Western Alliance Bancorporation (WAL) 10-Q 27 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 20, 2017
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	WAL
Entity Registrant Name	WESTERN ALLIANCE BANCORPORATION
Entity Central Index Key	1,212,545
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		105,490,079

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Cash and due from banks	$ 131,130	$ 168,066
Interest-bearing deposits in other financial institutions	519,224	116,425
Cash and cash equivalents	650,354	284,491
Money Market Funds, at Carrying Value	175	0
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016	0	1,053
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844	2,609,380
Held-to-maturity Securities	154,920	92,079
Investments in restricted stock, at cost	65,680	65,249
Trade and Loans Receivables Held-for-sale, Net, Not Part of Disposal Group	16,347	18,909
Loans:
Loans, net of deferred loan fees and costs	14,505,689	13,189,527
Less: Allowance for credit losses	(136,421)	(124,704)
Net loans held for investment	14,369,268	13,064,823
Premises and equipment, net	120,063	119,833
Other assets acquired through foreclosure, net	28,992	47,815
Bank owned life insurance	166,798	164,510
Goodwill	289,895	289,967
Other intangible assets, net	11,262	12,927
Deferred tax assets, net	83,772	95,194
Other assets	411,851	334,612
Total assets	19,922,221	17,200,842
Deposits:
Non-interest-bearing demand	7,608,671	5,632,926
Interest-bearing	9,296,112	8,916,937
Total deposits	16,904,783	14,549,863
Customer repurchase agreements	26,066	41,728
Other borrowings	0	80,000
Qualifying debt, net	372,851	367,937
Other liabilities	472,894	269,785
Total liabilities	17,776,594	15,309,313
Commitments and Contingencies
Stockholders’ equity:
Common stock - par value $0.0001; 200,000,000 authorized; 107,060,702 shares issued at September 30, 2017 and 106,371,093 at December 31, 2016	10	10
Treasury stock, at cost (1,567,203 shares at September 30, 2017 and 1,300,232 shares at December 31, 2016)	(40,004)	(26,362)
Additional paid in capital	1,418,835	1,400,140
Accumulated other comprehensive income (loss)	8,164	(4,695)
Retained earnings	758,622	522,436
Total stockholders’ equity	2,145,627	1,891,529
Total liabilities and stockholders’ equity	$ 19,922,221	$ 17,200,842

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Trading Securities, Debt, Amortized Cost	$ 0	$ 1,055
Amortized cost of investment securities available for sale	3,551,770	2,633,298
Held-to-maturity Securities, Fair Value	$ 160,582	$ 91,966
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	107,060,702	106,371,093
Common stock, shares outstanding	105,493,499	105,070,861

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest income:
Loans, including fees	$ 191,096	$ 167,914	$ 547,306	$ 467,715
Investment securities	22,152	13,797	58,010	37,278
Dividends	2,005	2,209	6,154	6,217
Other	2,583	830	5,584	1,885
Total interest income	217,836	184,750	617,054	513,095
Interest expense:
Deposits	11,449	8,072	29,506	21,993
Qualifying debt	4,708	4,048	13,539	8,746
Qualifying debt	84	68	333	366
Other	12	15	41	46
Total interest expense	16,253	12,203	43,419	31,151
Net interest income	201,583	172,547	573,635	481,944
Provision for credit losses	5,000	2,000	12,250	7,000
Net interest income after provision for credit losses	196,583	170,547	561,385	474,944
Non-interest income:
Service charges and fees	5,248	4,916	15,189	13,958
Card income	1,344	1,381	4,146	3,844
Income from bank owned life insurance	950	1,208	2,933	1,610
Income from equity investments	975	899	2,896	2,858
Foreign Currency Transaction Gain (Loss), before Tax	756	888	2,630	2,672
Lending related fees	97	708	746	4,509
Gain (loss) on sales of investment securities, net	319	0	907	1,001
Other income	599	683	1,834	1,923
Total non-interest income	10,288	10,683	31,281	32,375
Non-interest expense:
Salaries and employee benefits	52,730	49,542	156,596	139,108
Occupancy	7,507	6,856	21,328	20,359
Legal, professional, and directors' fees	6,038	5,691	23,324	17,010
Data processing	4,524	5,266	14,163	15,028
Insurance	3,538	3,144	10,355	9,430
Deposit costs	2,904	1,363	6,778	3,121
Loan and repossessed asset expenses	1,263	788	3,639	2,522
Card expense	801	252	2,187	1,376
Marketing	776	678	2,628	2,432
Intangible amortization	489	697	1,666	2,091
Net loss (gain) on sales / valuations of repossessed and other assets	266	(146)	(46)	(91)
Acquisition / restructure expense	0	2,729	0	6,391
Other expense	8,278	8,147	22,510	23,527
Total non-interest expense	89,114	85,007	265,128	242,304
Income before provision for income taxes	117,757	96,223	327,538	265,015
Income tax expense	34,899	29,171	91,352	75,017
Net income	$ 82,858	$ 67,052	$ 236,186	$ 189,998
Earnings per share
Basic	$ 0.80	$ 0.65	$ 2.27	$ 1.85
Diluted	$ 0.79	$ 0.64	$ 2.25	$ 1.84
Weighted average number of shares outstanding:
Basic	104,221	103,768	104,124	102,791
Diluted	104,942	104,564	104,941	103,532

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 82,858	$ 67,052	$ 236,186	$ 189,998
Other comprehensive income (loss), net:
Unrealized gain (loss) on AFS securities, net of tax effect of $(689), $4,671, $(9,894), and $(7,837), respectively	1,116	(7,415)	15,947	16,316
Unrealized gain (loss) on SERP, net of tax effect of $(71), $(4), $(93), and $(10)	114	6	150	18
Unrealized gain (loss) on junior subordinated debt, net of tax effect of $(394), $1,779, $1,649, and $895	641	(2,825)	(2,677)	(1,491)
Realized (gain) loss on sale of AFS securities included in income, net of tax effect of $122, $0, $346 and $290, respectively	(197)	0	(561)	(711)
Net other comprehensive income (loss)	1,674	(10,234)	12,859	14,132
Comprehensive income	$ 84,532	$ 56,818	$ 249,045	$ 204,130

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Unrealized gain on securities available-for-sale securities, tax	$ 689	$ (4,671)	$ 9,894	$ 7,837
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	(71)	(4)	(93)	(10)
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Unrealized Gain (Loss) Arising During Period, Tax	(394)	1,779	1,649	895
Realized gain on sale of securities, tax	$ 122	$ 0	$ 346	$ 290

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated (Deficit) [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2015	$ 1,591,502	$ 10	$ 1,323,473	$ 22,260	$ 262,638	$ (16,879)
Beginning balance, shares at Dec. 31, 2015		103,087,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	189,998				189,998
Exercise of stock options, shares		62,000
Exercise of stock options	755		755
Restricted stock grants, net, shares		673,000
Restricted stock grants, net	$ 14,513		14,513
Treasury Stock, Shares, Acquired	(301,495)	(301,000)
Restricted Stock Award, Forfeitures	$ (9,331)					(9,331)
Stock Issued During Period, Shares, New Issues		1,550,000
Stock Issued During Period, Value, New Issues	55,785		55,785
Other comprehensive (loss) income, net	14,132			14,132
Ending balance at Sep. 30, 2016	1,857,354	$ 10	1,394,526	36,392	452,636	(26,210)
Ending balance, shares at Sep. 30, 2016		105,071,000
Retained earnings	522,436
Beginning balance at Dec. 31, 2016	1,891,529	$ 10	1,400,140	(4,695)	522,436	(26,362)
Beginning balance, shares at Dec. 31, 2016		105,071,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	236,186				236,186
Exercise of stock options, shares		36,000
Exercise of stock options	786		786
Restricted stock grants, net, shares		653,000
Restricted stock grants, net	$ 17,909		17,909
Treasury Stock, Shares, Acquired	(266,883)	(267,000)
Restricted Stock Award, Forfeitures	$ (13,642)					(13,642)
Other comprehensive (loss) income, net	12,859			12,859
Ending balance at Sep. 30, 2017	2,145,627	$ 10	$ 1,418,835	$ 8,164	$ 758,622	$ (40,004)
Ending balance, shares at Sep. 30, 2017		105,493,000
Retained earnings	$ 758,622

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 236,186	$ 189,998
Adjustments to reconcile net income to cash provided by operating activities:
Provision for credit losses	12,250	7,000
Depreciation and amortization	9,956	9,272
Stock-based compensation	17,909	15,039
Excess tax benefit of stock-based compensation	(5,170)	(4,064)
Deferred income taxes	3,371	4,191
Amortization of net premiums for investment securities	14,926	9,659
Accretion of fair market value adjustments on loans acquired from business combinations	(20,994)	(22,278)
Accretion and amortization of fair market value adjustments on other assets and liabilities acquired from business combinations	1,898	2,323
Income from bank owned life insurance	(2,896)	(2,858)
(Gains) / Losses on:
Sales of investment securities	(907)	(1,001)
Sale of loans	117	(2,258)
Other assets acquired through foreclosure, net	(233)	304
Valuation adjustments of other repossessed assets, net	120	(127)
Sale of premises, equipment, and other assets, net	67	(268)
Changes in, net of acquisitions:
Other assets	11,696	20,498
Other liabilities	(7,213)	(10,948)
Net cash provided by operating activities	271,083	214,482
Investment securities - measured at fair value
Principal pay downs and maturities	0	256
Proceeds from sales	994	0
Investment securities - AFS
Purchases	(1,361,908)	(1,017,250)
Principal pay downs and maturities	370,231	323,426
Proceeds from sales	87,853	34,304
Purchases	62,489	52,607
Purchase of investment tax credits	(19,916)	(23,672)
(Purchase) sale of money market investments, net	(175)	(126)
Proceeds from bank owned life insurance	607	1,710
(Purchase) liquidation of restricted stock	(430)	(6,902)
Loan fundings and principal collections, net	(1,179,494)	(551,931)
Purchase of premises, equipment, and other assets, net	(7,644)	(9,324)
Proceeds from sale of other real estate owned and repossessed assets, net	20,748	6,034
Cash and cash equivalents (used) acquired in acquisitions, net	0	(1,272,187)
Net cash used in investing activities	(2,151,623)	(2,568,269)
Cash flows from financing activities:
Net increase (decrease) in deposits	2,354,920	2,412,537
Proceeds from issuance of subordinated debt	0	169,268
Net (decrease) increase in borrowings	(95,661)	(143,784)
Proceeds from exercise of common stock options	786	755
Purchases of treasury stock	(13,642)	(9,331)
Proceeds from issuance of stock in offerings, net	0	55,785
Net cash provided by financing activities	2,246,403	2,485,230
Net increase (decrease) in cash and cash equivalents	365,863	131,443
Cash and cash equivalents at beginning of period	284,491	224,640
Cash and cash equivalents at end of period	650,354	356,083
Cash paid (returned) during the period for:
Interest	47,815	35,056
Income taxes	79,522	46,863
Non-cash investing and financing activities during the period for:
Transfers to other assets acquired through foreclosure, net	1,812	11,888
Unfunded commitments originated	(47,217)	12,366
Non-cash assets acquired in acquisition	15,386	15,605
Non-cash liabilities acquired in acquisition	(2,677)	(1,491)
Changes in unrealized gain (loss) on AFS securities, net of tax	0	1,284,557
Changes in unrealized (loss) gain on junior subordinated debt, net of tax	$ 0	$ 12,559

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of operation WAL is a bank holding company headquartered in Phoenix, Arizona, incorporated under the laws of the state of Delaware. WAL provides a full spectrum of deposit, lending, treasury management, international banking, and online banking products and services through its wholly-owned banking subsidiary, WAB. WAB operates the following full-service banking divisions: ABA, BON, FIB, Bridge, and TPB. The Company also serves business customers through a national platform of specialized financial services including AAB, Corporate Finance, Equity Fund Resources, HFF, Life Sciences Group, Mortgage Warehouse Lending, Public and Nonprofit Finance, Renewable Resource Group, Resort Finance, and Technology Finance. In addition, the Company has one non-bank subsidiary, LVSP, which holds and manages certain non-performing loans and OREO. Basis of presentation The accounting and reporting policies of the Company are in accordance with GAAP and conform to practices within the financial services industry. The accounts of the Company and its consolidated subsidiaries are included in the Consolidated Financial Statements. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management's estimates and judgments are ongoing and are based on experience, current and expected future conditions, third-party evaluations and various other assumptions that management believes are reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities, as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from those estimates and assumptions used in the Consolidated Financial Statements and related notes. Material estimates that are particularly susceptible to significant changes in the near term relate to the determination of the allowance for credit losses; estimated cash flows related to PCI loans; fair value determinations related to acquisitions and certain assets and liabilities carried at fair value; and accounting for income taxes. Principles of consolidation As of September 30, 2017 , WAL has ten wholly-owned subsidiaries: WAB, LVSP, and eight unconsolidated subsidiaries used as business trusts in connection with the issuance of trust-preferred securities. The Bank has the following significant wholly-owned subsidiaries: WABT, which holds certain investment securities, municipal and nonprofit loans, and leases; WA PWI, LLC, which holds certain limited partnerships invested primarily in low income housing tax credits and small business investment corporations; and BW Real Estate, Inc., which operates as a real estate investment trust and holds certain of WAB's real estate loans and related securities. The Company does not have any other significant entities that should be considered for consolidation. All significant intercompany balances and transactions have been eliminated in consolidation. Reclassifications Certain amounts reported in prior periods may have been reclassified in the Consolidated Financial Statements to conform to the current presentation. The reclassifications have no effect on net income or stockholders’ equity as previously reported. Interim financial information The accompanying Unaudited Consolidated Financial Statements as of and for the three and nine months ended September 30, 2017 and 2016 have been prepared in condensed format and, therefore, do not include all of the information and footnotes required by GAAP for complete financial statements. These statements have been prepared on a basis that is substantially consistent with the accounting principles applied to the Company's audited Consolidated Financial Statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2016 . The information furnished in these interim statements reflects all adjustments which are, in the opinion of management, necessary for a fair statement of the results for each respective period presented. Such adjustments are of a normal, recurring nature. The results of operations in the interim statements are not necessarily indicative of the results that may be expected for any other quarter or for the full year. The interim financial information should be read in conjunction with the Company's audited Consolidated Financial Statements. Business combinations Business combinations are accounted for under the acquisition method of accounting in accordance with ASC 805, Business Combinations. Under the acquisition method, the acquiring entity in a business combination recognizes all of the acquired assets and assumed liabilities at their estimated fair values as of the date of acquisition. Any excess of the purchase price over the fair value of net assets and other identifiable intangible assets acquired is recorded as goodwill. To the extent the fair value of net assets acquired, including identified intangible assets, exceeds the purchase price, a bargain purchase gain is recognized. Changes to estimated fair values from a business combination are recognized as an adjustment to goodwill during the measurement period and are recognized in the proper reporting period in which the adjustment amounts are determined. Results of operations of an acquired business are included in the Consolidated Income Statement from the date of acquisition. Acquisition-related costs, including conversion and restructuring charges, are expensed as incurred. Investment securities Investment securities may be classified as HTM, AFS, or measured at fair value. The appropriate classification is initially decided at the time of purchase. Securities classified as HTM are those debt securities that the Company has both the intent and ability to hold to maturity regardless of changes in market conditions, liquidity needs, or general economic conditions. These securities are carried at amortized cost. The sale of a security within three months of its maturity date or after the majority of the principal outstanding has been collected is considered a maturity for purposes of classification and disclosure. Securities classified as AFS or trading securities measured at fair value are reported as an asset in the Consolidated Balance Sheet at their estimated fair value. As the fair value of AFS securities changes, the changes are reported net of income tax as an element of OCI, except for other-than-temporarily-impaired securities. When AFS securities are sold, the unrealized gain or loss is reclassified from OCI to non-interest income. The changes in the fair values of trading securities are reported in non-interest income. Securities classified as AFS are both equity and debt securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity. Any decision to sell a security classified as AFS would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Company’s assets and liabilities, liquidity needs, decline in credit quality, and regulatory capital considerations. Interest income is recognized based on the coupon rate and increased by accretion of discounts earned or decreased by the amortization of premiums paid over the contractual life of the security, adjusted for prepayment estimates, using the interest method. In estimating whether there are any OTTI losses, management considers the 1) length of time and the extent to which the fair value has been less than amortized cost; 2) financial condition and near term prospects of the issuer; 3) impact of changes in market interest rates; and 4) intent and ability of the Company to retain its investment for a period of time sufficient to allow for any anticipated recovery in fair value and whether it is not more likely than not the Company would be required to sell the security. Declines in the fair value of individual AFS debt securities that are deemed to be other-than-temporary are reflected in earnings when identified. The fair value of the debt security then becomes the new cost basis. For individual debt securities where the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary decline in fair value of the debt security related to 1) credit loss is recognized in earnings; and 2) interest rate, market, or other factors is recognized in other comprehensive income or loss. For individual debt securities where the Company either intends to sell the security or more likely than not will not recover all of its amortized cost, the OTTI is recognized in earnings equal to the entire difference between the security's cost basis and its fair value at the balance sheet date. For individual debt securities for which a credit loss has been recognized in earnings, interest accruals and amortization and accretion of premiums and discounts are suspended when the credit loss is recognized. Interest received after accruals have been suspended is recognized on a cash basis. Restricted stock WAB is a member of the Federal Reserve System and, as part of its membership, is required to maintain stock in the FRB in a specified ratio to its capital. In addition, WAB is a member of the FHLB system and, accordingly, maintains an investment in capital stock of the FHLB based on the borrowing capacity used. The Bank also maintains an investment in its primary correspondent bank. All of these investments are considered equity securities with no actively traded market. Therefore, the shares are considered restricted investment securities. These investments are carried at cost, which is equal to the value at which they may be redeemed. The dividend income received from the stock is reported in interest income. The Company conducts a periodic review and evaluation of its restricted stock to determine if any impairment exists. No impairment has been recorded to date. Loans, held for sale Loans, held for sale consist of SBA loans that the Company originates (or acquires) and intends to sell. These loans are carried at the lower of aggregate cost or fair value. Fair value is determined based on available market data for similar assets, expected cash flows, and appraisals of underlying collateral or the credit quality of the borrower. Gains and losses on the sale of loans are recognized pursuant to ASC 860, Transfers and Servicing . Interest income of these loans is accrued daily and loan origination fees and costs are deferred and included in the cost basis of the loan. The Company issues various representations and warranties associated with these loan sales. The Company has not experienced any losses as a result of these representations and warranties. Loans, held for investment The Company generally holds loans for investment and has the intent and ability to hold loans until their maturity. Therefore, they are reported at book value. Net loans are stated at the amount of unpaid principal, adjusted for net deferred fees and costs, purchase accounting fair value adjustments, and an allowance for credit losses. In addition, the book value of loans that are subject to a fair value hedge is adjusted for changes in value attributable to the effective portion of the hedged benchmark interest rate risk. The Company may also acquire loans through a business combination. These acquired loans are recorded at estimated fair value on the date of purchase, which is comprised of unpaid principal adjusted for estimated credit losses and interest rate fair value adjustments. Loans are evaluated individually at the acquisition date to determine if there has been credit deterioration since origination. Such loans may then be aggregated and accounted for as a pool of loans based on common characteristics. When the Company acquires such loans, the yield that may be accreted (accretable yield) is limited to the excess of the Company’s estimate of undiscounted cash flows expected to be collected over the Company’s initial investment in the loan. The excess of contractual cash flows over the cash flows expected to be collected may not be recognized as an adjustment to yield, loss, or a valuation allowance. Subsequent increases in cash flows expected to be collected generally are recognized prospectively through adjustment of the loan’s yield over the remaining life. Subsequent decreases to cash flows expected to be collected are recognized as impairment. The Company may not carry over or create a valuation allowance in the initial accounting for loans acquired under these circumstances. For purchased loans that are not deemed impaired at the acquisition date, fair value adjustments attributable to both credit and interest rates are accreted (or amortized) over the contractual life of the individual loan. For additional information, see " Note 3. Loans, Leases and Allowance for Credit Losses " of these Notes to Unaudited Consolidated Financial Statements. Loan fees collected for the origination of loans less direct loan origination costs (net deferred loan fees) are amortized over the contractual life of the loan through interest income. If the loan has scheduled payments, the amortization of the net deferred loan fee is calculated using the interest method over the contractual life of the loan. If the loan does not have scheduled payments, such as a line of credit, the net deferred loan fee is recognized as interest income on a straight-line basis over the contractual life of the loan commitment. Commitment fees based on a percentage of a customer’s unused line of credit and fees related to standby letters of credit are recognized over the commitment period. When loans are repaid, any remaining unamortized balances of premiums, discounts, or net deferred fees are recognized as interest income. Non-accrual loans: When a borrower discontinues making payments as contractually required by the note, the Company must determine whether it is appropriate to continue to accrue interest. The Company ceases accruing interest income when the loan has become delinquent by more than 90 days or when management determines that the full repayment of principal and collection of interest according to contractual terms is no longer likely. The Company may decide to continue to accrue interest on certain loans more than 90 days delinquent if the loans are well secured by collateral and in the process of collection. For all loan types, when a loan is placed on non-accrual status, all interest accrued but uncollected is reversed against interest income in the period in which the status is changed and, the Company makes a loan-level decision to apply either the cash basis or cost recovery method. The Company recognizes income on a cash basis only for those non-accrual loans for which the collection of the remaining principal balance is not in doubt. Under the cost recovery method, subsequent payments received from the customer are applied to principal and generally no further interest income is recognized until the principal has been paid in full or until circumstances have changed such that payments are again consistently received as contractually required. Impaired loans: A loan is identified as impaired when it is no longer probable that interest and principal will be collected according to the contractual terms of the original loan agreement. Generally, impaired loans are classified as non-accrual. However, in certain instances, impaired loans may continue on an accrual basis, if full repayment of all principal and interest is expected and the loan is both well secured and in the process of collection. Impaired loans are measured for reserve requirements in accordance with ASC 310, Receivables, 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 the collateral less applicable disposition costs if the loan is collateral dependent. The amount of an impairment reserve, if any, and any subsequent changes are recorded as a provision for credit losses. Losses are recorded as a charge-off when losses are confirmed. In addition to management's internal loan review process, regulators may from time to time direct the Company to modify loan grades, loan impairment calculations, or loan impairment methodology. Troubled Debt Restructured Loans : A TDR loan is a loan on which the Company, for reasons related to a borrower’s financial difficulties, grants a concession to the borrower that the Company would not otherwise consider. The loan terms that have been modified or restructured due to a borrower’s financial situation include, but are not limited to, a reduction in the stated interest rate, an extension of the maturity or renewal of the loan at an interest rate below current market, a reduction in the face amount of the debt, a reduction in the accrued interest, or deferral of interest payments. A TDR loan is also considered impaired. A TDR loan may be returned to accrual status when the loan is brought current, has performed in accordance with the contractual restructured terms for a reasonable period of time (generally six months) and the ultimate collectability of the total contractual restructured principal and interest is no longer in doubt. However, such loans continue to be considered impaired. Consistent with regulatory guidance, a TDR loan that is subsequently modified in another restructuring agreement but has shown sustained performance and classification as a TDR, will be removed from TDR status provided that the modified terms were market-based at the time of modification. Allowance for credit losses Credit risk is inherent in the business of extending loans and leases to borrowers, for which the Company must maintain an adequate allowance for credit losses. The allowance for credit losses is established through a provision for credit losses recorded to expense. Loans are charged against the allowance for credit losses when management believes that the contractual principal or interest will not be collected. Subsequent recoveries, if any, are credited to the allowance. The allowance is an amount believed adequate to absorb estimated probable losses on existing loans that may become uncollectable, based on evaluation of the collectability of loans and prior credit loss experience, together with other factors. The Company formally re-evaluates and establishes the appropriate level of the allowance for credit losses on a quarterly basis. The allowance consists of specific and general components. The specific allowance applies to impaired loans. For impaired collateral dependent loans, the reserve is calculated based on the collateral value, net of estimated disposition costs. Generally, the Company obtains independent collateral valuation analysis for each loan every twelve months. Loans not collateral dependent are evaluated based on the expected future cash flows discounted at the original contractual interest rate. The general allowance covers all non-impaired loans and incorporates several quantitative and qualitative factors, which are used for all of the Company's portfolio segments. Quantitative factors include company-specific, ten-year historical net charge-offs stratified by loans with similar characteristics. Qualitative factors include: 1) levels of and trends in delinquencies and impaired loans; 2) levels of and trends in charge-offs and recoveries; 3) trends in volume and terms of loans; 4) changes in underwriting standards or lending policies; 5) experience, ability, depth of lending staff; 6) national and local economic trends and conditions; 7) changes in credit concentrations; 8) out-of-market exposures; 9) changes in quality of loan review system; and 10) changes in the value of underlying collateral. Due to the credit concentration of the Company's loan portfolio in real estate secured loans, the value of collateral is heavily dependent on real estate values in Arizona, Nevada, and California. While management uses the best information available to make its evaluation, future adjustments to the allowance may be necessary if there are significant changes in economic or other conditions. In addition, regulators, as an integral part of their examination processes, periodically review the Bank's allowance for credit losses, and may require the Bank to make additions to the allowance based on their judgment about information available to them at the time of their examination. Management regularly reviews the assumptions and formulae used in determining the allowance and makes adjustments if required to reflect the current risk profile of the portfolio. Goodwill and other intangible assets The Company records as goodwill the excess of the purchase price over the fair value of the identifiable net assets acquired in accordance with applicable guidance. The Company performs its annual goodwill and intangibles impairment tests as of October 1 each year, or more often if events or circumstances indicate that the carrying value may not be recoverable. The Company can first elect to assess, through qualitative factors, whether it is more likely than not that goodwill is impaired. If the qualitative assessment indicates potential impairment, the Company will proceed with a two-step process. The first step tests for impairment, while the second step, if necessary, measures the impairment. The resulting impairment amount, if any, is charged to current period earnings as non-interest expense. The Company’s intangible assets consist primarily of core deposit intangible assets that are amortized over periods ranging from 5 to 10 years. The Company considers the remaining useful lives of its core deposit intangible assets each reporting period, as required by ASC 350, Intangibles—Goodwill and Other, to determine whether events and circumstances warrant a revision to the remaining period of amortization. If the estimate of an intangible asset’s remaining useful life has changed, the remaining carrying amount of the intangible asset is amortized prospectively over the revised remaining useful life. The Company has not revised its estimates of the useful lives of its core deposit intangibles during the three and nine months ended September 30, 2017 and 2016 . Other assets acquired through foreclosure Other assets acquired through foreclosure consist primarily of properties acquired as a result of, or in-lieu-of, foreclosure. Properties or other assets (primarily repossessed assets formerly leased) are classified as OREO and other repossessed property and are initially reported at fair value of the asset less estimated selling costs. Subsequent adjustments are based on the lower of carrying value or fair value less estimated costs to sell the property. Costs related to the development or improvement of the assets are capitalized and costs related to holding the assets are charged to non-interest expense. Property is evaluated regularly to ensure the recorded amount is supported by its current fair value and valuation allowances. Treasury Shares The Company separately presents treasury shares, which represent shares surrendered to the Company equal in value to the statutory payroll tax withholding obligations arising from the vesting of employee restricted stock awards. Treasury shares are carried at cost. Derivative financial instruments The Company uses interest-rate swaps to mitigate interest-rate risk associated with changes to 1) the fair value of certain fixed-rate financial instruments (fair value hedges) and 2) certain cash flows related to future interest payments on variable rate financial instruments (cash flow hedges). The Company recognizes derivatives as assets or liabilities in the Consolidated Balance Sheet at their fair value in accordance with ASC 815, Derivatives and Hedging . The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and further, on the type of hedging relationship. On the date the derivative contract is entered into, the Company designates the derivative as a fair value hedge or cash flow hedge. Derivative instruments designated in a hedge relationship to mitigate exposure to changes in the fair value of an asset or liability attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivative instruments designated in a hedge relationship to mitigate exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Changes in the fair value of a derivative that is designated and qualifies as a fair value hedge, along with changes in the fair value of the hedged asset or liability that are attributable to the hedged risk are recorded in current-period earnings. For a cash flow hedge, the effective portion of the change in the fair value of the derivative is recorded in AOCI and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Any ineffective portion of the change in fair value of a cash flow hedge is recognized immediately in non-interest income in the Consolidated Income Statement. Under both the fair value and cash flow hedge scenarios, changes in the fair value of derivatives not considered to be highly effective in hedging the change in fair value or the expected cash flows of the hedged item are recognized in earnings as non-interest income during the period of the change. The Company documents its hedge relationships, including identification of the hedging instruments and the hedged items, as well as its risk management objectives and strategies for undertaking the hedge transaction at the time the derivative contract is executed. Both at inception and at least quarterly thereafter, the Company assesses whether the derivatives used in hedging transactions are highly effective (as defined in the guidance) in offsetting changes in either the fair value or cash flows of the hedged item. Retroactive effectiveness is assessed, as well as the continued expectation that the hedge will remain effective prospectively. The Company discontinues hedge accounting prospectively when it is determined that a hedge is no longer highly effective. When hedge accounting is discontinued on a fair value hedge that no longer qualifies as an effective hedge, the derivative continues to be reported at fair value in the Consolidated Balance Sheet, but the carrying amount of the hedged item is no longer adjusted for future changes in fair value. The adjustment to the carrying amount of the hedged item that existed at the date hedge accounting is discontinued is amortized over the remaining life of the hedged item into earnings. Derivative instruments that are not designated as hedges, so called free-standing derivatives, are reported in the Consolidated Balance Sheet at fair value and the changes in fair value are recognized in earnings as non-interest income during the period of change. The Company may in the normal course of business purchase a financial instrument or originate a loan that contains an embedded derivative instrument. Upon purchasing the instrument or originating the loan, the Company assesses whether the economic characteristics of the embedded derivative are clearly and closely related to the economic characteristics of the remaining component of the financial instrument (i.e., the host contract) and whether a separate instrument with the same terms as the embedded instrument would meet the definition of a derivative instrument. When it is determined that the embedded derivative possesses economic characteristics that are not clearly and closely related to the economic characteristics of the host contract and a separate instrument with the same terms would qualify as a derivative instrument, the embedded derivative is separated from the host contract and carried at fair value. However, in cases where the host contract is measured at fair value, with changes in fair value reported in current earnings, or the Company is unable to reliably identify and measure an embedded derivative for separation from its host contract, the entire contract is carried in the Consolidated Balance Sheet at fair value and is not designated as a hedging instrument. Income taxes The Company is subject to income taxes in the United States and files a consolidated federal income tax return with all of its subsidiaries, with the exception of BW Real Estate, Inc. Deferred income taxes are recorded to reflect the effects of temporary differences between the financial reporting carrying amounts of assets and liabilities and their income tax bases using enacted tax rates that are expected to be in effect when the taxes are actually paid or recovered. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. Net deferred tax assets are recorded to the extent that these assets will more-likely-than-not be realized. In making these determinations, all available positive and negative evidence is considered, including scheduled reversals of deferred tax liabilities, tax planning strategies, projected future taxable income, and recent operating results. If it is determined that deferred income tax assets to be realized in the future are in excess of their net recorded amount, an adjustment to the valuation allowance will be recorded, which will reduce the Company's provision for income taxes. A tax benefit from an unrecognized tax benefit may be recognized when it is more-likely-than-not that the position will be sustained upon examination, including related appeals or litigation, based on technical merits. Income tax benefits must meet a more-likely-than-not recognition threshold at the effective date to be recognized. Interest and penalties related to unrecognized tax benefits are recognized as part of the provision for income taxes in the Consolidated Income Statement. Accrued interest and penalties are included in the related tax liability line with other liabilities in the Consolidated Balance Sheet. See " Note 11. Income Taxes " of these Notes to Unaudited Consolidated Financial Statements for further discussion on income taxes. Off-balance sheet instruments In the ordinary course of business, the Company has entered into off-balance sheet financial instrument arrangements consisting of commitments to extend credit and standby letters of credit. Such financial instruments are recorded in the Consolidated Financial Statements when they are funded. They involve, to varying degrees, elements of credit risk in excess of amounts recognized in the Consolidated Balance Sheet. Losses would be experienced when the Company is contractually obligated to make a payment under these instruments and must seek repayment from the borrower, which may not be as financially sound in the current period as they were when the commitment was originally made. 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. The Company enters into credit arrangements that generally provide for the termination of advances in the event of a covenant violation or other event of default. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the party. The commitments are collateralized by the same types of assets used as loan collateral. As with outstanding loans, the Company applies qualitative factors and utilization rates to its off-balance sheet obligations in determining an estimate of losses inherent in these contractual obli

