		—			2,859,179			13.1	%
Non-owner occupied commercial real estate	4,538,272			—		—			4,538,272			20.7	%
Construction and land	255,864			—		—			255,864			1.2	%
Owner occupied commercial real estate	2,048,478			—		—			2,048,478			9.4	%
Commercial and industrial	4,605,253			—		—			4,605,253			21.1	%
Commercial lending subsidiaries	2,676,268			—		—			2,676,268			12.3	%
	16,983,314			—		—			16,983,314			77.8	%
Total loans	21,372,556			431,413		23,497			21,827,466			100.0	%
Premiums, discounts and deferred fees and costs, net	45,817			—		(3,560		)	42,257
Loans including premiums, discounts and deferred fees and costs	21,418,373			431,413		19,937			21,869,723
Allowance for loan and lease losses	(134,381		)	—		(590		)	(134,971		)
Loans, net	$	21,283,992		$	431,413	$	19,347		$	21,734,752



	December 31, 2017
			Covered Loans						Percent of Total
	Non-Covered Loans		ACI		Non-ACI		Total		Percent of Total
Residential and other consumer:
1-4 single family residential	$	4,089,994	$	479,068	$	26,837	$	4,595,899	21.5	%
Government insured residential	26,820		—		—		26,820		0.1	%
Home equity loans and lines of credit	1,654		—		361		2,015		—	%
Other consumer loans	20,512		—		—		20,512		0.1	%
	4,138,980		479,068		27,198		4,645,246		21.7	%
Commercial: