Banner (BANR) 10-Q 4 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Entity Information [Line Items]
Entity Registrant Name	Banner Corporation
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Entity Central Index Key	946,673
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Voting Common Stock [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		32,331,108
Nonvoting Common Stock [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		76,928

CONSOLIDATED STATEMENTS OF FINA

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks		$ 188,418	$ 199,624
Interest bearing deposits		53,630	61,576
Total cash and cash equivalents		242,048	261,200
Securities—trading, amortized cost $27,275 and $27,246, respectively		25,574	22,318
Securities—available-for-sale, amortized cost $1,427,764 and $926,112, respectively		1,406,505	919,485
Securities—held-to-maturity, fair value $260,918 and $262,188, respectively		262,645	260,271
Federal Home Loan Bank (FHLB) stock		18,036	10,334
Loans held for sale (includes $137.7 million and $32.4 million, at fair value, respectively)		141,808	40,725
Loans receivable		7,556,046	7,598,884
Allowance for loan losses		92,207	89,028
Net loans		7,463,839	7,509,856
Accrued interest receivable		32,824	31,259
Real estate owned (REO), held for sale, net		328	360
Property and equipment, net		156,005	154,815
Goodwill		242,659	242,659
Other intangibles, net		21,251	22,655
Bank-owned life insurance (BOLI)		163,519	162,668
Deferred tax assets, net		76,843	71,427
Other assets		63,380	53,177
Total assets		10,317,264	9,763,209
Deposits:
Non-interest-bearing		3,383,439	3,265,544
Interest-bearing transaction and savings accounts		4,141,268	3,950,950
Interest-bearing certificates	[1]	1,018,355	966,937
Total deposits		8,543,062	8,183,431
Advances from FHLB		192,195	202
Other borrowings		101,844	95,860
Junior subordinated debentures at fair value (issued in connection with Trust Preferred Securities)		112,516	98,707
Accrued expenses and other liabilities		72,497	71,344
Deferred compensation		41,027	41,039
Total liabilities		9,063,141	8,490,583
COMMITMENTS AND CONTINGENCIES (Note 12)
SHAREHOLDERS’ EQUITY
Preferred stock - $0.01 par value per share, 500,000 shares authorized; no shares outstanding at March 31, 2018 and December 31, 2017		0	0
Retained earnings		79,773	90,535
Carrying value of shares held in trust for stock related compensation plans		7,371	7,351
Liability for common stock issued to stock related compensation plans		7,371	7,351
Accumulated other comprehensive income (loss) (AOCI)		1,390	(5,036)
Total shareholders' equity		1,254,123	1,272,626
Total liabilities & shareholders' equity		10,317,264	9,763,209
Voting Common Stock [Member]
SHAREHOLDERS’ EQUITY
Common stock and paid in capital		1,171,914	1,185,919
Nonvoting Common Stock [Member]
SHAREHOLDERS’ EQUITY
Common stock and paid in capital		$ 1,046	$ 1,208
[1]	Certificates of deposit include $5,000 and $11,000 of acquisition premiums at March 31, 2018 and December 31, 2017, respectively.

CONSOLIDATED STATEMENTS OF FIN3

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
ASSETS
Securities—trading, amortized cost basis	$ 27,275	$ 27,246
Securities—available-for-sale, amortized cost basis	1,427,764	926,112
Securities—held-to-maturity, fair value	$ 260,918	$ 262,188
SHAREHOLDERS’ EQUITY
Preferred stock, share par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	500,000	500,000
Preferred stock, shares outstanding	0	0
Voting Common Stock [Member]
SHAREHOLDERS’ EQUITY
Common stock, share par value	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	33,154,755	33,108,599
Common stock, shares outstanding	33,154,755	33,108,599
Nonvoting Common Stock [Member]
SHAREHOLDERS’ EQUITY
Common stock, share par value	$ 0.01	$ 0.01
Common stock, shares authorized	5,000,000	5,000,000
Common stock, shares issued	100,029	84,788
Common stock, shares outstanding	100,029	84,788
Loans [Member] | Recurring [Member]
ASSETS
Loans Held-for-sale, Fair Value Disclosure	$ 137,734	$ 32,392

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
INTEREST INCOME:
Loans receivable	$ 94,022	$ 91,288
Mortgage-backed securities	7,331	4,647
Securities and cash equivalents	3,467	3,161
Total interest income	104,820	99,096
INTEREST EXPENSE:
Deposits	3,358	2,791
FHLB advances	677	273
Other borrowings	70	74
Junior subordinated debentures	1,342	1,104
Total interest expense	5,447	4,242
Net interest income	99,373	94,854
PROVISION FOR LOAN LOSSES	2,000	2,000
Net interest income after provision for loan losses	97,373	92,854
NON-INTEREST INCOME:
Deposit fees and other service charges	11,296	10,389
Mortgage banking operations	4,864	4,603
Bank-owned life insurance (BOLI)	853	1,095
Miscellaneous	1,037	3,636
Other operating income	18,050	19,723
Net gain on sale of securities	4	13
Net change in valuation of financial instruments carried at fair value	3,308	(688)
Total non-interest income	21,362	19,048
NON-INTEREST EXPENSE:
Salary and employee benefits	50,067	46,063
Less capitalized loan origination costs	(4,011)	(4,316)
Occupancy and equipment	11,766	11,996
Information/computer data services	4,381	3,994
Payment and card processing expenses	3,700	3,223
Professional services	4,428	5,152
Advertising and marketing	1,830	1,328
Deposit insurance	1,341	1,266
State/municipal business and use taxes	713	799
REO operations	439	(966)
Amortization of core deposit intangibles	1,382	1,624
Miscellaneous	5,670	6,118
Total non-interest expense	81,706	76,281
Income before provision for income taxes	37,029	35,621
PROVISION FOR INCOME TAXES	8,239	11,828
NET INCOME	$ 28,790	$ 23,793
Earnings per common share:
Basic	$ 0.89	$ 0.72
Diluted	0.89	0.72
Cumulative dividends declared per common share	$ 0.35	$ 0.25
Weighted average number of common shares outstanding, Basic	32,397,568	32,933,444
Weighted average number of common shares outstanding, Diluted	32,516,456	33,051,459

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 28,790	$ 23,793
OTHER COMPREHENSIVE (LOSS) INCOME, NET OF INCOME TAXES:
Unrealized holding (loss) gain on available-for-sale securities arising during the period	(14,768)	2,448
Reclassification for net gains on available-for-sale securities realized in earnings	(2)	(13)
Changes in fair value of junior subordinated debentures related to instrument specific credit risk	(13,809)	0
Income tax related to other comprehensive (loss) income	6,802	(876)
Other comprehensive (loss) income	(21,777)	1,559
COMPREHENSIVE INCOME	$ 7,013	$ 25,352

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Common Stock and Paid in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance, beginning of the period (in shares) at Dec. 31, 2016		33,193,387
Balance, beginning of the period at Dec. 31, 2016	$ 1,305,710		$ 1,213,837	$ 95,328	$ (3,455)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	60,776			60,776
Other comprehensive loss, net of income tax	(786)				(786)
Reclassification of stranded tax effects from AOCI to retained earnings	0			795	(795)
Accrual of dividends on common stock	(66,364)			(66,364)
Repurchase of common stock		(545,166)
Proceeds from issuance of common stock for stockholder reinvestment program (in shares)		78,264
Repurchase of common stock, value	(31,045)		(31,045)
Amortization of stock-based compensation related to restricted stock grants, net of shares surrendered	4,335		4,335
Balance, end of the period (in shares) at Dec. 31, 2017		32,726,485
Balance, end of the period at Dec. 31, 2017	1,272,626		1,187,127	90,535	(5,036)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of reclassification of the instrument-specific credit risk portion of junior subordinated debentures fair value adjustments and reclassification of equity securities from available-for-sale	0			(28,203)	28,203
Net income	28,790			28,790
Other comprehensive loss, net of income tax	(21,777)				(21,777)
Accrual of dividends on common stock	(11,349)			(11,349)
Repurchase of common stock		(269,711)
Proceeds from issuance of common stock for stockholder reinvestment program (in shares)		(33,101)
Repurchase of common stock, value	(15,359)		(15,359)
Amortization of stock-based compensation related to restricted stock grants, net of shares surrendered	1,192		1,192
Balance, end of the period (in shares) at Mar. 31, 2018		32,423,673
Balance, end of the period at Mar. 31, 2018	$ 1,254,123		$ 1,172,960	$ 79,773	$ 1,390

CONSOLIDATED STATEMENTS OF CHA7

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Cumulative dividends declared per common share	$ 0.35	$ 0.25	$ 2

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES:
Net income	$ 28,790	$ 23,793
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation	3,584	2,888
Deferred income and expense, net of amortization	(608)	(265)
Amortization of core deposit intangibles	1,382	1,624
Gain on sale of securities	(4)	(13)
Net change in valuation of financial instruments carried at fair value	(3,308)	688
Proceeds from sales of securities—trading	0	0
Principal repayments and maturities of securities—trading	0	9
(Increase) decrease in deferred taxes	5,416	(3,625)
Increase in current taxes payable	6,569	295
Stock-based compensation	1,320	1,125
Increase in cash surrender value of BOLI	(844)	(1,085)
Gain on sale of loans, net of capitalized servicing rights	(3,375)	(5,496)
Loss (gain) on disposal of real estate held for sale and property and equipment	58	(1,039)
Provision for loan losses	2,000	2,000
Provision for losses on real estate held for sale	160	50
Origination of loans held for sale	(222,168)	(167,550)
Proceeds from sales of loans held for sale	124,460	339,878
Net change in:
Other assets	(5,100)	(9,412)
Other liabilities	(2,311)	(5,283)
Net cash (used in) provided from operating activities	(74,811)	185,832
INVESTING ACTIVITIES:
Purchases of securities—available-for-sale	(537,864)	(457,966)
Principal repayments and maturities of securities—available-for-sale	28,839	32,446
Proceeds from sales of securities—available-for-sale	0	2,165
Purchases of securities—held-to-maturity	(5,312)	0
Principal repayments and maturities of securities—held-to-maturity	2,358	954
Loan originations, net of principal repayments	40,846	119,569
Purchases of loans and participating interest in loans	(8,103)	(99,206)
Proceeds from sales of other loans	13,241	4,627
Purchases of property and equipment	(5,024)	(3,598)
Proceeds from sale of real estate held for sale and sale of other property, net	192	13,684
Proceeds from FHLB stock repurchase program	32,558	29,192
Purchase of FHLB stock	(40,260)	(27,020)
Other	228	75
Net cash used in investing activities	(478,301)	(385,078)
FINANCING ACTIVITIES:
Increase in deposits, net	359,631	300,546
Repayments of long-term Federal Home Loan Bank Advances	(2)	(2)
Proceeds from (repayments of) overnight and short term FHLB advances, net	192,000	(54,000)
Increase in other borrowings, net	5,984	14,560
Cash dividends paid	(8,165)	(7,615)
Taxes paid related to net share settlement of equity awards	129	445
Payments for Repurchase of Common Stock	15,359	809
Net cash provided from financing activities	533,960	252,235
NET CHANGE IN CASH AND CASH EQUIVALENTS	(19,152)	52,989
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	261,200	247,719
CASH AND CASH EQUIVALENTS, END OF PERIOD	242,048	300,708
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest paid in cash	5,185	4,202
(Refunds received) taxes paid, net	(3)	8,543
NON-CASH INVESTING AND FINANCING TRANSACTIONS:
Loans, net of discounts, specific loss allowances and unearned income, transferred to real estate owned and other repossessed assets	976	0
Dividends Payable	$ 11,450	$ 8,338

BASIS OF PRESENTATION AND SIGNI

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES The accompanying unaudited condensed consolidated financial statements include the accounts of Banner Corporation (the Company or Banner), a bank holding company incorporated in the State of Washington and its wholly-owned subsidiaries, Banner Bank and Islanders Bank (the Banks). These unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X as promulgated by the Securities and Exchange Commission (SEC). In preparing these financial statements, the Company has evaluated events and transactions subsequent to March 31, 2018 for potential recognition or disclosure. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the financial position and results of operations for the periods presented have been included. Certain information and disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC and the accounting standards for interim financial statements. Certain reclassifications have been made to the 2017 Consolidated Financial Statements and/or schedules to conform to the 2018 presentation. These reclassifications may have affected certain ratios for the prior periods. The effect of these reclassifications is considered immaterial. All significant intercompany transactions and balances have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect amounts reported in the financial statements. Various elements of the Company’s accounting policies, by their nature, are inherently subject to estimation techniques, valuation assumptions and other subjective assessments. In particular, management has identified several accounting policies that, due to the judgments, estimates and assumptions inherent in those policies, are significant to an understanding of Banner’s financial statements. These policies relate to (i) the methodology for the recognition of interest income, (ii) determination of the provision and allowance for loan losses, (iii) the valuation of financial assets and liabilities recorded at fair value, including other-than-temporary impairment (OTTI) losses, (iv) the valuation of intangibles, such as goodwill, core deposit intangibles (CDI) and mortgage servicing rights, (v) the valuation of real estate held for sale, (vi) the valuation of assets and liabilities acquired in business combinations and subsequent recognition of related income and expense, and (vii) the valuation or recognition of deferred tax assets and liabilities. These policies and judgments, estimates and assumptions are described in greater detail in subsequent notes to the Consolidated Financial Statements and Management’s Discussion and Analysis of Financial Condition and Results of Operations (Critical Accounting Policies) in our Annual Report on Form 10-K for the year ended December 31, 2017 filed with the SEC (2017 Form 10-K). There have been no significant changes in our application of these accounting policies during the first three months of 2018 , except as described in Note 2. The information included in this Form 10-Q should be read in conjunction with our 2017 Form 10-K. Interim results are not necessarily indicative of results for a full year or any other interim period.

ACCOUNTING STANDARDS RECENTLY I

ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED	ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers , which creates Topic 606 and supersedes Topic 605, Revenue Recognition . Subsequent to the issuance of ASU 2014-09, FASB issued ASU 2016-10 in April 2016 and issued ASU 2016-12 in May 2016. Both of these ASUs amend or clarify aspects of Topic 606. The core principle of Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In general, the new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. The Company adopted Topic 606 on January 1, 2018 using the full retrospective method, meaning the standard is applied to all periods presented in the financial statements with the cumulative effect of initially applying the standard recognized at the beginning of the earliest period presented. In adopting Topic 606, the Company applied the following five steps in determining the correct treatment for the applicable revenue streams: 1. Identify the contract with a customer; 2. Identify the performance obligations in the contract; 3. Determine the transaction price; 4. Allocate the transaction price to performance obligations in the contract, and 5. Recognize revenue when or as the Company satisfies the performance obligation. The majority of the Company’s revenue streams including interest income, deferred loan fee accretion, premium/discount accretion, gains on sales of loans and investments, loan servicing income and other loan fee income are outside the scope of Topic 606. Revenue streams reported as deposit fees and other service charges which include transaction based deposit fees, non-transaction based deposit fees, interchange fees on credit and debit cards and merchant service fees are within the scope of Topic 606. The Company applied the requirements of Topic 606 to the revenue streams that are within its scope. The adoption of Topic 606 did not result in any changes in the either timing or amount of recognized revenue in prior periods by the Company however, the presentation of certain costs associated with our merchant services will now be offset against deposit fees and other service charges in non-interest income. The Company previously recognized payment network related fees that were collected by Company and passed through to another party related to its merchant services as non-interest expense. The change in presentation resulted in $1.8 million of expenses for the three months ended March 31, 2018 being netted against deposit fees and other services charges and reported in non-interest income instead of as payment and card processing expenses in non-interest expense. In addition, to conform to the current period presentation, $1.8 million of merchant services related expenses for the three months ended March 31, 2017 were reclassified from payment and card processing expense in non-interest expense to being netted against deposit fees and other service charges in non-interest income. The Company elected to apply the practical expedient and therefore does not disclose information about remaining performance obligations that have an original expected term of one year or less and allows the Company to expense costs related to obtaining a contract as incurred when the amortization period would have been one year or less. The following table presents the impact of adopting of the new revenue standard on our Consolidated Statements of Operations for the three months ended March 31, 2018 and 2017 (in thousands): For the three months ended March 31, 2018 For the three months ended March 31, 2017 As Reported Balance without Adoption of ASC 606 Effect of Change As Reported Balance without Adoption of ASC 606 Effect of Change Non-interest income: Deposit fees and other service charges $ 11,296 $ 13,100 $ (1,804 ) $ 10,389 $ 12,186 $ (1,797 ) Non-interest expense: Payment and card processing expenses $ 3,700 $ 5,504 $ (1,804 ) $ 3,223 $ 5,020 $ (1,797 ) Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . The amendments in this ASU require equity securities to be measured at fair value with changes in the fair value recognized through net income. The amendments allow equity investments that do not have readily determinable fair values to be remeasured at fair value under certain circumstances and require enhanced disclosures about those investments. This ASU simplifies the impairment assessment of equity investments without readily determinable fair values. This ASU also eliminates 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. The amendments in this ASU require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This ASU excludes from net income gains or losses that the entity may not realize because those financial liabilities are not usually transferred or settled at their fair values before maturity. The amendments in this ASU require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or in the accompanying notes to the financial statements. The Company adopted this ASU on January 1, 2018. The adoption of this ASU resulted in the Company reclassifying $28.1 million from retained earnings to AOCI for the cumulative fair value adjustments on its junior subordinated debentures related to instrument specific credit risk. During the quarter end March 31, 2018 , the Company recorded a $10.5 million , net of tax, reduction in other comprehensive income (loss) for the change in instrument specific credit risk on its junior subordinated debentures; prior to the adoption of this ASU this amount would have been recorded in the Consolidated Statement of Operations. In addition, as a result of adopting this ASU the Company recorded a $137,000 reduction in retained earnings representing the unrealized loss on available for sale equity securities at the date of adoption. Any future changes in fair value on equity securities will be recorded in the Consolidated Statement of Operations. During the quarter ended March 31, 2018 , the Company recorded a $70,000 loss for the decrease in fair value of its equity securities as a component of the net change in financial instruments carried at fair value in the Consolidated Statement of Operations. At March 31, 2018 , the Company held $5.7 million of equity investment securities which were previously reported as available for sale securities and are now reported in other assets. In addition, the adoption of this ASU resulted in changing how the Company estimates the fair value portfolio loans for disclosure purposes. Fair values are estimated first by stratifying the portfolios of loans with similar financial characteristics. Loans are segregated by type such as multifamily real estate, residential mortgage, nonresidential mortgage, commercial/agricultural, consumer and other. Each loan category is further segmented into fixed- and adjustable-rate interest terms. An estimate of fair value is then calculated based on discounted cash flows using as a discount rate the current rate offered on similar products, plus an adjustment for liquidity to reflect the non-homogeneous nature of the loans, as well as, a quarterly loss rate based on historical losses to arrive at an estimated exit price fair value. Fair value for impaired loans is also based on recent appraisals or estimated cash flows discounted using rates commensurate with risk associated with the estimated cash flows. Assumptions regarding credit risk, cash flows and discount rates are judgmentally determined using available market information and specific borrower information. In February 2018, FASB issued ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The amendments in this ASU do not change the core principle of the guidance in Subtopic 825-10. Rather, the amendments in this ASU clarify the application of the guidance regarding the fair value measurement of equity securities without readily determinable fair value. The Company adopted this ASU on January 1, 2018. The impact of the Company's adoption of this ASU is described in the preceding paragraph. Leases (Topic 842) In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842) . The amendments in this ASU require lessees to recognize the following for all leases (with the exception of short-term) at the commencement date; a lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendments in this ASU leave lessor accounting largely unchanged, although certain targeted improvements were made to align lessor accounting with the lessee accounting model. This ASU simplifies the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is currently evaluating the provisions of ASU No. 2016-02 to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements and regulatory capital ratios and has contracted with a third party software solution to meet the new requirements of this ASU, with implementation currently in process. The Company leases 107 buildings and offices under non-cancelable operating leases, the majority of which will be subject to this ASU. While the Company has not quantified the impact to its balance sheet, upon the adoption of this ASU the Company expects to report increased assets and increased liabilities on its Consolidated Statements of Financial Condition as a result of recognizing right-of-use assets and lease liabilities related to these leases and certain equipment under non-cancelable operating lease agreements, which currently are not reflected in its Consolidated Statements of Financial Condition. Financial Instruments—Credit Losses (Topic 326) In June 2016, FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments . Current GAAP requires an “incurred loss” methodology for recognizing credit losses that delays recognition until it is probable a loss has been incurred. The main objective of this ASU is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The ASU affects loans, debt securities, trade receivables, net investments in leases, off-balance-sheet credit exposures, reinsurance receivables, and any other financial asset not excluded from the scope that have the contractual right to receive cash. The ASU replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. This ASU requires a financial asset (or group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) to present the net carrying value at the amount expected to be collected on the financial asset. The measurement of expected credit losses will be based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. This ASU broadens the information that an entity must consider in developing its expected credit loss estimate for assets measured either collectively or individually. The use of forecasted information incorporates more timely information in the estimate of expected credit loss, which will be more decision useful to users of the financial statements. This ASU will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company is still evaluating the effects this ASU will have on the Company’s Consolidated Financial Statements. The Company has formed an internal committee to oversee the project, engaged a third-party vendor to assist with the project and has completed its gap analysis phase of the project. In addition, the Company is in the process of selecting a second third-party vendor to assist with building and developing the required models. Upon adoption, the Company expects changes in the processes and procedures used to calculate the allowance for loan losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. The new guidance may result in an increase in the allowance for loan losses which will also reflect the new requirement to include the nonaccretable principal differences on purchased credit-impaired loans; however, the Company is still in the process of determining the magnitude of the change and its impact on the Consolidated Financial Statements. In addition, the current accounting policy and procedures for other-than-temporary impairment on investment securities available-for-sale will be replaced with an allowance approach. Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20) In March 2017, FASB issued ASU No. 2017-08, Premium Amortization on Purchased Callable Debt Securities . The amendments in this ASU shorten the premium amortization period for callable debt securities purchased at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. Under current GAAP, premiums and discounts on callable debt securities generally are amortized to the maturity date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to the maturity date. The amendments in this ASU more closely align the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company is still evaluating the effects this ASU will have on the Company’s Consolidated Financial Statements. Derivatives and Hedging (Topic 815) In August 2017, FASB issued ASU No. 2017-12, Targeted Improvements to Accounting for Hedging Activities . The amendments in this ASU are intended to provide investors better insight to an entity's risk management hedging strategies by permitting a company to recognize the economic results of its hedging strategies in its financial statements. The amendments in this ASU permit hedge accounting for hedging relationships involving nonfinancial risk and interest rate risk by removing certain limitations in cash flow and fair value hedging relationships. In addition, the ASU requires an entity to present the earnings effect of the hedging instrument in the same income statement line item in which the earnings effect of the hedged item is reported. This ASU is effective for fiscal years beginning after December 15, 2018, and early adoption is permitted. Adoption of ASU 2017-12 is not expected to have a material impact on the Company's Consolidated Financial Statements. Income Statement - Reporting Comprehensive Income (Topic 220) In February 2018, FASB Issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This ASU allows a reclassification from AOCI to retained earnings for the stranded tax effects on available-for-sale securities resulting from the 2017 Tax Act. The ASU eliminates the stranded tax effects resulting from the 2017 Tax Act and improves the usefulness of information reported to financial statement users. The ASU also requires certain disclosures about the stranded tax effects. This ASU is effective for all entities for fiscal years beginning after December 15, 2018. Early adoption is permitted, including adoption in any interim period, for reporting periods for which financial statements have not yet been issued. The ASU should be applied to either in the period of adoption or retrospectively to each period in which the effect of the change in the federal corporate tax rate is recognized. The Company elected to early adopt this ASU and to reclassify $795,000 of stranded tax effects from AOCI to retained earnings in the fourth quarter of 2017. Income Taxes (Topic 740) In March 2018, FASB issued ASU No. 2018-05, Income Taxes (Topic 740). This ASU was issued to provide guidance on the income tax accounting implications of the Tax Cuts and Jobs Act (the Act) and allows for entities to report provisional amounts for specific income tax effects of the Act for which the accounting under ASC Topic 740 was not yet complete but a reasonable estimate could be determined. A measurement period of one year is allowed to complete the accounting effects under ASC Topic 740 and revise any previous estimates reported. Any provisional amounts or subsequent adjustments included in an entity’s financial statements during the measurement period should be included in income from continuing operations as an adjustment to tax expense in the reporting period the amounts are determined. The Company adopted this ASU with the provisional adjustments as reported in the Consolidated Financial Statements in the 2017 Form 10-K. As of March 31, 2018, the Company did not incur any adjustments to the provisional recognition.

SECURITIES

SECURITIES	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
INTEREST-BEARING DEPOSITS AND SECURITIES	SECURITIES The amortized cost, gross unrealized gains and losses and estimated fair value of securities at March 31, 2018 and December 31, 2017 are summarized as follows (in thousands): March 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Trading: Municipal bonds $ 100 $ 100 Corporate bonds 27,175 25,474 $ 27,275 $ 25,574 Available-for-Sale: U.S. Government and agency obligations $ 145,280 $ 10 $ (1,984 ) $ 143,306 Municipal bonds 69,516 315 (873 ) 68,958 Corporate bonds 6,152 5 (45 ) 6,112 Mortgage-backed or related securities 1,179,084 718 (19,389 ) 1,160,413 Asset-backed securities 27,732 128 (144 ) 27,716 $ 1,427,764 $ 1,176 $ (22,435 ) $ 1,406,505 Held-to-Maturity: U.S. Government and agency obligations $ 1,260 $ 27 $ — $ 1,287 Municipal bonds: 192,931 2,334 (2,644 ) 192,621 Corporate bonds 3,941 — (8 ) 3,933 Mortgage-backed or related securities 64,513 19 (1,455 ) 63,077 $ 262,645 $ 2,380 $ (4,107 ) $ 260,918 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Trading: Municipal bonds $ 100 $ 100 Corporate bonds 27,132 22,058 Equity securities 14 160 $ 27,246 $ 22,318 Available-for-Sale: U.S. Government and agency obligations $ 72,829 $ 68 $ (431 ) $ 72,466 Municipal bonds 68,513 665 (445 ) 68,733 Corporate bonds 5,431 6 (44 ) 5,393 Mortgage-backed or related securities 745,956 1,003 (7,402 ) 739,557 Asset-backed securities 27,667 184 (93 ) 27,758 Equity securities 5,716 10 (148 ) 5,578 $ 926,112 $ 1,936 $ (8,563 ) $ 919,485 Held-to-Maturity: U.S. Government and agency obligations $ 1,024 $ 29 $ — $ 1,053 Municipal bonds: 189,860 3,385 (1,252 ) 191,993 Corporate bonds 3,978 7 — 3,985 Mortgage-backed or related securities 65,409 266 (518 ) 65,157 $ 260,271 $ 3,687 $ (1,770 ) $ 262,188 At March 31, 2018 and December 31, 2017 , the gross unrealized losses and the fair value for securities available-for-sale and held-to-maturity aggregated by the length of time that individual securities have been in a continuous unrealized loss position was as follows (in thousands): March 31, 2018 Less Than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-Sale: U.S. Government and agency obligations $ 112,704 $ (1,479 ) $ 22,943 $ (505 ) $ 135,647 $ (1,984 ) Municipal bonds 30,019 (463 ) 13,065 (410 ) 43,084 (873 ) Corporate bonds 647 (7 ) 4,550 (38 ) 5,197 (45 ) Mortgage-backed or related securities 835,758 (15,250 ) 114,653 (4,139 ) 950,411 (19,389 ) Asset-backed securities — — 9,873 (144 ) 9,873 (144 ) $ 979,128 $ (17,199 ) $ 165,084 $ (5,236 ) $ 1,144,212 $ (22,435 ) Held-to-Maturity Municipal bonds $ 55,484 $ (669 ) $ 32,189 $ (1,975 ) $ 87,673 $ (2,644 ) Corporate bonds 492 (8 ) — — 492 (8 ) Mortgage-backed or related securities 54,224 (1,229 ) 4,315 (226 ) 58,539 (1,455 ) $ 110,200 $ (1,906 ) $ 36,504 $ (2,201 ) $ 146,704 $ (4,107 ) December 31, 2017 Less Than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-Sale: U.S. Government and agency obligations $ 31,276 $ (211 ) $ 23,341 $ (220 ) $ 54,617 $ (431 ) Municipal bonds 20,879 (185 ) 13,360 (260 ) 34,239 (445 ) Corporate bonds 296 (4 ) 4,682 (40 ) 4,978 (44 ) Mortgage-backed or related securities 559,916 (5,138 ) 100,662 (2,264 ) 660,578 (7,402 ) Asset-backed securities — — 9,926 (93 ) 9,926 (93 ) Equity securities 5,480 (148 ) — — 5,480 (148 ) $ 617,847 $ (5,686 ) $ 151,971 $ (2,877 ) $ 769,818 $ (8,563 ) Held-to-Maturity Municipal bonds 21,839 (171 ) 34,314 (1,081 ) 56,153 (1,252 ) Mortgage-backed or related securities 38,023 (378 ) 4,434 (140 ) 42,457 (518 ) $ 59,862 $ (549 ) $ 38,748 $ (1,221 ) $ 98,610 $ (1,770 ) At March 31, 2018 , there were 277 securities—available-for-sale with unrealized losses, compared to 226 at December 31, 2017 . At March 31, 2018 , there were 100 securities—held-to-maturity with unrealized losses, compared to 66 at December 31, 2017 . Management does not believe that any individual unrealized loss as of March 31, 2018 or December 31, 2017 represented other-than-temporary impairment (OTTI). The decline in fair market value of these securities was generally due to changes in interest rates and changes in market-desired spreads subsequent to their purchase. There were no sales of securities—trading during the three-month periods ended March 31, 2018 or 2017. The Company did no t recognize any OTTI charges or recoveries on securities—trading during the three-month periods ended March 31, 2018 or 2017. There were no securities—trading in a nonaccrual status at March 31, 2018 or December 31, 2017 . Net unrealized holding gains of $3.4 million were recognized during the three months ended March 31, 2018 compared to $152,000 of net unrealized holdings gains recognized during the three months ended March 31, 2017 . There were no sales of securities—available-for-sale during the three months ended March 31, 2018 , although partial calls of securities resulted in a net gain of $4,000 for the three months ended March 31, 2018 . Sales of securities—available-for-sale totaled $2.2 million which resulted in a net gain of $13,000 for the three months ended March 31, 2017 . There were no securities—available-for-sale in a nonaccrual status at March 31, 2018 or December 31, 2017 . There were no sales of securities—held-to-maturity during the three-month periods ended March 31, 2018 and 2017. There were no securities—held-to-maturity in a nonaccrual status at March 31, 2018 or December 31, 2017 . The amortized cost and estimated fair value of securities at March 31, 2018 , by contractual maturity, are shown below (in thousands). Expected maturities will differ from contractual maturities because some securities may be called or prepaid with or without call or prepayment penalties. March 31, 2018 Trading Available-for-Sale Held-to-Maturity Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Maturing in one year or less $ 100 $ 100 $ 3,090 $ 3,081 $ 1,943 $ 1,942 Maturing after one year through five years — — 63,013 62,113 38,334 37,896 Maturing after five years through ten years — — 281,112 276,039 96,044 95,696 Maturing after ten years through twenty years 17,175 16,889 186,470 184,722 84,150 85,000 Maturing after twenty years 10,000 8,585 894,079 880,550 42,174 40,384 $ 27,275 $ 25,574 $ 1,427,764 $ 1,406,505 $ 262,645 $ 260,918 The following table presents, as of March 31, 2018 , investment securities which were pledged to secure borrowings, public deposits or other obligations as permitted or required by law (in thousands): March 31, 2018 Carrying Value Amortized Cost Fair Value Purpose or beneficiary: State and local governments public deposits $ 129,288 $ 129,325 $ 130,478 Interest rate swap counterparties 14,924 15,089 14,762 Repurchase agreements 118,820 120,410 118,588 Other 3,900 3,900 3,744 Total pledged securities $ 266,932 $ 268,724 $ 267,572

LOANS RECEIVABLE AND THE ALLOWA

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES	LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES Loans receivable at March 31, 2018 and December 31, 2017 are summarized as follows (dollars in thousands): March 31, 2018 December 31, 2017 Amount Percent of Total Amount Percent of Total Commercial real estate: Owner-occupied $ 1,278,814 16.9 % $ 1,284,363 16.9 % Investment properties 1,876,937 24.8 1,937,423 25.5 Multifamily real estate 321,039 4.2 314,188 4.1 Commercial construction 163,314 2.2 148,435 2.0 Multifamily construction 159,108 2.1 154,662 2.0 One- to four-family construction 434,204 5.7 415,327 5.5 Land and land development: Residential 167,783 2.2 164,516 2.2 Commercial 24,331 0.3 24,583 0.3 Commercial business 1,296,691 17.2 1,279,894 16.8 Agricultural business, including secured by farmland 307,243 4.2 338,388 4.4 One- to four-family residential 833,598 11.0 848,289 11.2 Consumer: Consumer secured by one- to four-family 522,826 6.9 522,931 6.9 Consumer—other 170,158 2.3 165,885 2.2 Total loans 7,556,046 100.0 % 7,598,884 100.0 % Less allowance for loan losses (92,207 ) (89,028 ) Net loans $ 7,463,839 $ 7,509,856 Loan amounts are net of unearned loan fees in excess of unamortized costs of $731,000 as of March 31, 2018 and were net of unamortized costs of $158,000 as of December 31, 2017 . Net loans include net discounts on acquired loans of $19.4 million and $21.1 million as of March 31, 2018 and December 31, 2017 , respectively. Purchased credit-impaired loans and purchased non-credit-impaired loans. Purchased loans, including loans acquired in business combinations, are recorded at their fair value at the acquisition date. Credit discounts are included in the determination of fair value; therefore, an allowance for loan and lease losses is not recorded at the acquisition date. Acquired loans are evaluated upon acquisition and classified as either purchased credit-impaired (PCI) or purchased non-credit-impaired. PCI loans reflect credit deterioration since origination such that it is probable at acquisition that the Company will be unable to collect all contractually required payments. The outstanding contractual unpaid principal balance of PCI loans, excluding acquisition accounting adjustments, was $29.8 million at March 31, 2018 and $32.5 million at December 31, 2017 . The carrying balance of PCI loans was $19.3 million at March 31, 2018 and $21.3 million at December 31, 2017 . The following table presents the changes in the accretable yield for PCI loans for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended 2018 2017 Balance, beginning of period $ 6,520 $ 8,717 Accretion to interest income (1,097 ) (1,320 ) Disposals 58 — Reclassifications from non-accretable difference 807 1,273 Balance, end of period $ 6,288 $ 8,670 As of March 31, 2018 and December 31, 2017 , the non-accretable difference between the contractually required payments and cash flows expected to be collected were $9.9 million and $11.3 million , respectively. Impaired Loans and the Allowance for Loan Losses. A loan is considered impaired when, based on current information and circumstances, the Company determines it is probable that it will be unable to collect all amounts due according to the contractual terms of the loan agreement, including scheduled interest payments. Factors involved in determining impairment include, but are not limited to, the financial condition of the borrower, the value of the underlying collateral and the current status of the economy. Impaired loans are comprised of loans on nonaccrual, troubled debt restructurings (TDRs) that are performing under their restructured terms, and loans that are 90 days or more past due, but are still on accrual. PCI loans are considered performing within the scope of the purchased credit-impaired accounting guidance and are not included in the impaired loan tables. The following tables provide information on impaired loans, excluding PCI loans, with and without allowance reserves at March 31, 2018 and December 31, 2017 . Recorded investment includes the unpaid principal balance or the carrying amount of loans less charge-offs and net deferred loan fees (in thousands): March 31, 2018 Unpaid Principal Balance Recorded Investment Related Allowance Without Allowance (1) With Allowance (2) Commercial real estate: Owner-occupied $ 3,872 $ 3,444 $ 199 $ 20 Investment properties 9,346 3,433 5,699 264 One- to four-family construction 186 186 — — Land and land development: Residential 1,134 798 — — Commercial business 4,008 3,038 534 39 Agricultural business/farmland 9,598 6,440 3,031 201 One- to four-family residential 8,579 3,136 5,362 182 Consumer: Consumer secured by one- to four-family 1,346 1,168 138 7 Consumer—other 180 76 71 4 $ 38,249 $ 21,719 $ 15,034 $ 717 December 31, 2017 Unpaid Principal Balance Recorded Investment Related Allowance Without Allowance (1) With Allowance (2) Commercial real estate: Owner-occupied $ 7,807 $ 6,447 $ 199 $ 18 Investment properties 11,296 4,200 6,884 263 One- to four-family construction 298 298 — — Land and land development: Residential 1,134 798 — — Commercial business 4,441 3,424 555 50 Agricultural business/farmland 9,388 6,230 3,031 264 One- to four-family residential 9,547 3,709 5,775 178 Consumer: Consumer secured by one- to four-family 1,498 1,324 139 7 Consumer—other 134 58 73 2 $ 45,543 $ 26,488 $ 16,656 $ 782 (1) Includes loans without an allowance reserve that have been individually evaluated for impairment and that evaluation concluded that no reserve was needed, and $10.6 million of homogenous and small balance loans as of both March 31, 2018 and December 31, 2017 , that are collectively evaluated for impairment for which a general reserve has been established. (2) Loans with a specific allowance reserve have been individually evaluated for impairment using either a discounted cash flow analysis or, for collateral dependent loans, current appraisals less costs to sell to establish realizable value. The following tables summarize our average recorded investment and interest income recognized on impaired loans by loan class for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended Three Months Ended Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized Commercial real estate: Owner-occupied $ 5,383 $ 3 $ 2,916 $ 2 Investment properties 9,972 83 8,893 49 Multifamily real estate — — 495 4 One- to four-family construction 605 4 1,180 20 Land and land development: Residential 798 — 1,899 17 Commercial — — 977 — Commercial business 4,007 7 4,504 7 Agricultural business/farmland 9,109 33 6,282 32 One- to four-family residential 8,892 101 10,404 83 Consumer: Consumer secured by one- to four-family 1,390 2 1,742 3 Consumer—other 149 1 268 3 $ 40,305 $ 234 $ 39,560 $ 220 Troubled Debt Restructurings. Some of the Company’s loans are reported as TDRs. Loans are reported as TDRs when the bank grants one or more concessions to a borrower experiencing financial difficulties that it would not otherwise consider. Examples of such concessions include forgiveness of principal or accrued interest, extending the maturity date(s) or providing a lower interest rate than would be normally available for a transaction of similar risk. Our TDRs have generally not involved forgiveness of amounts due, but almost always include a modification of multiple factors; the most common combination includes interest rate, payment amount and maturity date. As a result of these concessions, restructured loans are impaired as the Company will not collect all amounts due, both principal and interest, in accordance with the terms of the original loan agreement. Loans identified as TDRs are accounted for in accordance with the Company's impaired loan accounting policies. The following table presents TDRs by accrual and nonaccrual status at March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Accrual Status Nonaccrual Status Total TDRs Accrual Nonaccrual Total Commercial real estate: Owner-occupied $ 199 $ 85 $ 284 $ 199 $ 87 $ 286 Investment properties 5,699 — 5,699 6,884 — 6,884 Commercial business 534 — 534 555 — 555 Agricultural business, including secured by farmland 2,531 29 2,560 3,129 29 3,158 One- to four-family residential 5,092 457 5,549 5,136 801 5,937 Consumer: Consumer secured by one- to four-family 138 — 138 139 — 139 Consumer—other 71 — 71 73 — 73 $ 14,264 $ 571 $ 14,835 $ 16,115 $ 917 $ 17,032 As of both March 31, 2018 and December 31, 2017 , the Company had commitments to advance additional funds related to TDRs up to $45,000 . No new TDRs occurred during the three months ended March 31, 2018 or 2017 . There were no TDRs which incurred a payment default within twelve months of the restructure date during the three -month periods ended March 31, 2018 and 2017 . A default on a TDR results in either a transfer to nonaccrual status or a partial charge-off, or both. Credit Quality Indicators : To appropriately and effectively manage the ongoing credit quality of the Company’s loan portfolio, management has implemented a risk-rating or loan grading system for its loans. The system is a tool to evaluate portfolio asset quality throughout each applicable loan’s life as an asset of the Company. Generally, loans and leases are risk rated on an aggregate borrower/relationship basis with individual loans sharing similar ratings. There are some instances when specific situations relating to individual loans will provide the basis for different risk ratings within the aggregate relationship. Loans are graded on a scale of 1 to 9. A description of the general characteristics of these categories is shown below: Overall Risk Rating Definitions : Risk-ratings contain both qualitative and quantitative measurements and take into account the financial strength of a borrower and the structure of the loan or lease. Consequently, the definitions are to be applied in the context of each lending transaction and judgment must also be used to determine the appropriate risk rating, as it is not unusual for a loan or lease to exhibit characteristics of more than one risk-rating category. Consideration for the final rating is centered in the borrower’s ability to repay, in a timely fashion, both principal and interest. There were no material changes in the risk-rating or loan grading system in the three months ended March 31, 2018 . Risk Rating 1: Exceptional A credit supported by exceptional financial strength, stability, and liquidity. The risk rating of 1 is reserved for the Company’s top quality loans, generally reserved for investment grade credits underwritten to the standards of institutional credit providers. Risk Rating 2: Excellent A credit supported by excellent financial strength, stability and liquidity. The risk rating of 2 is reserved for very strong and highly stable customers with ready access to alternative financing sources. Risk Rating 3: Strong A credit supported by good overall financial strength and stability. Collateral margins are strong; cash flow is stable although susceptible to cyclical market changes. Risk Rating 4: Acceptable A credit supported by the borrower’s adequate financial strength and stability. Assets and cash flow are reasonably sound and provide for orderly debt reduction. Access to alternative financing sources will be more difficult to obtain. Risk Rating 5: Watch A credit with the characteristics of an acceptable credit which requires, however, more than the normal level of supervision and warrants formal quarterly management reporting. Credits in this category are not yet criticized or classified, but due to adverse events or aspects of underwriting require closer than normal supervision. Generally, credits should be watch credits in most cases for six months or less as the impact of stress factors are analyzed. Risk Rating 6: Special Mention A credit with potential weaknesses that deserves management’s close attention is risk rated a 6. If left uncorrected, these potential weaknesses will result in deterioration in the capacity to repay debt. A key distinction between Special Mention and Substandard is that in a Special Mention credit, there are identified weaknesses that pose potential risk(s) to the repayment sources, versus well defined weaknesses that pose risk(s) to the repayment sources. Assets in this category are expected to be in this category no more than 9 - 12 months as the potential weaknesses in the credit are resolved. Risk Rating 7: Substandard A credit with well defined weaknesses that jeopardize the ability to repay in full is risk rated a 7. These credits are inadequately protected by either the sound net worth and payment capacity of the borrower or the value of pledged collateral. These are credits with a distinct possibility of loss. Loans headed for foreclosure and/or legal action due to deterioration are rated 7 or worse. Risk Rating 8: Doubtful A credit with an extremely high probability of loss is risk rated 8. These credits have all the same critical weaknesses that are found in a substandard loan; however, the weaknesses are elevated to the point that based upon current information, collection or liquidation in full is improbable. While some loss on doubtful credits is expected, pending events may strengthen a credit making the amount and timing of any loss indeterminable. In these situations taking the loss is inappropriate until it is clear that the pending event has failed to strengthen the credit and improve the capacity to repay debt. Risk Rating 9: Loss A credit that is considered to be currently uncollectible or of such little value that it is no longer a viable bank asset is risk rated 9. Losses should be taken in the accounting period in which the credit is determined to be uncollectible. Taking a loss does not mean that a credit has absolutely no recovery or salvage value but, rather, it is not practical or desirable to defer writing off the credit, even though partial recovery may occur in the future. The following tables present the Company’s portfolio of risk-rated loans and non-risk-rated loans by grade or other characteristics as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 By class: Pass (Risk Ratings 1-5) (1) Special Mention Substandard Doubtful Loss Total Loans Commercial real estate: Owner-occupied $ 1,244,007 $ 13,686 $ 21,121 $ — $ — $ 1,278,814 Investment properties 1,866,062 — 10,875 — — 1,876,937 Multifamily real estate 320,533 — 506 — — 321,039 Commercial construction 163,314 — — — — 163,314 Multifamily construction 159,108 — — — — 159,108 One- to four-family construction 429,172 — 5,032 — — 434,204 Land and land development: Residential 156,144 10,321 1,318 — — 167,783 Commercial 21,507 — 2,824 — — 24,331 Commercial business 1,228,831 16,599 51,152 109 — 1,296,691 Agricultural business, including secured by farmland 286,925 6,203 14,115 — — 307,243 One- to four-family residential 827,788 553 5,257 — — 833,598 Consumer: Consumer secured by one- to four-family 520,263 — 2,563 — — 522,826 Consumer—other 169,889 11 258 — — 170,158 Total $ 7,393,543 $ 47,373 $ 115,021 $ 109 $ — $ 7,556,046 December 31, 2017 By class: Pass (Risk Ratings 1-5) (1) Special Mention Substandard Doubtful Loss Total Loans Commercial real estate: Owner-occupied $ 1,246,125 $ 12,227 $ 26,011 $ — $ — $ 1,284,363 Investment properties 1,918,940 9,118 9,365 — — 1,937,423 Multifamily real estate 313,432 — 756 — — 314,188 Commercial construction 148,435 — — — — 148,435 Multifamily construction 154,662 — — — — 154,662 One- to four-family construction 411,802 — 3,525 — — 415,327 Land and land development: Residential 153,073 10,554 889 — — 164,516 Commercial 21,665 — 2,918 — — 24,583 Commercial business 1,213,365 12,135 54,282 112 — 1,279,894 Agricultural business, including secured by farmland 321,110 3,852 13,426 — — 338,388 One- to four-family residential 842,304 569 5,416 — — 848,289 Consumer: Consumer secured by one- to four-family 520,675 — 2,256 — — 522,931 Consumer—other 165,594 13 278 — — 165,885 Total $ 7,431,182 $ 48,468 $ 119,122 $ 112 $ — $ 7,598,884 (1) The Pass category includes some performing loans that are part of homogenous pools which are not individually risk-rated. This includes all consumer loans, all one - to four -family residential loans and, as of March 31, 2018 and December 31, 2017 , in the commercial business category, $535.0 million and $296.8 million , respectively, of credit-scored small business loans. As loans in these pools become non-performing, they are individually risk-rated. The following tables provide additional detail on the age analysis of the Company’s past due loans as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Total Past Due Purchased Credit-Impaired Current Total Loans Loans 90 Days or More Past Due and Accruing Non-accrual Commercial real estate: Owner-occupied $ 189 $ 169 $ 3,079 $ 3,437 $ 6,372 $ 1,269,005 $ 1,278,814 $ — $ 3,444 Investment properties 1,402 — 1,109 2,511 7,072 1,867,354 1,876,937 — 3,433 Multifamily real estate — — — — 167 320,872 321,039 — — Commercial construction — — — — — 163,314 163,314 — — Multifamily construction — — — — — 159,108 159,108 — — One-to-four-family construction 4,323 320 186 4,829 440 428,935 434,204 — 186 Land and land development: Residential — 784 798 1,582 — 166,201 167,783 — 798 Commercial — — — — 2,824 21,507 24,331 — — Commercial business 1,744 702 2,137 4,583 1,829 1,290,279 1,296,691 1 3,037 Agricultural business, including secured by farmland 1,580 — 6,507 8,087 415 298,741 307,243 820 6,120 One- to four-family residential 4,467 476 2,501 7,444 129 826,025 833,598 591 2,815 Consumer: Consumer secured by one- to four-family 1,412 82 584 2,078 — 520,748 522,826 — 1,168 Consumer—other 847 148 35 1,030 68 169,060 170,158 7 69 Total $ 15,964 $ 2,681 $ 16,936 $ 35,581 $ 19,316 $ 7,501,149 $ 7,556,046 $ 1,419 $ 21,070 December 31, 2017 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Total Past Due Purchased Credit-Impaired Current Total Loans Loans 90 Days or More Past Due and Accruing Non-accrual Commercial real estate: Owner-occupied $ 5,323 $ 76 $ 5,490 $ 10,889 $ 7,682 $ 1,265,792 $ 1,284,363 $ — $ 6,447 Investment properties 1,737 — 4,096 5,833 7,166 1,924,424 1,937,423 — 4,199 Multifamily real estate 105 — — 105 169 313,914 314,188 — — Commercial construction — — — — — 148,435 148,435 — — Multifamily construction 3,416 — — 3,416 — 151,246 154,662 — — One-to-four-family construction 4,892 725 298 5,915 446 408,966 415,327 298 — Land and land development: Residential — — 798 798 — 163,718 164,516 — 798 Commercial — — — — 2,919 21,664 24,583 — — Commercial business 1,574 404 2,577 4,555 2,159 1,273,180 1,279,894 18 3,406 Agricultural business, including secured by farmland 598 533 2,017 3,148 565 334,675 338,388 — 6,132 One-to four-family residential 4,475 1,241 2,715 8,431 136 839,722 848,289 1,085 3,264 Consumer: Consumer secured by one- to four-family 1,355 62 713 2,130 — 520,801 522,931 85 1,239 Consumer—other 609 136 15 760 68 165,057 165,885 — 58 Total $ 24,084 $ 3,177 $ 18,719 $ 45,980 $ 21,310 $ 7,531,594 $ 7,598,884 $ 1,486 $ 25,543 The following tables provide additional information on the allowance for loan losses and loan balances individually and collectively evaluated for impairment at or for the three months ended March 31, 2018 and 2017 (in thousands): For the Three Months Ended March 31, 2018 Commercial Real Estate Multifamily Real Estate Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Beginning balance $ 22,824 $ 1,633 $ 27,568 $ 18,311 $ 4,053 $ 2,055 $ 3,866 $ 8,718 $ 89,028 Provision for loan losses (715 ) 959 1,024 1,923 (1,047 ) 1,450 1,913 (3,507 ) 2,000 Recoveries 1,352 — 174 170 — 290 112 — 2,098 Charge-offs — — — (519 ) (7 ) (16 ) (377 ) — (919 ) Ending balance $ 23,461 $ 2,592 $ 28,766 $ 19,885 $ 2,999 $ 3,779 $ 5,514 $ 5,211 $ 92,207 March 31, 2018 Commercial Real Estate Multifamily Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Individually evaluated for impairment $ 284 $ — $ — $ 39 $ 201 $ 182 $ 11 $ — $ 717 Collectively evaluated for impairment 23,177 2,592 28,766 19,799 2,707 3,597 5,503 5,211 91,352 Purchased credit-impaired loans — — — 47 91 — — — 138 Total allowance for loan losses $ 23,461 $ 2,592 $ 28,766 $ 19,885 $ 2,999 $ 3,779 $ 5,514 $ 5,211 $ 92,207 Loan balances: Individually evaluated for impairment $ 11,607 $ — $ 750 $ 534 $ 7,943 $ 5,092 $ 208 $ — $ 26,134 Collectively evaluated for impairment 3,130,700 320,872 944,726 1,294,328 298,885 828,377 692,708 — 7,510,596 Purchased credit-impaired loans 13,444 167 3,264 1,829 415 129 68 — 19,316 Total loans $ 3,155,751 $ 321,039 $ 948,740 $ 1,296,691 $ 307,243 $ 833,598 $ 692,984 $ — $ 7,556,046 For the Three Months Ended March 31, 2017 Commercial Real Estate Multifamily Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Beginning balance $ 20,993 $ 1,360 $ 34,252 $ 16,533 $ 2,967 $ 2,238 $ 4,104 $ 3,550 $ 85,997 Provision for loan losses (591 ) 18 (4,871 ) 4,688 324 (409 ) 5 2,836 2,000 Recoveries 70 — 83 173 113 145 94 — 678 Charge-offs — — — (1,626 ) (159 ) — (363 ) — (2,148 ) Ending balance $ 20,472 $ 1,378 $ 29,464 $ 19,768 $ 3,245 $ 1,974 $ 3,840 $ 6,386 $ 86,527 March 31, 2017 Commercial Real Estate Multifamily Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Individually evaluated for impairment $ 419 $ 62 $ 323 $ 62 $ 238 $ 229 $ 11 $ — $ 1,344 Collectively evaluated for impairment 20,053 1,316 29,122 19,706 3,007 1,745 3,829 6,386 85,164 Purchased credit-impaired loans — — 19 — — — — — 19 Total allowance for loan losses $ 20,472 $ 1,378 $ 29,464 $ 19,768 $ 3,245 $ 1,974 $ 3,840 $ 6,386 $ 86,527 Loan balances: Individually evaluated for impairment $ 9,506 $ 347 $ 4,006 $ 2,710 $ 3,815 $ 6,653 $ 220 $ — $ 27,257 Collectively evaluated for impairment 3,341,177 253,725 795,887 1,218,415 308,834 796,026 649,433 — 7,363,497 Purchased credit impaired loans 22,030 174 3,777 3,416 725 312 67 — 30,501 Total loans $ 3,372,713 $ 254,246 $ 803,670 $ 1,224,541 $ 313,374 $ 802,991 $ 649,720 $ — $ 7,421,255