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Investment Securities	2. INVESTMENT SECURITIES The carrying amounts and fair values of investment securities at September 30, 2017 and December 31, 2016 are summarized as follows: September 30, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Fair Value (in thousands) Held-to-maturity Tax-exempt $ 154,920 $ 5,791 $ (129 ) $ 160,582 Available-for-sale CDO $ 50 $ 15,503 $ — $ 15,553 Commercial MBS issued by GSEs 116,910 55 (3,171 ) 113,794 Corporate debt securities 105,047 404 (1,437 ) 104,014 CRA investments 50,997 — (349 ) 50,648 Preferred stock 91,926 4,174 — 96,100 Private label residential MBS 800,171 2,090 (4,646 ) 797,615 Residential MBS issued by GSEs 1,831,411 3,484 (15,889 ) 1,819,006 Tax-exempt 456,762 10,796 (4,785 ) 462,773 Trust preferred securities 32,000 — (2,792 ) 29,208 U.S. government sponsored agency securities 64,000 — (2,364 ) 61,636 U.S. treasury securities 2,496 3 (2 ) 2,497 Total AFS securities $ 3,551,770 $ 36,509 $ (35,435 ) $ 3,552,844 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Fair Value (in thousands) Held-to-maturity Tax-exempt $ 92,079 $ 433 $ (546 ) $ 91,966 Available-for-sale CDO $ 50 $ 13,440 $ — $ 13,490 Commercial MBS issued by GSEs 121,742 — (3,950 ) 117,792 Corporate debt securities 65,058 371 (1,285 ) 64,144 CRA investments 37,627 — (514 ) 37,113 Preferred stock 96,071 833 (2,242 ) 94,662 Private label residential MBS 440,272 182 (6,769 ) 433,685 Residential MBS issued by GSEs 1,369,289 3,046 (17,130 ) 1,355,205 Tax-exempt 409,693 8,477 (9,937 ) 408,233 Trust preferred securities 32,000 — (5,468 ) 26,532 U.S. government sponsored agency securities 59,000 — (2,978 ) 56,022 U.S. treasury securities 2,496 6 — 2,502 Total AFS securities $ 2,633,298 $ 26,355 $ (50,273 ) $ 2,609,380 Securities measured at fair value Residential MBS issued by GSEs $ 1,053 During the nine months ended September 30, 2017 , the Company sold all of its investment securities measured at fair value. No significant gain or loss was recognized upon sale of these securities. For additional information on the fair value changes of securities measured at fair value, see the trading securities table in " Note 13. Fair Value Accounting " of these Notes to Unaudited Consolidated Financial Statements. The Company conducts an OTTI analysis on a quarterly basis. The initial indication of OTTI for both debt and equity securities is a decline in the market value below the amount recorded for an investment, and taking into account the severity and duration of the decline. Another potential indication of OTTI is a downgrade below investment grade. In determining whether an impairment is OTTI, the Company considers the length of time and the extent to which the market value has been below cost, recent events specific to the issuer, including investment downgrades by rating agencies and economic conditions of its industry, and the Company’s ability and intent to hold the investment for a period of time sufficient to allow for any anticipated recovery. For marketable equity securities, the Company also considers the issuer’s financial condition, capital strength, and near-term prospects. For debt securities, for the purpose of an OTTI analysis, the Company also considers the cause of the price decline (general level of interest rates, credit spreads, and industry and issuer-specific factors), the issuer’s financial condition, near-term prospects, and current ability to make future payments in a timely manner, as well as the issuer’s ability to service debt, and any change in agencies’ ratings at the evaluation date from the acquisition date and any likely imminent action. The Company has reviewed securities for which there is an unrealized loss in accordance with its accounting policy for OTTI described above and determined that there are no impairment charges for the three and nine months ended September 30, 2017 and 2016 . The Company does not consider any securities to be other-than-temporarily impaired as of September 30, 2017 and December 31, 2016 . No assurance can be made that OTTI will not occur in future periods. Information pertaining to securities with gross unrealized losses at September 30, 2017 and December 31, 2016 , aggregated by investment category and length of time that individual securities have been in a continuous loss position follows: September 30, 2017 Less Than Twelve Months More Than Twelve Months Total Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (in thousands) Held-to-maturity Tax-exempt $ 129 $ 9,471 $ — $ — $ 129 $ 9,471 Available-for-sale Commercial MBS issued by GSEs $ 796 $ 35,545 $ 2,375 $ 76,349 $ 3,171 $ 111,894 Corporate debt securities 1,437 78,563 — — 1,437 78,563 CRA investments 349 50,648 — — 349 50,648 Private label residential MBS 2,295 327,580 2,351 134,429 4,646 462,009 Residential MBS issued by GSEs 11,994 1,005,130 3,895 184,589 15,889 1,189,719 Tax-exempt 1,121 120,904 3,664 68,248 4,785 189,152 Trust preferred securities — — 2,792 29,208 2,792 29,208 U.S. government sponsored agency securities 1,624 42,376 740 14,260 2,364 56,636 U.S. treasury securities 2 1,502 — — 2 1,502 Total AFS securities $ 19,618 $ 1,662,248 $ 15,817 $ 507,083 $ 35,435 $ 2,169,331 December 31, 2016 Less Than Twelve Months More Than Twelve Months Total Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (in thousands) Held-to-maturity Tax-exempt $ 546 $ 30,364 $ — $ — $ 546 $ 30,364 Available-for-sale Commercial MBS issued by GSEs $ 3,950 $ 117,792 $ — $ — $ 3,950 $ 117,792 Corporate debt securities 1,285 38,716 — — 1,285 38,716 CRA investments 514 37,113 — — 514 37,113 Preferred stock 2,188 63,151 54 1,471 2,242 64,622 Private label residential MBS 6,170 377,638 599 16,969 6,769 394,607 Residential MBS issued by GSEs 16,990 950,480 140 5,326 17,130 955,806 Tax-exempt 9,937 148,780 — — 9,937 148,780 Trust preferred securities — — 5,468 26,532 5,468 26,532 U.S. government sponsored agency securities 2,978 56,022 — — 2,978 56,022 Total AFS securities $ 44,012 $ 1,789,692 $ 6,261 $ 50,298 $ 50,273 $ 1,839,990 At September 30, 2017 and December 31, 2016 , the Company’s unrealized losses relate primarily to market interest rate increases since the securities' original purchase date. The total number of securities in an unrealized loss position at September 30, 2017 is 248 , compared to 244 at December 31, 2016 . In analyzing an issuer’s financial condition, management considers whether the securities are issued by the federal government or its agencies, whether downgrades by bond rating agencies have occurred, and industry analysis reports. Since material downgrades have not occurred and management does not intend to sell the debt securities in an unrealized loss position in the foreseeable future, none of the securities described in the above table or in this paragraph are deemed to be OTTI. The trust preferred securities have yields based on floating rate LIBOR, which are highly correlated to the federal funds rate. The low rate environment has had a negative effect on the market value of these securities, however, as the federal funds rate has increased since December 31, 2016, the unrealized losses on these securities have decreased. The amortized cost and fair value of securities as of September 30, 2017 , by contractual maturities, are shown below. MBS are shown separately as individual MBS are comprised of pools of loans with varying maturities. Therefore, these securities are listed separately in the maturity summary. September 30, 2017 Amortized Cost Estimated Fair Value (in thousands) Held-to-maturity After one year through five years $ 100 $ 101 After five years through ten years 15,116 15,503 After ten years 139,704 144,978 Total HTM securities $ 154,920 $ 160,582 Available-for-sale Due in one year or less $ 50,997 $ 50,648 After one year through five years 74,409 77,268 After five years through ten years 289,847 292,086 After ten years 388,025 402,427 Mortgage-backed securities 2,748,492 2,730,415 Total AFS securities $ 3,551,770 $ 3,552,844 The following tables summarize the carrying amount of the Company’s investment ratings position as of September 30, 2017 and December 31, 2016 : September 30, 2017 AAA Split-rated AAA/AA+ AA+ to AA- A+ to A- BBB+ to BBB- BB+ and below Unrated Totals (in thousands) Held-to-maturity Tax-exempt $ — $ — $ — $ — $ — $ — $ 154,920 $ 154,920 Available-for-sale CDO $ — $ — $ — $ — $ — $ 15,553 $ — $ 15,553 Commercial MBS issued by GSEs — 113,794 — — — — — 113,794 Corporate debt securities — — — 74,819 29,195 — — 104,014 CRA investments — 25,381 — — — — 25,267 50,648 Preferred stock — — — 10,575 66,193 4,315 15,017 96,100 Private label residential MBS 736,937 — 56,171 1,509 1,025 1,973 — 797,615 Residential MBS issued by GSEs — 1,819,006 — — — — — 1,819,006 Tax-exempt 63,991 25,264 224,235 147,407 — — 1,876 462,773 Trust preferred securities — — — — 29,208 — — 29,208 U.S. government sponsored agency securities — 61,636 — — — — — 61,636 U.S. treasury securities — 2,497 — — — — — 2,497 Total AFS securities (1) $ 800,928 $ 2,047,578 $ 280,406 $ 234,310 $ 125,621 $ 21,841 $ 42,160 $ 3,552,844 (1) Where ratings differ, the Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch. December 31, 2016 AAA Split-rated AAA/AA+ AA+ to AA- A+ to A- BBB+ to BBB- BB+ and below Unrated Totals (in thousands) Held-to-maturity Tax-exempt $ — $ — $ — $ — $ — $ — $ 92,079 $ 92,079 Available-for-sale CDO $ — $ — $ — $ — $ — $ 13,490 $ — $ 13,490 Commercial MBS issued by GSEs — 117,792 — — — — — 117,792 Corporate debt securities — — 5,429 38,715 20,000 — — 64,144 CRA investments — — — — — — 37,113 37,113 Preferred stock — — — — 64,486 14,658 15,518 94,662 Private label residential MBS 399,013 — 29,921 2,117 2,634 — — 433,685 Residential MBS issued by GSEs — 1,355,205 — — — — — 1,355,205 Tax-exempt 80,862 — 268,249 59,122 — — — 408,233 Trust preferred securities — — — — 26,532 — — 26,532 U.S. government sponsored agency securities — 56,022 — — — — — 56,022 U.S. treasury securities — 2,502 — — — — — 2,502 Total AFS securities (1) $ 479,875 $ 1,531,521 $ 303,599 $ 99,954 $ 113,652 $ 28,148 $ 52,631 $ 2,609,380 Securities measured at fair value Residential MBS issued by GSEs $ — $ 1,053 $ — $ — $ — $ — $ — $ 1,053 (1) Where ratings differ, the Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch. Securities with carrying amounts of approximately $975.1 million and $763.0 million at September 30, 2017 and December 31, 2016 , respectively, were pledged for various purposes as required or permitted by law. The following table presents gross gains and losses on sales of investment securities: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Gross gains $ 468 $ — $ 1,181 $ 2,057 Gross losses (149 ) — (274 ) (1,056 ) Net gains (losses) on sales of investment securities $ 319 $ — $ 907 $ 1,001

Loans, Leases and Allowance for

Loans, Leases and Allowance for Credit Losses	9 Months Ended
	Sep. 30, 2017
Receivables [Abstract]
Loans, Leases and Allowance for Credit Losses	3. LOANS, LEASES AND ALLOWANCE FOR CREDIT LOSSES The composition of the Company’s held for investment loan portfolio is as follows: September 30, 2017 December 31, 2016 (in thousands) Commercial and industrial $ 6,661,152 $ 5,755,021 Commercial real estate - non-owner occupied 3,628,415 3,543,956 Commercial real estate - owner occupied 2,042,262 2,013,276 Construction and land development 1,671,552 1,478,114 Residential real estate 376,716 259,432 Commercial leases 74,850 100,765 Consumer 50,742 38,963 Loans, net 14,505,689 13,189,527 Allowance for credit losses (136,421 ) (124,704 ) Total loans HFI $ 14,369,268 $ 13,064,823 Net deferred loan fees and costs as of September 30, 2017 and December 31, 2016 total $21.6 million and $22.3 million , respectively, which is a reduction in the carrying value of loans. Net unamortized purchase discounts on secondary market loan purchases total $8.4 million and $5.2 million as of September 30, 2017 and December 31, 2016 , respectively. Total loans held for investment are also net of interest rate and credit marks on acquired loans, which are a net reduction in the carrying value of loans. Interest rate marks were $17.0 million and $22.2 million as of September 30, 2017 and December 31, 2016 , respectively. Credit marks were $32.8 million and $47.3 million as of September 30, 2017 and December 31, 2016 , respectively. As of September 30, 2017 and December 31, 2016 , the Company has $16.3 million and $ 18.9 million of HFS loans, respectively. The following table presents the contractual aging of the recorded investment in past due loans held for investment by class of loans: September 30, 2017 Current 30-59 Days 60-89 Days Over 90 Days Total Total (in thousands) Commercial real estate Owner occupied $ 2,039,314 $ 1,687 $ — $ 1,261 $ 2,948 $ 2,042,262 Non-owner occupied 3,431,099 — — 585 585 3,431,684 Multi-family 196,731 — — — — 196,731 Commercial and industrial Commercial 6,657,204 1,066 162 2,720 3,948 6,661,152 Leases 74,850 — — — — 74,850 Construction and land development Construction 1,136,205 2,230 — — 2,230 1,138,435 Land 533,117 — — — — 533,117 Residential real estate 370,733 — — 5,983 5,983 376,716 Consumer 50,553 7 27 155 189 50,742 Total loans $ 14,489,806 $ 4,990 $ 189 $ 10,704 $ 15,883 $ 14,505,689 December 31, 2016 Current 30-59 Days 60-89 Days Over 90 Days Total Total (in thousands) Commercial real estate Owner occupied $ 2,009,728 $ 71 $ — $ 3,477 $ 3,548 $ 2,013,276 Non-owner occupied 3,339,121 672 2 — 674 3,339,795 Multi-family 204,161 — — — — 204,161 Commercial and industrial Commercial 5,747,368 549 584 6,520 7,653 5,755,021 Leases 100,761 — — 4 4 100,765 Construction and land development Construction 973,242 — — — — 973,242 Land 503,588 — — 1,284 1,284 504,872 Residential real estate 249,726 4,333 281 5,092 9,706 259,432 Consumer 38,765 26 2 170 198 38,963 Total loans $ 13,166,460 $ 5,651 $ 869 $ 16,547 $ 23,067 $ 13,189,527 The following table presents the recorded investment in non-accrual loans and loans past due ninety days or more and still accruing interest by class of loans: September 30, 2017 December 31, 2016 Non-accrual loans Loans past due 90 days or more and still accruing Non-accrual loans Loans past due 90 days or more and still accruing Current Past Due/ Total Current Past Due/ Total (in thousands) Commercial real estate Owner occupied $ 5,102 $ 1,261 $ 6,363 $ — $ 5,084 $ 3,264 $ 8,348 $ 285 Non-owner occupied — — — — 8,317 1 8,318 — Multi-family — — — — — — — — Commercial and industrial Commercial 38,875 2,677 41,552 44 10,893 6,043 16,936 775 Leases 15 — 15 — 28 3 31 — Construction and land development Construction — — — — — — — — Land 887 — 887 — — 1,284 1,284 — Residential real estate 39 5,983 6,022 — 99 5,093 5,192 — Consumer — 155 155 — — 163 163 7 Total $ 44,918 $ 10,076 $ 54,994 $ 44 $ 24,421 $ 15,851 $ 40,272 $ 1,067 The reduction in interest income associated with loans on non-accrual status was approximately $0.7 million and $0.6 million for the three months ended September 30, 2017 and 2016 , respectively, and $1.8 million and $1.5 million for the nine months ended September 30, 2017 and 2016 , respectively. The Company utilizes an internal asset classification system as a means of reporting problem and potential problem loans. Under the Company’s risk rating system, the Company classifies problem and potential problem loans as Special Mention, Substandard, Doubtful, and Loss. Substandard loans include those characterized by well-defined weaknesses and carry the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. Loans classified as Doubtful, or risk rated nine, have all the weaknesses inherent in those classified as Substandard with the added characteristic that the weaknesses present make collection or liquidation in full, on the basis of currently existing facts, conditions and values, highly questionable and improbable. The final rating of Loss covers loans considered uncollectible and having such little recoverable value that it is not practical to defer writing off the asset. Loans that do not currently expose the Company to sufficient risk to warrant classification in one of the aforementioned categories, but possess weaknesses that warrant management’s close attention, are deemed to be Special Mention. Risk ratings are updated, at a minimum, quarterly. The following tables present gross loans by risk rating: September 30, 2017 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Commercial real estate Owner occupied $ 1,951,070 $ 40,730 $ 48,847 $ 1,615 $ — $ 2,042,262 Non-owner occupied 3,372,861 42,619 16,204 — — 3,431,684 Multi-family 196,731 — — — — 196,731 Commercial and industrial Commercial 6,474,756 100,449 62,585 23,362 — 6,661,152 Leases 73,128 — 1,722 — — 74,850 Construction and land development Construction 1,116,667 9,496 12,272 — — 1,138,435 Land 526,473 4,637 2,007 — — 533,117 Residential real estate 368,722 1,350 6,644 — — 376,716 Consumer 50,505 80 157 — — 50,742 Total $ 14,130,913 $ 199,361 $ 150,438 $ 24,977 $ — $ 14,505,689 September 30, 2017 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Current (up to 29 days past due) $ 14,129,815 $ 197,067 $ 137,947 $ 24,977 $ — $ 14,489,806 Past due 30 - 59 days 946 2,257 1,787 — — 4,990 Past due 60 - 89 days 152 37 — — — 189 Past due 90 days or more — — 10,704 — — 10,704 Total $ 14,130,913 $ 199,361 $ 150,438 $ 24,977 $ — $ 14,505,689 Included in the $25.0 million balance of loans rated Doubtful as of September 30, 2017 , is one loan with a net balance of $23.4 million that was sold subsequent to quarter-end. For additional information related to the loan sale, see page 35 of these Notes to Unaudited Consolidated Financial Statements. December 31, 2016 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Commercial real estate Owner occupied $ 1,935,322 $ 53,634 $ 22,090 $ 2,230 $ — $ 2,013,276 Non-owner occupied 3,278,090 22,972 38,733 — — 3,339,795 Multi-family 203,964 197 — — — 204,161 Commercial and industrial Commercial 5,621,448 70,011 58,562 5,000 — 5,755,021 Leases 100,737 — 28 — — 100,765 Construction and land development Construction 961,290 — 11,952 — — 973,242 Land 501,569 337 2,966 — — 504,872 Residential real estate 252,304 929 6,199 — — 259,432 Consumer 38,698 64 201 — — 38,963 Total $ 12,893,422 $ 148,144 $ 140,731 $ 7,230 $ — $ 13,189,527 December 31, 2016 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Current (up to 29 days past due) $ 12,887,308 $ 147,838 $ 124,084 $ 7,230 $ — $ 13,166,460 Past due 30 - 59 days 5,433 96 122 — — 5,651 Past due 60 - 89 days 410 210 249 — — 869 Past due 90 days or more 271 — 16,276 — — 16,547 Total $ 12,893,422 $ 148,144 $ 140,731 $ 7,230 $ — $ 13,189,527 The table below reflects the recorded investment in loans classified as impaired: September 30, 2017 December 31, 2016 (in thousands) Impaired loans with a specific valuation allowance under ASC 310 (1) $ 8,773 $ 10,909 Impaired loans without a specific valuation allowance under ASC 310 (2) 112,583 88,300 Total impaired loans $ 121,356 $ 99,209 Valuation allowance related to impaired loans (3) $ (4,394 ) $ (4,239 ) (1) Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016 , respectively. (2) Includes TDR loans of $47.8 million and $58.3 million at September 30, 2017 and December 31, 2016 , respectively. (3) Includes valuation allowance related to TDR loans of $1.3 million and $0.6 million at September 30, 2017 and December 31, 2016 , respectively. The following table presents impaired loans by class: September 30, 2017 December 31, 2016 (in thousands) Commercial real estate Owner occupied $ 16,937 $ 20,748 Non-owner occupied 19,010 25,524 Multi-family — — Commercial and industrial Commercial 57,581 21,107 Leases 336 355 Construction and land development Construction — — Land 11,503 14,838 Residential real estate 15,794 16,391 Consumer 195 246 Total $ 121,356 $ 99,209 A valuation allowance is established for an impaired loan when the fair value of the loan is less than the recorded investment. In certain cases, portions of impaired loans are charged-off to realizable value instead of establishing a valuation allowance and are included, when applicable, in the table above as “Impaired loans without a specific valuation allowance under ASC 310.” However, before concluding that an impaired loan needs no associated valuation allowance, an assessment is made to consider all available and relevant information for the method used to evaluate impairment and the type of loan being assessed. The valuation allowance disclosed above is included in the allowance for credit losses reported in the Consolidated Balance Sheets as of September 30, 2017 and December 31, 2016 . The following table presents the average investment in impaired loans and income recognized on impaired loans: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Average investment in impaired loans $ 108,033 $ 106,357 $ 106,456 $ 112,901 Interest income recognized on impaired loans 1,040 959 3,075 3,122 Interest recognized on non-accrual loans, cash basis 694 245 1,372 642 The following table presents the average investment in impaired loans by loan class: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Commercial real estate Owner occupied $ 17,779 $ 17,155 $ 20,136 $ 19,323 Non-owner occupied 20,789 29,978 22,446 31,635 Multi-family — — — — Commercial and industrial Commercial 39,736 25,662 33,009 27,221 Leases 338 331 349 904 Construction and land development Construction — — — — Land 12,503 16,699 13,297 17,632 Residential real estate 16,692 16,272 17,011 15,890 Consumer 196 260 208 296 Total $ 108,033 $ 106,357 $ 106,456 $ 112,901 The average investment in TDR loans was $52.0 million and $63.9 million for the three months ended September 30, 2017 and 2016 , respectively, and $56.6 million and $71.4 million for the nine months ended September 30, 2017 and 2016 , respectively. The following table presents interest income on impaired loans by class: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Commercial real estate Owner occupied $ 166 $ 211 $ 530 $ 753 Non-owner occupied 279 285 798 936 Multi-family — — — — Commercial and industrial Commercial 303 90 777 319 Leases 4 4 11 40 Construction and land development Construction — — — — Land 163 240 551 686 Residential real estate 124 128 406 384 Consumer 1 1 2 4 Total $ 1,040 $ 959 $ 3,075 $ 3,122 The Company is not committed to lend significant additional funds on these impaired loans. The following table summarizes nonperforming assets: September 30, 2017 December 31, 2016 (in thousands) Non-accrual loans (1) $ 54,994 $ 40,272 Loans past due 90 days or more on accrual status (2) 44 1,067 Accruing troubled debt restructured loans 40,922 53,637 Total nonperforming loans 95,960 94,976 Other assets acquired through foreclosure, net 28,992 47,815 Total nonperforming assets $ 124,952 $ 142,791 (1) Includes non-accrual TDR loans of $8.9 million and $7.1 million at September 30, 2017 and December 31, 2016 , respectively. (2) Includes less than $0.1 million from loans acquired with deteriorated credit quality at each of the periods ended September 30, 2017 and December 31, 2016 . Loans Acquired with Deteriorated Credit Quality Changes in the accretable yield for loans acquired with deteriorated credit quality are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Balance, at beginning of period $ 14,247 $ 15,863 $ 15,177 $ 15,925 Additions due to acquisition — — — 4,301 Reclassifications from non-accretable to accretable yield (1) — 119 2,086 119 Accretion to interest income (690 ) (901 ) (2,374 ) (2,570 ) Reversal of fair value adjustments upon disposition of loans (2,199 ) (578 ) (3,531 ) (3,272 ) Balance, at end of period $ 11,358 $ 14,503 $ 11,358 $ 14,503 (1) The primary drivers of reclassification from non-accretable to accretable yield resulted from changes in estimated cash flows. Allowance for Credit Losses The following table summarizes the changes in the allowance for credit losses by portfolio type: Three Months Ended September 30, Construction and Land Development Commercial Real Estate Residential Real Estate Commercial and Industrial Consumer Total (in thousands) 2017 Beginning Balance $ 20,852 $ 28,593 $ 4,838 $ 76,734 $ 794 $ 131,811 Charge-offs — 175 — 2,921 61 3,157 Recoveries (226 ) (1,781 ) (108 ) (619 ) (33 ) (2,767 ) Provision (619 ) (1,474 ) (141 ) 7,192 42 5,000 Ending Balance $ 20,459 $ 28,725 $ 4,805 $ 81,624 $ 808 $ 136,421 2016 Beginning Balance $ 21,386 $ 24,867 $ 4,546 $ 70,547 $ 758 $ 122,104 Charge-offs — 72 79 2,558 — 2,709 Recoveries (302 ) (521 ) (179 ) (466 ) (21 ) (1,489 ) Provision (347 ) (450 ) (513 ) 3,406 (96 ) 2,000 Ending Balance $ 21,341 $ 24,866 $ 4,133 $ 71,861 $ 683 $ 122,884 Nine Months Ended September 30, Construction and Land Development Commercial Real Estate Residential Real Estate Commercial and Industrial Consumer Total (in thousands) 2017 Beginning Balance $ 21,175 $ 25,673 $ 3,851 $ 73,333 $ 672 $ 124,704 Charge-offs — 1,994 447 6,166 103 8,710 Recoveries (1,011 ) (2,719 ) (1,659 ) (2,705 ) (83 ) (8,177 ) Provision (1,727 ) 2,327 (258 ) 11,752 156 12,250 Ending Balance $ 20,459 $ 28,725 $ 4,805 $ 81,624 $ 808 $ 136,421 2016 Beginning Balance $ 18,976 $ 23,160 $ 5,278 $ 71,181 $ 473 $ 119,068 Charge-offs — 726 105 11,210 120 12,161 Recoveries (455 ) (4,956 ) (589 ) (2,846 ) (131 ) (8,977 ) Provision 1,910 (2,524 ) (1,629 ) 9,044 199 7,000 Ending Balance $ 21,341 $ 24,866 $ 4,133 $ 71,861 $ 683 $ 122,884 The following table presents impairment method information related to loans and allowance for credit losses by loan portfolio segment: Commercial Real Estate-Owner Occupied Commercial Real Estate-Non-Owner Occupied Commercial and Industrial Residential Real Estate Construction and Land Development Commercial Leases Consumer Total Loans (in thousands) Loans as of September 30, 2017: Recorded Investment: Impaired loans with an allowance recorded $ — $ — $ 8,773 $ — $ — $ — $ — $ 8,773 Impaired loans with no allowance recorded 16,936 19,010 48,807 15,794 11,503 336 197 112,583 Total loans individually evaluated for impairment 16,936 19,010 57,580 15,794 11,503 336 197 121,356 Loans collectively evaluated for impairment 2,014,282 3,496,683 6,603,572 360,315 1,660,049 74,514 50,545 14,259,960 Loans acquired with deteriorated credit quality 11,044 112,722 — 607 — — — 124,373 Total recorded investment $ 2,042,262 $ 3,628,415 $ 6,661,152 $ 376,716 $ 1,671,552 $ 74,850 $ 50,742 $ 14,505,689 Unpaid Principal Balance Impaired loans with an allowance recorded $ — $ — $ 8,977 $ — $ — $ — $ — $ 8,977 Impaired loans with no allowance recorded 23,966 27,418 80,622 25,017 28,369 1,539 10,813 197,744 Total loans individually evaluated for impairment 23,966 27,418 89,599 25,017 28,369 1,539 10,813 206,721 Loans collectively evaluated for impairment 2,014,282 3,496,683 6,603,572 360,315 1,660,049 74,514 50,545 14,259,960 Loans acquired with deteriorated credit quality 14,378 139,473 4,812 725 — — — 159,388 Total unpaid principal balance $ 2,052,626 $ 3,663,574 $ 6,697,983 $ 386,057 $ 1,688,418 $ 76,053 $ 61,358 $ 14,626,069 Related Allowance for Credit Losses Impaired loans with an allowance recorded $ — $ — $ 4,394 $ — $ — $ — $ — $ 4,394 Impaired loans with no allowance recorded — — — — — — — — Total loans individually evaluated for impairment — — 4,394 — — — — 4,394 Loans collectively evaluated for impairment 12,865 14,172 77,228 4,805 20,459 — 808 130,337 Loans acquired with deteriorated credit quality — 1,688 2 — — — — 1,690 Total allowance for credit losses $ 12,865 $ 15,860 $ 81,624 $ 4,805 $ 20,459 $ — $ 808 $ 136,421 Commercial Real Estate-Owner Occupied Commercial Real Estate-Non-Owner Occupied Commercial and Industrial Residential Real Estate Construction and Land Development Commercial Leases Consumer Total Loans (in thousands) Loans as of December 31, 2016: Recorded Investment: Impaired loans with an allowance recorded $ 3,125 $ — $ 7,766 $ — $ — $ — $ 18 $ 10,909 Impaired loans with no allowance recorded 17,624 25,524 13,340 16,391 14,838 355 228 88,300 Total loans individually evaluated for impairment 20,749 25,524 21,106 16,391 14,838 355 246 99,209 Loans collectively evaluated for impairment 1,981,176 3,383,585 5,733,915 242,409 1,443,952 100,410 38,717 12,924,164 Loans acquired with deteriorated credit quality 11,351 134,847 — 632 19,324 — — 166,154 Total recorded investment $ 2,013,276 $ 3,543,956 $ 5,755,021 $ 259,432 $ 1,478,114 $ 100,765 $ 38,963 $ 13,189,527 Unpaid Principal Balance Impaired loans with an allowance recorded $ 3,125 $ — $ 8,019 $ — $ — $ — $ 18 $ 11,162 Impaired loans with no allowance recorded 26,336 33,632 43,176 26,225 33,487 507 1,358 164,721 Total loans individually evaluated for impairment 29,461 33,632 51,195 26,225 33,487 507 1,376 175,883 Loans collectively evaluated for impairment 1,981,176 3,383,585 5,733,915 242,409 1,443,952 100,410 38,717 12,924,164 Loans acquired with deteriorated credit quality 14,878 165,275 925 738 19,858 — — 201,674 Total unpaid principal balance $ 2,025,515 $ 3,582,492 $ 5,786,035 $ 269,372 $ 1,497,297 $ 100,917 $ 40,093 $ 13,301,721 Related Allowance for Credit Losses Impaired loans with an allowance recorded $ 937 $ — $ 3,301 $ — $ — $ — $ 1 $ 4,239 Impaired loans with no allowance recorded — — — — — — — — Total loans individually evaluated for impairment 937 — 3,301 — — — 1 4,239 Loans collectively evaluated for impairment 11,403 12,646 69,673 3,851 20,398 — 671 118,642 Loans acquired with deteriorated credit quality — 687 359 — 777 — — 1,823 Total allowance for credit losses $ 12,340 $ 13,333 $ 73,333 $ 3,851 $ 21,175 $ — $ 672 $ 124,704 Troubled Debt Restructurings A TDR loan is a loan on which the Company, for reasons related to a borrower’s financial difficulties, grants a concession to the borrower that the Company would not otherwise consider. The loan terms that have been modified or restructured due to a borrower’s financial situation include, but are not limited to, a reduction in the stated interest rate, an extension of the maturity or renewal of the loan at an interest rate below current market, a reduction in the face amount of the debt, a reduction in the accrued interest, or deferral of interest payments. The majority of the Company's modifications are extensions in terms or deferral of payments which result in no lost principal or interest followed by reductions in interest rates or accrued interest. A TDR loan is also considered impaired. Consistent with regulatory guidance, a TDR loan that is subsequently modified in another restructuring agreement but has shown sustained performance and classification as a TDR, will be removed from TDR status provided that the modified terms were market-based at the time of modification. During the three months ended September 30, 2017 , the Company had two new TDR loans with a recorded investment of $1.9 million . During the nine months ended September 30, 2017 , the Company had three new TDR loan with a recorded investment of $6.8 million . No principal amounts were forgiven and there were no waived fees or other expenses resulting from the TDR. The Company did not have any new TDR loans during the three and nine months ended September 30, 2016 . During the three months ended September 30, 2017 , there was one CRE, owner occupied TDR loan with a net recorded investment of $0.1 million for which there was a payment default. During the nine months ended September 30, 2017 , there were three TDR loans with a net recorded investment of $0.5 million for which there was a payment default. During the three months ended September 30, 2016 , there were no TDR loans for which there was a payment default. During the nine months ended September 30, 2016 , there were two TDR loans with a net recorded investment of $5.7 million for which there was a payment default. A TDR loan is deemed to have a payment default when it becomes past due 90 days, goes on non-accrual, or is restructured again. Payment defaults, along with other qualitative indicators, are considered by management in the determination of the allowance for credit losses. At September 30, 2017 and December 31, 2016 there were no loan commitments outstanding on TDR loans. Loan Purchases and Sales For the three months ended September 30, 2017 and 2016 , secondary market loan purchases totaled $216.8 million and $163.7 million , respectively. For the nine months ended September 30, 2017 and 2016 , secondary market loan purchases totaled $666.8 million and $262.0 million , respectively. For 2017 , these purchased loans consisted of $520.4 million of commercial and industrial loans and $146.4 million of residential real estate loans. For 2016 , these purchased loans consisted of commercial and industrial loans. During the three months ended September 30, 2017 , the Company sold commercial and industrial loans with a carrying value of $41.3 million and did not recognize a significant net gain or loss on the sales. During the nine months ended September 30, 2017 , the Company sold loans, which consisted primarily of commercial and industrial loans, with a carrying value of $50.5 million and recognized a net loss of $0.1 million . During the nine months ended September 30, 2016 , the Company sold loans, which consisted primarily of CRE and commercial and industrial loans, with a carrying value of $37.1 million and recognized a net gain of $ 2.1 million . During the three months ended September 30, 2017 , the Company recognized a charge-off of $1.4 million related to one non-accrual loan with a net balance of $23.4 million at quarter-end, which is also included in the $25.0 million balance of loans rated Doubtful as of September 30, 2017 , as shown in the risk rating tables on page 28. Subsequent to September 30, 2017 , the Company sold this loan and did not incur an additional loss on the sale.

Other Assets Acquired Through F

Other Assets Acquired Through Foreclosure	9 Months Ended
	Sep. 30, 2017
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]
Other Assets Acquired Through Foreclosure	4. OTHER ASSETS ACQUIRED THROUGH FORECLOSURE The following table represents the changes in other assets acquired through foreclosure: Three Months Ended September 30, 2017 Gross Balance Valuation Allowance Net Balance (in thousands) Balance, beginning of period $ 35,037 $ (4,049 ) $ 30,988 Transfers to other assets acquired through foreclosure, net 430 — 430 Proceeds from sale of other real estate owned and repossessed assets, net (2,491 ) 330 (2,161 ) Valuation adjustments, net — (343 ) (343 ) Gains (losses), net (1) 78 — 78 Balance, end of period $ 33,054 $ (4,062 ) $ 28,992 Three Months Ended September 30, 2016 Balance, beginning of period $ 56,467 $ (6,623 ) $ 49,844 Transfers to other assets acquired through foreclosure, net 1,162 — 1,162 Proceeds from sale of other real estate owned and repossessed assets, net (1,260 ) 32 (1,228 ) Valuation adjustments, net — (184 ) (184 ) Gains (losses), net (1) 25 — 25 Balance, end of period $ 56,394 $ (6,775 ) $ 49,619 Nine Months Ended September 30, 2017 Gross Balance Valuation Allowance Net Balance (in thousands) Balance, beginning of period $ 54,138 $ (6,323 ) $ 47,815 Transfers to other assets acquired through foreclosure, net 1,812 — 1,812 Proceeds from sale of other real estate owned and repossessed assets, net (23,129 ) 2,381 (20,748 ) Valuation adjustments, net — (120 ) (120 ) (Losses) gains, net (1) 233 — 233 Balance, end of period $ 33,054 $ (4,062 ) $ 28,992 Nine Months Ended September 30, 2016 Balance, beginning of period $ 52,984 $ (9,042 ) $ 43,942 Transfers to other assets acquired through foreclosure, net 11,888 — 11,888 Proceeds from sale of other real estate owned and repossessed assets, net (8,174 ) 2,140 (6,034 ) Valuation adjustments, net — 127 127 (Losses) gains, net (1) (304 ) — (304 ) Balance, end of period $ 56,394 $ (6,775 ) $ 49,619 (1) There were zero net gains related to initial transfers to other assets during the three months ended September 30, 2017 and 2016 and $0.1 million and zero net gains related to initial transfers to other assets during the nine months ended September 30, 2017 and 2016 , respectively. At September 30, 2017 and 2016 , the majority of the Company’s repossessed assets consisted of properties located in Nevada. The Company held 20 properties at September 30, 2017 , compared to 31 at December 31, 2016 , and 33 at September 30, 2016 .