REAL ESTATE OWNED, NET

REAL ESTATE OWNED, NET	3 Months Ended
	Mar. 31, 2018
Real Estate [Abstract]
REAL ESTATE OWNED, NET	REAL ESTATE OWNED, NET The following table presents the changes in REO for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended 2018 2017 Balance, beginning of the period $ 360 $ 11,081 Additions from loan foreclosures 128 — Proceeds from dispositions of REO — (9,193 ) Gain on sale of REO — 1,202 Valuation adjustments in the period (160 ) (50 ) Balance, end of the period $ 328 $ 3,040 REO properties are recorded at the estimated fair value of the property, less expected selling costs, establishing a new cost basis. Subsequently, REO properties are carried at the lower of the new cost basis or updated fair market values, based on updated appraisals of the underlying properties, as received. Valuation allowances on the carrying value of REO may be recognized based on updated appraisals or on management’s authorization to reduce the selling price of a property. At March 31, 2018 and December 31, 2017 , the Company had $98,000 and $0 , respectively, of foreclosed one- to four-family residential real estate properties held as REO. The recorded investment in one- to four-family residential loans in the process of foreclosure was $1.6 million at March 31, 2018 compared with $2.0 million at December 31, 2017.

GOODWILL, OTHER INTANGIBLE ASSE

GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS	GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS Goodwill and Other Intangible Assets: At March 31, 2018 , intangible assets are comprised of goodwill, CDI, and favorable leasehold intangibles (LHI) acquired in business combinations. Goodwill represents the excess of the purchase considerations paid over the fair value of the assets acquired, net of the fair values of liabilities assumed in a business combination, and is not amortized but is reviewed annually for impairment. At December 31, 2017, the Company completed its qualitative assessment of goodwill and concluded that it is more likely than not that the fair value of Banner, the reporting unit, exceeds the carrying value. CDI represents the value of transaction-related deposits and the value of the customer relationships associated with the deposits. LHI represents the value ascribed to leases assumed in an acquisition in which the lease terms are favorable compared to a market lease at the date of acquisition. The Company amortizes CDI and LHI over their estimated useful lives and reviews them at least annually for events or circumstances that could impair their value. The following table summarizes the changes in the Company’s goodwill and other intangibles for the three months ended March 31, 2018 and the year ended December 31, 2017 (in thousands): Goodwill CDI LHI Total Balance, December 31, 2016 $ 244,583 $ 29,701 $ 461 $ 274,745 Amortization — (6,247 ) (184 ) (6,431 ) Other changes (1) (1,924 ) (1,076 ) — (3,000 ) Balance, December 31, 2017 242,659 22,378 277 265,314 Amortization — (1,382 ) (22 ) (1,404 ) Balance, March 31, 2018 $ 242,659 $ 20,996 $ 255 $ 263,910 (1) Acquired goodwill and CDI were adjusted for the sale of the Utah branches in 2017. The following table presents the estimated amortization expense with respect to CDI for the periods indicated (in thousands): Estimated Amortization Remainder of 2018 $ 3,990 2019 4,683 2020 3,996 2021 3,307 2022 2,524 Thereafter 2,496 $ 20,996 Mortgage Servicing Rights: Mortgage servicing rights are reported in other assets. Mortgage servicing rights are initially recorded at fair value and are amortized in proportion to, and over the period of, the estimated future net servicing income of the underlying financial assets. Mortgage servicing rights are subsequently evaluated for impairment based upon the fair value of the rights compared to the amortized cost (remaining unamortized initial fair value). If the fair value is less than the amortized cost, a valuation allowance is created through an impairment charge, which is recognized in servicing fee income within mortgage banking operations on the consolidated statement of operations. However, if the fair value is greater than the amortized cost, the amount above the amortized cost is not recognized in the carrying value. During the three months ended March 31, 2018 and 2017 , the Company did not record any impairment charges or recoveries against mortgage servicing rights. The unpaid principal balance for loans which mortgage servicing rights have been recorded totaled $2.23 billion and $2.19 billion at March 31, 2018 and December 31, 2017 , respectively. Custodial accounts maintained in connection with this servicing totaled $19.1 million and $10.2 million at March 31, 2018 and December 31, 2017 , respectively. An analysis of our mortgage servicing rights for the three months ended March 31, 2018 and 2017 is presented below (in thousands): Three Months Ended 2018 2017 Balance, beginning of the period $ 14,738 $ 15,249 Additions—amounts capitalized 821 945 Additions—through purchase 15 — Amortization (1) (957 ) (922 ) Balance, end of the period (2) $ 14,617 $ 15,272 (1) Amortization of mortgage servicing rights is recorded as a reduction of loan servicing income within mortgage banking operations and any unamortized balance is fully amortized if the loan repays in full. (2) There was no valuation allowance as of March 31, 2018 and 2017 .

DEPOSITS

DEPOSITS	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
DEPOSITS	DEPOSITS Deposits consisted of the following at March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Non-interest-bearing accounts $ 3,383,439 $ 3,265,544 Interest-bearing checking 1,043,840 971,137 Regular savings accounts 1,637,814 1,557,500 Money market accounts 1,459,614 1,422,313 Total interest-bearing transaction and saving accounts 4,141,268 3,950,950 Certificates of deposit: Certificates of deposit less than or equal to $250,000 865,353 813,997 Certificates of deposit greater than $250,000 153,002 152,940 Total certificates of deposit (1) 1,018,355 966,937 Total deposits $ 8,543,062 $ 8,183,431 Included in total deposits: Public fund transaction and savings accounts $ 190,311 $ 198,719 Public fund interest-bearing certificates 24,928 23,685 Total public deposits $ 215,239 $ 222,404 Total brokered deposits $ 169,523 $ 57,228 (1) Certificates of deposit include $5,000 and $11,000 of acquisition premiums at March 31, 2018 and December 31, 2017 , respectively. At March 31, 2018 and December 31, 2017 , the Company had certificates of deposit of $156.3 million and $155.9 million , respectively, that were equal to or greater than $250,000. Scheduled maturities and weighted average interest rates of certificate accounts at March 31, 2018 are as follows (dollars in thousands): March 31, 2018 Amount Weighted Average Rate Maturing in one year or less $ 703,650 0.63 % Maturing after one year through two years 146,484 0.98 Maturing after two years through three years 128,810 1.31 Maturing after three years through four years 23,571 1.11 Maturing after four years through five years 13,460 1.33 Maturing after five years 2,380 1.06 Total certificates of deposit $ 1,018,355 0.79 %

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE ACCOUNTING AND MEASUREMENT	FAIR VALUE OF FINANCIAL INSTRUMENTS The following table presents estimated fair values of the Company’s financial instruments as of March 31, 2018 and December 31, 2017 , whether or not measured at fair value in the Consolidated Statements of Financial Condition (in thousands): March 31, 2018 December 31, 2017 Level Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Assets: Cash and cash equivalents 1 $ 242,048 $ 242,048 $ 261,200 $ 261,200 Securities—trading 2,3 25,574 25,574 22,318 22,318 Securities—available-for-sale 2 1,406,505 1,406,505 919,485 919,485 Securities—held-to-maturity 2 259,204 257,477 256,793 258,710 Securities—held-to-maturity 3 3,441 3,441 3,478 3,478 Loans held for sale 2 141,808 141,898 40,725 40,923 Loans receivable 3 7,556,046 7,462,004 7,598,884 7,445,990 FHLB stock 3 18,036 18,036 10,334 10,334 Bank-owned life insurance 1 163,519 163,519 162,668 162,668 Mortgage servicing rights 3 14,617 20,560 14,738 19,835 Equity securities 1 5,698 5,698 — — Derivatives: Interest rate swaps 2 4,592 4,592 5,083 5,083 Interest rate lock and forward sales commitments 2 683 683 523 523 Liabilities: Demand, interest checking and money market accounts 2 5,886,893 5,886,893 5,658,994 5,658,994 Regular savings 2 1,637,814 1,637,814 1,557,500 1,557,500 Certificates of deposit 2 1,018,355 994,616 966,937 947,517 FHLB advances 2 192,195 192,195 202 202 Other borrowings 2 101,844 101,844 95,860 95,860 Junior subordinated debentures 3 112,516 112,516 98,707 98,707 Derivatives: Interest rate swaps 2 4,592 4,592 5,083 5,083 Interest rate lock and forward sales commitments 2 260 260 201 201 The Company measures and discloses certain assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (that is, not a forced liquidation or distressed sale). GAAP establishes a consistent framework for measuring fair value and disclosure requirements about fair value measurements. Among other things, the accounting standard requires the reporting entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s estimates for market assumptions. These two types of inputs create the following fair value hierarchy: • Level 1 – Quoted prices in active markets for identical instruments. An active market is a market in which transactions occur with sufficient frequency and volume to provide pricing information on an ongoing basis. A quoted price in an active market provides the most reliable evidence of fair value and shall be used to measure fair value whenever available. • Level 2 – Observable inputs other than Level 1 including quoted prices in active markets for similar instruments, quoted prices in less active markets for identical or similar instruments, or other observable inputs that can be corroborated by observable market data. • Level 3 – Unobservable inputs supported by little or no market activity for financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation; also includes observable inputs from non-binding single dealer quotes not corroborated by observable market data. The estimated fair value amounts of financial instruments have been determined by the Company using available market information and appropriate valuation methodologies. However, considerable judgment is required to interpret data to develop the estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize at a future date. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. In addition, reasonable comparability between financial institutions may not be likely due to the wide range of permitted valuation techniques and numerous estimates that must be made given the absence of active secondary markets for certain financial instruments. This lack of uniform valuation methodologies also introduces a greater degree of subjectivity to these estimated fair values. Transfers between levels of the fair value hierarchy are deemed to occur at the end of the reporting period. Items Measured at Fair Value on a Recurring Basis: The following tables present financial assets and liabilities measured at fair value on a recurring basis and the level within the fair value hierarchy of the fair value measurements for those assets and liabilities as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Level 1 Level 2 Level 3 Total Assets: Securities—trading Municipal bonds $ — $ 100 $ — $ 100 Corporate bonds (Trust Preferred Securities) — — 25,474 25,474 — 100 25,474 25,574 Securities—available-for-sale U.S. Government and agency obligations — 143,306 — 143,306 Municipal bonds — 68,958 — 68,958 Corporate bonds — 6,112 — 6,112 Mortgage-backed or related securities — 1,160,413 — 1,160,413 Asset-backed securities — 27,716 — 27,716 — 1,406,505 — 1,406,505 Loans held for sale — 137,734 — 137,734 Equity securities — 5,698 — 5,698 Derivatives Interest rate swaps — 4,592 — 4,592 Interest rate lock and forward sales commitments — 683 — 683 $ — $ 1,555,312 $ 25,474 $ 1,580,786 Liabilities: Junior subordinated debentures, net of unamortized deferred issuance costs $ — $ — $ 112,516 $ 112,516 Derivatives Interest rate swaps — 4,592 — 4,592 Interest rate lock and forward sales commitments — 260 — 260 $ — $ 4,852 $ 112,516 $ 117,368 December 31, 2017 Level 1 Level 2 Level 3 Total Assets: Securities—trading Municipal bonds $ — $ 100 $ — $ 100 Corporate Bonds (Trust Preferred Securities) — — 22,058 22,058 Equity securities — 160 — 160 — 260 22,058 22,318 Securities—available-for-sale U.S. Government and agency obligations — 72,466 — 72,466 Municipal bonds — 68,733 — 68,733 Corporate bonds — 5,393 — 5,393 Mortgage-backed securities — 739,557 — 739,557 Asset-backed securities — 27,758 — 27,758 Equity securities — 5,578 — 5,578 — 919,485 — 919,485 Loans held for sale — 32,392 — 32,392 Derivatives Interest rate swaps — 5,083 — 5,083 Interest rate lock and forward sales commitments — 523 — 523 $ — $ 957,743 $ 22,058 $ 979,801 Liabilities: Junior subordinated debentures, net of unamortized deferred issuance costs $ — $ — $ 98,707 $ 98,707 Derivatives Interest rate swaps — 5,083 — 5,083 Interest rate lock and forward sales commitments — 201 — 201 $ — $ 5,284 $ 98,707 $ 103,991 The following methods were used to estimate the fair value of each class of financial instruments above: Securities: The estimated fair values of investment securities and mortgaged-backed securities are priced using current active market quotes, if available, which are considered Level 1 measurements. For most of the portfolio, matrix pricing based on the securities’ relationship to other benchmark quoted prices is used to establish the fair value. These measurements are considered Level 2. Due to the continued limited activity in the trust preferred markets that have limited the observability of market spreads for some of the Company’s Trust Preferred Securities (TPS) securities, management has classified these securities as a Level 3 fair value measure. Management periodically reviews the pricing information received from third-party pricing services and tests those prices against other sources to validate the reported fair values. Loans Held for Sale: Fair values for residential mortgage loans held for sale are determined by comparing actual loan rates to current secondary market prices for similar loans. Fair values for multifamily loans held for sale are calculated based on discounted cash flows using as a discount rate a combination of market spreads for similar loan types added to selected index rates. Mortgage Servicing Rights: Fair values are estimated based on an independent dealer analysis of discounted cash flows. The evaluation utilizes assumptions market participants would use in determining fair value including prepayment speeds, delinquency and foreclosure rates, the discount rate, servicing costs, and the timing of cash flows. The mortgage servicing portfolio is stratified by loan type and fair value estimates are adjusted up or down based on the serviced loan interest rates versus current rates on new loan originations since the most recent independent analysis. Junior Subordinated Debentures: The fair value of junior subordinated debentures is estimated using a discounted cash flow approach. The significant inputs included in the estimation of fair value are the credit risk adjusted spread and three month LIBOR. The credit risk adjusted spread represents the nonperformance risk of the liability. The Company utilizes an external valuation firm to assist management in validating the reasonableness of the credit risk adjusted spread used to determine the fair value. The junior subordinated debentures are carried at fair value which represents the estimated amount that would be paid to transfer these liabilities in an orderly transaction amongst market participants. Due to credit concerns in the capital markets and inactivity in the trust preferred markets that have limited the observability of market spreads, management has classified this as a Level 3 fair value measure. Derivatives: Derivatives include interest rate swap agreements, interest rate lock commitments to originate loans held for sale and forward sales contracts to sell loans and securities related to mortgage banking activities. Fair values for these instruments, which generally change as a result of changes in the level of market interest rates, are estimated based on dealer quotes and secondary market sources. Off-Balance-Sheet Items: Off-balance-sheet financial instruments include unfunded commitments to extend credit, including standby letters of credit, and commitments to purchase investment securities. The fair value of these instruments is not considered to be material. Limitations: The fair value estimates presented herein are based on pertinent information available to management as of March 31, 2018 and December 31, 2017 . The factors used in the fair values estimates are subject to change subsequent to the dates the fair value estimates are completed, therefore, current estimates of fair value may differ significantly from the amounts presented herein. Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3): The following table provides a description of the valuation technique, unobservable inputs, and qualitative information about the unobservable inputs for certain of the Company's assets and liabilities classified as Level 3 and measured at fair value on a recurring and non-recurring basis at March 31, 2018 and December 31, 2017 : Weighted Average Rate / Range Financial Instruments Valuation Techniques Unobservable Inputs March 31, 2018 December 31, 2017 Corporate Bonds (TPS securities) Discounted cash flows Discount rate 6.31 % 6.69 % Junior subordinated debentures Discounted cash flows Discount rate 6.31 % 6.69 % Impaired loans Collateral Valuations Discount to appraised value 8.5 % 8.5% to 20.0% REO Appraisals Discount to appraised value 61 % 42 % TPS securities : Management believes that the credit risk-adjusted spread used to develop the discount rate utilized in the fair value measurement of TPS securities is indicative of the risk premium a willing market participant would require under current market conditions for instruments with similar contractual rates and terms and conditions and issuers with similar credit risk profiles and with similar expected probability of default. Management attributes the change in fair value of these instruments, compared to their par value, primarily to perceived general market adjustments to the risk premiums for these types of assets subsequent to their issuance. Junior subordinated debentures : Similar to the TPS securities discussed above, management believes that the credit risk-adjusted spread utilized in the fair value measurement of the junior subordinated debentures is indicative of the risk premium a willing market participant would require under current market conditions for an issuer with Banner's credit risk profile. Management attributes the change in fair value of the junior subordinated debentures, compared to their par value, primarily to perceived general market adjustments to the risk premiums for these types of liabilities subsequent to their issuance. Future contractions in the risk adjusted spread relative to the spread currently utilized to measure the Company's junior subordinated debentures at fair value as of March 31, 2018 , or the passage of time, will result in negative fair value adjustments. At March 31, 2018 , the discount rate utilized was based on a credit spread of 400 basis points and three-month LIBOR of 231 basis points. The following tables provide a reconciliation of the assets and liabilities measured at fair value using significant unobservable inputs (Level 3) on a recurring basis during the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended March 31, 2018 Level 3 Fair Value Inputs TPS Securities Borrowings—Junior Subordinated Debentures Beginning balance $ 22,058 $ 98,707 Total gains or losses recognized Assets gains 3,416 — Liabilities losses (1) — 13,809 Ending balance at March 31, 2018 $ 25,474 $ 112,516 Three Months Ended March 31, 2017 Level 3 Fair Value Inputs TPS Securities Borrowings—Junior Subordinated Debentures Beginning balance $ 21,143 $ 95,200 Total gains or losses recognized Assets gains 218 — Liabilities losses — 840 Ending balance at March 31, 2017 $ 21,361 $ 96,040 (1) The change in fair value on the junior subordinated debentures in 2018 was recorded in other comprehensive income (loss). The Company has elected to continue to recognize the interest income and dividends from the securities reclassified to fair value from available-for-sale as a component of interest income as was done in prior years when they were classified as available-for-sale. Interest expense related to the junior subordinated debentures continues to be measured based on contractual interest rates and reported in interest expense. The change in fair market value on TPS securities and on junior subordinated debentures prior to 2018 has been recorded as a component of non-interest income. Beginning in 2018, the change in fair value of the junior subordinated debentures, which represent changes in instrument specific credit risk, are recorded in other comprehensive income (loss). Items Measured at Fair Value on a Non-recurring Basis: The following tables present financial assets measured at fair value on a non-recurring basis and the level within the fair value hierarchy of the fair value measurements for those assets as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Level 1 Level 2 Level 3 Total Impaired loans $ — $ — $ 500 $ 500 REO — — 328 328 December 31, 2017 Level 1 Level 2 Level 3 Total Impaired loans $ — $ — $ 6,535 $ 6,535 REO — — 360 360 The following table presents the losses resulting from non-recurring fair value adjustments for the three months ended March 31, 2018 and 2017 (in thousands): Three months ended March 31, 2018 2017 REO $ (160 ) $ (50 ) Total loss from non-recurring measurements $ (160 ) $ (50 ) Impaired loans : Impaired loans are measured based on the present value of expected future cash flows discounted at the loan's effective interest rate or, as a practical expedient, at the loan's observable market price or the fair value of collateral if the loan is collateral dependent. If this practical expedient is used, the impaired loans are considered to be held at fair value. Subsequent changes in the value of impaired loans are included within the provision for loan losses in the same manner in which impairment initially was recognized or as a reduction in the provision that would otherwise be reported. Impaired loans are periodically evaluated to determine if valuation adjustments, or partial write-downs, should be recorded. The need for valuation adjustments arises when observable market prices or current appraised values of collateral indicate a shortfall in collateral value compared to current carrying values of the related loan. If the Company determines that the value of the impaired loan is less than the carrying value of the loan, the Company either establishes an impairment reserve as a specific component of the allowance for loan losses or charges off the impaired amount. These valuation adjustments are considered non-recurring fair value adjustments. The remaining impaired loans are evaluated for reserve needs in homogenous pools within the Company’s methodology for assessing the adequacy of the allowance for loan losses. REO : The Company records REO (acquired through a lending relationship) at fair value on a non-recurring basis. Fair value adjustments on REO are based on updated real estate appraisals which are based on current market conditions. All REO properties are recorded at the lower of the estimated fair value of the real estate, less expected selling costs, or the carrying amount of the defaulted loans. From time to time, non-recurring fair value adjustments to REO are recorded to reflect partial write-downs based on an observable market price or current appraised value of property. Banner considers any valuation inputs related to REO to be Level 3 inputs. The individual carrying values of these assets are reviewed for impairment at least annually and any additional impairment charges are expensed to operations.