Other Borrowings

Other Borrowings	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Other Borrowings	5. OTHER BORROWINGS The following table summarizes the Company’s borrowings as of September 30, 2017 and December 31, 2016 : September 30, 2017 December 31, 2016 (in thousands) Short-Term: FHLB advances $ — $ 80,000 Total short-term borrowings $ — $ 80,000 The Company maintains other lines of credit with correspondent banks totaling $167.5 million , of which $22.5 million is secured by pledged securities and has a floating interest rate of one-month or three-month LIBOR plus 1.50%. The remaining $145.0 million is unsecured and has a floating interest rate of one-month LIBOR plus 3.25%. As of September 30, 2017 and December 31, 2016 , there were no outstanding balances on the Company's lines of credit. The Company maintains lines of credit with the FHLB and the FRB. The Company’s borrowing capacity is determined based on collateral pledged, generally consisting of investment securities and loans, at the time of the borrowing. At September 30, 2017 , the Company had no short-term borrowings. At December 31, 2016 , short-term FHLB advances of $80.0 million had a weighted average interest rate of 0.55% . As of September 30, 2017 and December 31, 2016 , the Company had additional available credit with the FHLB of approximately $2.29 billion and $2.15 billion , respectively, and with the FRB of approximately $1.16 billion and $997.0 million , respectively.

Qualifying Debt

Qualifying Debt	9 Months Ended
	Sep. 30, 2017
Qualifying Debt Disclosure [Abstract]
Qualifying Debt	6. QUALIFYING DEBT Subordinated Debt The Company has $175.0 million of subordinated debentures with a maturity date of July 1, 2056. Beginning on or after July 1, 2021, the Company may redeem the debentures, in whole or in part, at their principal amount plus any accrued and unpaid interest. The subordinated debt was recorded net of issuance costs of $5.5 million . The debentures have a fixed interest rate of 6.25% per annum. WAB has $150.0 million of subordinated debt, which was recorded net of debt issuance costs of $1.8 million , and matures July 15, 2025. The subordinated debt has a fixed interest rate of 5.00% through June 30, 2020 and then converts to a variable rate of 3.20% plus three-month LIBOR through maturity. To hedge the interest rate risk on the Company's subordinated debt issuances, the Company entered into fair value interest rate hedges with pay variable/receive fixed swaps. The carrying value of all subordinated debt, which includes the effective portion of related hedges, totals $306.1 million and $305.8 million at September 30, 2017 and December 31, 2016 , respectively. Junior Subordinated Debt The Company has formed or acquired through acquisition eight statutory business trusts, which exist for the exclusive purpose of issuing Cumulative Trust Preferred Securities. With the exception of debt issued by Bridge Capital Trust I and Bridge Capital Trust II, junior subordinated debt is recorded at fair value at each reporting date due to the FVO election made by the Company under ASC 825. The Company did not make the FVO election for the junior subordinated debt acquired as part of the Bridge acquisition. Accordingly, the carrying value of these trusts does not reflect the current fair value of the debt and includes a fair market value adjustment established at acquisition that is being accreted over the remaining life of the trusts. The carrying value of junior subordinated debt was $66.7 million and $62.2 million at September 30, 2017 and December 31, 2016 , respectively. The weighted average interest rate of all junior subordinated debt as of September 30, 2017 was 3.67% , which is three-month LIBOR plus the contractual spread of 2.34%, compared to a weighted average interest rate of 3.34% at December 31, 2016 .

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Stockholder's Equity	7. STOCKHOLDERS' EQUITY Stock-Based Compensation Restricted Stock Awards Restricted stock awards granted to employees in 2017 and 2016 generally vest over a three -year period. Stock grants made to non-employee WAL directors during 2017 became fully vested at June 30, 2017. The Company estimates the compensation cost for stock grants based upon the grant date fair value. Stock compensation cost is recognized on a straight-line basis over the requisite service period for the entire award. The aggregate grant date fair value for the restricted stock awards granted during the three and nine months ended September 30, 2017 was $2.7 million and $18.9 million , respectively. Stock compensation expense related to restricted stock awards and stock options granted to employees are included in Salaries and employee benefits in the Consolidated Income Statement. For restricted stock awards granted to WAL directors, the related stock compensation expense is included in Legal, professional, and directors' fees in the Consolidated Income Statement. For the three and nine months ended September 30, 2017 , the Company recognized $2.7 million and $11.3 million and in stock-based compensation expense related to all restricted stock award grants, compared to $2.7 million and $10.2 million for the three and nine months ended September 30, 2016 , respectively. In addition, the Company grants shares of restricted stock to certain members of executive management that have both performance and service conditions that affect vesting. The performance condition is based on achieving an EPS target over a one-year performance period. During the three months ended September 30, 2017 , the Company granted 104,455 shares of these restricted stock awards to new members of executive management. The grant date fair value of these awards was $5.2 million . For the three and nine months ended September 30, 2017 , the Company recognized $0.8 million and $1.6 million , respectively, in stock-based compensation expense related to these performance-based restricted stock grants, compared to $0.3 million and $0.8 million for the three and nine months ended September 30, 2016 , respectively. Performance Stock Units The Company grants members of its executive management committee performance stock units that do not vest unless the Company achieves a specified cumulative EPS target over a three-year performance period. The number of shares issued will vary based on the cumulative EPS target that is achieved. The Company estimates the cost of performance stock units based upon the grant date fair value and expected vesting percentage over the three-year performance period. For the three and nine months ended September 30, 2017 , the Company recognized $1.9 million and $4.5 million , respectively, in stock-based compensation expense related to these performance stock units, compared to $1.2 million and $3.5 million for the three and nine months ended September 30, 2016 , respectively. The three-year performance period for the 2014 grant ended on December 31, 2016, and the Company's cumulative EPS for the performance period exceeded the level required for a maximum award under the terms of the grant. As a result, executive management committee members were entitled to the maximum award of 206,050 shares, which was paid out in the first quarter of 2017 . Treasury Shares During the three and nine months ended September 30, 2017 , the Company purchased treasury shares of 64,705 and 266,883 , respectively, at a weighted average price of $51.82 and $51.10 per share, respectively. During the three and nine months ended September 30, 2016 , the Company purchased treasury shares of 8,328 and 301,495 , respectively, at a weighted average price of $34.30 and $30.95 per share, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Accumulated Other Comprehensive Income	8. ACCUMULATED OTHER COMPREHENSIVE INCOME The following table summarizes the changes in accumulated other comprehensive income (loss) by component, net of tax, for the periods indicated: Three Months Ended September 30, Unrealized holding gains (losses) on AFS Unrealized holding gains (losses) on SERP Unrealized holding gains (losses) on junior subordinated debt Impairment loss on securities Total (in thousands) Balance, June 30, 2017 $ (449 ) $ 157 $ 6,638 $ 144 $ 6,490 Other comprehensive income (loss) before reclassifications 1,116 114 641 — 1,871 Amounts reclassified from accumulated other comprehensive income (197 ) — — — (197 ) Net current-period other comprehensive income (loss) 919 114 641 — 1,674 Balance, September 30, 2017 $ 470 $ 271 $ 7,279 $ 144 $ 8,164 Balance, June 30, 2016 $ 33,013 $ 102 $ 13,367 $ 144 $ 46,626 Other comprehensive (loss) income before reclassifications (7,415 ) 6 (2,825 ) — (10,234 ) Amounts reclassified from accumulated other comprehensive income — — — — — Net current-period other comprehensive (loss) income (7,415 ) 6 (2,825 ) — (10,234 ) Balance, September 30, 2016 $ 25,598 $ 108 $ 10,542 $ 144 $ 36,392 Nine Months Ended September 30, Unrealized holding gains (losses) on AFS Unrealized holding gains (losses) on SERP Unrealized holding gains (losses) on junior subordinated debt Impairment loss on securities Total (in thousands) Balance, December 31, 2016 $ (14,916 ) $ 121 $ 9,956 $ 144 $ (4,695 ) Other comprehensive income (loss) before reclassifications 15,947 150 (2,677 ) 13,420 Amounts reclassified from accumulated other comprehensive income (561 ) — — — (561 ) Net current-period other comprehensive income (loss) 15,386 150 (2,677 ) — 12,859 Balance, September 30, 2017 $ 470 $ 271 $ 7,279 $ 144 $ 8,164 Balance, December 31, 2015 $ 9,993 $ 90 $ 12,033 $ 144 $ 22,260 Other comprehensive income (loss) before reclassifications 16,316 18 (1,491 ) — 14,843 Amounts reclassified from accumulated other comprehensive income (711 ) — — — (711 ) Net current-period other comprehensive income (loss) 15,605 18 (1,491 ) — 14,132 Balance, September 30, 2016 $ 25,598 $ 108 $ 10,542 $ 144 $ 36,392 The following table presents reclassifications out of accumulated other comprehensive income: Three Months Ended September 30, Nine Months Ended September 30, Income Statement Classification 2017 2016 2017 2016 (in thousands) Gain (loss) on sales of investment securities, net $ 319 $ — $ 907 $ 1,001 Income tax (expense) benefit (122 ) — (346 ) (290 ) Net of tax $ 197 $ — $ 561 $ 711

Derivatives and Hedging

Derivatives and Hedging	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	9. DERIVATIVES AND HEDGING ACTIVITIES The Company is a party to various derivative instruments. Derivative instruments are contracts between two or more parties that have a notional amount and an underlying variable, require a small or no initial investment, and allow for the net settlement of positions. A derivative’s notional amount serves as the basis for the payment provision of the contract and takes the form of units, such as shares or dollars. A derivative’s underlying variable is a specified interest rate, security price, commodity price, foreign exchange rate, index, or other variable. The interaction between the notional amount and the underlying variable determines the number of units to be exchanged between the parties and influences the fair value of the derivative contract. The primary type of derivatives that the Company uses are interest rate swaps. Generally, these instruments are used to help manage the Company's exposure to interest rate risk and meet client financing and hedging needs. Derivatives are recorded at fair value in the Consolidated Balance Sheets, after taking into account the effects of bilateral collateral and master netting agreements. These agreements allow the Company to settle all derivative contracts held with the same counterparty on a net basis, and to offset net derivative positions with related cash collateral, where applicable. As of September 30, 2017 , December 31, 2016 , and September 30, 2016 , the Company does not have any significant outstanding cash flow hedges or free-standing derivatives. Derivatives Designated in Hedge Relationships The Company utilizes derivatives that have been designated as part of a hedge relationship in accordance with the applicable accounting guidance to minimize the exposure to changes in benchmark interest rates and volatility of net interest income and EVE to interest rate fluctuations. The primary derivative instruments used to manage interest rate risk are interest rate swaps, which convert the contractual interest rate index of agreed-upon amounts of assets and liabilities (i.e., notional amounts) to another interest rate index. The Company has entered into pay fixed/receive variable interest rate swaps designated as fair value hedges of certain fixed rate loans. As a result, the Company receives variable-rate interest payments in exchange for making fixed-rate payments over the lives of the contracts without exchanging the notional amounts. The Company has also entered into pay variable/receive fixed interest rate swaps, designated as fair value hedges on its fixed rate subordinated debt offerings. As a result, the Company is paying a floating rate of three-month LIBOR plus 3.16% and is receiving semi-annual fixed payments of 5.00% to match the payments on the $150.0 million subordinated debt. For the fair value hedge on the Company's $175.0 million subordinated debentures issued on June 16, 2016, the Company is paying a floating rate of three-month LIBOR plus 3.25% and is receiving quarterly fixed payments of 6.25% to match the payments on the debt. Fair Values, Volume of Activity, and Gain/Loss Information Related to Derivative Instruments The following table summarizes the fair values of the Company's derivative instruments on a gross and net basis as of September 30, 2017 , December 31, 2016 , and September 30, 2016 . The change in the notional amounts of these derivatives from September 30, 2016 to September 30, 2017 indicates the volume of the Company's derivative transaction activity during these periods. The derivative asset and liability balances are presented on a gross basis, prior to the application of bilateral collateral and master netting agreements. Total derivative assets and liabilities are adjusted to take into account the impact of legally enforceable master netting agreements that allow the Company to settle all derivative contracts with the same counterparty on a net basis and to offset the net derivative position with the related collateral. Where master netting agreements are not in effect or are not enforceable under bankruptcy laws, the Company does not adjust those derivative amounts with counterparties. The fair value of derivative contracts, after taking into account the effects of master netting agreements, is included in other assets or other liabilities in the Consolidated Balance Sheets, as indicated in the following table: September 30, 2017 December 31, 2016 September 30, 2016 Fair Value Fair Value Fair Value Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities (in thousands) Derivatives designated as hedging instruments: Fair value hedges Interest rate swaps $ 1,016,694 $ 1,656 $ 59,346 $ 993,485 $ 4,220 $ 65,749 $ 988,337 $ 4,350 $ 100,067 Total 1,016,694 1,656 59,346 993,485 4,220 65,749 988,337 4,350 100,067 Netting adjustments (1) — 1,588 1,588 — 1,869 1,869 — — — Net derivatives in the balance sheet $ 1,016,694 $ 68 $ 57,758 $ 993,485 $ 2,351 $ 63,880 $ 988,337 $ 4,350 $ 100,067 (1) Netting adjustments represent the amounts recorded to convert the Company's derivative balances from a gross basis to a net basis in accordance with the applicable accounting guidance. Fair value hedges An assessment of effectiveness is performed at initiation of a hedge and on a quarterly basis thereafter. All of the Company's fair value hedges remained “highly effective” as of September 30, 2017 , December 31, 2016 , and September 30, 2016 . The following table summarizes the gains (losses) on fair value hedges for the three and nine months ended September 30, 2017 and 2016 , all of which are recorded in non-interest income. Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Hedge of Fixed Rate Loans (1) Gain (loss) on "pay fixed" swap $ 4,437 $ 7,225 $ 3,820 $ (35,087 ) (Loss) gain on receive fixed rate loans (4,423 ) (7,206 ) (3,780 ) 35,113 Net ineffectiveness $ 14 $ 19 $ 40 $ 26 Hedge of Fixed Rate Subordinated Debt Issuances (1) (Loss) gain on "receive fixed" swap $ (1,767 ) $ (3,793 ) $ 19 $ 395 Gain (loss) on subordinated debt 1,767 3,793 (19 ) (395 ) Net ineffectiveness $ — $ — $ — $ — (1) The fair value of derivatives contracts are carried as other assets and other liabilities in the Consolidated Balance Sheets. The effective portion of hedging gains (losses) is recorded as basis adjustments to the underlying hedged asset or liability. Gains and losses on both the hedging derivative and hedged item are recorded through non-interest income with a resulting net income impact for the amount of ineffectiveness. Counterparty Credit Risk Like other financial instruments, derivatives contain an element of credit risk. This risk is measured as the expected positive replacement value of the contracts. Management generally enters into bilateral collateral and master netting agreements that provide for the net settlement of all contracts with the same counterparty. Additionally, management monitors counterparty credit risk exposure on each contract to determine appropriate limits on the Company's total credit exposure across all product types. In general, the Company has a zero credit threshold with regard to derivative exposure with counterparties. Management reviews the Company's collateral positions on a daily basis and exchanges collateral with counterparties in accordance with standard ISDA documentation and other related agreements. The Company generally holds collateral in the form of cash deposits or highly rated securities issued by the U.S. Treasury or government-sponsored enterprises, such as GNMA, FNMA, and FHLMC. The total collateral netted against net derivative liabilities totaled $59.3 million at September 30, 2017 , $65.7 million at December 31, 2016 , and $100.1 million at September 30, 2016 . The following table summarizes the Company's largest exposure to an individual counterparty at the dates indicated: September 30, 2017 December 31, 2016 September 30, 2016 (in thousands) Largest gross exposure (derivative asset) to an individual counterparty $ 945 $ 2,351 $ 4,159 Collateral posted by this counterparty — 1,691 4,131 Derivative liability with this counterparty 44,053 — — Collateral pledged to this counterparty 65,051 — — Net exposure after netting adjustments and collateral $ — $ 660 $ 28 Credit Risk Contingent Features Management has entered into certain derivative contracts that require the Company to post collateral to the counterparties when these contracts are in a net liability position. Conversely, the counterparties may be required to post collateral when these contracts are in a net asset position. The amount of collateral to be posted is based on the amount of the net liability and exposure thresholds. As of September 30, 2017 , December 31, 2016 , and September 30, 2016 the aggregate fair value of all derivative contracts with credit risk contingent features (i.e., those containing collateral posting provisions) held by the Company that were in a net liability position totaled $57.8 million , $63.9 million , and $100.1 million , respectively. As of September 30, 2017 , the Company was in an over-collateralized net position of $25.1 million after considering $84.4 million of collateral held in the form of cash and securities. As of December 31, 2016 and September 30, 2016 , the Company was in an over-collateralized position of $24.3 million and $23.1 million , respectively.

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Share	10. EARNINGS PER SHARE Diluted EPS is based on the weighted average outstanding common shares during each period, including common stock equivalents. Basic EPS is based on the weighted average outstanding common shares during the period. The following table presents the calculation of basic and diluted EPS: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands, except per share amounts) Weighted average shares - basic 104,221 103,768 104,124 102,791 Dilutive effect of stock awards 721 796 817 741 Weighted average shares - diluted 104,942 104,564 104,941 103,532 Net income $ 82,858 $ 67,052 $ 236,186 $ 189,998 Earnings per share - basic 0.80 0.65 2.27 1.85 Earnings per share - diluted 0.79 0.64 2.25 1.84 The Company had no anti-dilutive stock options outstanding at each of the periods ended September 30, 2017 and 2016 .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	11. INCOME TAXES The effective tax rate was 29.64% and 30.32% for the three months ended September 30, 2017 and 2016 , respectively. For the nine months ended September 30, 2017 and 2016 , the Company's effective tax rate was 27.89% and 28.31% , respectively. As of September 30, 2017 , the net deferred tax asset was $83.8 million , a decrease of $11.4 million from December 31, 2016 . This overall decrease in the net deferred tax asset was primarily the result of increases in the fair market value of AFS securities and the overall increase in accrued deferred loan costs. Although realization is not assured, the Company believes that the realization of the recognized deferred tax asset of $83.8 million at September 30, 2017 is more-likely-than-not based on expectations as to future taxable income and based on available tax planning strategies within the meaning of ASC 740, Income Taxes , that could be implemented if necessary to prevent a carryover from expiring. At September 30, 2017 and December 31, 2016 , the Company had no deferred tax valuation allowance. The deferred tax asset related to federal and state NOL carryovers outstanding at each of the periods ended September 30, 2017 and December 31, 2016 available to reduce the tax liability in future years totaled $8.8 million and $9.0 million , respectively. These tax benefits relate entirely to federal NOL carryovers (subject to an annual limitation imposed by IRC Section 382). The Company’s ability to use federal NOL carryovers, as well as its ability to use certain future tax deductions called NUBILs associated with the Company's acquisitions is subject to annual limitations. In management’s opinion, it is more-likely-than-not that the results of future operations will generate sufficient taxable income to realize all of the deferred tax benefits related to these NOL carryovers and NUBILs. Investments in LIHTC The Company invests in LIHTC funds that are designed to generate a return primarily through the realization of federal tax credits. Investments in LIHTC and unfunded LIHTC obligations are included as part of other assets and other liabilities, respectively, in the Consolidated Balance Sheets and total $252.9 million and $149.4 million , respectively, as of September 30, 2017 , compared to $187.4 million and $84.4 million as of December 31, 2016 . For the three months ended September 30, 2017 and 2016 , $6.8 million and $5.5 million , respectively, of amortization related to LIHTC investments was recognized as a component of income tax expense. For the nine months ended September 30, 2017 and 2016 , $19.5 million and $13.7 million of amortization related to LIHTC investments was recognized as a component of income tax expense, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. COMMITMENTS AND CONTINGENCIES Unfunded Commitments and Letters of Credit The Company is party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit. They involve, to varying degrees, elements of credit risk in excess of amounts recognized in the Consolidated Balance Sheets. Lines of credit are obligations to lend money to a borrower. Credit risk arises when the borrower's current financial condition may indicate less ability to pay than when the commitment was originally made. In the case of standby letters of credit, the risk arises from the potential failure of the customer to perform according to the terms of a contract. In such a situation, the third party might draw on the standby letter of credit to pay for completion of the contract and the Company would look to its customer to repay these funds with interest. To minimize the risk, the Company uses the same credit policies in making commitments and conditional obligations as it would for a loan to that customer. Standby letters of credit and financial guarantees are commitments issued by the Company to guarantee the performance of a customer to a third party in borrowing arrangements. The Company generally has recourse to recover from the customer any amounts paid under the guarantees. Typically, letters of credit issued have expiration dates within one year. A summary of the contractual amounts for unfunded commitments and letters of credit are as follows: September 30, 2017 December 31, 2016 (in thousands) Commitments to extend credit, including unsecured loan commitments of $322,991 at September 30, 2017 and $360,840 at December 31, 2016 $ 5,378,255 $ 4,428,495 Credit card commitments and financial guarantees 140,728 115,536 Standby letters of credit, including unsecured letters of credit of $11,383 at September 30, 2017 and $6,431 at December 31, 2016 129,489 78,576 Total $ 5,648,472 $ 4,622,607 Commitments to extend credit are agreements to lend to a customer provided that 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. The Company enters into credit arrangements that generally provide for the termination of advances in the event of a covenant violation or other event of default. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the party. The commitments are collateralized by the same types of assets used as loan collateral. The Company has exposure to credit losses from unfunded commitments and letters of credit. As funds have not been disbursed on these commitments, they are not reported as loans outstanding. Credit losses related to these commitments are included in other liabilities as a separate loss contingency and are not included in the allowance for credit losses reported in " Note 3. Loans, Leases and Allowance for Credit Losses " of these Consolidated Financial Statements. This loss contingency for unfunded loan commitments and letters of credit was $5.6 million and $7.0 million as of September 30, 2017 and December 31, 2016 , respectively. Changes to this liability are adjusted through non-interest expense. Concentrations of Lending Activities The Company’s lending activities are driven in large part by the customers served in the market areas where the Company has branch offices in the states of Arizona, Nevada, and California. Despite the geographic concentration of lending activities, the Company does not have a single external customer from which it derives 10% or more of its revenues. The Company monitors concentrations within four broad categories: geography, industry, product, and collateral. The Company's loan portfolio includes significant credit exposure to the CRE market. As of September 30, 2017 and December 31, 2016 , CRE related loans accounted for approximately 51% and 53% of total loans, respectively. Substantially all of these loans are secured by first liens with an initial loan to value ratio of generally not more than 75% . Approximately 36% of these CRE loans, excluding construction and land loans, were owner-occupied at each of the periods ended September 30, 2017 and December 31, 2016 . Contingencies The Company is involved in various lawsuits of a routine nature that are being handled and defended in the ordinary course of the Company’s business. Expenses are being incurred in connection with these lawsuits, but in the opinion of management, based in part on consultation with outside legal counsel, the resolution of these lawsuits and associated defense costs will not have a material impact on the Company’s financial position, results of operations, or cash flows. Lease Commitments The Company leases the majority of its office locations and many of these leases contain multiple renewal options and provisions for increased rents. Total rent expense of $2.8 million for each of the three months ended September 30, 2017 and 2016 was included in occupancy expense. For the nine months ended September 30, 2017 and 2016 , total rent expense was $8.2 million and $8.1 million , respectively.

Fair Value Accounting

Fair Value Accounting	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Accounting	13. FAIR VALUE ACCOUNTING The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, the income approach, and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability. ASC 825 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under ASC 825 are described in " Note 1. Summary of Significant Accounting Policies " of these Notes to Unaudited Consolidated Financial Statements. In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and the Company’s creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. The Company’s valuation methodologies may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Furthermore, the reported fair value amounts have not been comprehensively revalued since the presentation dates, and therefore, estimates of fair value after the balance sheet date may differ significantly from the amounts presented herein. A more detailed description of the valuation methodologies used for assets and liabilities measured at fair value is set forth below. Transfers between levels in the fair value hierarchy are recognized as of the end of the month following the event or change in circumstances that caused the transfer. Under ASC 825, the Company elected the FVO treatment for junior subordinated debt held by WAL. This election is irrevocable and results in the recognition of unrealized gains and losses on these items at each reporting date. Due to the Company's election to early adopt an element of ASU 2016-01, effective January 1, 2015, these unrealized gains and losses are recognized as part of other comprehensive income rather than earnings. The Company did not elect FVO treatment for the junior subordinated debt assumed in the Bridge Capital Holdings acquisition in 2015. All securities for which the fair value measurement option had been elected are included in a separate line item in the Consolidated Balance Sheets as securities measured at fair value. During the nine months ended September 30, 2017 , the Company sold all of its investment securities measured at fair value. No significant gain or loss was recognized upon sale of these securities. For the three and nine months ended September 30, 2017 and 2016 , gains and losses from fair value changes on securities and junior subordinated debt were as follows: Changes in Fair Values for Items Measured at Fair Value Unrealized Gain/(Loss) on Assets and Liabilities Measured at Fair Value, Net Interest Income on Securities Interest Expense on Junior Subordinated Debt Total Changes Included in Current-Period Earnings Total Changes Included in OCI (in thousands) Three Months Ended September 30, 2017 Securities measured at fair value $ — $ — $ — $ — $ — Junior subordinated debt 1,035 — (835 ) (835 ) 641 Total $ 1,035 $ — $ (835 ) $ (835 ) $ 641 Nine Months Ended September 30, 2017 Securities measured at fair value $ — $ 9 $ — $ 9 $ — Junior subordinated debt (4,327 ) — (2,376 ) (2,376 ) (2,677 ) Total $ (4,327 ) $ 9 $ (2,376 ) $ (2,367 ) $ (2,677 ) Three Months Ended September 30, 2016 Securities measured at fair value $ (12 ) $ 11 $ — $ (1 ) $ — Junior subordinated debt (4,604 ) — (702 ) (625 ) (2,825 ) Total $ (4,616 ) $ 11 $ (702 ) $ (626 ) $ (2,825 ) Nine Months Ended September 30, 2016 Securities measured at fair value $ (18 ) $ 33 $ — $ 15 $ — Junior subordinated debt (2,386 ) — (2,075 ) (1,843 ) (1,491 ) Total $ (2,404 ) $ 33 $ (2,075 ) $ (1,828 ) $ (1,491 ) Interest income on securities measured at fair value is accounted for similarly to those classified as AFS. Any premiums or discounts are recognized in interest income over the term of the securities. Interest expense on junior subordinated debt is also determined under a constant yield calculation. Fair value on a recurring basis Financial assets and financial liabilities measured at fair value on a recurring basis include the following: Securities measured at fair value: All of the Company’s securities measured at fair value, which consist of MBS, are reported at fair value utilizing Level 2 inputs in the same manner as described below for AFS securities. AFS securities: Preferred stock, CRA investments, and certain corporate debt securities are reported at fair value utilizing Level 1 inputs. Other securities classified as AFS are reported at fair value utilizing Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the bond’s terms and conditions, among other things. Historically, the Company has estimated the fair value of its CDO securities utilizing Level 3 inputs, which include pricing indications from comparable securities. During the year ended December 31, 2016, these securities were transferred from Level 3 to Level 2 as a result of an increase in the availability and reliability of the observable inputs utilized in the securities' fair value measurement. Independent pricing service: The Company's independent pricing service provides pricing information on the majority of the Company's Level 1 and 2 securities. Management independently evaluates the fair value measurements received from the Company's third party pricing service through multiple review steps. First, management reviews what has transpired in the marketplace with respect to interest rates, credit spreads, volatility, and mortgage rates, among other things, and develops an expectation of changes to the securities' valuations from the previous quarter. Then, management obtains market values from additional sources. The pricing service provides management with observable market data including interest rate curves and mortgage prepayment speed grids, as well as dealer quote sheets, new bond offering sheets, and historical trade documentation. Management reviews the assumptions and decides whether they are reasonable. Management may compare interest rates, credit spreads, and prepayments speeds used as part of the assumptions to those that management believes are reasonable. Management may price securities using the provided assumptions to determine whether they can develop similar prices on like securities. Any discrepancies between management’s review and the prices provided by the vendor are discussed with the vendor and the Company’s other valuation advisors. Lastly, management selects a sample of investment securities and compares the values provided by its primary third party pricing service to the market values obtained from secondary sources and evaluates those with notable variances. Interest rate swaps: Interest rate swaps are reported at fair value utilizing Level 2 inputs. The Company obtains dealer quotations to value its interest rate swaps. Junior subordinated debt: The Company estimates the fair value of its junior subordinated debt using a discounted cash flow model which incorporates the effect of the Company’s own credit risk in the fair value of the liabilities (Level 3). The Company’s cash flow assumptions are based on contractual cash flows as the Company anticipates that it will pay the debt according to its contractual terms. As of September 30, 2017 , the Company estimates the discount rate at 5.42% , which represents an implied credit spread of 4.09% plus three-month LIBOR ( 1.33% ). As of December 31, 2016 , the Company estimated the discount rate at 5.66% , which was a 4.66% credit spread plus three-month LIBOR ( 1.00% ). The fair value of assets and liabilities measured at fair value on a recurring basis was determined using the following inputs as of the periods presented: Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Fair Value (in thousands) September 30, 2017 Assets: Available-for-sale CDO $ — $ 15,553 $ — $ 15,553 Commercial MBS issued by GSEs — 113,794 — 113,794 Corporate debt securities — 104,014 — 104,014 CRA investments 50,648 — — 50,648 Preferred stock 96,100 — — 96,100 Private label residential MBS — 797,615 — 797,615 Residential MBS issued by GSEs — 1,819,006 — 1,819,006 Tax-exempt — 462,773 — 462,773 Trust preferred securities — 29,208 — 29,208 U.S. government sponsored agency securities — 61,636 — 61,636 U.S. treasury securities — 2,497 — 2,497 Total AFS securities $ 146,748 $ 3,406,096 $ — $ 3,552,844 Loans - HFS $ — $ 16,347 $ — $ 16,347 Derivative assets (1) — 1,656 — 1,656 Liabilities: Junior subordinated debt (2) $ — $ — $ 54,737 $ 54,737 Derivative liabilities (1) — 59,346 — 59,346 (1) Derivative assets and liabilities relate to interest rate swaps, see " Note 9. Derivatives and Hedging Activities ." In addition, the carrying value of loans is increased by $44,721 and the net carrying value of subordinated debt is decreased by $12,307 as of September 30, 2017 , which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment. Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value (in thousands) December 31, 2016 Assets: Measured at fair value Residential MBS issued by GSEs $ — $ 1,053 $ — $ 1,053 Available-for-sale CDO — 13,490 — 13,490 Commercial MBS issued by GSEs — 117,792 — 117,792 Corporate debt securities 20,000 44,144 — 64,144 CRA investments 37,113 — — 37,113 Preferred stock 94,662 — — 94,662 Private label residential MBS — 433,685 — 433,685 Residential MBS issued by GSEs — 1,355,205 — 1,355,205 Tax-exempt — 408,233 — 408,233 Trust preferred securities — 26,532 — 26,532 U.S. government sponsored agency securities — 56,022 — 56,022 U.S. treasury securities — 2,502 — 2,502 Total AFS securities $ 151,775 $ 2,457,605 $ — $ 2,609,380 Loans - HFS $ — $ 18,909 $ — $ 18,909 Derivative assets (1) — 4,220 — 4,220 Liabilities: Junior subordinated debt (2) $ — $ — $ 50,410 $ 50,410 Derivative liabilities (1) — 65,749 — 65,749 (1) Derivative assets and liabilities relate to interest rate swaps, see " Note 9. Derivatives and Hedging Activities ." In addition, the carrying value of loans is increased by $48,161 and the net carrying value of subordinated debt is decreased by $12,325 as of December 31, 2016 , which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment. For the three and nine months ended September 30, 2017 and 2016 , the change in Level 3 assets and liabilities measured at fair value on a recurring basis was as follows: Junior Subordinated Debt Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Beginning balance $ 55,772 $ 44,710 $ 50,410 $ 46,928 Transfers into Level 3 — — — — Total gains (losses) for the period Included in other comprehensive income (1,035 ) 4,604 4,327 2,386 Ending balance $ 54,737 $ 49,314 $ 54,737 $ 49,314 CDO Securities Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Beginning balance $ — $ 10,183 $ — $ 10,060 Transfers into Level 3 — — — — Total gains (losses) for the period Included in other comprehensive income — 369 — 492 Ending balance $ — $ 10,552 $ — $ 10,552 The Company transferred all CDO securities from Level 3 to Level 2 during the year ended December 31, 2016 as a result of an increase in the availability and reliability of the observable inputs utilized in the securities' fair value measurement. The Company recognized this transfer between levels on October 31, 2016, in accordance with its policy to recognize transfers between levels in the fair value hierarchy as of the end of the month following the event or change in circumstance that caused the transfer. For Level 3 assets and liabilities measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 , the significant unobservable inputs used in the fair value measurements were as follows: September 30, 2017 Valuation Technique Significant Unobservable Inputs Input Value (in thousands) Junior subordinated debt $ 54,737 Discounted cash flow Implied credit rating of the Company 5.42 % December 31, 2016 Valuation Technique Significant Unobservable Inputs Input Value (in thousands) Junior subordinated debt $ 50,410 Discounted cash flow Implied credit rating of the Company 5.66 % The significant unobservable inputs used in the fair value measurement of the Company’s junior subordinated debt as of September 30, 2017 and December 31, 2016 was the implied credit risk for the Company, calculated as the difference between the 20-year 'BB' rated financial index over the corresponding swap index. Fair value on a nonrecurring basis Certain assets are measured at fair value on a nonrecurring basis. That is, the assets are not measured at fair value on an ongoing basis, but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). The following table presents such assets carried on the balance sheet by caption and by level within the ASC 825 hierarchy: Fair Value Measurements at the End of the Reporting Period Using Total Quoted Prices in Active Markets for Identical Assets (Level 1) Active Markets for Similar Assets (Level 2) Unobservable Inputs (Level 3) (in thousands) As of September 30, 2017: Impaired loans with specific valuation allowance $ 4,379 $ — $ — $ 4,379 Impaired loans without specific valuation allowance (1) 70,170 — — 70,170 Other assets acquired through foreclosure 28,992 — — 28,992 As of December 31, 2016: Impaired loans with specific valuation allowance $ 6,670 $ — $ — $ 6,670 Impaired loans without specific valuation allowance (1) 60,738 — — 60,738 Other assets acquired through foreclosure 47,815 — — 47,815 (1) Net of loan balances with charge-offs of $42.4 million and $27.6 million as of September 30, 2017 and December 31, 2016 , respectively. For Level 3 assets measured at fair value on a nonrecurring basis as of September 30, 2017 and December 31, 2016 , the significant unobservable inputs used in the fair value measurements were as follows: September 30, 2017 Valuation Technique(s) Significant Unobservable Inputs Range (in thousands) Impaired loans $ 74,549 Collateral method Third party appraisal or valuation Costs to sell 4.0% to 10.0% Discounted cash flow method Discount rate Contractual loan rate 4.0% to 7.0% Scheduled cash collections Probability of default 0% to 20.0% Proceeds from non-real estate collateral Loss given default 0% to 70.0% Other assets acquired through foreclosure 28,992 Collateral method Third party appraisal Costs to sell 4.0% to 10.0% December 31, 2016 Valuation Technique(s) Significant Unobservable Inputs Range (in thousands) Impaired loans $ 67,408 Collateral method Third party appraisal Costs to sell 4.0% to 10.0% Discounted cash flow method Discount rate Contractual loan rate 4.0% to 7.0% Scheduled cash collections Probability of default 0% to 20.0% Proceeds from non-real estate collateral Loss given default 0% to 70.0% Other assets acquired through foreclosure 47,815 Collateral method Third party appraisal Costs to sell 4.0% to 10.0% Impaired loans: The specific reserves for collateral dependent impaired loans are based on collateral value, net of estimated disposition costs and other identified quantitative inputs. Collateral value is determined based on independent third-party appraisals or internally-developed discounted cash flow analyses. Appraisals may utilize a single valuation approach or a combination of approaches, including comparable sales and the income approach. Fair value is determined, where possible, using market prices derived from an appraisal or evaluation, which are considered to be Level 2. However, certain assumptions and unobservable inputs are often used by the appraiser, therefore qualifying the assets as Level 3 in the fair value hierarchy. In addition, when adjustments are made to an appraised value to reflect various factors such as the age of the appraisal or known changes in the market or the collateral, such valuation inputs are considered unobservable and the fair value measurement is categorized as a Level 3 measurement. Internal discounted cash flow analyses are also utilized to estimate the fair value of impaired loans, which considers internally-developed, unobservable inputs such as discount rates, default rates, and loss severity. Total Level 3 impaired loans had an estimated fair value of $74.5 million and $67.4 million at September 30, 2017 and December 31, 2016 , respectively. Impaired loans with a specific valuation allowance had a gross estimated fair value of $8.8 million and $10.9 million at September 30, 2017 and December 31, 2016 , respectively, which was reduced by a specific valuation allowance of $4.4 million and $4.2 million , respectively. Other assets acquired through foreclosure: Other assets acquired through foreclosure consist of properties acquired as a result of, or in-lieu-of, foreclosure. These assets are initially reported at the fair value determined by independent appraisals using appraised value less estimated cost to sell. Such properties are generally re-appraised every twelve months. There is risk for subsequent volatility. Costs relating to the development or improvement of the assets are capitalized and costs relating to holding the assets are charged to expense. Fair value is determined, where possible, using market prices derived from an appraisal or evaluation, which are considered to be Level 2. However, certain assumptions and unobservable inputs are often used by the appraiser, therefore qualifying the assets as Level 3 in the fair value hierarchy. When significant adjustments are based on unobservable inputs, such as when a current appraised value is not available or management determines the fair value of the collateral is further impaired below the appraised value and there is no observable market price, the resulting fair value measurement has been categorized as a Level 3 measurement. The Company had $29.0 million and $47.8 million of such assets at September 30, 2017 and December 31, 2016 , respectively. Credit vs. non-credit losses Under the provisions of ASC 320, Investments-Debt and Equity Securities , OTTI is separated into the amount of total impairment related to the credit loss and the amount of the total impairment related to all other factors. The amount of the total OTTI related to the credit loss is recognized in earnings. The amount of the total impairment related to all other factors is recognized in OCI. For the three and nine months ended September 30, 2017 and 2016 , the Company determined that no securities experienced credit losses. There is no OTTI balance recognized in comprehensive income as of September 30, 2017 and 2016 . FAIR VALUE OF FINANCIAL INSTRUMENTS The estimated fair value of the Company’s financial instruments is as follows: September 30, 2017 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in thousands) Financial assets: Investment securities: HTM $ 154,920 $ — $ 160,582 $ — $ 160,582 AFS 3,552,844 146,748 3,406,096 — 3,552,844 Derivative assets 1,656 — 1,656 — 1,656 Loans, net 14,385,615 — 13,999,391 74,549 14,073,940 Accrued interest receivable 72,374 — 72,374 — 72,374 Financial liabilities: Deposits $ 16,904,783 $ — $ 16,911,392 $ — $ 16,911,392 Customer repurchase agreements 26,066 — 26,066 — 26,066 Qualifying debt 372,851 — — 399,855 399,855 Derivative liabilities 59,346 — 59,346 — 59,346 Accrued interest payable 10,958 — 10,958 — 10,958 December 31, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in thousands) Financial assets: Investment securities: HTM $ 92,079 $ — $ 91,966 $ — $ 91,966 AFS 2,609,380 151,775 2,457,605 — 2,609,380 Trading 1,053 — 1,053 — 1,053 Derivative assets 4,220 — 4,220 — 4,220 Loans, net 13,083,732 — 12,736,336 67,408 12,803,744 Accrued interest receivable 70,320 — 70,320 — 70,320 Financial liabilities: Deposits $ 14,549,863 $ — $ 14,553,931 $ — $ 14,553,931 Customer repurchase agreements 41,728 — 41,728 — 41,728 FHLB advances 80,000 — 80,000 — 80,000 Qualifying debt 367,937 — — 375,626 375,626 Derivative liabilities 65,749 — 65,749 — 65,749 Accrued interest payable 15,354 — 15,354 — 15,354 Interest rate risk The Company assumes interest rate risk (the risk to the Company’s earnings and capital from changes in interest rate levels) as a result of its normal operations. As a result, the fair values of the Company’s financial instruments, as well as its future net interest income will change when interest rate levels change and that change may be either favorable or unfavorable to the Company. Interest rate risk exposure is measured using interest rate sensitivity analysis to determine the Company's change in EVE and net interest income resulting from hypothetical changes in interest rates. If potential changes to EVE and net interest income resulting from hypothetical interest rate changes are not within the limits established by the BOD, the BOD may direct management to adjust the asset and liability mix to bring interest rate risk within BOD-approved limits. WAB has an ALCO charged with managing interest rate risk within the BOD-approved limits. Limits are structured to prohibit an interest rate risk profile that does not conform to both management and BOD risk tolerances. There is also ALCO reporting at the Parent level for reviewing interest rate risk for the Company, which gets reported to the BOD and its Finance and Investment Committee. Fair value of commitments The estimated fair value of standby letters of credit outstanding at September 30, 2017 and December 31, 2016 is insignificant. Loan commitments on which the committed interest rates are less than the current market rate are also insignificant at September 30, 2017 and December 31, 2016 .