INCOME TAXES AND DEFERRED TAXES

INCOME TAXES AND DEFERRED TAXES	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES AND DEFERRED TAXES	INCOME TAXES AND DEFERRED TAXES The Company files a consolidated income tax return including all of its wholly-owned subsidiaries on a calendar year basis. Income taxes are accounted for using the asset and liability method. Under this method, a deferred tax asset or liability is determined based on the enacted tax rates which will be in effect when the differences between the financial statement carrying amounts and tax basis of existing assets and liabilities are expected to be reported in the Company’s income tax returns. The effect on deferred taxes of a change in tax rates is recognized in income in the period of change. A valuation allowance is recognized as a reduction to deferred tax assets when management determines it is more likely than not that deferred tax assets will not be available to offset future income tax liabilities. Accounting standards for income taxes prescribe a recognition threshold and measurement process for financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in a tax return, and also provide guidance on the de-recognition of previously recorded benefits and their classification, as well as the proper recording of interest and penalties, accounting in interim periods, disclosures and transition. The Company periodically reviews its income tax positions based on tax laws and regulations and financial reporting considerations, and records adjustments as appropriate. This review takes into consideration the status of current taxing authorities’ examinations of the Company’s tax returns, recent positions taken by the taxing authorities on similar transactions, if any, and the overall tax environment. As of March 31, 2018 , the Company had an insignificant amount of unrecognized tax benefits for uncertain tax positions, none of which would materially affect the effective tax rate if recognized. The Company does not anticipate that the amount of unrecognized tax benefits will significantly increase or decrease in the next twelve months. The Company’s policy is to recognize interest and penalties on unrecognized tax benefits in the income tax expense. The Company files consolidated income tax returns in the U.S. federal jurisdiction and in the Oregon, California, Utah and Idaho state jurisdictions. In December 2017, the federal government enacted the Tax Cuts and Jobs Act (2017 Tax Act), which among other provisions, reduced the federal marginal corporate income tax rate from 35% to 21%. As a result of the passage of the 2017 Tax Act, the Company recorded a $42.6 million charge in December 2017, for the revaluation of its net deferred tax to account for the future impact of the decrease in the corporate income tax rate and other provisions of the legislation. The charge was recorded as an increase to tax expense and reduction of the net deferred asset. The Company’s 2017 financial results reflected the income tax effects of the 2017 Tax Act for which the accounting was complete and provisional amounts for those specific income tax effects of the 2017 Tax Act for which the accounting is incomplete but a reasonable estimate could be determined. As a result, these amounts could be adjusted during the measurement period, which will end in December 2018. The Company did not identify any items for which the income tax effects of the 2017 Tax Act have not been completed and a reasonable estimate could not be determined as of December 31, 2017. The $42.6 million charge recorded by the Company includes $4.2 million of provisional income tax expense related to Alternative Minimum Tax (AMT) credits that are limited under Internal Revenue Code of 1986 Section 383, which resulted in a reduction in the AMT deferred tax asset. The utilization of the limited AMT credits under the refundable AMT credit law is uncertain and will require further analysis as guidance is released during 2018. No adjustment to the provisional amounts was recorded during the quarter ended March 31, 2018 . Tax credit investments: The Company invests in low income housing tax credit funds that are designed to generate a return primarily through the realization of federal tax credits. The Company accounts for these investments by amortizing the cost of tax credit investments over the life of the investment using a proportional amortization method and tax credit investment amortization expense is a component of the provision for income taxes. The following table presents the balances of the Company’s tax credit investments and related unfunded commitments at March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Tax credit investments $ 9,223 $ 7,311 Unfunded commitments—tax credit investments 5,483 4,417 The following table presents other information related to the Company's tax credit investments for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended 2018 2017 Tax credits and other tax benefits recognized $ 364 $ 285 Tax credit amortization expense included in provision for income taxes 288 199

CALCULATION OF WEIGHTED AVERAGE

CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE (EPS)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE (EPS)	CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE (EPS) The following table reconciles basic to diluted weighted shares outstanding used to calculate earnings per share data (in thousands, except shares and per share data): Three Months Ended 2018 2017 Net income $ 28,790 $ 23,793 Basic weighted average shares outstanding 32,397,568 32,933,444 Plus unvested restricted stock 118,888 118,015 Diluted weighted shares outstanding 32,516,456 33,051,459 Earnings per common share Basic $ 0.89 $ 0.72 Diluted $ 0.89 $ 0.72 As of March 31, 2018 , warrants expiring on November 21, 2018 to purchase up to $18.6 million ( 243,998 shares, post reverse-split) of common stock were not included in the computation of diluted earnings per share because the exercise price of the warrants was greater than the average market price of common shares.

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION PLANS AND STOCK OPTIONS	STOCK-BASED COMPENSATION PLANS The Company operates the following stock-based compensation plans as approved by its shareholders: • 2012 Restricted Stock and Incentive Bonus Plan (2012 Restricted Stock Plan). • 2014 Omnibus Incentive Plan (the 2014 Plan). The purpose of these plans is to promote the success and enhance the value of the Company by providing a means for attracting and retaining highly skilled employees, officers and directors of Banner Corporation and its affiliates and linking their personal interests with those of the Company's shareholders. Under these plans the Company currently has outstanding restricted stock share grants and restricted stock unit grants. 2012 Restricted Stock and Incentive Bonus Plan Under the 2012 Restricted Stock Plan, which was initially approved on April 24, 2012, the Company is authorized to issue up to 300,000 shares of its common stock to provide a means for attracting and retaining highly skilled officers of Banner Corporation and its affiliates. Shares granted under the 2012 Restricted Stock Plan have a minimum vesting period of three years. The 2012 Restricted Stock Plan will continue in effect for a term of ten years, after which no further awards may be granted. The 2012 Restricted Stock Plan was amended on April 23, 2013 to provide for the ability to grant (1) cash-denominated incentive-based awards payable in cash or common stock, including those that are eligible to qualify as qualified performance-based compensation for the purposes of Section 162(m) of the Code and (2) restricted stock awards that qualify as qualified performance-based compensation for the purposes of Section 162(m) of the Code. Vesting requirements may include time-based conditions, performance-based conditions, or market-based conditions. As of March 31, 2018 , the Company had granted 270,467 shares of restricted stock from the 2012 Restricted Stock Plan (as amended and restated), of which 253,865 shares had vested and 16,602 shares remain unvested. 2014 Omnibus Incentive Plan The 2014 Plan was approved by shareholders on April 22, 2014. The 2014 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance units, other stock-based awards and other cash awards, and provides for vesting requirements which may include time-based or performance-based conditions. The Company reserved 900,000 shares of its common stock for issuance under the 2014 Plan in connection with the exercise of awards. As of March 31, 2018 , 346,914 restricted stock shares and 34,975 restricted stock units have been granted under the 2014 Plan of which 123,885 restricted stock shares and 26,154 restricted stock units have vested. The expense associated with all restricted stock grants (including restricted stock shares and restricted stock units) was $1.3 million and $1.1 million for the three -month periods ended March 31, 2018 and March 31, 2017, respectively. Unrecognized compensation expense for these awards as of March 31, 2018 was $6.6 million and will be amortized over the next 28 months .

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Lease Commitments — The Company leases 107 buildings and offices under non-cancelable operating leases. The leases contain various provisions for increases in rental rates, based either on changes in the published Consumer Price Index or a predetermined escalation schedule. Substantially all of the leases provide the Company with the option to extend the lease term one or more times following expiration of the initial term. Financial Instruments with Off-Balance-Sheet Risk — The Company has financial instruments with off-balance-sheet risk generated in the normal course of business to meet the financing needs of our customers. These financial instruments include commitments to extend credit, commitments related to standby letters of credit, commitments to originate loans, commitments to sell loans, commitments to buy and sell securities. These instruments involve, to varying degrees, elements of credit and interest rate risk similar to the risk involved in on-balance-sheet items recognized in our Consolidated Statements of Financial Condition. Our exposure to credit loss in the event of nonperformance by the other party to the financial instrument from commitments to extend credit and standby letters of credit is represented by the contractual notional amount of those instruments. We use the same credit policies in making commitments and conditional obligations as for on-balance-sheet instruments. Outstanding commitments for which no asset or liability for the notional amount has been recorded consisted of the following at the dates indicated (in thousands): Contract or Notional Amount March 31, 2018 December 31, 2017 Commitments to extend credit $ 2,386,614 $ 2,300,593 Standby letters of credit and financial guarantees 13,958 14,579 Commitments to originate loans 66,479 56,030 Risk participation agreement 4,141 11,451 Derivatives also included in Note 13: Commitments to originate loans held for sale 47,848 43,502 Commitments to sell loans secured by one- to four-family residential properties 38,409 33,069 Commitments to sell securities related to mortgage banking activities 107,500 57,000 Commitments to extend credit are agreements to lend to a customer, as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Many of the commitments may expire without being drawn upon; therefore, the total commitment amounts do not necessarily represent future cash requirements. Each customer’s creditworthiness is evaluated on a case-by-case basis. The amount of collateral obtained, if deemed necessary upon extension of credit, is based on management’s credit evaluation of the customer. The type of collateral held varies, but may include accounts receivable, inventory, property, plant and equipment, and income producing commercial properties. The Company's reserve for unfunded loan commitments was $2.4 million and $2.4 million at March 31, 2018 and December 31, 2017 , respectively. Standby letters of credit are conditional commitments issued to guarantee a customer’s performance or payment to a third party. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. Through the acquisition of AmericanWest, Banner Bank assumed a risk participation agreement. Under the risk participation agreement, Banner Bank guarantees the financial performance of a borrower on the participated portion of an interest rate swap on a loan. Interest rates on residential one- to four-family mortgage loan applications are typically rate locked (committed) to customers during the application stage for periods ranging from 30 to 60 days, the most typical period being 45 days. Traditionally, these loan applications with rate lock commitments had the pricing for the sale of these loans locked with various qualified investors under a best-efforts delivery program at or near the time the interest rate is locked with the customer. The Bank then attempts to deliver these loans before their rate locks expired. This arrangement generally required delivery of the loans prior to the expiration of the rate lock. Delays in funding the loans required a lock extension. The cost of a lock extension at times was borne by the customer and at times by the Bank. These lock extension costs have not had a material impact to our operations. The Company enters into forward commitments at specific prices and settlement dates to deliver either: (1) residential mortgage loans for purchase by secondary market investors (i.e., Freddie Mac or Fannie Mae), or (2) mortgage-backed securities to broker/dealers. The purpose of these forward commitments is to offset the movement in interest rates between the execution of its residential mortgage rate lock commitments with borrowers and the sale of those loans to the secondary market investor. There were no counterparty default losses on forward contracts during the three months ended March 31, 2018 or March 31, 2017 . Market risk with respect to forward contracts arises principally from changes in the value of contractual positions due to changes in interest rates. The Company limits its exposure to market risk by monitoring differences between commitments to customers and forward contracts with market investors and securities broker/dealers. In the event the Company has forward delivery contract commitments in excess of available mortgage loans, the transaction is completed by either paying or receiving a fee to or from the investor or broker/dealer equal to the increase or decrease in the market value of the forward contract. In the normal course of business, the Company and/or its subsidiaries have various legal proceedings and other contingent matters outstanding. These proceedings and the associated legal claims are often contested and the outcome of individual matters is not always predictable. These claims and counter-claims typically arise during the course of collection efforts on problem loans or with respect to action to enforce liens on properties in which the Banks hold a security interest. Based upon the information known to management at this time, the Company and the Banks are not a party to any legal proceedings that management believes would have a material adverse effect on the results of operations or consolidated financial position at March 31, 2018 . In connection with certain asset sales, the Banks typically make representations and warranties about the underlying assets conforming to specified guidelines. If the underlying assets do not conform to the specifications, the Bank may have an obligation to repurchase the assets or indemnify the purchaser against any loss. The Banks believe that the potential for material loss under these arrangements is remote. Accordingly, the fair value of such obligations is not material.

DERIVATIVES AND HEDGING

DERIVATIVES AND HEDGING	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES AND HEDGING	DERIVATIVES AND HEDGING The Company, through its Banner Bank subsidiary, is party to various derivative instruments that are used for asset and liability management and customer financing needs. Derivative instruments are contracts between two or more parties that have a notional amount and an underlying variable, require no net investment and allow for the net settlement of positions. The notional amount serves as the basis for the payment provision of the contract and takes the form of units, such as shares or dollars. The underlying variable represents a specified interest rate, index, or other component. The interaction between the notional amount and the underlying variable determines the number of units to be exchanged between the parties and influences the market value of the derivative contract. The Company obtains dealer quotations to value its derivative contracts. The Company's predominant derivative and hedging activities involve interest rate swaps related to certain term loans and forward sales contracts associated with mortgage banking activities. Generally, these instruments help the Company manage exposure to market risk and meet customer financing needs. Market risk represents the possibility that economic value or net interest income will be adversely affected by fluctuations in external factors such as market-driven interest rates and prices or other economic factors. Derivatives Designated in Hedge Relationships The Company's fixed rate loans result in exposure to losses in value or net interest income as interest rates change. The risk management objective for hedging fixed rate loans is to effectively convert the fixed rate received to a floating rate. The Company has hedged exposure to changes in the fair value of certain fixed rate loans through the use of interest rate swaps. For a qualifying fair value hedge, changes in the value of the derivatives are recognized in current period earnings along with the corresponding changes in the fair value of the designated hedged item attributable to the risk being hedged. Under a prior program, customers received fixed interest rate commercial loans and the Banner Bank subsequently hedged that fixed rate loan by entering into an interest rate swap with a dealer counterparty. Banner Bank receives fixed rate payments from the customers on the loans and makes similar fixed rate payments to the dealer counterparty on the swaps in exchange for variable rate payments based on the one-month LIBOR index. Some of these interest rate swaps are designated as fair value hedges. Through application of the “short cut method of accounting,” there is an assumption that the hedges are effective. Banner Bank discontinued originating interest rate swaps under this program in 2008. As of March 31, 2018 and December 31, 2017 , the notional values or contractual amounts and fair values of the Company's derivatives designated in hedge relationships were as follows (in thousands): Asset Derivatives Liability Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (2) Notional/ Contract Amount Fair Value (2) Interest rate swaps $ 4,257 $ 355 $ 4,350 $ 447 $ 4,257 $ 355 $ 4,350 $ 447 (1) Included in Loans receivable on the Consolidated Statements of Financial Condition. (2) Included in Other liabilities on the Consolidated Statements of Financial Condition. Derivatives Not Designated in Hedge Relationships Interest Rate Swaps: Banner Bank uses an interest rate swap program for commercial loan customers, that provides the client with a variable rate loan and enters into an interest rate swap in which the client locks in a fixed rate and the Bank receives a variable rate payment. The Bank offsets its risk exposure by entering into an offsetting interest rate swap with a dealer counterparty for the same notional amount and length of term as the client interest rate swap providing the dealer counterparty with a fixed-rate payment in exchange for a variable-rate payment. These swaps do not qualify as designated hedges; therefore, each swap is accounted for as a free standing derivative. Mortgage Banking: In the normal course of business, the Company sells originated one- to four-family and multifamily mortgage loans into the secondary mortgage loan markets. During the period of loan origination and prior to the sale of the loans in the secondary market, the Company has exposure to movements in interest rates associated with written interest rate lock commitments with potential borrowers to originate one- to four-family loans that are intended to be sold and for closed one- to four-family and multifamily mortgage loans held for sale that are awaiting sale and delivery into the secondary market. The Company attempts to economically hedge the risk of changing interest rates associated with these mortgage loan commitments by entering into forward sales contracts to sell one- to four-family and multifamily mortgage loans or mortgage-backed securities to broker/dealers as specific prices and dates. As of March 31, 2018 and December 31, 2017 , the notional values or contractual amounts and fair values of the Company's derivatives not designated in hedge relationships were as follows (in thousands): Asset Derivatives Liability Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (2) Notional/ Contract Amount Fair Value (2) Interest rate swaps $ 272,627 $ 4,236 $ 285,047 $ 4,636 $ 272,627 $ 4,236 $ 285,047 $ 4,636 Mortgage loan commitments 30,799 294 29,739 225 17,049 153 13,763 153 Forward sales contracts 98,409 389 43,069 298 47,500 107 47,000 48 $ 401,835 $ 4,919 $ 357,855 $ 5,159 $ 337,176 $ 4,496 $ 345,810 $ 4,837 (1) Included in Other assets on the Consolidated Statements of Financial Condition, with the exception of certain interest swaps and mortgage loan commitments (with a fair value of $381,000 at March 31, 2018 and $499,000 at December 31, 2017 ), which are included in Loans receivable. (2) Included in Other liabilities on the Consolidated Statements of Financial Condition. Gains (losses) recognized in income on derivatives not designated in hedge relationships for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Location on Consolidated Statements of Operations Three Months Ended 2018 2017 Mortgage loan commitments Mortgage banking operations $ 68 $ 361 Forward sales contracts Mortgage banking operations (11 ) (474 ) $ 57 $ (113 ) The Company is exposed to credit-related losses in the event of nonperformance by the counterparty to these agreements. Credit risk of the financial contract is controlled through the credit approval, limits, and monitoring procedures and management does not expect the counterparties to fail their obligations. In connection with the interest rate swaps between Banner Bank and the dealer counterparties, the agreements contain a provision where if Banner Bank fails to maintain its status as a well/adequately capitalized institution, then the counterparty could terminate the derivative positions and Banner Bank would be required to settle its obligations. Similarly, Banner Bank could be required to settle its obligations under certain of its agreements if specific regulatory events occur, such as a publicly issued prompt corrective action directive, cease and desist order, or a capital maintenance agreement that required Banner Bank to maintain a specific capital level. If Banner Bank had breached any of these provisions at March 31, 2018 or December 31, 2017 , it could have been required to settle its obligations under the agreements at the termination value. As of March 31, 2018 and December 31, 2017 , the termination value of derivatives in a net liability position related to these agreements was $800,000 and $3.7 million , respectively. The Company generally posts collateral against derivative liabilities in the form of cash, government agency-issued bonds, mortgage-backed securities, or commercial mortgage-backed securities. Collateral posted against derivative liabilities was $17.1 million and $16.9 million as of March 31, 2018 and December 31, 2017 , respectively. Derivative assets and liabilities are recorded at fair value on the balance sheet and do not take into account the effects of master netting agreements. Master netting agreements allow the Company to settle all derivative contracts held with a single counterparty on a net basis and to offset net derivative positions with related collateral where applicable. The following tables illustrate the potential effect of the Company's derivative master netting arrangements, by type of financial instrument, on the Company's Consolidated Statements of Financial Condition as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Gross Amounts of Financial Instruments Not Offset in the Consolidated Statements of Financial Condition Gross Amounts Recognized Amounts offset in the Statement of Financial Condition Net Amounts in the Statement of Financial Condition Netting Adjustment Per Applicable Master Netting Agreements Fair Value of Financial Collateral in the Statement of Financial Condition Net Amount Derivative assets Interest rate swaps $ 4,592 $ — $ 4,592 $ (123 ) $ — $ 4,469 $ 4,592 $ — $ 4,592 $ (123 ) $ — $ 4,469 Derivative liabilities Interest rate swaps $ 4,592 $ — $ 4,592 $ (123 ) $ (767 ) $ 3,702 $ 4,592 $ — $ 4,592 $ (123 ) $ (767 ) $ 3,702 December 31, 2017 Gross Amounts of Financial Instruments Not Offset in the Consolidated Statements of Financial Condition Gross Amounts Recognized Amounts offset in the Statement of Financial Condition Net Amounts in the Statement of Financial Condition Netting Adjustment Per Applicable Master Netting Agreements Fair Value of Financial Collateral in the Statement of Financial Condition Net Amount Derivative assets Interest rate swaps $ 5,083 $ — $ 5,083 $ (656 ) $ — $ 4,427 $ 5,083 $ — $ 5,083 $ (656 ) $ — $ 4,427 Derivative liabilities Interest rate swaps $ 5,083 $ — $ 5,083 $ (656 ) $ (3,467 ) $ 960 $ 5,083 $ — $ 5,083 $ (656 ) $ (3,467 ) $ 960

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS (Notes)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	REVENUE FROM CONTRACTS WITH CUSTOMERS Disaggregation of Revenue: Deposit fees and other service charges for the three months ended March 31, 2018 and 2017 are summarized as follows (in thousands): Three Months Ended 2018 2017 Deposit service charges $ 4,320 $ 4,062 Debit and credit interchange fees 7,320 6,538 Debit and credit card expense (1,970 ) (1,687 ) Merchant services income 2,261 2,187 Merchant services expenses (1,804 ) (1,797 ) Other service charges 1,169 1,086 Total deposit fees and other service charges $ 11,296 $ 10,389 Deposit fees and other service charges Deposit fees and other service charges include transaction and non-transaction based deposit fees. Transaction based fees on deposit accounts are charged to deposit customers for specific services provided to the customer. These fees include such items as wire fees, official check fees, and overdraft fees. These are contract specific to each individual transaction and do not extend beyond the individual transaction. The performance obligation is completed and the fees are recognized at the time the specific transactional service is provided to the customer. Non-transactional deposit fees are typically monthly account maintenance fees charged on deposit accounts. These are day-to-day contracts that can be canceled by either party without notice. The performance obligation is satisfied and the fees are recognized on a monthly basis after the service period is completed. Debit and credit card interchange income and expenses Debit and credit card interchange income represent fees earned when a credit or debit card issued by the Banks is used to purchase goods or services at a merchant. The merchant's bank pays the Banks a default interchange rate set by MasterCard on a transaction by transaction basis. The merchant acquiring bank can stop accepting the Banks’ cards at any time and the Banks can stop further use of cards issued by them at any time. The performance obligation is satisfied and the fees are earned when the cost of the transaction is charged to the Banks cardholders’ card. Direct expenses associated with the credit and debit card are recorded as a net reduction against the interchange income. Merchant services income Merchant services income represents fees earned by the Banks for card payment services provided to its merchant customers. The Banks have a contract with a third party to provide card payment services to the Banks’ merchants that contract for those services. The third party provider has contracts with the Banks’ merchants to provide the card payment services. The Banks do not have a direct contractual relationship with its merchants for these services. The Banks set the rates for the services provided by the third party. The third party provider passes the payments made by the Banks’ merchants through to the Banks. The Banks, in turn, pays the third party provider for the services it provides to the Banks’ merchants. These payments to the third party provider are recorded as expenses as a net reduction against fee income. In addition, a portion of the payment received by the Banks represents interchange fees which are passed through to the card issuing bank. Income is primarily earned based on the dollar volume and number of transactions processed. The performance obligation is satisfied and the related fee is earned when each payment is accepted by the processing network.

BASIS OF PRESENTATION AND SIG23

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	The accompanying unaudited condensed consolidated financial statements include the accounts of Banner Corporation (the Company or Banner), a bank holding company incorporated in the State of Washington and its wholly-owned subsidiaries, Banner Bank and Islanders Bank (the Banks). These unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X as promulgated by the Securities and Exchange Commission (SEC). In preparing these financial statements, the Company has evaluated events and transactions subsequent to March 31, 2018 for potential recognition or disclosure. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the financial position and results of operations for the periods presented have been included. Certain information and disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC and the accounting standards for interim financial statements. Certain reclassifications have been made to the 2017 Consolidated Financial Statements and/or schedules to conform to the 2018 presentation. These reclassifications may have affected certain ratios for the prior periods. The effect of these reclassifications is considered immaterial. All significant intercompany transactions and balances have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect amounts reported in the financial statements. Various elements of the Company’s accounting policies, by their nature, are inherently subject to estimation techniques, valuation assumptions and other subjective assessments. In particular, management has identified several accounting policies that, due to the judgments, estimates and assumptions inherent in those policies, are significant to an understanding of Banner’s financial statements. These policies relate to (i) the methodology for the recognition of interest income, (ii) determination of the provision and allowance for loan losses, (iii) the valuation of financial assets and liabilities recorded at fair value, including other-than-temporary impairment (OTTI) losses, (iv) the valuation of intangibles, such as goodwill, core deposit intangibles (CDI) and mortgage servicing rights, (v) the valuation of real estate held for sale, (vi) the valuation of assets and liabilities acquired in business combinations and subsequent recognition of related income and expense, and (vii) the valuation or recognition of deferred tax assets and liabilities. These policies and judgments, estimates and assumptions are described in greater detail in subsequent notes to the Consolidated Financial Statements and Management’s Discussion and Analysis of Financial Condition and Results of Operations (Critical Accounting Policies) in our Annual Report on Form 10-K for the year ended December 31, 2017 filed with the SEC (2017 Form 10-K). There have been no significant changes in our application of these accounting policies during the first three months of 2018 , except as described in Note 2. The information included in this Form 10-Q should be read in conjunction with our 2017 Form 10-K. Interim results are not necessarily indicative of results for a full year or any other interim period.

ACCOUNTING STANDARDS RECENTLY24

ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED Impact of new revenue standard on Consolidated Statements of Operations (Tables)	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The following table presents the impact of adopting of the new revenue standard on our Consolidated Statements of Operations for the three months ended March 31, 2018 and 2017 (in thousands): For the three months ended March 31, 2018 For the three months ended March 31, 2017 As Reported Balance without Adoption of ASC 606 Effect of Change As Reported Balance without Adoption of ASC 606 Effect of Change Non-interest income: Deposit fees and other service charges $ 11,296 $ 13,100 $ (1,804 ) $ 10,389 $ 12,186 $ (1,797 ) Non-interest expense: Payment and card processing expenses $ 3,700 $ 5,504 $ (1,804 ) $ 3,223 $ 5,020 $ (1,797 )

SECURITIES (Tables)

SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Securities	The amortized cost, gross unrealized gains and losses and estimated fair value of securities at March 31, 2018 and December 31, 2017 are summarized as follows (in thousands): March 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Trading: Municipal bonds $ 100 $ 100 Corporate bonds 27,175 25,474 $ 27,275 $ 25,574 Available-for-Sale: U.S. Government and agency obligations $ 145,280 $ 10 $ (1,984 ) $ 143,306 Municipal bonds 69,516 315 (873 ) 68,958 Corporate bonds 6,152 5 (45 ) 6,112 Mortgage-backed or related securities 1,179,084 718 (19,389 ) 1,160,413 Asset-backed securities 27,732 128 (144 ) 27,716 $ 1,427,764 $ 1,176 $ (22,435 ) $ 1,406,505 Held-to-Maturity: U.S. Government and agency obligations $ 1,260 $ 27 $ — $ 1,287 Municipal bonds: 192,931 2,334 (2,644 ) 192,621 Corporate bonds 3,941 — (8 ) 3,933 Mortgage-backed or related securities 64,513 19 (1,455 ) 63,077 $ 262,645 $ 2,380 $ (4,107 ) $ 260,918 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Trading: Municipal bonds $ 100 $ 100 Corporate bonds 27,132 22,058 Equity securities 14 160 $ 27,246 $ 22,318 Available-for-Sale: U.S. Government and agency obligations $ 72,829 $ 68 $ (431 ) $ 72,466 Municipal bonds 68,513 665 (445 ) 68,733 Corporate bonds 5,431 6 (44 ) 5,393 Mortgage-backed or related securities 745,956 1,003 (7,402 ) 739,557 Asset-backed securities 27,667 184 (93 ) 27,758 Equity securities 5,716 10 (148 ) 5,578 $ 926,112 $ 1,936 $ (8,563 ) $ 919,485 Held-to-Maturity: U.S. Government and agency obligations $ 1,024 $ 29 $ — $ 1,053 Municipal bonds: 189,860 3,385 (1,252 ) 191,993 Corporate bonds 3,978 7 — 3,985 Mortgage-backed or related securities 65,409 266 (518 ) 65,157 $ 260,271 $ 3,687 $ (1,770 ) $ 262,188
Schedule of Securities with Continuous Loss Position	At March 31, 2018 and December 31, 2017 , the gross unrealized losses and the fair value for securities available-for-sale and held-to-maturity aggregated by the length of time that individual securities have been in a continuous unrealized loss position was as follows (in thousands): March 31, 2018 Less Than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-Sale: U.S. Government and agency obligations $ 112,704 $ (1,479 ) $ 22,943 $ (505 ) $ 135,647 $ (1,984 ) Municipal bonds 30,019 (463 ) 13,065 (410 ) 43,084 (873 ) Corporate bonds 647 (7 ) 4,550 (38 ) 5,197 (45 ) Mortgage-backed or related securities 835,758 (15,250 ) 114,653 (4,139 ) 950,411 (19,389 ) Asset-backed securities — — 9,873 (144 ) 9,873 (144 ) $ 979,128 $ (17,199 ) $ 165,084 $ (5,236 ) $ 1,144,212 $ (22,435 ) Held-to-Maturity Municipal bonds $ 55,484 $ (669 ) $ 32,189 $ (1,975 ) $ 87,673 $ (2,644 ) Corporate bonds 492 (8 ) — — 492 (8 ) Mortgage-backed or related securities 54,224 (1,229 ) 4,315 (226 ) 58,539 (1,455 ) $ 110,200 $ (1,906 ) $ 36,504 $ (2,201 ) $ 146,704 $ (4,107 ) December 31, 2017 Less Than 12 Months 12 Months or More Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-Sale: U.S. Government and agency obligations $ 31,276 $ (211 ) $ 23,341 $ (220 ) $ 54,617 $ (431 ) Municipal bonds 20,879 (185 ) 13,360 (260 ) 34,239 (445 ) Corporate bonds 296 (4 ) 4,682 (40 ) 4,978 (44 ) Mortgage-backed or related securities 559,916 (5,138 ) 100,662 (2,264 ) 660,578 (7,402 ) Asset-backed securities — — 9,926 (93 ) 9,926 (93 ) Equity securities 5,480 (148 ) — — 5,480 (148 ) $ 617,847 $ (5,686 ) $ 151,971 $ (2,877 ) $ 769,818 $ (8,563 ) Held-to-Maturity Municipal bonds 21,839 (171 ) 34,314 (1,081 ) 56,153 (1,252 ) Mortgage-backed or related securities 38,023 (378 ) 4,434 (140 ) 42,457 (518 ) $ 59,862 $ (549 ) $ 38,748 $ (1,221 ) $ 98,610 $ (1,770 )
Schedule of Securities by Contractual Maturity Date	The amortized cost and estimated fair value of securities at March 31, 2018 , by contractual maturity, are shown below (in thousands). Expected maturities will differ from contractual maturities because some securities may be called or prepaid with or without call or prepayment penalties. March 31, 2018 Trading Available-for-Sale Held-to-Maturity Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Maturing in one year or less $ 100 $ 100 $ 3,090 $ 3,081 $ 1,943 $ 1,942 Maturing after one year through five years — — 63,013 62,113 38,334 37,896 Maturing after five years through ten years — — 281,112 276,039 96,044 95,696 Maturing after ten years through twenty years 17,175 16,889 186,470 184,722 84,150 85,000 Maturing after twenty years 10,000 8,585 894,079 880,550 42,174 40,384 $ 27,275 $ 25,574 $ 1,427,764 $ 1,406,505 $ 262,645 $ 260,918
Schedule of Pledged Securities	The following table presents, as of March 31, 2018 , investment securities which were pledged to secure borrowings, public deposits or other obligations as permitted or required by law (in thousands): March 31, 2018 Carrying Value Amortized Cost Fair Value Purpose or beneficiary: State and local governments public deposits $ 129,288 $ 129,325 $ 130,478 Interest rate swap counterparties 14,924 15,089 14,762 Repurchase agreements 118,820 120,410 118,588 Other 3,900 3,900 3,744 Total pledged securities $ 266,932 $ 268,724 $ 267,572

LOANS RECEIVABLE AND THE ALLO26

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Schedule of Loans Receivable, Including Loans Held for Sale	Loans receivable at March 31, 2018 and December 31, 2017 are summarized as follows (dollars in thousands): March 31, 2018 December 31, 2017 Amount Percent of Total Amount Percent of Total Commercial real estate: Owner-occupied $ 1,278,814 16.9 % $ 1,284,363 16.9 % Investment properties 1,876,937 24.8 1,937,423 25.5 Multifamily real estate 321,039 4.2 314,188 4.1 Commercial construction 163,314 2.2 148,435 2.0 Multifamily construction 159,108 2.1 154,662 2.0 One- to four-family construction 434,204 5.7 415,327 5.5 Land and land development: Residential 167,783 2.2 164,516 2.2 Commercial 24,331 0.3 24,583 0.3 Commercial business 1,296,691 17.2 1,279,894 16.8 Agricultural business, including secured by farmland 307,243 4.2 338,388 4.4 One- to four-family residential 833,598 11.0 848,289 11.2 Consumer: Consumer secured by one- to four-family 522,826 6.9 522,931 6.9 Consumer—other 170,158 2.3 165,885 2.2 Total loans 7,556,046 100.0 % 7,598,884 100.0 % Less allowance for loan losses (92,207 ) (89,028 ) Net loans $ 7,463,839 $ 7,509,856 Loan amounts are net of unearned loan fees in excess of unamortized costs of $731,000 as of March 31, 2018 and were net of unamortized costs of $158,000 as of December 31, 2017 . Net loans include net discounts on acquired loans of $19.4 million and $21.1 million as of March 31, 2018 and December 31, 2017 , respectively.
Schedule of Purchased Credit-Impaired Loans, Changes in Accretable Yield	The following table presents the changes in the accretable yield for PCI loans for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended 2018 2017 Balance, beginning of period $ 6,520 $ 8,717 Accretion to interest income (1,097 ) (1,320 ) Disposals 58 — Reclassifications from non-accretable difference 807 1,273 Balance, end of period $ 6,288 $ 8,670
Impaired loans excluding purchased credit impaired loans [Table Text Block]	The following tables provide information on impaired loans, excluding PCI loans, with and without allowance reserves at March 31, 2018 and December 31, 2017 . Recorded investment includes the unpaid principal balance or the carrying amount of loans less charge-offs and net deferred loan fees (in thousands): March 31, 2018 Unpaid Principal Balance Recorded Investment Related Allowance Without Allowance (1) With Allowance (2) Commercial real estate: Owner-occupied $ 3,872 $ 3,444 $ 199 $ 20 Investment properties 9,346 3,433 5,699 264 One- to four-family construction 186 186 — — Land and land development: Residential 1,134 798 — — Commercial business 4,008 3,038 534 39 Agricultural business/farmland 9,598 6,440 3,031 201 One- to four-family residential 8,579 3,136 5,362 182 Consumer: Consumer secured by one- to four-family 1,346 1,168 138 7 Consumer—other 180 76 71 4 $ 38,249 $ 21,719 $ 15,034 $ 717 December 31, 2017 Unpaid Principal Balance Recorded Investment Related Allowance Without Allowance (1) With Allowance (2) Commercial real estate: Owner-occupied $ 7,807 $ 6,447 $ 199 $ 18 Investment properties 11,296 4,200 6,884 263 One- to four-family construction 298 298 — — Land and land development: Residential 1,134 798 — — Commercial business 4,441 3,424 555 50 Agricultural business/farmland 9,388 6,230 3,031 264 One- to four-family residential 9,547 3,709 5,775 178 Consumer: Consumer secured by one- to four-family 1,498 1,324 139 7 Consumer—other 134 58 73 2 $ 45,543 $ 26,488 $ 16,656 $ 782 (1) Includes loans without an allowance reserve that have been individually evaluated for impairment and that evaluation concluded that no reserve was needed, and $10.6 million of homogenous and small balance loans as of both March 31, 2018 and December 31, 2017 , that are collectively evaluated for impairment for which a general reserve has been established. (2) Loans with a specific allowance reserve have been individually evaluated for impairment using either a discounted cash flow analysis or, for collateral dependent loans, current appraisals less costs to sell to establish realizable value.
Schedule of Impaired Loans With and Without Specific Reserves	The following tables summarize our average recorded investment and interest income recognized on impaired loans by loan class for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended Three Months Ended Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized Commercial real estate: Owner-occupied $ 5,383 $ 3 $ 2,916 $ 2 Investment properties 9,972 83 8,893 49 Multifamily real estate — — 495 4 One- to four-family construction 605 4 1,180 20 Land and land development: Residential 798 — 1,899 17 Commercial — — 977 — Commercial business 4,007 7 4,504 7 Agricultural business/farmland 9,109 33 6,282 32 One- to four-family residential 8,892 101 10,404 83 Consumer: Consumer secured by one- to four-family 1,390 2 1,742 3 Consumer—other 149 1 268 3 $ 40,305 $ 234 $ 39,560 $ 220
Schedule of Troubled Debt Restructurings	The following table presents TDRs by accrual and nonaccrual status at March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Accrual Status Nonaccrual Status Total TDRs Accrual Nonaccrual Total Commercial real estate: Owner-occupied $ 199 $ 85 $ 284 $ 199 $ 87 $ 286 Investment properties 5,699 — 5,699 6,884 — 6,884 Commercial business 534 — 534 555 — 555 Agricultural business, including secured by farmland 2,531 29 2,560 3,129 29 3,158 One- to four-family residential 5,092 457 5,549 5,136 801 5,937 Consumer: Consumer secured by one- to four-family 138 — 138 139 — 139 Consumer—other 71 — 71 73 — 73 $ 14,264 $ 571 $ 14,835 $ 16,115 $ 917 $ 17,032 As of both March 31, 2018 and December 31, 2017 , the Company had commitments to advance additional funds related to TDRs up to $45,000 .
Schedule of Risk-Rated Loans and Non-Risk Rated Loans by Grade and Other Characteristics	The following tables present the Company’s portfolio of risk-rated loans and non-risk-rated loans by grade or other characteristics as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 By class: Pass (Risk Ratings 1-5) (1) Special Mention Substandard Doubtful Loss Total Loans Commercial real estate: Owner-occupied $ 1,244,007 $ 13,686 $ 21,121 $ — $ — $ 1,278,814 Investment properties 1,866,062 — 10,875 — — 1,876,937 Multifamily real estate 320,533 — 506 — — 321,039 Commercial construction 163,314 — — — — 163,314 Multifamily construction 159,108 — — — — 159,108 One- to four-family construction 429,172 — 5,032 — — 434,204 Land and land development: Residential 156,144 10,321 1,318 — — 167,783 Commercial 21,507 — 2,824 — — 24,331 Commercial business 1,228,831 16,599 51,152 109 — 1,296,691 Agricultural business, including secured by farmland 286,925 6,203 14,115 — — 307,243 One- to four-family residential 827,788 553 5,257 — — 833,598 Consumer: Consumer secured by one- to four-family 520,263 — 2,563 — — 522,826 Consumer—other 169,889 11 258 — — 170,158 Total $ 7,393,543 $ 47,373 $ 115,021 $ 109 $ — $ 7,556,046 December 31, 2017 By class: Pass (Risk Ratings 1-5) (1) Special Mention Substandard Doubtful Loss Total Loans Commercial real estate: Owner-occupied $ 1,246,125 $ 12,227 $ 26,011 $ — $ — $ 1,284,363 Investment properties 1,918,940 9,118 9,365 — — 1,937,423 Multifamily real estate 313,432 — 756 — — 314,188 Commercial construction 148,435 — — — — 148,435 Multifamily construction 154,662 — — — — 154,662 One- to four-family construction 411,802 — 3,525 — — 415,327 Land and land development: Residential 153,073 10,554 889 — — 164,516 Commercial 21,665 — 2,918 — — 24,583 Commercial business 1,213,365 12,135 54,282 112 — 1,279,894 Agricultural business, including secured by farmland 321,110 3,852 13,426 — — 338,388 One- to four-family residential 842,304 569 5,416 — — 848,289 Consumer: Consumer secured by one- to four-family 520,675 — 2,256 — — 522,931 Consumer—other 165,594 13 278 — — 165,885 Total $ 7,431,182 $ 48,468 $ 119,122 $ 112 $ — $ 7,598,884 (1) The Pass category includes some performing loans that are part of homogenous pools which are not individually risk-rated. This includes all consumer loans, all one - to four -family residential loans and, as of March 31, 2018 and December 31, 2017 , in the commercial business category, $535.0 million and $296.8 million , respectively, of credit-scored small business loans. As loans in these pools become non-performing, they are individually risk-rated.
Schedule of Age Analysis of the Company's Past Due Loans	The following tables provide additional detail on the age analysis of the Company’s past due loans as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Total Past Due Purchased Credit-Impaired Current Total Loans Loans 90 Days or More Past Due and Accruing Non-accrual Commercial real estate: Owner-occupied $ 189 $ 169 $ 3,079 $ 3,437 $ 6,372 $ 1,269,005 $ 1,278,814 $ — $ 3,444 Investment properties 1,402 — 1,109 2,511 7,072 1,867,354 1,876,937 — 3,433 Multifamily real estate — — — — 167 320,872 321,039 — — Commercial construction — — — — — 163,314 163,314 — — Multifamily construction — — — — — 159,108 159,108 — — One-to-four-family construction 4,323 320 186 4,829 440 428,935 434,204 — 186 Land and land development: Residential — 784 798 1,582 — 166,201 167,783 — 798 Commercial — — — — 2,824 21,507 24,331 — — Commercial business 1,744 702 2,137 4,583 1,829 1,290,279 1,296,691 1 3,037 Agricultural business, including secured by farmland 1,580 — 6,507 8,087 415 298,741 307,243 820 6,120 One- to four-family residential 4,467 476 2,501 7,444 129 826,025 833,598 591 2,815 Consumer: Consumer secured by one- to four-family 1,412 82 584 2,078 — 520,748 522,826 — 1,168 Consumer—other 847 148 35 1,030 68 169,060 170,158 7 69 Total $ 15,964 $ 2,681 $ 16,936 $ 35,581 $ 19,316 $ 7,501,149 $ 7,556,046 $ 1,419 $ 21,070 December 31, 2017 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Total Past Due Purchased Credit-Impaired Current Total Loans Loans 90 Days or More Past Due and Accruing Non-accrual Commercial real estate: Owner-occupied $ 5,323 $ 76 $ 5,490 $ 10,889 $ 7,682 $ 1,265,792 $ 1,284,363 $ — $ 6,447 Investment properties 1,737 — 4,096 5,833 7,166 1,924,424 1,937,423 — 4,199 Multifamily real estate 105 — — 105 169 313,914 314,188 — — Commercial construction — — — — — 148,435 148,435 — — Multifamily construction 3,416 — — 3,416 — 151,246 154,662 — — One-to-four-family construction 4,892 725 298 5,915 446 408,966 415,327 298 — Land and land development: Residential — — 798 798 — 163,718 164,516 — 798 Commercial — — — — 2,919 21,664 24,583 — — Commercial business 1,574 404 2,577 4,555 2,159 1,273,180 1,279,894 18 3,406 Agricultural business, including secured by farmland 598 533 2,017 3,148 565 334,675 338,388 — 6,132 One-to four-family residential 4,475 1,241 2,715 8,431 136 839,722 848,289 1,085 3,264 Consumer: Consumer secured by one- to four-family 1,355 62 713 2,130 — 520,801 522,931 85 1,239 Consumer—other 609 136 15 760 68 165,057 165,885 — 58 Total $ 24,084 $ 3,177 $ 18,719 $ 45,980 $ 21,310 $ 7,531,594 $ 7,598,884 $ 1,486 $ 25,543
Allowance for Credit Losses on Financing Receivables	The following tables provide additional information on the allowance for loan losses and loan balances individually and collectively evaluated for impairment at or for the three months ended March 31, 2018 and 2017 (in thousands): For the Three Months Ended March 31, 2018 Commercial Real Estate Multifamily Real Estate Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Beginning balance $ 22,824 $ 1,633 $ 27,568 $ 18,311 $ 4,053 $ 2,055 $ 3,866 $ 8,718 $ 89,028 Provision for loan losses (715 ) 959 1,024 1,923 (1,047 ) 1,450 1,913 (3,507 ) 2,000 Recoveries 1,352 — 174 170 — 290 112 — 2,098 Charge-offs — — — (519 ) (7 ) (16 ) (377 ) — (919 ) Ending balance $ 23,461 $ 2,592 $ 28,766 $ 19,885 $ 2,999 $ 3,779 $ 5,514 $ 5,211 $ 92,207 March 31, 2018 Commercial Real Estate Multifamily Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Individually evaluated for impairment $ 284 $ — $ — $ 39 $ 201 $ 182 $ 11 $ — $ 717 Collectively evaluated for impairment 23,177 2,592 28,766 19,799 2,707 3,597 5,503 5,211 91,352 Purchased credit-impaired loans — — — 47 91 — — — 138 Total allowance for loan losses $ 23,461 $ 2,592 $ 28,766 $ 19,885 $ 2,999 $ 3,779 $ 5,514 $ 5,211 $ 92,207 Loan balances: Individually evaluated for impairment $ 11,607 $ — $ 750 $ 534 $ 7,943 $ 5,092 $ 208 $ — $ 26,134 Collectively evaluated for impairment 3,130,700 320,872 944,726 1,294,328 298,885 828,377 692,708 — 7,510,596 Purchased credit-impaired loans 13,444 167 3,264 1,829 415 129 68 — 19,316 Total loans $ 3,155,751 $ 321,039 $ 948,740 $ 1,296,691 $ 307,243 $ 833,598 $ 692,984 $ — $ 7,556,046 For the Three Months Ended March 31, 2017 Commercial Real Estate Multifamily Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Beginning balance $ 20,993 $ 1,360 $ 34,252 $ 16,533 $ 2,967 $ 2,238 $ 4,104 $ 3,550 $ 85,997 Provision for loan losses (591 ) 18 (4,871 ) 4,688 324 (409 ) 5 2,836 2,000 Recoveries 70 — 83 173 113 145 94 — 678 Charge-offs — — — (1,626 ) (159 ) — (363 ) — (2,148 ) Ending balance $ 20,472 $ 1,378 $ 29,464 $ 19,768 $ 3,245 $ 1,974 $ 3,840 $ 6,386 $ 86,527 March 31, 2017 Commercial Real Estate Multifamily Construction and Land Commercial Business Agricultural Business One- to Four-Family Residential Consumer Unallocated Total Allowance for loan losses: Individually evaluated for impairment $ 419 $ 62 $ 323 $ 62 $ 238 $ 229 $ 11 $ — $ 1,344 Collectively evaluated for impairment 20,053 1,316 29,122 19,706 3,007 1,745 3,829 6,386 85,164 Purchased credit-impaired loans — — 19 — — — — — 19 Total allowance for loan losses $ 20,472 $ 1,378 $ 29,464 $ 19,768 $ 3,245 $ 1,974 $ 3,840 $ 6,386 $ 86,527 Loan balances: Individually evaluated for impairment $ 9,506 $ 347 $ 4,006 $ 2,710 $ 3,815 $ 6,653 $ 220 $ — $ 27,257 Collectively evaluated for impairment 3,341,177 253,725 795,887 1,218,415 308,834 796,026 649,433 — 7,363,497 Purchased credit impaired loans 22,030 174 3,777 3,416 725 312 67 — 30,501 Total loans $ 3,372,713 $ 254,246 $ 803,670 $ 1,224,541 $ 313,374 $ 802,991 $ 649,720 $ — $ 7,421,255

REAL ESTATE OWNED, NET (Tables)

REAL ESTATE OWNED, NET (Tables)	3 Months Ended
	Mar. 31, 2018
Real Estate [Abstract]
Schedule of Changes in Real Estate Owned, Net of Valuation Adjustments	The following table presents the changes in REO for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended 2018 2017 Balance, beginning of the period $ 360 $ 11,081 Additions from loan foreclosures 128 — Proceeds from dispositions of REO — (9,193 ) Gain on sale of REO — 1,202 Valuation adjustments in the period (160 ) (50 ) Balance, end of the period $ 328 $ 3,040

GOODWILL, OTHER INTANGIBLE AS28

GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Goodwill and Intangible Assets	The following table summarizes the changes in the Company’s goodwill and other intangibles for the three months ended March 31, 2018 and the year ended December 31, 2017 (in thousands): Goodwill CDI LHI Total Balance, December 31, 2016 $ 244,583 $ 29,701 $ 461 $ 274,745 Amortization — (6,247 ) (184 ) (6,431 ) Other changes (1) (1,924 ) (1,076 ) — (3,000 ) Balance, December 31, 2017 242,659 22,378 277 265,314 Amortization — (1,382 ) (22 ) (1,404 ) Balance, March 31, 2018 $ 242,659 $ 20,996 $ 255 $ 263,910 (1) Acquired goodwill and CDI were adjusted for the sale of the Utah branches in 2017.
Schedule of Estimated Annual Amortization Expense	The following table presents the estimated amortization expense with respect to CDI for the periods indicated (in thousands): Estimated Amortization Remainder of 2018 $ 3,990 2019 4,683 2020 3,996 2021 3,307 2022 2,524 Thereafter 2,496 $ 20,996
Schedule of Servicing Assets at Amortized Value	An analysis of our mortgage servicing rights for the three months ended March 31, 2018 and 2017 is presented below (in thousands): Three Months Ended 2018 2017 Balance, beginning of the period $ 14,738 $ 15,249 Additions—amounts capitalized 821 945 Additions—through purchase 15 — Amortization (1) (957 ) (922 ) Balance, end of the period (2) $ 14,617 $ 15,272 (1) Amortization of mortgage servicing rights is recorded as a reduction of loan servicing income within mortgage banking operations and any unamortized balance is fully amortized if the loan repays in full. (2) There was no valuation allowance as of March 31, 2018 and 2017 .