Segments

Segments	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segments	14. SEGMENTS The Company's reportable segments are aggregated based primarily on geographic location, services offered, and markets served. The Company's regional segments, which include Arizona, Nevada, Southern California, and Northern California, provide full service banking and related services to their respective markets. The operations from the regional segments correspond to the following banking divisions: ABA in Arizona, BON and FIB in Nevada, TPB in Southern California, and Bridge in Northern California. The Company's NBL segments provide specialized banking services to niche markets. The Company's NBL reportable segments include HOA Services, Public & Nonprofit Finance, Technology & Innovation, HFF, and Other NBLs. These NBLs are managed centrally and are broader in geographic scope than the Company's other segments, though still predominately located within the Company's core market areas. The HOA Services NBL corresponds to the AAB division. The operations of Public and Nonprofit Finance are combined into one reportable segment. The Technology & Innovation NBL includes the operations of Equity Fund Resources, Life Sciences Group, Renewable Resource Group, and Technology Finance. The HFF NBL includes the hotel franchise loan portfolio acquired from GE Capital US Holdings, Inc. on April 20, 2016. The Other NBLs segment consists of Corporate Finance, Mortgage Warehouse Lending, and Resort Finance. The Corporate & Other segment consists of corporate-related items, income and expense items not allocated to the Company's other reportable segments, and inter-segment eliminations. The Company's segment reporting process begins with the assignment of all loan and deposit accounts directly to the segments where these products are originated and/or serviced. Equity capital is assigned to each segment based on the risk profile of their assets and liabilities. With the exception of goodwill, which is assigned a 100% weighting, equity capital allocations ranged from 0% to 12% during the year, with a funds credit provided for the use of this equity as a funding source. Any excess or deficient equity not allocated to segments based on risk is assigned to the Corporate & Other segment. Net interest income, provision for credit losses, and non-interest expense amounts are recorded in their respective segment to the extent that the amounts are directly attributable to those segments. Net interest income is recorded in each segment on a TEB with a corresponding increase in income tax expense, which is eliminated in the Corporate & Other segment. Further, net interest income of a reportable segment includes a funds transfer pricing process that matches assets and liabilities with similar interest rate sensitivity and maturity characteristics. Using this funds transfer pricing methodology, liquidity is transferred between users and providers. A net user of funds has lending/investing in excess of deposits/borrowings and a net provider of funds has deposits/borrowings in excess of lending/investing. A segment that is a user of funds is charged for the use of funds, while a provider of funds is credited through funds transfer pricing, which is determined based on the average life of the assets or liabilities in the portfolio. The net income amount for each reportable segment is further derived by the use of expense allocations. Certain expenses not directly attributable to a specific segment are allocated across all segments based on key metrics, such as number of employees, average loan balances, and average deposit balances. These types of expenses include information technology, operations, human resources, finance, risk management, credit administration, legal, and marketing. Income taxes are applied to each segment based on the effective tax rate for the geographic location of the segment. Any difference in the corporate tax rate and the aggregate effective tax rates in the segments are adjusted in the Corporate & Other segment. The following is a summary of operating segment information for the periods indicated: Regional Segments Balance Sheet: Consolidated Company Arizona Nevada Southern California Northern California At September 30, 2017 (in millions) Assets: Cash, cash equivalents, and investment securities $ 4,424.0 $ 1.9 $ 7.7 $ 1.9 $ 1.7 Loans, net of deferred loan fees and costs 14,521.9 3,131.2 1,685.6 1,873.5 1,260.7 Less: allowance for credit losses (136.4 ) (30.7 ) (16.8 ) (20.4 ) (12.6 ) Total loans 14,385.5 3,100.5 1,668.8 1,853.1 1,248.1 Other assets acquired through foreclosure, net 29.0 2.3 13.7 — 0.2 Goodwill and other intangible assets, net 301.2 — 23.2 — 156.8 Other assets 782.5 45.8 58.4 13.9 17.4 Total assets $ 19,922.2 $ 3,150.5 $ 1,771.8 $ 1,868.9 $ 1,424.2 Liabilities: Deposits $ 16,904.8 $ 5,198.1 $ 3,950.5 $ 2,512.2 $ 1,535.6 Borrowings and qualifying debt 372.9 — — — — Other liabilities 498.9 13.4 23.3 3.6 11.1 Total liabilities 17,776.6 5,211.5 3,973.8 2,515.8 1,546.7 Allocated equity: 2,145.6 390.4 251.5 216.6 299.2 Total liabilities and stockholders' equity $ 19,922.2 $ 5,601.9 $ 4,225.3 $ 2,732.4 $ 1,845.9 Excess funds provided (used) — 2,451.4 2,453.5 863.5 421.7 Income Statement: Three Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 201,583 $ 52,637 $ 36,310 $ 26,811 $ 21,932 Provision for credit losses 5,000 (289 ) (2,044 ) (58 ) 3,144 Net interest income (expense) after provision for credit losses 196,583 52,926 38,354 26,869 18,788 Non-interest income 10,288 1,265 2,354 971 1,796 Non-interest expense (89,114 ) (18,844 ) (14,748 ) (12,340 ) (11,317 ) Income (loss) before income taxes 117,757 35,347 25,960 15,500 9,267 Income tax expense (benefit) 34,899 13,857 9,086 6,517 3,897 Net income (loss) $ 82,858 $ 21,490 $ 16,874 $ 8,983 $ 5,370 Nine Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 573,635 $ 145,839 $ 108,028 $ 81,087 $ 63,686 Provision for (recovery of) credit losses 12,250 109 (5,378 ) (20 ) 4,238 Net interest income (expense) after provision for credit losses 561,385 145,730 113,406 81,107 59,448 Non-interest income 31,281 3,567 6,800 2,602 5,839 Non-interest expense (265,128 ) (55,388 ) (45,733 ) (38,063 ) (36,188 ) Income (loss) before income taxes 327,538 93,909 74,473 45,646 29,099 Income tax expense (benefit) 91,352 36,831 26,066 19,194 12,236 Net income (loss) $ 236,186 $ 57,078 $ 48,407 $ 26,452 $ 16,863 National Business Lines Balance Sheet: HOA Public & Nonprofit Finance Technology & Innovation Hotel Franchise Finance Other NBLs Corporate & Other At September 30, 2017 Assets: (in millions) Cash, cash equivalents, and investment securities $ — $ — $ — $ — $ — $ 4,410.8 Loans, net of deferred loan fees and costs 157.3 1,574.5 1,049.2 1,272.5 2,513.0 4.4 Less: allowance for credit losses (1.6 ) (16.1 ) (9.9 ) (2.7 ) (25.5 ) (0.1 ) Total loans 155.7 1,558.4 1,039.3 1,269.8 2,487.5 4.3 Other assets acquired through foreclosure, net — — — — — 12.8 Goodwill and other intangible assets, net — — 121.1 0.1 — — Other assets 0.4 12.2 5.3 5.2 10.1 613.8 Total assets $ 156.1 $ 1,570.6 $ 1,165.7 $ 1,275.1 $ 2,497.6 $ 5,041.7 Liabilities: Deposits $ 2,153.3 $ — $ 1,459.5 $ — $ — $ 95.6 Borrowings and qualifying debt — — — — — 372.9 Other liabilities 1.1 46.4 0.7 0.4 136.1 262.8 Total liabilities 2,154.4 46.4 1,460.2 0.4 136.1 731.3 Allocated equity: 57.4 126.0 234.6 104.3 207.2 258.4 Total liabilities and stockholders' equity $ 2,211.8 $ 172.4 $ 1,694.8 $ 104.7 $ 343.3 $ 989.7 Excess funds provided (used) 2,055.7 (1,398.2 ) 529.1 (1,170.4 ) (2,154.3 ) (4,052.0 ) Income Statement: Three Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 13,746 $ 7,269 $ 20,415 $ 15,346 $ 16,933 $ (9,816 ) Provision for credit losses 40 91 (83 ) 1,116 4,416 (1,333 ) Net interest income (expense) after provision for credit losses 13,706 7,178 20,498 14,230 12,517 (8,483 ) Non-interest income 136 15 1,855 — 379 1,517 Non-interest expense (7,011 ) (1,871 ) (8,824 ) (1,905 ) (5,286 ) (6,968 ) Income (loss) before income taxes 6,831 5,322 13,529 12,325 7,610 (13,934 ) Income tax expense (benefit) 2,562 1,028 5,075 4,622 2,853 (14,598 ) Net income (loss) $ 4,269 $ 4,294 $ 8,454 $ 7,703 $ 4,757 $ 664 Nine Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 40,275 $ 21,242 $ 59,610 $ 42,337 $ 46,380 $ (34,849 ) Provision for (recovery of) credit losses 332 796 816 2,924 10,265 (1,832 ) Net interest income (expense) after provision for credit losses 39,943 20,446 58,794 39,413 36,115 (33,017 ) Non-interest income 417 40 5,689 — 1,632 4,695 Non-interest expense (21,416 ) (6,107 ) (26,685 ) (7,949 ) (14,573 ) (13,026 ) Income (loss) before income taxes 18,944 14,379 37,798 31,464 23,174 (41,348 ) Income tax expense (benefit) 7,104 4,424 14,175 11,799 8,690 (49,167 ) Net income (loss) $ 11,840 $ 9,955 $ 23,623 $ 19,665 $ 14,484 $ 7,819 Regional Segments Balance Sheet: Consolidated Company Arizona Nevada Southern California Northern California At December 31, 2016 (in millions) Assets: Cash, cash equivalents, and investment securities $ 3,052.3 $ 1.9 $ 10.1 $ 2.1 $ 1.9 Loans, net of deferred loan fees and costs 13,208.5 2,955.9 1,725.5 1,766.8 1,095.4 Less: allowance for credit losses (124.7 ) (30.1 ) (18.5 ) (19.4 ) (8.8 ) Total loans 13,083.8 2,925.8 1,707.0 1,747.4 1,086.6 Other assets acquired through foreclosure, net 47.8 6.2 18.0 — 0.3 Goodwill and other intangible assets, net 302.9 — 23.7 — 157.5 Other assets 714.0 42.9 58.8 14.5 14.3 Total assets $ 17,200.8 $ 2,976.8 $ 1,817.6 $ 1,764.0 $ 1,260.6 Liabilities: Deposits $ 14,549.8 $ 3,843.4 $ 3,731.5 $ 2,382.6 $ 1,543.6 Borrowings and qualifying debt 447.9 — — — — Other liabilities 311.6 12.8 28.3 12.9 12.4 Total liabilities 15,309.3 3,856.2 3,759.8 2,395.5 1,556.0 Allocated equity: 1,891.5 346.6 250.7 201.6 283.7 Total liabilities and stockholders' equity $ 17,200.8 $ 4,202.8 $ 4,010.5 $ 2,597.1 $ 1,839.7 Excess funds provided (used) — 1,226.0 2,192.9 833.1 579.1 Income Statement: Three Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 172,547 $ 45,531 $ 35,977 $ 26,488 $ 22,181 Provision for (recovery of) credit losses 2,000 2,399 (1,009 ) (105 ) 144 Net interest income (expense) after provision for credit losses 170,547 43,132 36,986 26,593 22,037 Non-interest income 10,683 1,180 2,264 686 2,916 Non-interest expense (85,007 ) (16,084 ) (14,801 ) (11,532 ) (12,706 ) Income (loss) before income taxes 96,223 28,228 24,449 15,747 12,247 Income tax expense (benefit) 29,171 11,074 8,557 6,621 5,150 Net income (loss) $ 67,052 $ 17,154 $ 15,892 $ 9,126 $ 7,097 Nine Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 481,944 $ 125,191 $ 102,016 $ 76,719 $ 67,272 Provision for (recovery of) credit losses 7,000 10,875 (3,526 ) 145 2,112 Net interest income (expense) after provision for credit losses 474,944 114,316 105,542 76,574 65,160 Non-interest income 32,375 5,749 6,420 1,907 7,858 Non-interest expense (242,304 ) (45,090 ) (44,371 ) (33,401 ) (40,154 ) Income (loss) before income taxes 265,015 74,975 67,591 45,080 32,864 Income tax expense (benefit) 75,017 29,413 23,657 18,956 13,819 Net income (loss) $ 189,998 $ 45,562 $ 43,934 $ 26,124 $ 19,045 National Business Lines Balance Sheet: HOA Public & Nonprofit Finance Technology & Innovation Hotel Franchise Finance Other NBLs Corporate & Other At December 31, 2016 Assets: (in millions) Cash, cash equivalents, and investment securities $ — $ — $ — $ — $ — $ 3,036.3 Loans, net of deferred loan fees and costs 116.8 1,454.3 1,011.4 1,292.1 1,776.9 13.4 Less: allowance for credit losses (1.3 ) (15.6 ) (10.6 ) (0.8 ) (19.0 ) (0.6 ) Total loans 115.5 1,438.7 1,000.8 1,291.3 1,757.9 12.8 Other assets acquired through foreclosure, net — — — — — 23.3 Goodwill and other intangible assets, net — — 121.5 0.2 — — Other assets 0.3 15.6 7.2 5.3 11.1 544.0 Total assets $ 115.8 $ 1,454.3 $ 1,129.5 $ 1,296.8 $ 1,769.0 $ 3,616.4 Liabilities: Deposits $ 1,890.3 $ — $ 1,038.2 $ — $ — $ 120.2 Borrowings and qualifying debt — — — — — 447.9 Other liabilities 0.7 50.5 2.0 1.4 17.5 173.1 Total liabilities 1,891.0 50.5 1,040.2 1.4 17.5 741.2 Allocated equity: 65.6 117.1 224.1 107.1 145.5 149.5 Total liabilities and stockholders' equity $ 1,956.6 $ 167.6 $ 1,264.3 $ 108.5 $ 163.0 $ 890.7 Excess funds provided (used) 1,840.8 (1,286.7 ) 134.8 (1,188.3 ) (1,606.0 ) (2,725.7 ) Income Statement: Three Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 11,312 $ 5,012 $ 18,143 $ 13,370 $ 12,060 $ (17,527 ) Provision for (recovery of) credit losses 72 (315 ) (557 ) — 1,372 (1) Net interest income (expense) after provision for credit losses 11,240 5,327 18,700 13,370 10,688 (17,526 ) Non-interest income 125 19 1,871 — 728 894 Non-interest expense (6,062 ) (1,974 ) (8,837 ) (3,207 ) (3,972 ) (5,832 ) Income (loss) before income taxes 5,303 3,372 11,734 10,163 7,444 (22,464 ) Income tax expense (benefit) 1,989 1,265 4,400 3,811 2,791 (16,487 ) Net income (loss) $ 3,314 $ 2,107 $ 7,334 $ 6,352 $ 4,653 $ (5,977 ) Nine Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 29,853 $ 15,259 $ 51,083 $ 25,438 $ 35,220 $ (46,107 ) Provision for (recovery of) credit losses 160 (509 ) (2,336 ) — 3,309 (3,230 ) Net interest income (expense) after provision for credit losses 29,693 15,768 53,419 25,438 31,911 (42,877 ) Non-interest income 340 22 4,623 — 1,598 3,858 Non-interest expense (17,423 ) (5,927 ) (23,177 ) (5,764 ) (11,007 ) (15,990 ) Income (loss) before income taxes 12,610 9,863 34,865 19,674 22,502 (55,009 ) Income tax expense (benefit) 4,729 3,699 13,074 7,378 8,438 (48,146 ) Net income (loss) $ 7,881 $ 6,164 $ 21,791 $ 12,296 $ 14,064 $ (6,863 )

Mergers, Acquisitions and Dispo

Mergers, Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions	15. MERGERS, ACQUISITIONS AND DISPOSITIONS Acquisition of GE Capital US Holdings, Inc. Loan Portfolio On April 20, 2016, WAB completed its acquisition of GE Capital US Holdings, Inc.'s domestic select-service hotel franchise finance loan portfolio, paying cash of $1.27 billion . The acquisition was undertaken, in part, to expand the Company's national reach and diversify the Company's loan portfolio. Effective April 20, 2016, the results of the acquired loan portfolio are reflected in the Company's HFF NBL operating segment. There were no acquisition / restructure expenses related to the acquisition recognized during the three and nine months ended September 30, 2017 . For the three and nine months ended September 30, 2016 , acquisition / restructure expenses related to the acquisition totaled $1.7 million and $3.6 million , respectively. The transaction was accounted for under the acquisition method of accounting in accordance with ASC 805. Assets purchased and liabilities assumed were recorded at their respective acquisition date estimated fair values. The fair values of assets acquired and liabilities assumed are subject to adjustment during the first twelve months after the acquisition date if additional information becomes available to indicate a more accurate or appropriate value for an asset or liability. During the six months ended June 30, 2017, the Company recognized measurement period adjustments totaling $0.1 million for tax related items. The measurement period for the HFF acquisition ended on April 20, 2017. Therefore, the fair values of these assets acquired and liabilities assumed were considered final effective April 20, 2017. The recognized amounts of identifiable assets acquired and liabilities assumed, at their as adjusted acquisition date fair values, are as follows: April 20, 2016 (in thousands) Assets: Loans $ 1,280,997 Other assets 3,632 Total assets $ 1,284,629 Liabilities: Other liabilities $ 12,559 Total liabilities 12,559 Net assets acquired $ 1,272,070 Consideration paid Cash $ 1,272,187 Goodwill $ 117 The following table presents pro forma information as if the acquisition was completed on January 1, 2015. The pro forma information includes adjustments for interest income on loans acquired and excludes acquisition / restructure expense. The pro forma information is not necessarily indicative of the results of operations as they would have been had the transactions been effected on the assumed dates. Three Months Ended September 30, 2016 Nine Months Ended September 30, 2016 (in thousands, except per share amounts) Interest income $ 180,335 $ 523,962 Non-interest income 10,683 32,375 Net income 65,349 194,095 Earnings per share - basic 0.63 1.89 Earnings per share - diluted 0.62 1.87

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	16. RELATED PARTY TRANSACTIONS Principal stockholders, directors, and executive officers of the Company, their immediate family members, and companies they control or own more than a 10% interest in, are considered to be related parties. In the ordinary course of business, the Company engages in various related party transactions, including extending credit and bank service transactions. All related party transactions are subject to review and approval pursuant to the Company's Related Party Transactions policy. On April 1, 2017, the Company hired an executive officer who was previously the Managing Partner of an external consulting firm that the Company actively uses for risk management services. Prior to joining the Company, the executive officer sold his interest in this external consulting firm and was paid with a combination of cash and a $1.0 million note that will be paid in equal installments ending in 2019. Expenses to this external consulting firm as well as sponsorships, donations and other services to related parties totaled less than $3.0 million during each of the nine months ended September 30, 2017 and 2016 .