DEPOSITS (Tables)

DEPOSITS (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Schedule of Deposit Liabilities	Deposits consisted of the following at March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Non-interest-bearing accounts $ 3,383,439 $ 3,265,544 Interest-bearing checking 1,043,840 971,137 Regular savings accounts 1,637,814 1,557,500 Money market accounts 1,459,614 1,422,313 Total interest-bearing transaction and saving accounts 4,141,268 3,950,950 Certificates of deposit: Certificates of deposit less than or equal to $250,000 865,353 813,997 Certificates of deposit greater than $250,000 153,002 152,940 Total certificates of deposit (1) 1,018,355 966,937 Total deposits $ 8,543,062 $ 8,183,431 Included in total deposits: Public fund transaction and savings accounts $ 190,311 $ 198,719 Public fund interest-bearing certificates 24,928 23,685 Total public deposits $ 215,239 $ 222,404 Total brokered deposits $ 169,523 $ 57,228 (1) Certificates of deposit include $5,000 and $11,000 of acquisition premiums at March 31, 2018 and December 31, 2017 , respectively.
Maturities of Certificates of Deposit	Scheduled maturities and weighted average interest rates of certificate accounts at March 31, 2018 are as follows (dollars in thousands): March 31, 2018 Amount Weighted Average Rate Maturing in one year or less $ 703,650 0.63 % Maturing after one year through two years 146,484 0.98 Maturing after two years through three years 128,810 1.31 Maturing after three years through four years 23,571 1.11 Maturing after four years through five years 13,460 1.33 Maturing after five years 2,380 1.06 Total certificates of deposit $ 1,018,355 0.79 %

FAIR VALUE OF FINANCIAL INSTR30

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Instruments, by Balance Sheet Grouping	The following table presents estimated fair values of the Company’s financial instruments as of March 31, 2018 and December 31, 2017 , whether or not measured at fair value in the Consolidated Statements of Financial Condition (in thousands): March 31, 2018 December 31, 2017 Level Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Assets: Cash and cash equivalents 1 $ 242,048 $ 242,048 $ 261,200 $ 261,200 Securities—trading 2,3 25,574 25,574 22,318 22,318 Securities—available-for-sale 2 1,406,505 1,406,505 919,485 919,485 Securities—held-to-maturity 2 259,204 257,477 256,793 258,710 Securities—held-to-maturity 3 3,441 3,441 3,478 3,478 Loans held for sale 2 141,808 141,898 40,725 40,923 Loans receivable 3 7,556,046 7,462,004 7,598,884 7,445,990 FHLB stock 3 18,036 18,036 10,334 10,334 Bank-owned life insurance 1 163,519 163,519 162,668 162,668 Mortgage servicing rights 3 14,617 20,560 14,738 19,835 Equity securities 1 5,698 5,698 — — Derivatives: Interest rate swaps 2 4,592 4,592 5,083 5,083 Interest rate lock and forward sales commitments 2 683 683 523 523 Liabilities: Demand, interest checking and money market accounts 2 5,886,893 5,886,893 5,658,994 5,658,994 Regular savings 2 1,637,814 1,637,814 1,557,500 1,557,500 Certificates of deposit 2 1,018,355 994,616 966,937 947,517 FHLB advances 2 192,195 192,195 202 202 Other borrowings 2 101,844 101,844 95,860 95,860 Junior subordinated debentures 3 112,516 112,516 98,707 98,707 Derivatives: Interest rate swaps 2 4,592 4,592 5,083 5,083 Interest rate lock and forward sales commitments 2 260 260 201 201
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present financial assets and liabilities measured at fair value on a recurring basis and the level within the fair value hierarchy of the fair value measurements for those assets and liabilities as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Level 1 Level 2 Level 3 Total Assets: Securities—trading Municipal bonds $ — $ 100 $ — $ 100 Corporate bonds (Trust Preferred Securities) — — 25,474 25,474 — 100 25,474 25,574 Securities—available-for-sale U.S. Government and agency obligations — 143,306 — 143,306 Municipal bonds — 68,958 — 68,958 Corporate bonds — 6,112 — 6,112 Mortgage-backed or related securities — 1,160,413 — 1,160,413 Asset-backed securities — 27,716 — 27,716 — 1,406,505 — 1,406,505 Loans held for sale — 137,734 — 137,734 Equity securities — 5,698 — 5,698 Derivatives Interest rate swaps — 4,592 — 4,592 Interest rate lock and forward sales commitments — 683 — 683 $ — $ 1,555,312 $ 25,474 $ 1,580,786 Liabilities: Junior subordinated debentures, net of unamortized deferred issuance costs $ — $ — $ 112,516 $ 112,516 Derivatives Interest rate swaps — 4,592 — 4,592 Interest rate lock and forward sales commitments — 260 — 260 $ — $ 4,852 $ 112,516 $ 117,368 December 31, 2017 Level 1 Level 2 Level 3 Total Assets: Securities—trading Municipal bonds $ — $ 100 $ — $ 100 Corporate Bonds (Trust Preferred Securities) — — 22,058 22,058 Equity securities — 160 — 160 — 260 22,058 22,318 Securities—available-for-sale U.S. Government and agency obligations — 72,466 — 72,466 Municipal bonds — 68,733 — 68,733 Corporate bonds — 5,393 — 5,393 Mortgage-backed securities — 739,557 — 739,557 Asset-backed securities — 27,758 — 27,758 Equity securities — 5,578 — 5,578 — 919,485 — 919,485 Loans held for sale — 32,392 — 32,392 Derivatives Interest rate swaps — 5,083 — 5,083 Interest rate lock and forward sales commitments — 523 — 523 $ — $ 957,743 $ 22,058 $ 979,801 Liabilities: Junior subordinated debentures, net of unamortized deferred issuance costs $ — $ — $ 98,707 $ 98,707 Derivatives Interest rate swaps — 5,083 — 5,083 Interest rate lock and forward sales commitments — 201 — 201 $ — $ 5,284 $ 98,707 $ 103,991
Schedule of Valuation Technique, Unobservable Input, and Qualitative Information for Unobservable Inputs	The following table provides a description of the valuation technique, unobservable inputs, and qualitative information about the unobservable inputs for certain of the Company's assets and liabilities classified as Level 3 and measured at fair value on a recurring and non-recurring basis at March 31, 2018 and December 31, 2017 : Weighted Average Rate / Range Financial Instruments Valuation Techniques Unobservable Inputs March 31, 2018 December 31, 2017 Corporate Bonds (TPS securities) Discounted cash flows Discount rate 6.31 % 6.69 % Junior subordinated debentures Discounted cash flows Discount rate 6.31 % 6.69 % Impaired loans Collateral Valuations Discount to appraised value 8.5 % 8.5% to 20.0% REO Appraisals Discount to appraised value 61 % 42 %
Schedule of Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables provide a reconciliation of the assets and liabilities measured at fair value using significant unobservable inputs (Level 3) on a recurring basis during the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended March 31, 2018 Level 3 Fair Value Inputs TPS Securities Borrowings—Junior Subordinated Debentures Beginning balance $ 22,058 $ 98,707 Total gains or losses recognized Assets gains 3,416 — Liabilities losses (1) — 13,809 Ending balance at March 31, 2018 $ 25,474 $ 112,516 Three Months Ended March 31, 2017 Level 3 Fair Value Inputs TPS Securities Borrowings—Junior Subordinated Debentures Beginning balance $ 21,143 $ 95,200 Total gains or losses recognized Assets gains 218 — Liabilities losses — 840 Ending balance at March 31, 2017 $ 21,361 $ 96,040
Schedule of Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis	The following tables present financial assets measured at fair value on a non-recurring basis and the level within the fair value hierarchy of the fair value measurements for those assets as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Level 1 Level 2 Level 3 Total Impaired loans $ — $ — $ 500 $ 500 REO — — 328 328 December 31, 2017 Level 1 Level 2 Level 3 Total Impaired loans $ — $ — $ 6,535 $ 6,535 REO — — 360 360 The following table presents the losses resulting from non-recurring fair value adjustments for the three months ended March 31, 2018 and 2017 (in thousands): Three months ended March 31, 2018 2017 REO $ (160 ) $ (50 ) Total loss from non-recurring measurements $ (160 ) $ (50 )

INCOME TAXES AND DEFERRED TAX31

INCOME TAXES AND DEFERRED TAXES INCOME TAXES AND DEFERRED TAXES (Tables)	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The following table presents the balances of the Company’s tax credit investments and related unfunded commitments at March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Tax credit investments $ 9,223 $ 7,311 Unfunded commitments—tax credit investments 5,483 4,417 The following table presents other information related to the Company's tax credit investments for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended 2018 2017 Tax credits and other tax benefits recognized $ 364 $ 285 Tax credit amortization expense included in provision for income taxes 288 199

CALCULATION OF WEIGHTED AVERA32

CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE (EPS) (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Weighted Shares Outstanding	The following table reconciles basic to diluted weighted shares outstanding used to calculate earnings per share data (in thousands, except shares and per share data): Three Months Ended 2018 2017 Net income $ 28,790 $ 23,793 Basic weighted average shares outstanding 32,397,568 32,933,444 Plus unvested restricted stock 118,888 118,015 Diluted weighted shares outstanding 32,516,456 33,051,459 Earnings per common share Basic $ 0.89 $ 0.72 Diluted $ 0.89 $ 0.72

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Financial Instruments With Off-Balance-Sheet Risks	Outstanding commitments for which no asset or liability for the notional amount has been recorded consisted of the following at the dates indicated (in thousands): Contract or Notional Amount March 31, 2018 December 31, 2017 Commitments to extend credit $ 2,386,614 $ 2,300,593 Standby letters of credit and financial guarantees 13,958 14,579 Commitments to originate loans 66,479 56,030 Risk participation agreement 4,141 11,451 Derivatives also included in Note 13: Commitments to originate loans held for sale 47,848 43,502 Commitments to sell loans secured by one- to four-family residential properties 38,409 33,069 Commitments to sell securities related to mortgage banking activities 107,500 57,000

DERIVATIVES AND HEDGING (Tables

DERIVATIVES AND HEDGING (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivatives Designated in Hedge Relationships	As of March 31, 2018 and December 31, 2017 , the notional values or contractual amounts and fair values of the Company's derivatives designated in hedge relationships were as follows (in thousands): Asset Derivatives Liability Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (2) Notional/ Contract Amount Fair Value (2) Interest rate swaps $ 4,257 $ 355 $ 4,350 $ 447 $ 4,257 $ 355 $ 4,350 $ 447 (1) Included in Loans receivable on the Consolidated Statements of Financial Condition. (2) Included in Other liabilities on the Consolidated Statements of Financial Condition.
Schedule of Derivatives Not Designated in Hedge Relationships	As of March 31, 2018 and December 31, 2017 , the notional values or contractual amounts and fair values of the Company's derivatives not designated in hedge relationships were as follows (in thousands): Asset Derivatives Liability Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (1) Notional/ Contract Amount Fair Value (2) Notional/ Contract Amount Fair Value (2) Interest rate swaps $ 272,627 $ 4,236 $ 285,047 $ 4,636 $ 272,627 $ 4,236 $ 285,047 $ 4,636 Mortgage loan commitments 30,799 294 29,739 225 17,049 153 13,763 153 Forward sales contracts 98,409 389 43,069 298 47,500 107 47,000 48 $ 401,835 $ 4,919 $ 357,855 $ 5,159 $ 337,176 $ 4,496 $ 345,810 $ 4,837 (1) Included in Other assets on the Consolidated Statements of Financial Condition, with the exception of certain interest swaps and mortgage loan commitments (with a fair value of $381,000 at March 31, 2018 and $499,000 at December 31, 2017 ), which are included in Loans receivable. (2) Included in Other liabilities on the Consolidated Statements of Financial Condition. Gains (losses) recognized in income on derivatives not designated in hedge relationships for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Location on Consolidated Statements of Operations Three Months Ended 2018 2017 Mortgage loan commitments Mortgage banking operations $ 68 $ 361 Forward sales contracts Mortgage banking operations (11 ) (474 ) $ 57 $ (113 )
Offsetting Assets and Liabilities	The following tables illustrate the potential effect of the Company's derivative master netting arrangements, by type of financial instrument, on the Company's Consolidated Statements of Financial Condition as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Gross Amounts of Financial Instruments Not Offset in the Consolidated Statements of Financial Condition Gross Amounts Recognized Amounts offset in the Statement of Financial Condition Net Amounts in the Statement of Financial Condition Netting Adjustment Per Applicable Master Netting Agreements Fair Value of Financial Collateral in the Statement of Financial Condition Net Amount Derivative assets Interest rate swaps $ 4,592 $ — $ 4,592 $ (123 ) $ — $ 4,469 $ 4,592 $ — $ 4,592 $ (123 ) $ — $ 4,469 Derivative liabilities Interest rate swaps $ 4,592 $ — $ 4,592 $ (123 ) $ (767 ) $ 3,702 $ 4,592 $ — $ 4,592 $ (123 ) $ (767 ) $ 3,702 December 31, 2017 Gross Amounts of Financial Instruments Not Offset in the Consolidated Statements of Financial Condition Gross Amounts Recognized Amounts offset in the Statement of Financial Condition Net Amounts in the Statement of Financial Condition Netting Adjustment Per Applicable Master Netting Agreements Fair Value of Financial Collateral in the Statement of Financial Condition Net Amount Derivative assets Interest rate swaps $ 5,083 $ — $ 5,083 $ (656 ) $ — $ 4,427 $ 5,083 $ — $ 5,083 $ (656 ) $ — $ 4,427 Derivative liabilities Interest rate swaps $ 5,083 $ — $ 5,083 $ (656 ) $ (3,467 ) $ 960 $ 5,083 $ — $ 5,083 $ (656 ) $ (3,467 ) $ 960

REVENUE FROM CONTRACTS WITH C35

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	Deposit fees and other service charges for the three months ended March 31, 2018 and 2017 are summarized as follows (in thousands): Three Months Ended 2018 2017 Deposit service charges $ 4,320 $ 4,062 Debit and credit interchange fees 7,320 6,538 Debit and credit card expense (1,970 ) (1,687 ) Merchant services income 2,261 2,187 Merchant services expenses (1,804 ) (1,797 ) Other service charges 1,169 1,086 Total deposit fees and other service charges $ 11,296 $ 10,389

ACCOUNTING STANDARDS RECENTLY36

ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED Available for sale securities - equity securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Securities—available-for-sale	$ 1,406,505	$ 919,485
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities—available-for-sale		$ 5,578

ACCOUNTING STANDARDS RECENTLY37

ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED Revenue Recognition Standard ASC 606 (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Deposit Fees and Other Service Charges	$ 11,296	$ 10,389
Payment and card processing expenses	3,700	3,223
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Deposit Fees and Other Service Charges	13,100	12,186
Payment and card processing expenses	5,504	5,020
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Deposit Fees and Other Service Charges	(1,804)	(1,797)
Payment and card processing expenses	$ (1,804)	$ (1,797)

SECURITIES (Schedule of Securit

SECURITIES (Schedule of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Securities [Line Items]
Securities—trading, Amortized Cost	$ 27,275	$ 27,246
Securities—trading	25,574	22,318
Available-for-sale Securities, Amortized Cost	1,427,764	926,112
Available-for-sale Securities, Gross Unrealized Gains	1,176	1,936
Available-for-sale Securities, Gross Unrealized Losses	(22,435)	(8,563)
Securities—available-for-sale	1,406,505	919,485
Held-to-maturity Securities, Amortized Cost	262,645	260,271
Held-to-maturity Securities, Gross Unrealized Gains	2,380	3,687
Held-to-maturity Securities, Gross Unrealized Losses	4,107	1,770
Securities—held-to-maturity	260,918	262,188
U.S. Government and agency obligations [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	145,280	72,829
Available-for-sale Securities, Gross Unrealized Gains	10	68
Available-for-sale Securities, Gross Unrealized Losses	(1,984)	(431)
Securities—available-for-sale	143,306	72,466
Held-to-maturity Securities, Amortized Cost	1,260	1,024
Held-to-maturity Securities, Gross Unrealized Gains	27	29
Held-to-maturity Securities, Gross Unrealized Losses	0	0
Securities—held-to-maturity	1,287	1,053
Municipal bonds [Member]
Schedule of Securities [Line Items]
Securities—trading, Amortized Cost	100	100
Securities—trading	100	100
Available-for-sale Securities, Amortized Cost	69,516	68,513
Available-for-sale Securities, Gross Unrealized Gains	315	665
Available-for-sale Securities, Gross Unrealized Losses	(873)	(445)
Securities—available-for-sale	68,958	68,733
Held-to-maturity Securities, Amortized Cost	192,931	189,860
Held-to-maturity Securities, Gross Unrealized Gains	2,334	3,385
Held-to-maturity Securities, Gross Unrealized Losses	2,644	1,252
Securities—held-to-maturity	192,621	191,993
Corporate bonds [Member]
Schedule of Securities [Line Items]
Securities—trading, Amortized Cost	27,175	27,132
Securities—trading	25,474	22,058
Available-for-sale Securities, Amortized Cost	6,152	5,431
Available-for-sale Securities, Gross Unrealized Gains	5	6
Available-for-sale Securities, Gross Unrealized Losses	(45)	(44)
Securities—available-for-sale	6,112	5,393
Held-to-maturity Securities, Amortized Cost	3,941	3,978
Held-to-maturity Securities, Gross Unrealized Gains	0	7
Held-to-maturity Securities, Gross Unrealized Losses	8	0
Securities—held-to-maturity	3,933	3,985
Mortgage-backed or related securities [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	1,179,084	745,956
Available-for-sale Securities, Gross Unrealized Gains	718	1,003
Available-for-sale Securities, Gross Unrealized Losses	(19,389)	(7,402)
Securities—available-for-sale	1,160,413	739,557
Held-to-maturity Securities, Amortized Cost	64,513	65,409
Held-to-maturity Securities, Gross Unrealized Gains	19	266
Held-to-maturity Securities, Gross Unrealized Losses	1,455	518
Securities—held-to-maturity	63,077	65,157
Asset-backed Securities [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	27,732	27,667
Available-for-sale Securities, Gross Unrealized Gains	128	184
Available-for-sale Securities, Gross Unrealized Losses	(144)	(93)
Securities—available-for-sale	$ 27,716	27,758
Equity Securities [Member]
Schedule of Securities [Line Items]
Securities—trading, Amortized Cost		14
Securities—trading		160
Available-for-sale Securities, Amortized Cost		5,716
Available-for-sale Securities, Gross Unrealized Gains		10
Available-for-sale Securities, Gross Unrealized Losses		(148)
Securities—available-for-sale		$ 5,578

SECURITIES (Securities with Con

SECURITIES (Securities with Continuous Loss Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 979,128	$ 617,847
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(17,199)	(5,686)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	165,084	151,971
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(5,236)	(2,877)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,144,212	769,818
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(22,435)	(8,563)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	110,200	59,862
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,906	549
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	36,504	38,748
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,201)	(1,221)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	146,704	98,610
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,107	1,770
U.S. Government and agency obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	112,704	31,276
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,479)	(211)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	22,943	23,341
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(505)	(220)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	135,647	54,617
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(1,984)	(431)
Municipal bonds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	30,019	20,879
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(463)	(185)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	13,065	13,360
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(410)	(260)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	43,084	34,239
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(873)	(445)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	55,484	21,839
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	669	171
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	32,189	34,314
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,975)	(1,081)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	87,673	56,153
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,644	1,252
Corporate bonds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	647	296
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(7)	(4)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	4,550	4,682
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(38)	(40)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	5,197	4,978
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(45)	(44)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	492
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	492
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	8
Mortgage-backed or related securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	835,758	559,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(15,250)	(5,138)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	114,653	100,662
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(4,139)	(2,264)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	950,411	660,578
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(19,389)	(7,402)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	54,224	38,023
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,229	378
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	4,315	4,434
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(226)	(140)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	58,539	42,457
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	1,455	518
Asset-backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	9,873	9,926
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(144)	(93)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	9,873	9,926
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (144)	(93)
Equity Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		5,480
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(148)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		5,480
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (148)

SECURITIES (Securities Debt Mat

SECURITIES (Securities Debt Maturities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Trading Securities, Amortized Cost, Maturing in one year or less	$ 100
Trading Securities, Amortized Cost, Maturing after one year through five years	0
Trading Securities, Amortized Cost, Maturing after five years through ten years	0
Trading Securities, Amortized Cost, Maturing after ten years through twenty years	17,175
Trading Securities, Amortized Cost, Maturing after twenty years	10,000
Trading Securities, Amortized Cost	27,275	$ 27,246
Trading Securities, Fair Value, Maturing in one year or less	100
Trading Securities, Fair Value, Maturing after one year through five years	0
Trading Securities, Fair Value, Maturing after five years through ten years	0
Trading Securities, Fair Value, Maturing after ten years through twenty years	16,889
Trading Securities, Fair Value, Maturing after twenty years	8,585
Trading Securities, Fair Value	25,574	22,318
Available-for-sale Securities, Amortized Cost, Maturing in one year or less	3,090
Available-for-sale Securities, Amortized Cost, Maturing after one year through five years	63,013
Available-for-sale Securities, Amortized Cost, Maturing after five years through ten years	281,112
Available-for-sale Securities, Amortized Cost, Maturing after ten years through twenty years	186,470
Available-for-sale Securities, Amortized Cost, Maturing after twenty years	894,079
Available-for-sale Securities, Amortized Cost	1,427,764	926,112
Available-for-sale Securities, Fair Value, Maturing in one year or less	3,081
Available-for-sale Securities, Fair Value, Maturing after one year through five years	62,113
Available-for-sale Securities, Fair Value, Maturing after five years through ten years	276,039
Available-for-sale Securities, Fair Value, Maturing after ten years through twenty years	184,722
Available-for-sale Securities, Fair Value, Maturing after twenty years	880,550
Available-for-sale Securities, Fair Value	1,406,505	919,485
Held-to-maturity Securities, Amortized Cost, Maturing in one year or less	1,943
Held-to-maturity Securities, Amortized Cost, Maturing after one year through five years	38,334
Held-to-maturity Securities, Amortized Cost, Maturing after five years through ten years	96,044
Held-to-maturity Securities, Amortized Cost, Maturing after ten years through twenty years	84,150
Held-to-maturity Securities, Amortized Cost, Maturing after twenty years	42,174
Held-to-maturity Securities, Amortized Cost	262,645	260,271
Held-to-maturity Securities, Fair Value, Maturing in one year or less	1,942
Held-to-maturity Securities, Fair Value, Maturing after one year through five years	37,896
Held-to-maturity Securities, Fair Value, Maturing after five years through ten years	95,696
Held-to-maturity Securities, Fair Value, Maturing after ten years through twenty years	85,000
Held-to-maturity Securities, Fair Value, Maturing after twenty years	40,384
Held-to-maturity Securities, Fair Value	$ 260,918	$ 262,188

SECURITIES (Securities Pledged)

SECURITIES (Securities Pledged) (Details) $ in Thousands	Mar. 31, 2018USD ($)
Pledged Financial Instruments, Not Separately Reported, Securities [Abstract]
Securities pledged for State and Local Government Public Deposits, Carrying Value	$ 129,288
Securities pledged for Interest Rate Swap Counterparties, Carrying Value	14,924
Securities pledged for Repurchase Agreements, Carrying Value	118,820
Pledged Financial Instruments, Not Separately Reported, Interest-bearing Deposits for Other Debt Facilities	3,900
Total pledged securities, Carrying Value	266,932
Securities pledged for State and Local Government public deposits, Amortized Cost	129,325
Securities pledged for Interest Rate Swap Counterparties, Amortized Cost	15,089
Securities pledged for Repurchase Agreements, Amortized Cost	120,410
Pledged Financial Instruments, Not Separately Reported, Interest-bearing Deposits for Other Debt Facilities, Amortized Cost	3,900
Total pledged securities, Amortized Cost	268,724
Securities pledged for State and Local Government Public Deposits, Fair Value	130,478
Securities pledged for Interest Rate Swap Counterparties, Fair Value	14,762
Securities pledged for Retail Repurchase Agreements, Fair Value	118,588
Pledged Financial Instruments, Not Separately Reported, Interest-bearing Deposits for Other Debt Facilities, Fair Value	3,744
Total pledged securities, Fair Value	$ 267,572

SECURITIES (Textual) (Details)

SECURITIES (Textual) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)security	Mar. 31, 2017USD ($)security	Dec. 31, 2017security
Trading Securities [Abstract]
Trading Securities, Sale Proceeds	$ 0	$ 0
Trading Securities, Realized Gain (Loss)	0	0
Trading Securities, OTTI (Recovery) Charges	$ 0	0
Trading Securities, Number of Securities on Nonaccrual Status | security	0		0
Trading Securities, Unrealized Holding Gain	$ 3,373,000	200,000
Available-for-sale Securities [Abstract]
Available-for-sale Securities, Number of Securities in Unrealized Loss Position | security	277		226
Available-for-sale Securities, Sale Proceeds	$ 0	2,200,000
Available-for-sale Securities, Gross Realized Gain (Loss)	4,000	13,000
Available-for-sale Securities, OTTI Charges	$ 0	$ 0
Available-for-sale Securities, Number of Securities in Nonaccrual Status | security	0		0
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities, Number of Securities in Unrealized Loss Position | security	100		66
Held-to-maturity Securities, Number of Securities Sold | security	0	0
Held-to-maturity Securities, Sale Proceeds	$ 0
Held-to-maturity Securities, OTTI Charges	$ 0	$ 0
Held-to-maturity Securities, Number of Securities in Nonaccrual Status | security	0		0

LOANS RECEIVABLE AND THE ALLO43

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Loans by Type) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 7,556,046	$ 7,598,884	$ 7,421,255
Allowance for loan losses	92,207	89,028	86,527	$ 85,997
Net loans	$ 7,463,839	$ 7,509,856
Percent of total loans	100.00%	100.00%
Unearned loan fees in excess of unamortized costs	$ 731	$ (200)
Discount on acquired loans, net	19,400	21,100
Commerical real estate - owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 1,278,814	$ 1,284,363
Percent of total loans	16.90%	16.90%
Commercial real estate - investment properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 1,876,937	$ 1,937,423
Percent of total loans	24.80%	25.50%
Multifamily real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 321,039	$ 314,188	254,246
Allowance for loan losses	$ 2,592	$ 1,633	1,378	1,360
Percent of total loans	4.20%	4.10%
Commercial construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 163,314	$ 148,435
Percent of total loans	2.20%	2.00%
Multifamily construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 159,108	$ 154,662
Percent of total loans	2.10%	2.00%
One- to four-family construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 434,204	$ 415,327
Percent of total loans	5.70%	5.50%
Land and land development - residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 167,783	$ 164,516
Percent of total loans	2.20%	2.20%
Land and land development - commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 24,331	$ 24,583
Percent of total loans	0.30%	0.30%
Commercial business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 1,296,691	$ 1,279,894	1,224,541
Allowance for loan losses	$ 19,885	$ 18,311	19,768	16,533
Percent of total loans	17.20%	16.80%
Agricultural business, including secured by farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 307,243	$ 338,388	313,374
Allowance for loan losses	$ 2,999	$ 4,053	3,245	2,967
Percent of total loans	4.20%	4.40%
One- to four-family residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 833,598	$ 848,289	802,991
Allowance for loan losses	$ 3,779	$ 2,055	$ 1,974	$ 2,238
Percent of total loans	11.00%	11.20%
Consumer secured by one- to four-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 522,826	$ 522,931
Percent of total loans	6.90%	6.90%
Consumer - other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 170,158	$ 165,885
Percent of total loans	2.30%	2.20%

LOANS RECEIVABLE AND THE ALLO44

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Purchased Credit-Impaired Loans, Changes in Accretable Yield) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Receivables [Abstract]
Outstanding contractual unpaid balance of purchased credit-impaired loans	$ 29,800		$ 32,500
Carrying balance of purchased credit-impaired loans	19,316	$ 30,501	21,310
Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	6,520	8,717
Accretion to interest income	(1,097)	(1,320)
Disposals	58	0
Reclassifications from non-accretable difference	807	1,273
Balance, end of period	6,288	$ 8,670
Certain Loans Acquired in Transfer, Nonaccretable Difference	$ 9,900
Non-accretable difference			$ 11,300

LOANS RECEIVABLE AND THE ALLO45

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Impaired Loans With and Without Specific Reserves) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 38,249		$ 45,543
Recorded Investment, Without Allowance	21,719		26,488
Recorded Investment, With Allowance	15,034		16,656
Related Allowance	717		782
Average Recorded Investment	40,305	$ 39,560
Interest Income Recognized	234	220
Commerical real estate - owner-occupied [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,872		7,807
Recorded Investment, Without Allowance	3,444		6,447
Recorded Investment, With Allowance	199		199
Related Allowance	20		18
Average Recorded Investment	5,383	2,916
Interest Income Recognized	3	2
Commercial real estate - investment properties [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	9,346		11,296
Recorded Investment, Without Allowance	3,433		4,200
Recorded Investment, With Allowance	5,699		6,884
Related Allowance	264		263
Average Recorded Investment	9,972	8,893
Interest Income Recognized	83	49
Multifamily real estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	495
Interest Income Recognized	0	4
One- to four-family construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	186		298
Recorded Investment, Without Allowance	186		298
Recorded Investment, With Allowance	0		0
Related Allowance	0		0
Average Recorded Investment	605	1,180
Interest Income Recognized	4	20
Land and land development - residential [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	1,134		1,134
Recorded Investment, Without Allowance	798		798
Recorded Investment, With Allowance	0		0
Related Allowance	0		0
Average Recorded Investment	798	1,899
Interest Income Recognized	0	17
Land and land development - commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	977
Interest Income Recognized	0	0
Commercial business [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	4,008		4,441
Recorded Investment, Without Allowance	3,038		3,424
Recorded Investment, With Allowance	534		555
Related Allowance	39		50
Average Recorded Investment	4,007	4,504
Interest Income Recognized	7	7
Agricultural business, including secured by farmland [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	9,598		9,388
Recorded Investment, Without Allowance	6,440		6,230
Recorded Investment, With Allowance	3,031		3,031
Related Allowance	201		264
Average Recorded Investment	9,109	6,282
Interest Income Recognized	33	32
One- to four-family residential [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	8,579		9,547
Recorded Investment, Without Allowance	3,136		3,709
Recorded Investment, With Allowance	5,362		5,775
Related Allowance	182		178
Average Recorded Investment	8,892	10,404
Interest Income Recognized	101	83
Consumer secured by one- to four-family [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	1,346		1,498
Recorded Investment, Without Allowance	1,168		1,324
Recorded Investment, With Allowance	138		139
Related Allowance	7		7
Average Recorded Investment	1,390	1,742
Interest Income Recognized	2	3
Consumer - other [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	180		134
Recorded Investment, Without Allowance	76		58
Recorded Investment, With Allowance	71		73
Related Allowance	4		$ 2
Average Recorded Investment	149	268
Interest Income Recognized	$ 1	$ 3

LOANS RECEIVABLE AND THE ALLO46

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Troubled Debt Restructuring) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	$ 14,264	$ 16,115
TDRs on Nonaccrual Status	571	917
Total TDRs	14,835	17,032
Commitments to advance funds related to TDRs, maximum additional amounts	45	45
Commerical real estate - owner-occupied [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	199	199
TDRs on Nonaccrual Status	85	87
Total TDRs	284	286
Commercial real estate - investment properties [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	5,699	6,884
TDRs on Nonaccrual Status	0	0
Total TDRs	5,699	6,884
Commercial business [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	534	555
TDRs on Nonaccrual Status	0	0
Total TDRs	534	555
Agricultural business, including secured by farmland [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	2,531	3,129
TDRs on Nonaccrual Status	29	29
Total TDRs	2,560	3,158
One- to four-family residential [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	5,092	5,136
TDRs on Nonaccrual Status	457	801
Total TDRs	5,549	5,937
Consumer secured by one- to four-family [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	138	139
TDRs on Nonaccrual Status	0	0
Total TDRs	138	139
Consumer - other [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	71	73
TDRs on Nonaccrual Status	0	0
Total TDRs	$ 71	$ 73

LOANS RECEIVABLE AND THE ALLO47

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Newly Restructured Loans) (Details)	3 Months Ended
	Dec. 31, 2017contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	0

LOANS RECEIVABLE AND THE ALLO48

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Troubled Debt Restructuring Which Incurred Payment Default) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDRs Which Incurred a Payment Default	$ 0	$ 0

LOANS RECEIVABLE AND THE ALLO49

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Risk-Rated and Non-Risk Rated Loans by Grade and Other Characteristic) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	$ 7,556,046	$ 7,598,884	$ 7,421,255
Owner-occupied Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,278,814	1,284,363
Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,876,937	1,937,423
Multifamily real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	321,039	314,188	254,246
Commercial construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	163,314	148,435
Multifamily construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	159,108	154,662
One- to four-family construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	434,204	415,327
Land and land development - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	167,783	164,516
Land and land development - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	24,331	24,583
Commercial business [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,296,691	1,279,894	1,224,541
Agricultural Business/Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	307,243	338,388	313,374
One- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	833,598	848,289	$ 802,991
Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	522,826	522,931
Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	170,158	165,885
Pass (Risk Ratings 1-5) [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	7,393,543	7,431,182
Pass (Risk Ratings 1-5) [Member] | Owner-occupied Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,244,007	1,246,125
Pass (Risk Ratings 1-5) [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,866,062	1,918,940
Pass (Risk Ratings 1-5) [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	320,533	313,432
Pass (Risk Ratings 1-5) [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	163,314	148,435
Pass (Risk Ratings 1-5) [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	159,108	154,662
Pass (Risk Ratings 1-5) [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	429,172	411,802
Pass (Risk Ratings 1-5) [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	156,144	153,073
Pass (Risk Ratings 1-5) [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	21,507	21,665
Pass (Risk Ratings 1-5) [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,228,831	1,213,365
Pass (Risk Ratings 1-5) [Member] | Small Credit-Scored Business Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	535,000	296,800
Pass (Risk Ratings 1-5) [Member] | Agricultural Business/Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	286,925	321,110
Pass (Risk Ratings 1-5) [Member] | One- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	827,788	842,304
Pass (Risk Ratings 1-5) [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	520,263	520,675
Pass (Risk Ratings 1-5) [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	169,889	165,594
Special mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	47,373	48,468
Special mention [Member] | Owner-occupied Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	13,686	12,227
Special mention [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	9,118
Special mention [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Special mention [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Special mention [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Special mention [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Special mention [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	10,321	10,554
Special mention [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Special mention [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	16,599	12,135
Special mention [Member] | Agricultural Business/Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	6,203	3,852
Special mention [Member] | One- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	553	569
Special mention [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Special mention [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	11	13
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	115,021	119,122
Substandard [Member] | Owner-occupied Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	21,121	26,011
Substandard [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	10,875	9,365
Substandard [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	506	756
Substandard [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Substandard [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Substandard [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	5,032	3,525
Substandard [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	1,318	889
Substandard [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	2,824	2,918
Substandard [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	51,152	54,282
Substandard [Member] | Agricultural Business/Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	14,115	13,426
Substandard [Member] | One- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	5,257	5,416
Substandard [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	2,563	2,256
Substandard [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	258	278
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	109	112
Doubtful [Member] | Owner-occupied Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	109	112
Doubtful [Member] | Agricultural Business/Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | One- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Doubtful [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Owner-occupied Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Agricultural Business/Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | One- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	0	0
Loss [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable	$ 0	$ 0

LOANS RECEIVABLE AND THE ALLO50

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Age Analysis of Company's Past Due Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 35,581	$ 45,980
Purchased Credit-Impaired	19,316	21,310	$ 30,501
Current	7,501,149	7,531,594
Total loans	7,556,046	7,598,884	7,421,255
Loans 90 days or more past due and still accruing	1,419	1,486
Nonaccrual loans	21,070	25,543
Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,437	10,889
Purchased Credit-Impaired	6,372	7,682
Current	1,269,005	1,265,792
Total loans	1,278,814	1,284,363
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	3,444	6,447
Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,511	5,833
Purchased Credit-Impaired	7,072	7,166
Current	1,867,354	1,924,424
Total loans	1,876,937	1,937,423
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	3,433	4,199
Multifamily real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	105
Purchased Credit-Impaired	167	169	174
Current	320,872	313,914
Total loans	321,039	314,188	254,246
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	0	0
Commercial construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Purchased Credit-Impaired	0	0
Current	163,314	148,435
Total loans	163,314	148,435
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	0	0
Multifamily construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	3,416
Purchased Credit-Impaired	0	0
Current	159,108	151,246
Total loans	159,108	154,662
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	0	0
One- to four-family construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,829	5,915
Purchased Credit-Impaired	440	446
Current	428,935	408,966
Total loans	434,204	415,327
Loans 90 days or more past due and still accruing	0	298
Nonaccrual loans	186	0
Land and land development - residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,582	798
Purchased Credit-Impaired	0	0
Current	166,201	163,718
Total loans	167,783	164,516
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	798	798
Land and land development - commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Purchased Credit-Impaired	2,824	2,919
Current	21,507	21,664
Total loans	24,331	24,583
Loans 90 days or more past due and still accruing	0	0
Nonaccrual loans	0	0
Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,583	4,555
Purchased Credit-Impaired	1,829	2,159	3,416
Current	1,290,279	1,273,180
Total loans	1,296,691	1,279,894	1,224,541
Loans 90 days or more past due and still accruing	1	18
Nonaccrual loans	3,037	3,406
Agricultural business, including secured by farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	8,087	3,148
Purchased Credit-Impaired	415	565	725
Current	298,741	334,675
Total loans	307,243	338,388	313,374
Loans 90 days or more past due and still accruing	820	0
Nonaccrual loans	6,120	6,132
One- to four-family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	7,444	8,431
Purchased Credit-Impaired	129	136	312
Current	826,025	839,722
Total loans	833,598	848,289	$ 802,991
Loans 90 days or more past due and still accruing	591	1,085
Nonaccrual loans	2,815	3,264
Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,078	2,130
Purchased Credit-Impaired	0	0
Current	520,748	520,801
Total loans	522,826	522,931
Loans 90 days or more past due and still accruing	0	85
Nonaccrual loans	1,168	1,239
Consumer - other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,030	760
Purchased Credit-Impaired	68	68
Current	169,060	165,057
Total loans	170,158	165,885
Loans 90 days or more past due and still accruing	7	0
Nonaccrual loans	69	58
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	15,964	24,084
30 to 59 Days Past Due [Member] | Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	189	5,323
30 to 59 Days Past Due [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,402	1,737
30 to 59 Days Past Due [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	105
30 to 59 Days Past Due [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
30 to 59 Days Past Due [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	3,416
30 to 59 Days Past Due [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,323	4,892
30 to 59 Days Past Due [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
30 to 59 Days Past Due [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
30 to 59 Days Past Due [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,744	1,574
30 to 59 Days Past Due [Member] | Agricultural business, including secured by farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,580	598
30 to 59 Days Past Due [Member] | One- to four-family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,467	4,475
30 to 59 Days Past Due [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,412	1,355
30 to 59 Days Past Due [Member] | Consumer - other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	847	609
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,681	3,177
60 to 89 Days Past Due [Member] | Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	169	76
60 to 89 Days Past Due [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60 to 89 Days Past Due [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60 to 89 Days Past Due [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60 to 89 Days Past Due [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60 to 89 Days Past Due [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	320	725
60 to 89 Days Past Due [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	784	0
60 to 89 Days Past Due [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60 to 89 Days Past Due [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	702	404
60 to 89 Days Past Due [Member] | Agricultural business, including secured by farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	533
60 to 89 Days Past Due [Member] | One- to four-family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	476	1,241
60 to 89 Days Past Due [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	82	62
60 to 89 Days Past Due [Member] | Consumer - other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	148	136
90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	16,936	18,719
90 Days or More Past Due [Member] | Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,079	5,490
90 Days or More Past Due [Member] | Commercial real estate - investment properties [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,109	4,096
90 Days or More Past Due [Member] | Multifamily real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
90 Days or More Past Due [Member] | Commercial construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
90 Days or More Past Due [Member] | Multifamily construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
90 Days or More Past Due [Member] | One- to four-family construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	186	298
90 Days or More Past Due [Member] | Land and land development - residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	798	798
90 Days or More Past Due [Member] | Land and land development - commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
90 Days or More Past Due [Member] | Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,137	2,577
90 Days or More Past Due [Member] | Agricultural business, including secured by farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	6,507	2,017
90 Days or More Past Due [Member] | One- to four-family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,501	2,715
90 Days or More Past Due [Member] | Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	584	713
90 Days or More Past Due [Member] | Consumer - other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 35	$ 15

LOANS RECEIVABLE AND THE ALLO51

LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	$ 89,028	$ 85,997
Provision for loan losses	2,000	2,000
Recoveries	2,098	678
Charge-offs	(919)	(2,148)
Allowance for loan losses, Ending balance	92,207	86,527
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			$ 717		$ 1,344
Allowance collectively evaluated for impairment			91,352		85,164
Allowance for purchased credit-impaired loans			138		19
Total allowance for loan losses	89,028	85,997	92,207	$ 89,028	86,527
Loans individually evaluated for impairment			26,134		27,257
Loans collectively evaluated for impairment			7,510,596		7,363,497
Purchased Credit-Impaired			19,316	21,310	30,501
Total loans			7,556,046	7,598,884	7,421,255
Commercial real estate [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	22,824	20,993
Provision for loan losses	(715)	(591)
Recoveries	1,352	70
Charge-offs	0	0
Allowance for loan losses, Ending balance	23,461	20,472
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			284		419
Allowance collectively evaluated for impairment			23,177		20,053
Allowance for purchased credit-impaired loans			0		0
Total allowance for loan losses	22,824	20,993	23,461	22,824	20,472
Loans individually evaluated for impairment			11,607		9,506
Loans collectively evaluated for impairment			3,130,700		3,341,177
Purchased Credit-Impaired			13,444		22,030
Total loans			3,155,751		3,372,713
Multifamily real estate [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	1,633	1,360
Provision for loan losses	959	18
Recoveries	0	0
Charge-offs	0	0
Allowance for loan losses, Ending balance	2,592	1,378
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			0		62
Allowance collectively evaluated for impairment			2,592		1,316
Allowance for purchased credit-impaired loans			0		0
Total allowance for loan losses	1,633	1,360	2,592	1,633	1,378
Loans individually evaluated for impairment			0		347
Loans collectively evaluated for impairment			320,872		253,725
Purchased Credit-Impaired			167	169	174
Total loans			321,039	314,188	254,246
Construction and Land [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	27,568	34,252
Provision for loan losses	1,024	(4,871)
Recoveries	174	83
Charge-offs	0	0
Allowance for loan losses, Ending balance	28,766	29,464
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			0		323
Allowance collectively evaluated for impairment			28,766		29,122
Allowance for purchased credit-impaired loans			0		19
Total allowance for loan losses	27,568	34,252	28,766	27,568	29,464
Loans individually evaluated for impairment			750		4,006
Loans collectively evaluated for impairment			944,726		795,887
Purchased Credit-Impaired			3,264		3,777
Total loans			948,740		803,670
Commercial business [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	18,311	16,533
Provision for loan losses	1,923	4,688
Recoveries	170	173
Charge-offs	(519)	(1,626)
Allowance for loan losses, Ending balance	19,885	19,768
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			39		62
Allowance collectively evaluated for impairment			19,799		19,706
Allowance for purchased credit-impaired loans			47		0
Total allowance for loan losses	18,311	16,533	19,885	18,311	19,768
Loans individually evaluated for impairment			534		2,710
Loans collectively evaluated for impairment			1,294,328		1,218,415
Purchased Credit-Impaired			1,829	2,159	3,416
Total loans			1,296,691	1,279,894	1,224,541
Agricultural Business/Farmland [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	4,053	2,967
Provision for loan losses	(1,047)	324
Recoveries	0	113
Charge-offs	(7)	(159)
Allowance for loan losses, Ending balance	2,999	3,245
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			201		238
Allowance collectively evaluated for impairment			2,707		3,007
Allowance for purchased credit-impaired loans			91		0
Total allowance for loan losses	4,053	2,967	2,999	4,053	3,245
Loans individually evaluated for impairment			7,943		3,815
Loans collectively evaluated for impairment			298,885		308,834
Purchased Credit-Impaired			415	565	725
Total loans			307,243	338,388	313,374
One- to four-family [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	2,055	2,238
Provision for loan losses	1,450	(409)
Recoveries	290	145
Charge-offs	(16)	0
Allowance for loan losses, Ending balance	3,779	1,974
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			182		229
Allowance collectively evaluated for impairment			3,597		1,745
Allowance for purchased credit-impaired loans			0		0
Total allowance for loan losses	2,055	2,238	3,779	2,055	1,974
Loans individually evaluated for impairment			5,092		6,653
Loans collectively evaluated for impairment			828,377		796,026
Purchased Credit-Impaired			129	136	312
Total loans			833,598	848,289	802,991
Consumer [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	3,866	4,104
Provision for loan losses	1,913	5
Recoveries	112	94
Charge-offs	(377)	(363)
Allowance for loan losses, Ending balance	5,514	3,840
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			11		11
Allowance collectively evaluated for impairment			5,503		3,829
Allowance for purchased credit-impaired loans			0		0
Total allowance for loan losses	3,866	4,104	5,514	3,866	3,840
Loans individually evaluated for impairment			208		220
Loans collectively evaluated for impairment			692,708		649,433
Purchased Credit-Impaired			68		67
Total loans			692,984		649,720
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	8,718	3,550
Provision for loan losses	(3,507)	2,836
Recoveries	0	0
Charge-offs	0	0
Allowance for loan losses, Ending balance	5,211	6,386
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment			0		0
Allowance collectively evaluated for impairment			5,211		6,386
Allowance for purchased credit-impaired loans			0		0
Total allowance for loan losses	$ 8,718	$ 3,550	5,211	$ 8,718	6,386
Loans individually evaluated for impairment			0		0
Loans collectively evaluated for impairment			0		0
Purchased Credit-Impaired			0		0
Total loans			$ 0		$ 0