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Nature of Operation	Nature of operation WAL is a bank holding company headquartered in Phoenix, Arizona, incorporated under the laws of the state of Delaware. WAL provides a full spectrum of deposit, lending, treasury management, international banking, and online banking products and services through its wholly-owned banking subsidiary, WAB. WAB operates the following full-service banking divisions: ABA, BON, FIB, Bridge, and TPB. The Company also serves business customers through a national platform of specialized financial services including AAB, Corporate Finance, Equity Fund Resources, HFF, Life Sciences Group, Mortgage Warehouse Lending, Public and Nonprofit Finance, Renewable Resource Group, Resort Finance, and Technology Finance. In addition, the Company has one non-bank subsidiary, LVSP, which holds and manages certain non-performing loans and OREO.
Basis of Presentation	Basis of presentation The accounting and reporting policies of the Company are in accordance with GAAP and conform to practices within the financial services industry. The accounts of the Company and its consolidated subsidiaries are included in the Consolidated Financial Statements.
Use of Estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management's estimates and judgments are ongoing and are based on experience, current and expected future conditions, third-party evaluations and various other assumptions that management believes are reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities, as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from those estimates and assumptions used in the Consolidated Financial Statements and related notes. Material estimates that are particularly susceptible to significant changes in the near term relate to the determination of the allowance for credit losses; estimated cash flows related to PCI loans; fair value determinations related to acquisitions and certain assets and liabilities carried at fair value; and accounting for income taxes.
Principles of Consolidation	Principles of consolidation As of September 30, 2017 , WAL has ten wholly-owned subsidiaries: WAB, LVSP, and eight unconsolidated subsidiaries used as business trusts in connection with the issuance of trust-preferred securities. The Bank has the following significant wholly-owned subsidiaries: WABT, which holds certain investment securities, municipal and nonprofit loans, and leases; WA PWI, LLC, which holds certain limited partnerships invested primarily in low income housing tax credits and small business investment corporations; and BW Real Estate, Inc., which operates as a real estate investment trust and holds certain of WAB's real estate loans and related securities. The Company does not have any other significant entities that should be considered for consolidation. All significant intercompany balances and transactions have been eliminated in consolidation.
Reclassifications	Reclassifications Certain amounts reported in prior periods may have been reclassified in the Consolidated Financial Statements to conform to the current presentation. The reclassifications have no effect on net income or stockholders’ equity as previously reported.
Business Combinations	Business combinations Business combinations are accounted for under the acquisition method of accounting in accordance with ASC 805, Business Combinations. Under the acquisition method, the acquiring entity in a business combination recognizes all of the acquired assets and assumed liabilities at their estimated fair values as of the date of acquisition. Any excess of the purchase price over the fair value of net assets and other identifiable intangible assets acquired is recorded as goodwill. To the extent the fair value of net assets acquired, including identified intangible assets, exceeds the purchase price, a bargain purchase gain is recognized. Changes to estimated fair values from a business combination are recognized as an adjustment to goodwill during the measurement period and are recognized in the proper reporting period in which the adjustment amounts are determined. Results of operations of an acquired business are included in the Consolidated Income Statement from the date of acquisition. Acquisition-related costs, including conversion and restructuring charges, are expensed as incurred.
Investment Securities	Investment securities Investment securities may be classified as HTM, AFS, or measured at fair value. The appropriate classification is initially decided at the time of purchase. Securities classified as HTM are those debt securities that the Company has both the intent and ability to hold to maturity regardless of changes in market conditions, liquidity needs, or general economic conditions. These securities are carried at amortized cost. The sale of a security within three months of its maturity date or after the majority of the principal outstanding has been collected is considered a maturity for purposes of classification and disclosure. Securities classified as AFS or trading securities measured at fair value are reported as an asset in the Consolidated Balance Sheet at their estimated fair value. As the fair value of AFS securities changes, the changes are reported net of income tax as an element of OCI, except for other-than-temporarily-impaired securities. When AFS securities are sold, the unrealized gain or loss is reclassified from OCI to non-interest income. The changes in the fair values of trading securities are reported in non-interest income. Securities classified as AFS are both equity and debt securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity. Any decision to sell a security classified as AFS would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Company’s assets and liabilities, liquidity needs, decline in credit quality, and regulatory capital considerations. Interest income is recognized based on the coupon rate and increased by accretion of discounts earned or decreased by the amortization of premiums paid over the contractual life of the security, adjusted for prepayment estimates, using the interest method. In estimating whether there are any OTTI losses, management considers the 1) length of time and the extent to which the fair value has been less than amortized cost; 2) financial condition and near term prospects of the issuer; 3) impact of changes in market interest rates; and 4) intent and ability of the Company to retain its investment for a period of time sufficient to allow for any anticipated recovery in fair value and whether it is not more likely than not the Company would be required to sell the security. Declines in the fair value of individual AFS debt securities that are deemed to be other-than-temporary are reflected in earnings when identified. The fair value of the debt security then becomes the new cost basis. For individual debt securities where the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary decline in fair value of the debt security related to 1) credit loss is recognized in earnings; and 2) interest rate, market, or other factors is recognized in other comprehensive income or loss. For individual debt securities where the Company either intends to sell the security or more likely than not will not recover all of its amortized cost, the OTTI is recognized in earnings equal to the entire difference between the security's cost basis and its fair value at the balance sheet date. For individual debt securities for which a credit loss has been recognized in earnings, interest accruals and amortization and accretion of premiums and discounts are suspended when the credit loss is recognized. Interest received after accruals have been suspended is recognized on a cash basis.
Restricted Stock	Restricted stock WAB is a member of the Federal Reserve System and, as part of its membership, is required to maintain stock in the FRB in a specified ratio to its capital. In addition, WAB is a member of the FHLB system and, accordingly, maintains an investment in capital stock of the FHLB based on the borrowing capacity used. The Bank also maintains an investment in its primary correspondent bank. All of these investments are considered equity securities with no actively traded market. Therefore, the shares are considered restricted investment securities. These investments are carried at cost, which is equal to the value at which they may be redeemed. The dividend income received from the stock is reported in interest income. The Company conducts a periodic review and evaluation of its restricted stock to determine if any impairment exists.
Loans, held for sale	Loans, held for sale Loans, held for sale consist of SBA loans that the Company originates (or acquires) and intends to sell. These loans are carried at the lower of aggregate cost or fair value. Fair value is determined based on available market data for similar assets, expected cash flows, and appraisals of underlying collateral or the credit quality of the borrower. Gains and losses on the sale of loans are recognized pursuant to ASC 860, Transfers and Servicing . Interest income of these loans is accrued daily and loan origination fees and costs are deferred and included in the cost basis of the loan. The Company issues various representations and warranties associated with these loan sales. The Company has not experienced any losses as a result of these representations and warranties.
Loans, Interest and Fees from Loans	Loans, held for investment The Company generally holds loans for investment and has the intent and ability to hold loans until their maturity. Therefore, they are reported at book value. Net loans are stated at the amount of unpaid principal, adjusted for net deferred fees and costs, purchase accounting fair value adjustments, and an allowance for credit losses. In addition, the book value of loans that are subject to a fair value hedge is adjusted for changes in value attributable to the effective portion of the hedged benchmark interest rate risk. The Company may also acquire loans through a business combination. These acquired loans are recorded at estimated fair value on the date of purchase, which is comprised of unpaid principal adjusted for estimated credit losses and interest rate fair value adjustments. Loans are evaluated individually at the acquisition date to determine if there has been credit deterioration since origination. Such loans may then be aggregated and accounted for as a pool of loans based on common characteristics. When the Company acquires such loans, the yield that may be accreted (accretable yield) is limited to the excess of the Company’s estimate of undiscounted cash flows expected to be collected over the Company’s initial investment in the loan. The excess of contractual cash flows over the cash flows expected to be collected may not be recognized as an adjustment to yield, loss, or a valuation allowance. Subsequent increases in cash flows expected to be collected generally are recognized prospectively through adjustment of the loan’s yield over the remaining life. Subsequent decreases to cash flows expected to be collected are recognized as impairment. The Company may not carry over or create a valuation allowance in the initial accounting for loans acquired under these circumstances. For purchased loans that are not deemed impaired at the acquisition date, fair value adjustments attributable to both credit and interest rates are accreted (or amortized) over the contractual life of the individual loan. For additional information, see " Note 3. Loans, Leases and Allowance for Credit Losses " of these Notes to Unaudited Consolidated Financial Statements. Loan fees collected for the origination of loans less direct loan origination costs (net deferred loan fees) are amortized over the contractual life of the loan through interest income. If the loan has scheduled payments, the amortization of the net deferred loan fee is calculated using the interest method over the contractual life of the loan. If the loan does not have scheduled payments, such as a line of credit, the net deferred loan fee is recognized as interest income on a straight-line basis over the contractual life of the loan commitment. Commitment fees based on a percentage of a customer’s unused line of credit and fees related to standby letters of credit are recognized over the commitment period. When loans are repaid, any remaining unamortized balances of premiums, discounts, or net deferred fees are recognized as interest income. Non-accrual loans: When a borrower discontinues making payments as contractually required by the note, the Company must determine whether it is appropriate to continue to accrue interest. The Company ceases accruing interest income when the loan has become delinquent by more than 90 days or when management determines that the full repayment of principal and collection of interest according to contractual terms is no longer likely. The Company may decide to continue to accrue interest on certain loans more than 90 days delinquent if the loans are well secured by collateral and in the process of collection. For all loan types, when a loan is placed on non-accrual status, all interest accrued but uncollected is reversed against interest income in the period in which the status is changed and, the Company makes a loan-level decision to apply either the cash basis or cost recovery method. The Company recognizes income on a cash basis only for those non-accrual loans for which the collection of the remaining principal balance is not in doubt. Under the cost recovery method, subsequent payments received from the customer are applied to principal and generally no further interest income is recognized until the principal has been paid in full or until circumstances have changed such that payments are again consistently received as contractually required. Impaired loans: A loan is identified as impaired when it is no longer probable that interest and principal will be collected according to the contractual terms of the original loan agreement. Generally, impaired loans are classified as non-accrual. However, in certain instances, impaired loans may continue on an accrual basis, if full repayment of all principal and interest is expected and the loan is both well secured and in the process of collection. Impaired loans are measured for reserve requirements in accordance with ASC 310, Receivables, 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 the collateral less applicable disposition costs if the loan is collateral dependent. The amount of an impairment reserve, if any, and any subsequent changes are recorded as a provision for credit losses. Losses are recorded as a charge-off when losses are confirmed. In addition to management's internal loan review process, regulators may from time to time direct the Company to modify loan grades, loan impairment calculations, or loan impairment methodology. Troubled Debt Restructured Loans : A TDR loan is a loan on which the Company, for reasons related to a borrower’s financial difficulties, grants a concession to the borrower that the Company would not otherwise consider. The loan terms that have been modified or restructured due to a borrower’s financial situation include, but are not limited to, a reduction in the stated interest rate, an extension of the maturity or renewal of the loan at an interest rate below current market, a reduction in the face amount of the debt, a reduction in the accrued interest, or deferral of interest payments. A TDR loan is also considered impaired. A TDR loan may be returned to accrual status when the loan is brought current, has performed in accordance with the contractual restructured terms for a reasonable period of time (generally six months) and the ultimate collectability of the total contractual restructured principal and interest is no longer in doubt. However, such loans continue to be considered impaired. Consistent with regulatory guidance, a TDR loan that is subsequently modified in another restructuring agreement but has shown sustained performance and classification as a TDR, will be removed from TDR status provided that the modified terms were market-based at the time of modification.
Allowance for Credit Losses	Allowance for credit losses Credit risk is inherent in the business of extending loans and leases to borrowers, for which the Company must maintain an adequate allowance for credit losses. The allowance for credit losses is established through a provision for credit losses recorded to expense. Loans are charged against the allowance for credit losses when management believes that the contractual principal or interest will not be collected. Subsequent recoveries, if any, are credited to the allowance. The allowance is an amount believed adequate to absorb estimated probable losses on existing loans that may become uncollectable, based on evaluation of the collectability of loans and prior credit loss experience, together with other factors. The Company formally re-evaluates and establishes the appropriate level of the allowance for credit losses on a quarterly basis. The allowance consists of specific and general components. The specific allowance applies to impaired loans. For impaired collateral dependent loans, the reserve is calculated based on the collateral value, net of estimated disposition costs. Generally, the Company obtains independent collateral valuation analysis for each loan every twelve months. Loans not collateral dependent are evaluated based on the expected future cash flows discounted at the original contractual interest rate. The general allowance covers all non-impaired loans and incorporates several quantitative and qualitative factors, which are used for all of the Company's portfolio segments. Quantitative factors include company-specific, ten-year historical net charge-offs stratified by loans with similar characteristics. Qualitative factors include: 1) levels of and trends in delinquencies and impaired loans; 2) levels of and trends in charge-offs and recoveries; 3) trends in volume and terms of loans; 4) changes in underwriting standards or lending policies; 5) experience, ability, depth of lending staff; 6) national and local economic trends and conditions; 7) changes in credit concentrations; 8) out-of-market exposures; 9) changes in quality of loan review system; and 10) changes in the value of underlying collateral. Due to the credit concentration of the Company's loan portfolio in real estate secured loans, the value of collateral is heavily dependent on real estate values in Arizona, Nevada, and California. While management uses the best information available to make its evaluation, future adjustments to the allowance may be necessary if there are significant changes in economic or other conditions. In addition, regulators, as an integral part of their examination processes, periodically review the Bank's allowance for credit losses, and may require the Bank to make additions to the allowance based on their judgment about information available to them at the time of their examination. Management regularly reviews the assumptions and formulae used in determining the allowance and makes adjustments if required to reflect the current risk profile of the portfolio.
Goodwill and Other Intangible Assets	Goodwill and other intangible assets The Company records as goodwill the excess of the purchase price over the fair value of the identifiable net assets acquired in accordance with applicable guidance. The Company performs its annual goodwill and intangibles impairment tests as of October 1 each year, or more often if events or circumstances indicate that the carrying value may not be recoverable. The Company can first elect to assess, through qualitative factors, whether it is more likely than not that goodwill is impaired. If the qualitative assessment indicates potential impairment, the Company will proceed with a two-step process. The first step tests for impairment, while the second step, if necessary, measures the impairment. The resulting impairment amount, if any, is charged to current period earnings as non-interest expense. The Company’s intangible assets consist primarily of core deposit intangible assets that are amortized over periods ranging from 5 to 10 years. The Company considers the remaining useful lives of its core deposit intangible assets each reporting period, as required by ASC 350, Intangibles—Goodwill and Other, to determine whether events and circumstances warrant a revision to the remaining period of amortization. If the estimate of an intangible asset’s remaining useful life has changed, the remaining carrying amount of the intangible asset is amortized prospectively over the revised remaining useful life.
Other Assets Acquired Through Foreclosure	Other assets acquired through foreclosure Other assets acquired through foreclosure consist primarily of properties acquired as a result of, or in-lieu-of, foreclosure. Properties or other assets (primarily repossessed assets formerly leased) are classified as OREO and other repossessed property and are initially reported at fair value of the asset less estimated selling costs. Subsequent adjustments are based on the lower of carrying value or fair value less estimated costs to sell the property. Costs related to the development or improvement of the assets are capitalized and costs related to holding the assets are charged to non-interest expense. Property is evaluated regularly to ensure the recorded amount is supported by its current fair value and valuation allowances.
Treasury Stock [Text Block]	Treasury Shares The Company separately presents treasury shares, which represent shares surrendered to the Company equal in value to the statutory payroll tax withholding obligations arising from the vesting of employee restricted stock awards. Treasury shares are carried at cost.
Derivative Financial Instruments	Derivative financial instruments The Company uses interest-rate swaps to mitigate interest-rate risk associated with changes to 1) the fair value of certain fixed-rate financial instruments (fair value hedges) and 2) certain cash flows related to future interest payments on variable rate financial instruments (cash flow hedges). The Company recognizes derivatives as assets or liabilities in the Consolidated Balance Sheet at their fair value in accordance with ASC 815, Derivatives and Hedging . The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and further, on the type of hedging relationship. On the date the derivative contract is entered into, the Company designates the derivative as a fair value hedge or cash flow hedge. Derivative instruments designated in a hedge relationship to mitigate exposure to changes in the fair value of an asset or liability attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivative instruments designated in a hedge relationship to mitigate exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Changes in the fair value of a derivative that is designated and qualifies as a fair value hedge, along with changes in the fair value of the hedged asset or liability that are attributable to the hedged risk are recorded in current-period earnings. For a cash flow hedge, the effective portion of the change in the fair value of the derivative is recorded in AOCI and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Any ineffective portion of the change in fair value of a cash flow hedge is recognized immediately in non-interest income in the Consolidated Income Statement. Under both the fair value and cash flow hedge scenarios, changes in the fair value of derivatives not considered to be highly effective in hedging the change in fair value or the expected cash flows of the hedged item are recognized in earnings as non-interest income during the period of the change. The Company documents its hedge relationships, including identification of the hedging instruments and the hedged items, as well as its risk management objectives and strategies for undertaking the hedge transaction at the time the derivative contract is executed. Both at inception and at least quarterly thereafter, the Company assesses whether the derivatives used in hedging transactions are highly effective (as defined in the guidance) in offsetting changes in either the fair value or cash flows of the hedged item. Retroactive effectiveness is assessed, as well as the continued expectation that the hedge will remain effective prospectively. The Company discontinues hedge accounting prospectively when it is determined that a hedge is no longer highly effective. When hedge accounting is discontinued on a fair value hedge that no longer qualifies as an effective hedge, the derivative continues to be reported at fair value in the Consolidated Balance Sheet, but the carrying amount of the hedged item is no longer adjusted for future changes in fair value. The adjustment to the carrying amount of the hedged item that existed at the date hedge accounting is discontinued is amortized over the remaining life of the hedged item into earnings. Derivative instruments that are not designated as hedges, so called free-standing derivatives, are reported in the Consolidated Balance Sheet at fair value and the changes in fair value are recognized in earnings as non-interest income during the period of change. The Company may in the normal course of business purchase a financial instrument or originate a loan that contains an embedded derivative instrument. Upon purchasing the instrument or originating the loan, the Company assesses whether the economic characteristics of the embedded derivative are clearly and closely related to the economic characteristics of the remaining component of the financial instrument (i.e., the host contract) and whether a separate instrument with the same terms as the embedded instrument would meet the definition of a derivative instrument. When it is determined that the embedded derivative possesses economic characteristics that are not clearly and closely related to the economic characteristics of the host contract and a separate instrument with the same terms would qualify as a derivative instrument, the embedded derivative is separated from the host contract and carried at fair value. However, in cases where the host contract is measured at fair value, with changes in fair value reported in current earnings, or the Company is unable to reliably identify and measure an embedded derivative for separation from its host contract, the entire contract is carried in the Consolidated Balance Sheet at fair value and is not designated as a hedging instrument.
Income Taxes	Income taxes The Company is subject to income taxes in the United States and files a consolidated federal income tax return with all of its subsidiaries, with the exception of BW Real Estate, Inc. Deferred income taxes are recorded to reflect the effects of temporary differences between the financial reporting carrying amounts of assets and liabilities and their income tax bases using enacted tax rates that are expected to be in effect when the taxes are actually paid or recovered. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. Net deferred tax assets are recorded to the extent that these assets will more-likely-than-not be realized. In making these determinations, all available positive and negative evidence is considered, including scheduled reversals of deferred tax liabilities, tax planning strategies, projected future taxable income, and recent operating results. If it is determined that deferred income tax assets to be realized in the future are in excess of their net recorded amount, an adjustment to the valuation allowance will be recorded, which will reduce the Company's provision for income taxes. A tax benefit from an unrecognized tax benefit may be recognized when it is more-likely-than-not that the position will be sustained upon examination, including related appeals or litigation, based on technical merits. Income tax benefits must meet a more-likely-than-not recognition threshold at the effective date to be recognized. Interest and penalties related to unrecognized tax benefits are recognized as part of the provision for income taxes in the Consolidated Income Statement. Accrued interest and penalties are included in the related tax liability line with other liabilities in the Consolidated Balance Sheet. See " Note 11. Income Taxes " of these Notes to Unaudited Consolidated Financial Statements for further discussion on income taxes.
Off-Balance Sheet Instruments	Off-balance sheet instruments In the ordinary course of business, the Company has entered into off-balance sheet financial instrument arrangements consisting of commitments to extend credit and standby letters of credit. Such financial instruments are recorded in the Consolidated Financial Statements when they are funded. They involve, to varying degrees, elements of credit risk in excess of amounts recognized in the Consolidated Balance Sheet. Losses would be experienced when the Company is contractually obligated to make a payment under these instruments and must seek repayment from the borrower, which may not be as financially sound in the current period as they were when the commitment was originally made. 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. The Company enters into credit arrangements that generally provide for the termination of advances in the event of a covenant violation or other event of default. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the party. The commitments are collateralized by the same types of assets used as loan collateral. As with outstanding loans, the Company applies qualitative factors and utilization rates to its off-balance sheet obligations in determining an estimate of losses inherent in these contractual obligations. The estimate for credit losses on off-balance sheet instruments is included in other liabilities and the charge to income that establishes this liability is included in non-interest expense. The Company also has off-balance sheet arrangements related to its derivative instruments. Derivative instruments are recognized in the Consolidated Financial Statements at fair value and their notional values are carried off-balance sheet. See " Note 9. Derivatives and Hedging Activities " of these Notes to Unaudited Consolidated Financial Statements for further discussion.
Fair Values of Financial Instruments	Fair values of financial instruments The Company uses fair value measurements to record fair value adjustments to certain assets and liabilities. ASC 820, Fair Value Measurement , establishes a framework for measuring fair value and a three-level valuation hierarchy for disclosure of fair value measurement, as well as enhances disclosure requirements for fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The Company uses various valuation approaches, including market, income, and/or cost approaches. ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the factors market participants would consider in pricing the asset or liability developed based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs, as follows: • Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. • Level 2 - Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These might include quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, prepayment speeds, volatilities, etc.) or model-based valuation techniques where all significant assumptions are observable, either directly or indirectly, in the market. • Level 3 - Valuation is generated from model-based techniques where one or more significant inputs are not observable, either directly or indirectly, in the market. These unobservable assumptions reflect the Company’s own estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques may include use of matrix pricing, discounted cash flow models, and similar techniques. The availability of observable inputs varies based on the nature of the specific financial instrument. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for disclosure purposes, the level in the fair value hierarchy within which the fair value measurement in its entirety falls is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Fair value is a market-based measure considered from the perspective of a market participant who may purchase the asset or assume the liability rather than an entity-specific measure. When market assumptions are available, ASC 820 requires the Company to make assumptions regarding the assumptions that market participants would use to estimate the fair value of the financial instrument at the measurement date. ASC 825, Financial Instruments , requires disclosure of fair value information about financial instruments, whether or not recognized in the balance sheet, for which it is practicable to estimate that value. Management uses its best judgment in estimating the fair value of the Company’s financial instruments; however, there are inherent limitations in any estimation technique. Therefore, for substantially all financial instruments, the fair value estimates presented herein are not necessarily indicative of the amounts the Company could have realized in a sales transaction at September 30, 2017 and 2016 . The estimated fair value amounts for September 30, 2017 and 2016 have been measured as of period-end, and have not been re-evaluated or updated for purposes of these Consolidated Financial Statements subsequent to those dates. As such, the estimated fair values of these financial instruments subsequent to the reporting date may be different than the amounts reported at period-end. The information in " Note 13. Fair Value Accounting " in these Notes to Unaudited Consolidated Financial Statements should not be interpreted as an estimate of the fair value of the entire Company since a fair value calculation is only required for a limited portion of the Company’s assets and liabilities. Due to the wide range of valuation techniques and the degree of subjectivity used in making the estimate, comparisons between the Company’s disclosures and those of other companies or banks may not be meaningful. The following methods and assumptions were used by the Company in estimating the fair value of its financial instruments: Cash and cash equivalents The carrying amounts reported in the Consolidated Balance Sheets for cash and due from banks approximate their fair value. Money market investments The carrying amounts reported in the Consolidated Balance Sheets for money market investments approximate their fair value. Investment securities The fair values of CRA investments, exchange-listed preferred stock, and certain corporate debt securities are based on quoted market prices and are categorized as Level 1 in the fair value hierarchy. The fair values of other investment securities were determined based on matrix pricing. Matrix pricing is a mathematical technique that utilizes observable market inputs including, for example, yield curves, credit ratings, and prepayment speeds. Fair values determined using matrix pricing are generally categorized as Level 2 in the fair value hierarchy. During the year ended December 31, 2016, the Company's CDO securities were transferred from Level 3 to Level 2 as a result of an increase in the availability and reliability of the observable inputs utilized in the securities' fair value measurement. Previously, quoted prices and quoted prices for similar assets were not available. Therefore, the Company would engage a third party to estimate the future cash flows and discount rate using third party quotes adjusted based on assumptions a market participant would assume necessary for each specific security, which resulted in fair values for these securities being categorized as Level 3 in the fair value hierarchy. Restricted stock WAB is a member of the Federal Reserve System and the FHLB and, accordingly, maintains investments in the capital stock of the FRB and the FHLB. WAB also maintains an investment in its primary correspondent bank. These investments are carried at cost since no ready market exists for them, and they have no quoted market value. The Company conducts a periodic review and evaluation of its restricted stock to determine if any impairment exists. The fair values of these investments have been categorized as Level 2 in the fair value hierarchy. Loans The fair value of loans is estimated based on discounted cash flows using interest rates currently being offered for loans with similar terms to borrowers with similar credit quality and adjustments that the Company believes a market participant would consider in determining fair value based on a third party independent valuation. As a result, the fair value for loans is categorized as Level 2 in the fair value hierarchy, excluding impaired loans which are categorized as Level 3. Accrued interest receivable and payable The carrying amounts reported in the Consolidated Balance Sheets for accrued interest receivable and payable approximate their fair value. Derivative financial instruments All derivatives are recognized in the Consolidated Balance Sheets at their fair value. The fair value for derivatives is determined based on market prices, broker-dealer quotations on similar products, or other related input parameters. As a result, the fair values have been categorized as Level 2 in the fair value hierarchy. Deposits The fair value disclosed for demand and savings deposits is by definition equal to the amount payable on demand at their reporting date (that is, their carrying amount), which the Company believes a market participant would consider in determining fair value. The carrying amount for variable-rate deposit accounts approximates their fair value. Fair values for fixed-rate certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered on certificates to a schedule of aggregated expected monthly maturities on these deposits. The fair value measurement of the deposit liabilities is categorized as Level 2 in the fair value hierarchy. FHLB advances and customer repurchase agreements The fair values of the Company’s borrowings are estimated using discounted cash flow analyses, based on the market rates for similar types of borrowing arrangements. The FHLB advances and customer repurchase agreements have been categorized as Level 2 in the fair value hierarchy due to their short durations. Subordinated debt The fair value of subordinated debt is based on the market rate for the respective subordinated debt security. Subordinated debt has been categorized as Level 3 in the fair value hierarchy. Junior subordinated debt Junior subordinated debt is valued based on a discounted cash flow model which uses as inputs Treasury Bond rates and the 'BB' rated financial index. Junior subordinated debt has been categorized as Level 3 in the fair value hierarchy. Off-balance sheet instruments The fair value of the Company’s off-balance sheet instruments (lending commitments and standby letters of credit) is based on quoted fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements, and the counterparties’ credit standing.
Recent Accounting Pronouncements	Recent accounting pronouncements In May 2014, the FASB issued guidance within ASU 2014-09, Revenue from Contracts with Customers . The amendments in ASU 2014-09 to Topic 606, Revenue from Contracts with Customers, creates a common revenue standard and clarifies the principles for recognizing revenue that can be applied consistently across various transactions, industries, and capital markets. The amendments in the ASU clarify that an entity should recognize 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. As part of that principle, the entity should identify the contract(s) with the customer, identify the performance obligation(s) of the contract, determine the transaction price, allocate that transaction price to the performance obligation(s) of the contract, and then recognize revenue when or as the entity satisfies the performance obligation(s). In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers - Deferral of the Effective Date , which deferred the original effective date of ASU No. 2014-09 by one year. Accordingly, the amendments in ASU No. 2014-09 will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that annual reporting period. The amendments will be applied through the election of one of two retrospective methods. Substantially all of the Company's revenue is generated from interest income related to loans and investment securities, which are not within the scope of this guidance. The contracts that are within the scope of this guidance include service charges and fees on deposit accounts and warrant related income. The Company has completed its review of contracts and other agreements that are within the scope of this guidance and did not identify any material changes to the timing of revenue recognition. The Company will adopt the amendments beginning January 1, 2018 through use of the modified retrospective transition method and expects to expand its qualitative and quantitative disclosures of revenue recognition upon adoption. In January 2016, the FASB issued guidance within ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . The amendments in ASU 2016-01 to Subtopic 825-10, Financial Instruments, contain the following elements: 1) requires equity investments to be measured at fair value with changes in fair value recognized in net income; 2) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; 3) eliminates the requirement for public entities to disclose the methods 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; 4) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; 5) requires an entity to present separately in OCI 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; 6) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or accompanying notes to the financial statements; 7) clarifies that the entity should evaluate the need for a valuation allowance on a deferred tax asset related to AFS securities in combination with the entity's other deferred tax assets. The amendments are effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Except for the early application of the amendment noted in item 5) above, which the Company elected to early adopt effective January 1, 2015 as discussed in the Company's Annual Report on Form 10-K for the year ended December 31, 2015, early adoption of the amendments in this Update is not permitted. As discussed in item 1) above, changes in the fair value of the Company's equity investments, which consist of preferred stock of $96.1 million at September 30, 2017 , will be recognized in net income, rather than in AOCI. As a result, there may be greater volatility in earnings each reporting period related to fair value changes. However, as preferred stock is less than 3% of the Company's total AFS portfolio, the adoption of this amendment and the other amendments in this guidance are not expected to have a material impact on the Company's Consolidated Financial Statements. In February 2016, the FASB issued guidance within ASU 2016-02, Leases . The amendments in ASU 2016-02 to Topic 842, Leases, require lessees to recognize the lease assets and lease liabilities arising from operating leases in the statement of financial position. The accounting applied by a lessor is largely unchanged from that applied under previous GAAP. The amendments in this Update are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. Management is in the early stages of its implementation assessment, which includes identifying the population of the Company's leases that are within the scope of the new guidance, gathering all key lease data, and considering new lease software options that will facilitate application of the new accounting requirements. In June 2016, the FASB issued guidance within ASU 2016-13, Measurement of Credit Losses on Financial Instruments . The amendments in ASU 2016-13 to Topic 326, Financial Instruments - Credit Losses, require that an organization measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. The ASU also requires enhanced disclosures, including qualitative and quantitative disclosures that provide additional information about the amounts recorded in the financial statements. Additionally, the ASU amends the accounting for credit losses on AFS debt securities and purchased financial assets with credit deterioration. The amendments in this Update are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Management has formed a Steering Committee and established an implementation team made up of subject matter experts across different functions within the Company, including Finance, Risk, Credit, and IT, that will facilitate all phases of planning and implementation of the new guidance. The team is working with certain external consultants and is in the final stages of completing its gap assessment. The team has also evaluated numerous modeling packages and has made preliminary decisions on various model approaches. Further, the team is also in the process of evaluating its control framework to identify risks resulting from new processes, judgments, and data. In August 2016, the FASB issued guidance within ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments. The amendments in ASU 2016-15 to Topic 230, Statement of Cash Flows, provide guidance on eight specific cash flow classification issues: 1) debt prepayment or debt extinguishment costs; 2) settlement of zero-coupon debt instruments; 3) contingent consideration payments made after a business combination; 4) proceeds from the settlement of insurance claims; 5) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; 6) distributions received from equity method investments; 7) beneficial interest in securitization transactions; and 8) separately identifiable cash flows and the application of the predominance principle. The amendments in this Update are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. However, an entity is required to adopt all of the amendments in the same period. The amendments in this Update should be applied using a retrospective transition method to each period presented. The adoption of this guidance is not expected to have a significant impact on the Company's Consolidated Statement of Cash Flows. In January 2017, the FASB issued guidance within ASU 2017-01, Clarifying the Definition of a Business . The amendments in ASU 2017-01 to Topic 805, Business Combinations, clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments in this Update should be applied prospectively and are effective for annual periods beginning after December 31, 2017, including interim periods within those periods. The adoption of this guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. In January 2017, the FASB issued guidance within ASU 2017-04, Simplifying the Test for Goodwill Impairment . The amendments in ASU 2017-04 to Topic 350, Intangibles - Goodwill and Other, modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. Accordingly, the amendments eliminate Step 2 from the goodwill impairment test because goodwill impairment will no longer be determined by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The amendments in this Update should be applied on a prospective basis and are effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed after January 1, 2017. The adoption of this guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. In February 2017, the FASB issued guidance within ASU 2017-05, Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets . The amendments in ASU 2017-05 to Subtopic 610-20, Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets, clarify the scope of Subtopic 610-20 and add guidance for partial sales of nonfinancial assets, including partial sales of real estate. Under current GAAP, there are several different accounting models to evaluate whether the transfer of certain assets qualify for sale treatment. The new standard reduces the number of potential accounting models that might apply and clarifies which model does apply in various circumstances. An entity may elect to apply the amendments in this Update either retrospectively to each period presented in the financial statements or, retrospectively with a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. The amendments in this Update are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Early adoption is permitted for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. The adoption of this guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. In March 2017, the FASB issued guidance within ASU 2017-08, Premium Amortization on Purchased Callable Debt Securities . The amendments in ASU 2017-08 to Subtopic 310-20, Receivables-Nonrefundable Fees and Other Costs, shorten the amortization period for certain purchased callable debt securities held at a premium to the earliest call date, which more closely align the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities. Under current GAAP, entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The amendments in this Update should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The amendments in this Update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. The adoption of this guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. In May 2017, the FASB issued guidance within ASU 2017-09, Scope of Modification Accounting . The amendments in ASU 2017-09 to Topic 718, Compensation - Stock Compensation, provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. An entity should account for the effects of a modification unless all of the following conditions are met: the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified; the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; and the classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. The amendments in this Update should be applied prospectively to an award modified on or after the adoption date. The amendments in this Update are effective for annual periods, and interim periods within those annual periods, beginning after December 31, 2017. Early adoption is permitted, including adoption in any interim period. The adoption of this guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. In August 2017, the FASB issued guidance within ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities . The amendments in ASU 2017-12 to Topic 815, Derivatives and Hedging, is intended to more closely align hedge accounting with companies' risk management strategies, simplify the application of hedge accounting, and increase transparency as to the scope and results of hedging programs. The guidance also amends the presentation and disclosure requirements and changes how companies assess effectiveness. Under the new guidance, public companies will have until the end of the first quarter in which a hedge is designated to perform an initial assessment of a hedge's effectiveness. After initial qualification, the new guidance permits a qualitative effectiveness assessment for certain hedges instead of a quantitative test if the company can reasonably support an expectation of high effectiveness throughout the term of the hedge. Additional disclosures include cumulative basis adjustments for fair value hedges and the effect of hedging on individual income statement line items. The amendments in this Update are effective for fiscal years beginning after December 15, 2018, and interim period within those fiscal years. Early adoption is permitted in any interim period after issuance of the Update. Management is in the process of evaluating the effects that the standard is expected to have on the Company's Consolidated Financial Statements and related disclosures. Recently adopted accounting guidance In November 2015, the FASB issued guidance within ASU 2015-17, Income Taxes . The amendments in ASU 2015-17 to Topic 740, Income Taxes, changes the presentation of deferred income tax liabilities and assets, from previously bifurcated current and noncurrent, to a single noncurrent amount on the classified statement of financial position. The amendment was effective for the annual period ending after December 15, 2016, and for and interim periods within those annual periods. The adoption of this guidance did not have a material impact on the Company's Consolidated Financial Statements. In March 2016, the FASB issued guidance within ASU 2016-05, Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships . The amendments in ASU 2016-05 to Topic 815, Derivatives and Hedging, clarify that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under Topic 815 does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. The amendments in this Update were effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The adoption of this guidance did not have a material impact on the Company's Consolidated Financial Statements.