REAL ESTATE OWNED, NET (REO Rol

REAL ESTATE OWNED, NET (REO Rollforward) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Real Estate Owned [Roll Forward]
Balance, beginning of the period	$ 360	$ 11,081
Additions from loan foreclosures	128	0
Proceeds from dispositions of REO	0	(9,193)
Gain on sale of REO	0	1,202
Valuation adjustments in the period	(160)	(50)
Balance, end of the period	$ 328	$ 3,040

REAL ESTATE OWNED, NET REAL EST

REAL ESTATE OWNED, NET REAL ESTATE OWNED, NET (Textual) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Real Estate Owned [Line Items]
Real Estate Owned	$ 328,000	$ 360,000	$ 3,040,000	$ 11,081,000
Mortgage Loans in Process of Foreclosure, Amount	1,600,000	2,042,000
One- to four-family residential [Member]
Real Estate Owned [Line Items]
Real Estate Owned	$ 98,000	$ 0

GOODWILL, OTHER INTANGIBLE AS54

GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS (Finite-Lived Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Finite-lived Intangible Assets [Roll Forward]
Goodwill, beginning of period	$ 242,659	$ 244,583
Goodwill and other intangibles, net, beginning of period	265,314	274,745
Amortization	(1,404)	(6,431)
Goodwill, end of period	242,659	242,659
Goodwill and other intangibles, net, end of period	263,910	265,314
Goodwill, Other Increase (Decrease)		(1,924)
Intangible Assets (including Goodwill), Other Changes		(3,000)
Core Deposit Intangibles [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite lived assets Balance, beginning of period	22,378	29,701
Amortization	(1,382)	(6,247)
Finite lived assets Balance, end of period	20,996	22,378
Finite-Lived Intangible Assets, Other Changes		(1,076)
Leasehold Improvements [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite lived assets Balance, beginning of period	277	461
Amortization	(22)	(184)
Finite lived assets Balance, end of period	$ 255	277
Finite-Lived Intangible Assets, Other Changes		$ 0

GOODWILL, OTHER INTANGIBLE AS55

GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS (Estimated Annual Amortization Expense) (Details) - Core Deposit Intangibles [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Remainder of 2017	$ 3,990
2,018	4,683
2,019	3,996
2,020	3,307
2,021	2,524
Thereafter	2,496
Finite lived assets, net	$ 20,996	$ 22,378	$ 29,701

GOODWILL, OTHER INTANGIBLE AS56

GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS (Mortgage Servicing Rights) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Servicing Asset at Amortized Value, Balance [Roll Forward]
Servicing Asset at Amortized Cost, Additions, Acquisitions		$ 15	$ 0
Mortgage Servicing Rights [Member]
Morgage Servicing Rights at Amortized Value [Line Items]
Loans Serviced For Others		2,230,000		$ 2,190,000
Custodial Accounts		19,100		$ 10,200
Servicing Asset at Amortized Value, Balance [Roll Forward]
Balance, net of valuation allowance, beginning of the period		14,738	15,249
Additions—amounts capitalized		821	945
Amortization	[1]	(957)	(922)
Balance, net of valuation allowance, end of the period	[2]	14,617	$ 15,272
Valuation allowance, end of period		$ 0
[1]	Amortization of mortgage servicing rights is recorded as a reduction of loan servicing income within mortgage banking operations and any unamortized balance is fully amortized if the loan repays in full.
[2]	There was no valuation allowance as of March 31, 2018 and 2017.

DEPOSITS (Deposit Liabilities)

DEPOSITS (Deposit Liabilities) (Details) - USD ($)		Mar. 31, 2018	Dec. 31, 2017
Deposits:
Non-interest-bearing accounts		$ 3,383,439,000	$ 3,265,544,000
Interest-bearing checking		1,043,840,000	971,137,000
Regular savings accounts		1,637,814,000	1,557,500,000
Money market accounts		1,459,614,000	1,422,313,000
Total interest-bearing transaction and saving accounts		4,141,268,000	3,950,950,000
Certificates of deposit less than or equal to $250,000		865,353,000	813,997,000
Certificates of deposit greater than $250,000		153,002,000	152,940,000
Total certificates of deposit	[1]	1,018,355,000	966,937,000
Total deposits		8,543,062,000	8,183,431,000
Included in total deposits:
Public fund transaction and savings accounts		190,311,000	198,719,000
Public fund interest-bearing certificates		24,928,000	23,685,000
Total public deposits		215,239,000	222,404,000
Total brokered deposits		169,523,000	57,228,000
CD acquisition premium		$ 5,000	$ 11,000
[1]	Certificates of deposit include $5,000 and $11,000 of acquisition premiums at March 31, 2018 and December 31, 2017, respectively.

DEPOSITS DEPOSITS (Maturities a

DEPOSITS DEPOSITS (Maturities and Weighted Average Interest Rates of Certificates of Deposit) (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Maturities of Time Deposits [Abstract]
Maturing in one year or less		$ 703,650
Maturing after one year through two years		146,484
Maturing after two years through three years		128,810
Maturing after three years through four years		23,571
Maturing after four years through five years		13,460
Maturing after five years		2,380
Total certificates of deposit	[1]	$ 1,018,355	$ 966,937
Weighted Average Rate [Abstract]
Maturing in one year or less		0.63%
Maturing after one year through two years		0.98%
Maturing after two years through three years		1.31%
Maturing after three years through four years		1.11%
Maturing after four years through five years		1.33%
Maturing after five years		1.06%
Total certificates of deposit		0.79%
[1]	Certificates of deposit include $5,000 and $11,000 of acquisition premiums at March 31, 2018 and December 31, 2017, respectively.

DEPOSITS DEPOSITS (Textual) (De

DEPOSITS DEPOSITS (Textual) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Time Deposits, at or Above FDIC Insurance Limit	$ 156.3	$ 155.9

FAIR VALUE OF FINANCIAL INSTR60

FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value By Balance Sheet Location) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Securities—trading	$ 25,574	$ 22,318
Securities—available-for-sale	1,406,505	919,485
Securities—held-to-maturity	260,918	262,188
Liabilities:
FHLB advances at fair value	192,195	202
Carrying Value
Assets:
Cash and cash equivalents	242,048	261,200
Securities—trading	25,574	22,318
Securities—available-for-sale	1,406,505	919,485
Loans receivable held for sale	141,808	40,725
Loans receivable	7,556,046	7,598,884
FHLB stock	18,036	10,334
Bank-owned life insurance	163,519	162,668
Mortgage servicing rights	14,617	14,738
Marketable Securities, Equity Securities	5,698	0
Liabilities:
Demand, interest checking and money market accounts	5,886,893	5,658,994
Regular savings	1,637,814	1,557,500
Certificates of deposit	1,018,355	966,937
FHLB advances at fair value	192,195	202
Other borrowings	101,844	95,860
Junior subordinated debentures at fair value	112,516	98,707
Estimated Fair Value
Assets:
Cash and cash equivalents	242,048	261,200
Securities—trading	25,574	22,318
Securities—available-for-sale	1,406,505	919,485
Loans receivable held for sale	141,898	40,923
Loans receivable	7,462,004	7,445,990
FHLB stock	18,036	10,334
Bank-owned life insurance	163,519	162,668
Mortgage servicing rights	20,560	19,835
Marketable Securities, Equity Securities	5,698	0
Liabilities:
Demand, interest checking and money market accounts	5,886,893	5,658,994
Regular savings	1,637,814	1,557,500
Certificates of deposit	994,616	947,517
FHLB advances at fair value	192,195	202
Other borrowings	101,844	95,860
Junior subordinated debentures at fair value	112,516	98,707
Interest rate swaps [Member] | Carrying Value
Assets:
Derivatives:	4,592	5,083
Liabilities:
Derivatives:	4,592	5,083
Interest rate swaps [Member] | Estimated Fair Value
Assets:
Derivatives:	4,592	5,083
Liabilities:
Derivatives:	4,592	5,083
Interest Rate Forward Sales Commitments [Member] | Carrying Value
Assets:
Derivatives:	683	523
Liabilities:
Derivatives:	260	201
Interest Rate Forward Sales Commitments [Member] | Estimated Fair Value
Assets:
Derivatives:	683	523
Liabilities:
Derivatives:	260	201
Fair Value, Inputs, Level 2 [Member] | Carrying Value
Assets:
Securities—held-to-maturity	259,204	256,793
Fair Value, Inputs, Level 2 [Member] | Estimated Fair Value
Assets:
Securities—held-to-maturity	257,477	258,710
Fair Value, Inputs, Level 3 [Member] | Carrying Value
Assets:
Securities—held-to-maturity	3,441	3,478
Fair Value, Inputs, Level 3 [Member] | Estimated Fair Value
Assets:
Securities—held-to-maturity	$ 3,441	$ 3,478

FAIR VALUE OF FINANCIAL INSTR61

FAIR VALUE OF FINANCIAL INSTRUMENTS (Assets and Liabilities Measured on a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	$ 25,574	$ 22,318
Securities—available-for-sale	1,406,505	919,485
Advances from FHLB	192,195	202
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	25,574	22,318
Securities—available-for-sale	1,406,505	919,485
Total assets	1,580,786	979,801
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	112,516	98,707
Total liabilities	117,368	103,991
Recurring [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	683	5,083
Derivative liabilities	260	5,083
Recurring [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	4,592	523
Derivative liabilities	4,592	201
Recurring [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	143,306	72,466
Recurring [Member] | Municipal bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	100	100
Securities—available-for-sale	68,958	68,733
Recurring [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	6,112	5,393
Recurring [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	25,474	22,058
Recurring [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	1,160,413	739,557
Recurring [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	27,716	27,758
Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading		160
Securities—available-for-sale		5,578
Recurring [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	137,734	32,392
Recurring [Member] | Securities (Assets) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities, Equity Securities	5,698
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Securities—available-for-sale	0	0
Total assets	0	0
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	0	0
Total liabilities	0	0
Recurring [Member] | Level 1 [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Level 1 [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Level 1 [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Municipal bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Recurring [Member] | Level 1 [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Level 1 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading		0
Securities—available-for-sale		0
Recurring [Member] | Level 1 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	0	0
Recurring [Member] | Level 1 [Member] | Securities (Assets) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities, Equity Securities	0
Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	100	260
Securities—available-for-sale	1,406,505	919,485
Total assets	1,555,312	957,743
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	0	0
Total liabilities	4,852	5,284
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	683	5,083
Derivative liabilities	260	5,083
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	4,592	523
Derivative liabilities	4,592	201
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	143,306	72,466
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	100	100
Securities—available-for-sale	68,958	68,733
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	6,112	5,393
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	1,160,413	739,557
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	27,716	27,758
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading		160
Securities—available-for-sale		5,578
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	137,734	32,392
Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Securities (Assets) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities, Equity Securities	5,698
Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	25,474	22,058
Securities—available-for-sale	0	0
Total assets	25,474	22,058
Junior subordinated debentures net of unamortized deferred issuance costs at fair value	112,516	98,707
Total liabilities	112,516	98,707
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate lock and forward sale commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Government and agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	0	0
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | TPS and TRUP CDOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading	25,474	22,058
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—available-for-sale	0	0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities—trading		0
Securities—available-for-sale		0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	0	$ 0
Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Securities (Assets) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities, Equity Securities	$ 0

FAIR VALUE OF FINANCIAL INSTR62

FAIR VALUE OF FINANCIAL INSTRUMENTS (Valuation Technique) (Details) - Fair Value, Inputs, Level 3 [Member]	3 Months Ended			12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2015	Dec. 31, 2017
Junior Subordinated Debt [Member] | Discounted cash flows [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate, Description of Variable Rate Basis		three-month LIBOR
Fair Value Inputs, Discount Rate, Basis Spread on Variable Rate Basis	4.00%
Junior Subordinated Debt [Member] | Weighted Average [Member] | Discounted cash flows [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	6.31%			6.69%
Corporate Bonds (TPS securities) [Member] | Weighted Average [Member] | Discounted cash flows [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	6.31%			6.69%
Impaired Loans [Member] | Weighted Average [Member] | discount to appraised value [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
fair value inputs, discount to appraised value	0.085
Impaired Loans [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	0.00%
Impaired Loans [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate				0.00%
Impaired Loans [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate				0.00%
Real Estate Owned [Member] | Weighted Average [Member] | discount to appraised value [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
fair value inputs, discount to appraised value	0.61			0.42
Real Estate Owned [Member] | Minimum [Member] | Discounted cash flows [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	17.00%			0.00%
Real Estate Owned [Member] | Maximum [Member] | Discounted cash flows [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	42.00%			45.00%

FAIR VALUE OF FINANCIAL INSTR63

FAIR VALUE OF FINANCIAL INSTRUMENTS (Unobservable Inputs Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Junior Subordinated Debt [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 98,707	$ 95,200
Liabilities (gains) losses	13,809	840
Ending balance	112,516	96,040
TPS Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	22,058	21,143
Assets gains (losses), including OTTI	3,416	218
Ending balance	$ 25,474	$ 21,361

FAIR VALUE OF FINANCIAL INSTR64

FAIR VALUE OF FINANCIAL INSTRUMENTS (Assets Measured on Nonrecurring Basis) (Details) - Nonrecurring [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ (500)	$ (6,535)
REO	328	360
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
REO	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
REO	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	(500)	(6,535)
REO	328	360
Gains (losses) resulting from nonrecurring fair value adjustments	(160)	(50)
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) resulting from nonrecurring fair value adjustments	$ (160)	$ (50)

INCOME TAXES AND DEFERRED TAX65

INCOME TAXES AND DEFERRED TAXES INCOME TAXES AND DEFERRED TAXES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax credit investments	$ 9,223		$ 7,311
Unfunded commitments—tax credit investments	5,483		$ 4,417
Tax credits and other tax benefits recognized	364	$ 285
Tax credit amortization expense included in provision for income taxes	$ 288	$ 199

CALCULATION OF WEIGHTED AVERA66

CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 28,790	$ 23,793	$ 60,776
Basic weighted average shares outstanding	32,397,568	32,933,444
Plus unvested restricted stock	118,888	118,015
Diluted weighted shares outstanding	32,516,456	33,051,459
Earnings per common share
Basic	$ 0.89	$ 0.72
Diluted	$ 0.89	$ 0.72

CALCULATION OF WEIGHTED AVERA67

CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE - Textuals (Details) - Warrant [Member] - Common Stock [Member] $ in Millions	Mar. 31, 2018USD ($)shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrants outstanding | $	$ 18.6
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrants outstanding, number of shares | shares	243,998

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS (Details) - USD ($) $ in Millions	3 Months Ended		47 Months Ended	71 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2018
Restricted Stock Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Expense	$ 1.3	$ 1.1
Compensation Cost Not yet Recognized	$ 6.6		$ 6.6	$ 6.6
Compensation Cost Not yet Recognized, Period for Recognition	28 months
2012 Restricted Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Authorized	300,000		300,000	300,000
2012 Restricted Stock Plan [Member] | Restricted Stock Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period	3 years
Award Expiration Period	10 years
Restricted stock granted				270,467
Restricted stock grants, shares vested				253,865
Restricted stock grants, shares non-vested	16,602		16,602	16,602
2014 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Authorized	900,000		900,000	900,000
2014 Omnibus Incentive Plan [Member] | Restricted Stock Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted			346,914
Restricted stock grants, shares vested			123,885
2014 Omnibus Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted			34,975
Restricted stock grants, shares vested			26,154

COMMITMENTS AND CONTINGENCIES69

COMMITMENTS AND CONTINGENCIES (Commitments Without Recorded Liability) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)location	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Reserve for Unfunded Loan Commitments	$ 2,400,000		$ 2,400,000
Number of Properties Subject to Non-cancelable Operating Leases | location	107
Mortgage loan applications, day interest rate is locked	45 days
Minimum [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage loan applications, day interest rate is locked	30 days
Maximum [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage loan applications, day interest rate is locked	60 days
Commitments to extend credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	$ 2,386,614,000		2,300,593,000
Standby letters of credit and financial guarantees [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	13,958,000		14,579,000
Commitments to originate loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	66,479,000		56,030,000
Risk Participation Agreement [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	4,141,000		11,451,000
Commitments to originate loans held for sale [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	47,848,000		43,502,000
Commitments to sell loans secured by one- to four residential properties [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	38,409,000		33,069,000
Counterparty default losses on forward contracts	0	$ 0
Commitments to sell securities related to mortgage banking activities [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	107,500,000		$ 57,000,000
Counterparty default losses on forward contracts	$ 0	$ 0

DERIVATIVES AND HEDGING (Deriva

DERIVATIVES AND HEDGING (Derivatives Designated as Hedging, by Balance Sheet Location) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 4,592	$ 5,083
Liability Derivatives, Fair Value	4,592	5,083
Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	4,592	5,083
Liability Derivatives, Fair Value	4,592	5,083
Interest rate swaps [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional/Contract Amount	4,257	4,350
Liability Derivatives, Notional/Contract Amount	4,257	4,350
Interest rate swaps [Member] | Designated as Hedging Instrument [Member] | Loans Receivable [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	355	447
Interest rate swaps [Member] | Designated as Hedging Instrument [Member] | Other liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	$ 355	$ 447

DERIVATIVES AND HEDGING (Deri71

DERIVATIVES AND HEDGING (Derivatives Not Designated as Hedging, by Balance Sheet Location) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 4,592	$ 5,083
Liability Derivatives, Fair Value	4,592	5,083
Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	4,592	5,083
Liability Derivatives, Fair Value	4,592	5,083
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional/Contract Amount	401,835	357,855
Liability Derivatives, Notional/Contract Amount	337,176	345,810
Not Designated as Hedging Instrument [Member] | Other assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	4,919	5,159
Not Designated as Hedging Instrument [Member] | Other liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	4,496	4,837
Not Designated as Hedging Instrument [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional/Contract Amount	272,627	285,047
Liability Derivatives, Notional/Contract Amount	272,627	285,047
Not Designated as Hedging Instrument [Member] | Interest rate swaps [Member] | Other assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	4,236	4,636
Not Designated as Hedging Instrument [Member] | Interest rate swaps [Member] | Loans Receivable [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	381	499
Not Designated as Hedging Instrument [Member] | Interest rate swaps [Member] | Other liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	4,236	4,636
Not Designated as Hedging Instrument [Member] | Mortgage loan commitments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional/Contract Amount	30,799	29,739
Liability Derivatives, Notional/Contract Amount	17,049	13,763
Not Designated as Hedging Instrument [Member] | Mortgage loan commitments [Member] | Other assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	294	225
Not Designated as Hedging Instrument [Member] | Mortgage loan commitments [Member] | Other liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	153	153
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional/Contract Amount	98,409	43,069
Liability Derivatives, Notional/Contract Amount	47,500	47,000
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Other assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	389	298
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Other liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	$ 107	$ 48

DERIVATIVES AND HEDGING (Gain (

DERIVATIVES AND HEDGING (Gain (Loss) On Derivatives Not Designated in Hedging Relationship) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income, net	$ 57	$ (113)
Mortgage loan commitments [Member] | Mortgage banking operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income, net	68	361
Forward sales contracts [Member] | Mortgage banking operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income, net	$ (11)	$ (474)

DERIVATIVES AND HEDGING (Narrat

DERIVATIVES AND HEDGING (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative net liability position	$ 0.8	$ 3.7
Collateral posted	$ 17.1	$ 16.9

DERIVATIVES AND HEDGING (Deri74

DERIVATIVES AND HEDGING (Derivative Offsetting) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Derivative Assets, Gross Amounts Recognized	$ 4,592	$ 5,083
Derivative Assets, Amounts offsett in the Statement of Financial Condition	0	0
Derivative Assets, Net Amounts in the Statement of Financial Condition	4,592	5,083
Derivative Assets, Netting Adjustment Per Applicable Master Netting Agreements	(123)	(656)
Derivative Assets, Fair Value of Financial Collateral in the Statement of Financial Condiation	0	0
Derivative Assets, Net Amount	4,469	4,427
Offsetting Derivative Liabilities [Abstract]
Derivative Liabilities, Gross Amounts Recognized	4,592	5,083
Derivative Liabilities, Amounts offset in the Statement of Financial Condition	0	0
Derivative Liabilities, Net Amounts of the Statement of Financial Condition	4,592	5,083
Derivative Liabilities, Net Adjustment Per Applicable Master Netting Agreements	(123)	(656)
Derivative Liabilities, Fair Value of Financial Collateral in the Statement of Financial Condition	(767)	(3,467)
Derivative Liabilities, Net Amount	3,702	960
Interest rate swaps [Member]
Offsetting Derivative Assets [Abstract]
Derivative Assets, Gross Amounts Recognized	4,592	5,083
Derivative Assets, Amounts offsett in the Statement of Financial Condition	0	0
Derivative Assets, Net Amounts in the Statement of Financial Condition	4,592	5,083
Derivative Assets, Netting Adjustment Per Applicable Master Netting Agreements	(123)	(656)
Derivative Assets, Fair Value of Financial Collateral in the Statement of Financial Condiation	0	0
Derivative Assets, Net Amount	4,469	4,427
Offsetting Derivative Liabilities [Abstract]
Derivative Liabilities, Gross Amounts Recognized	4,592	5,083
Derivative Liabilities, Amounts offset in the Statement of Financial Condition	0	0
Derivative Liabilities, Net Amounts of the Statement of Financial Condition	4,592	5,083
Derivative Liabilities, Net Adjustment Per Applicable Master Netting Agreements	(123)	(656)
Derivative Liabilities, Fair Value of Financial Collateral in the Statement of Financial Condition	(767)	(3,467)
Derivative Liabilities, Net Amount	$ 3,702	$ 960

REVENUE FROM CONTRACTS WITH C75

REVENUE FROM CONTRACTS WITH CUSTOMERS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from Contract with Customer [Abstract]
Fees and Commissions, Depositor Accounts	$ 4,320	$ 4,062
Fees and Commissions, Credit and Debit Cards	7,320	6,538
Debit and Credit Card Expense	(1,970)	(1,687)
Merchant Discount Fees	2,261	2,187
Merchant Services Expenses	(1,804)	(1,797)
Other Service Charges	1,169	1,086
Total Deposit Fees and Other Service Charges	$ 11,296	$ 10,389