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Carrying Amounts and Fair Values of Investment Securities	The carrying amounts and fair values of investment securities at September 30, 2017 and December 31, 2016 are summarized as follows: September 30, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Fair Value (in thousands) Held-to-maturity Tax-exempt $ 154,920 $ 5,791 $ (129 ) $ 160,582 Available-for-sale CDO $ 50 $ 15,503 $ — $ 15,553 Commercial MBS issued by GSEs 116,910 55 (3,171 ) 113,794 Corporate debt securities 105,047 404 (1,437 ) 104,014 CRA investments 50,997 — (349 ) 50,648 Preferred stock 91,926 4,174 — 96,100 Private label residential MBS 800,171 2,090 (4,646 ) 797,615 Residential MBS issued by GSEs 1,831,411 3,484 (15,889 ) 1,819,006 Tax-exempt 456,762 10,796 (4,785 ) 462,773 Trust preferred securities 32,000 — (2,792 ) 29,208 U.S. government sponsored agency securities 64,000 — (2,364 ) 61,636 U.S. treasury securities 2,496 3 (2 ) 2,497 Total AFS securities $ 3,551,770 $ 36,509 $ (35,435 ) $ 3,552,844 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Fair Value (in thousands) Held-to-maturity Tax-exempt $ 92,079 $ 433 $ (546 ) $ 91,966 Available-for-sale CDO $ 50 $ 13,440 $ — $ 13,490 Commercial MBS issued by GSEs 121,742 — (3,950 ) 117,792 Corporate debt securities 65,058 371 (1,285 ) 64,144 CRA investments 37,627 — (514 ) 37,113 Preferred stock 96,071 833 (2,242 ) 94,662 Private label residential MBS 440,272 182 (6,769 ) 433,685 Residential MBS issued by GSEs 1,369,289 3,046 (17,130 ) 1,355,205 Tax-exempt 409,693 8,477 (9,937 ) 408,233 Trust preferred securities 32,000 — (5,468 ) 26,532 U.S. government sponsored agency securities 59,000 — (2,978 ) 56,022 U.S. treasury securities 2,496 6 — 2,502 Total AFS securities $ 2,633,298 $ 26,355 $ (50,273 ) $ 2,609,380 Securities measured at fair value Residential MBS issued by GSEs $ 1,053
Unrealized Losses and Fair Value of Investment Securities in Continuous Unrealized Loss Position	Information pertaining to securities with gross unrealized losses at September 30, 2017 and December 31, 2016 , aggregated by investment category and length of time that individual securities have been in a continuous loss position follows: September 30, 2017 Less Than Twelve Months More Than Twelve Months Total Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (in thousands) Held-to-maturity Tax-exempt $ 129 $ 9,471 $ — $ — $ 129 $ 9,471 Available-for-sale Commercial MBS issued by GSEs $ 796 $ 35,545 $ 2,375 $ 76,349 $ 3,171 $ 111,894 Corporate debt securities 1,437 78,563 — — 1,437 78,563 CRA investments 349 50,648 — — 349 50,648 Private label residential MBS 2,295 327,580 2,351 134,429 4,646 462,009 Residential MBS issued by GSEs 11,994 1,005,130 3,895 184,589 15,889 1,189,719 Tax-exempt 1,121 120,904 3,664 68,248 4,785 189,152 Trust preferred securities — — 2,792 29,208 2,792 29,208 U.S. government sponsored agency securities 1,624 42,376 740 14,260 2,364 56,636 U.S. treasury securities 2 1,502 — — 2 1,502 Total AFS securities $ 19,618 $ 1,662,248 $ 15,817 $ 507,083 $ 35,435 $ 2,169,331 December 31, 2016 Less Than Twelve Months More Than Twelve Months Total Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (in thousands) Held-to-maturity Tax-exempt $ 546 $ 30,364 $ — $ — $ 546 $ 30,364 Available-for-sale Commercial MBS issued by GSEs $ 3,950 $ 117,792 $ — $ — $ 3,950 $ 117,792 Corporate debt securities 1,285 38,716 — — 1,285 38,716 CRA investments 514 37,113 — — 514 37,113 Preferred stock 2,188 63,151 54 1,471 2,242 64,622 Private label residential MBS 6,170 377,638 599 16,969 6,769 394,607 Residential MBS issued by GSEs 16,990 950,480 140 5,326 17,130 955,806 Tax-exempt 9,937 148,780 — — 9,937 148,780 Trust preferred securities — — 5,468 26,532 5,468 26,532 U.S. government sponsored agency securities 2,978 56,022 — — 2,978 56,022 Total AFS securities $ 44,012 $ 1,789,692 $ 6,261 $ 50,298 $ 50,273 $ 1,839,990
Amortized Cost and Fair Value of Investment Securities by Contractual Maturities	The amortized cost and fair value of securities as of September 30, 2017 , by contractual maturities, are shown below. MBS are shown separately as individual MBS are comprised of pools of loans with varying maturities. Therefore, these securities are listed separately in the maturity summary. September 30, 2017 Amortized Cost Estimated Fair Value (in thousands) Held-to-maturity After one year through five years $ 100 $ 101 After five years through ten years 15,116 15,503 After ten years 139,704 144,978 Total HTM securities $ 154,920 $ 160,582 Available-for-sale Due in one year or less $ 50,997 $ 50,648 After one year through five years 74,409 77,268 After five years through ten years 289,847 292,086 After ten years 388,025 402,427 Mortgage-backed securities 2,748,492 2,730,415 Total AFS securities $ 3,551,770 $ 3,552,844
Investment Securities by Credit Rating Type	The following tables summarize the carrying amount of the Company’s investment ratings position as of September 30, 2017 and December 31, 2016 : September 30, 2017 AAA Split-rated AAA/AA+ AA+ to AA- A+ to A- BBB+ to BBB- BB+ and below Unrated Totals (in thousands) Held-to-maturity Tax-exempt $ — $ — $ — $ — $ — $ — $ 154,920 $ 154,920 Available-for-sale CDO $ — $ — $ — $ — $ — $ 15,553 $ — $ 15,553 Commercial MBS issued by GSEs — 113,794 — — — — — 113,794 Corporate debt securities — — — 74,819 29,195 — — 104,014 CRA investments — 25,381 — — — — 25,267 50,648 Preferred stock — — — 10,575 66,193 4,315 15,017 96,100 Private label residential MBS 736,937 — 56,171 1,509 1,025 1,973 — 797,615 Residential MBS issued by GSEs — 1,819,006 — — — — — 1,819,006 Tax-exempt 63,991 25,264 224,235 147,407 — — 1,876 462,773 Trust preferred securities — — — — 29,208 — — 29,208 U.S. government sponsored agency securities — 61,636 — — — — — 61,636 U.S. treasury securities — 2,497 — — — — — 2,497 Total AFS securities (1) $ 800,928 $ 2,047,578 $ 280,406 $ 234,310 $ 125,621 $ 21,841 $ 42,160 $ 3,552,844 (1) Where ratings differ, the Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch. December 31, 2016 AAA Split-rated AAA/AA+ AA+ to AA- A+ to A- BBB+ to BBB- BB+ and below Unrated Totals (in thousands) Held-to-maturity Tax-exempt $ — $ — $ — $ — $ — $ — $ 92,079 $ 92,079 Available-for-sale CDO $ — $ — $ — $ — $ — $ 13,490 $ — $ 13,490 Commercial MBS issued by GSEs — 117,792 — — — — — 117,792 Corporate debt securities — — 5,429 38,715 20,000 — — 64,144 CRA investments — — — — — — 37,113 37,113 Preferred stock — — — — 64,486 14,658 15,518 94,662 Private label residential MBS 399,013 — 29,921 2,117 2,634 — — 433,685 Residential MBS issued by GSEs — 1,355,205 — — — — — 1,355,205 Tax-exempt 80,862 — 268,249 59,122 — — — 408,233 Trust preferred securities — — — — 26,532 — — 26,532 U.S. government sponsored agency securities — 56,022 — — — — — 56,022 U.S. treasury securities — 2,502 — — — — — 2,502 Total AFS securities (1) $ 479,875 $ 1,531,521 $ 303,599 $ 99,954 $ 113,652 $ 28,148 $ 52,631 $ 2,609,380 Securities measured at fair value Residential MBS issued by GSEs $ — $ 1,053 $ — $ — $ — $ — $ — $ 1,053 (1) Where ratings differ, the Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch.
Gross Gains and (Losses) on Sales of Investment Securities	The following table presents gross gains and losses on sales of investment securities: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Gross gains $ 468 $ — $ 1,181 $ 2,057 Gross losses (149 ) — (274 ) (1,056 ) Net gains (losses) on sales of investment securities $ 319 $ — $ 907 $ 1,001

Loans, Leases and Allowance f27

Loans, Leases and Allowance for Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2017
Receivables [Abstract]
Schedule of Held for Investment Loan Portfolio Composition of Loans, Leases and Allowance for Credit Losses	The composition of the Company’s held for investment loan portfolio is as follows: September 30, 2017 December 31, 2016 (in thousands) Commercial and industrial $ 6,661,152 $ 5,755,021 Commercial real estate - non-owner occupied 3,628,415 3,543,956 Commercial real estate - owner occupied 2,042,262 2,013,276 Construction and land development 1,671,552 1,478,114 Residential real estate 376,716 259,432 Commercial leases 74,850 100,765 Consumer 50,742 38,963 Loans, net 14,505,689 13,189,527 Allowance for credit losses (136,421 ) (124,704 ) Total loans HFI $ 14,369,268 $ 13,064,823
Contractual Aging of Loan Portfolio by Class of Loans Including Loans Held for Sale and Excluding Deferred Fees/Costs	The following table presents the contractual aging of the recorded investment in past due loans held for investment by class of loans: September 30, 2017 Current 30-59 Days 60-89 Days Over 90 Days Total Total (in thousands) Commercial real estate Owner occupied $ 2,039,314 $ 1,687 $ — $ 1,261 $ 2,948 $ 2,042,262 Non-owner occupied 3,431,099 — — 585 585 3,431,684 Multi-family 196,731 — — — — 196,731 Commercial and industrial Commercial 6,657,204 1,066 162 2,720 3,948 6,661,152 Leases 74,850 — — — — 74,850 Construction and land development Construction 1,136,205 2,230 — — 2,230 1,138,435 Land 533,117 — — — — 533,117 Residential real estate 370,733 — — 5,983 5,983 376,716 Consumer 50,553 7 27 155 189 50,742 Total loans $ 14,489,806 $ 4,990 $ 189 $ 10,704 $ 15,883 $ 14,505,689 December 31, 2016 Current 30-59 Days 60-89 Days Over 90 Days Total Total (in thousands) Commercial real estate Owner occupied $ 2,009,728 $ 71 $ — $ 3,477 $ 3,548 $ 2,013,276 Non-owner occupied 3,339,121 672 2 — 674 3,339,795 Multi-family 204,161 — — — — 204,161 Commercial and industrial Commercial 5,747,368 549 584 6,520 7,653 5,755,021 Leases 100,761 — — 4 4 100,765 Construction and land development Construction 973,242 — — — — 973,242 Land 503,588 — — 1,284 1,284 504,872 Residential real estate 249,726 4,333 281 5,092 9,706 259,432 Consumer 38,765 26 2 170 198 38,963 Total loans $ 13,166,460 $ 5,651 $ 869 $ 16,547 $ 23,067 $ 13,189,527
Summary of Recorded Investment in Nonaccrual Loans and Loans Past Due 90 Days Still Accruing Interest by Loan Class	The following table presents the recorded investment in non-accrual loans and loans past due ninety days or more and still accruing interest by class of loans: September 30, 2017 December 31, 2016 Non-accrual loans Loans past due 90 days or more and still accruing Non-accrual loans Loans past due 90 days or more and still accruing Current Past Due/ Total Current Past Due/ Total (in thousands) Commercial real estate Owner occupied $ 5,102 $ 1,261 $ 6,363 $ — $ 5,084 $ 3,264 $ 8,348 $ 285 Non-owner occupied — — — — 8,317 1 8,318 — Multi-family — — — — — — — — Commercial and industrial Commercial 38,875 2,677 41,552 44 10,893 6,043 16,936 775 Leases 15 — 15 — 28 3 31 — Construction and land development Construction — — — — — — — — Land 887 — 887 — — 1,284 1,284 — Residential real estate 39 5,983 6,022 — 99 5,093 5,192 — Consumer — 155 155 — — 163 163 7 Total $ 44,918 $ 10,076 $ 54,994 $ 44 $ 24,421 $ 15,851 $ 40,272 $ 1,067
Loans by Risk Rating	The following tables present gross loans by risk rating: September 30, 2017 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Commercial real estate Owner occupied $ 1,951,070 $ 40,730 $ 48,847 $ 1,615 $ — $ 2,042,262 Non-owner occupied 3,372,861 42,619 16,204 — — 3,431,684 Multi-family 196,731 — — — — 196,731 Commercial and industrial Commercial 6,474,756 100,449 62,585 23,362 — 6,661,152 Leases 73,128 — 1,722 — — 74,850 Construction and land development Construction 1,116,667 9,496 12,272 — — 1,138,435 Land 526,473 4,637 2,007 — — 533,117 Residential real estate 368,722 1,350 6,644 — — 376,716 Consumer 50,505 80 157 — — 50,742 Total $ 14,130,913 $ 199,361 $ 150,438 $ 24,977 $ — $ 14,505,689 September 30, 2017 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Current (up to 29 days past due) $ 14,129,815 $ 197,067 $ 137,947 $ 24,977 $ — $ 14,489,806 Past due 30 - 59 days 946 2,257 1,787 — — 4,990 Past due 60 - 89 days 152 37 — — — 189 Past due 90 days or more — — 10,704 — — 10,704 Total $ 14,130,913 $ 199,361 $ 150,438 $ 24,977 $ — $ 14,505,689 Included in the $25.0 million balance of loans rated Doubtful as of September 30, 2017 , is one loan with a net balance of $23.4 million that was sold subsequent to quarter-end. For additional information related to the loan sale, see page 35 of these Notes to Unaudited Consolidated Financial Statements. December 31, 2016 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Commercial real estate Owner occupied $ 1,935,322 $ 53,634 $ 22,090 $ 2,230 $ — $ 2,013,276 Non-owner occupied 3,278,090 22,972 38,733 — — 3,339,795 Multi-family 203,964 197 — — — 204,161 Commercial and industrial Commercial 5,621,448 70,011 58,562 5,000 — 5,755,021 Leases 100,737 — 28 — — 100,765 Construction and land development Construction 961,290 — 11,952 — — 973,242 Land 501,569 337 2,966 — — 504,872 Residential real estate 252,304 929 6,199 — — 259,432 Consumer 38,698 64 201 — — 38,963 Total $ 12,893,422 $ 148,144 $ 140,731 $ 7,230 $ — $ 13,189,527 December 31, 2016 Pass Special Mention Substandard Doubtful Loss Total (in thousands) Current (up to 29 days past due) $ 12,887,308 $ 147,838 $ 124,084 $ 7,230 $ — $ 13,166,460 Past due 30 - 59 days 5,433 96 122 — — 5,651 Past due 60 - 89 days 410 210 249 — — 869 Past due 90 days or more 271 — 16,276 — — 16,547 Total $ 12,893,422 $ 148,144 $ 140,731 $ 7,230 $ — $ 13,189,527
Impaired Loans by Loan Class	The following table presents impaired loans by class: September 30, 2017 December 31, 2016 (in thousands) Commercial real estate Owner occupied $ 16,937 $ 20,748 Non-owner occupied 19,010 25,524 Multi-family — — Commercial and industrial Commercial 57,581 21,107 Leases 336 355 Construction and land development Construction — — Land 11,503 14,838 Residential real estate 15,794 16,391 Consumer 195 246 Total $ 121,356 $ 99,209
Recorded Investment in Loans Classified as Impaired	The following table presents the average investment in impaired loans and income recognized on impaired loans: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Average investment in impaired loans $ 108,033 $ 106,357 $ 106,456 $ 112,901 Interest income recognized on impaired loans 1,040 959 3,075 3,122 Interest recognized on non-accrual loans, cash basis 694 245 1,372 642 The table below reflects the recorded investment in loans classified as impaired: September 30, 2017 December 31, 2016 (in thousands) Impaired loans with a specific valuation allowance under ASC 310 (1) $ 8,773 $ 10,909 Impaired loans without a specific valuation allowance under ASC 310 (2) 112,583 88,300 Total impaired loans $ 121,356 $ 99,209 Valuation allowance related to impaired loans (3) $ (4,394 ) $ (4,239 ) (1) Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016 , respectively. (2) Includes TDR loans of $47.8 million and $58.3 million at September 30, 2017 and December 31, 2016 , respectively. (3) Includes valuation allowance related to TDR loans of $1.3 million and $0.6 million at September 30, 2017 and December 31, 2016 , respectively.
Average Investment in Impaired Loans by Loan Class	The following table presents the average investment in impaired loans by loan class: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Commercial real estate Owner occupied $ 17,779 $ 17,155 $ 20,136 $ 19,323 Non-owner occupied 20,789 29,978 22,446 31,635 Multi-family — — — — Commercial and industrial Commercial 39,736 25,662 33,009 27,221 Leases 338 331 349 904 Construction and land development Construction — — — — Land 12,503 16,699 13,297 17,632 Residential real estate 16,692 16,272 17,011 15,890 Consumer 196 260 208 296 Total $ 108,033 $ 106,357 $ 106,456 $ 112,901
Interest Income on Impaired Loans by Loan Class	The following table presents interest income on impaired loans by class: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Commercial real estate Owner occupied $ 166 $ 211 $ 530 $ 753 Non-owner occupied 279 285 798 936 Multi-family — — — — Commercial and industrial Commercial 303 90 777 319 Leases 4 4 11 40 Construction and land development Construction — — — — Land 163 240 551 686 Residential real estate 124 128 406 384 Consumer 1 1 2 4 Total $ 1,040 $ 959 $ 3,075 $ 3,122
Tabular Disclosure of Nonperforming Assets	The following table summarizes nonperforming assets: September 30, 2017 December 31, 2016 (in thousands) Non-accrual loans (1) $ 54,994 $ 40,272 Loans past due 90 days or more on accrual status (2) 44 1,067 Accruing troubled debt restructured loans 40,922 53,637 Total nonperforming loans 95,960 94,976 Other assets acquired through foreclosure, net 28,992 47,815 Total nonperforming assets $ 124,952 $ 142,791 (1) Includes non-accrual TDR loans of $8.9 million and $7.1 million at September 30, 2017 and December 31, 2016 , respectively. (2)
Accretable Yield Table	Changes in the accretable yield for loans acquired with deteriorated credit quality are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Balance, at beginning of period $ 14,247 $ 15,863 $ 15,177 $ 15,925 Additions due to acquisition — — — 4,301 Reclassifications from non-accretable to accretable yield (1) — 119 2,086 119 Accretion to interest income (690 ) (901 ) (2,374 ) (2,570 ) Reversal of fair value adjustments upon disposition of loans (2,199 ) (578 ) (3,531 ) (3,272 ) Balance, at end of period $ 11,358 $ 14,503 $ 11,358 $ 14,503 (1) The primary drivers of reclassification from non-accretable to accretable yield resulted from changes in estimated cash flows.
Allowances for Credit Losses	The following table summarizes the changes in the allowance for credit losses by portfolio type: Three Months Ended September 30, Construction and Land Development Commercial Real Estate Residential Real Estate Commercial and Industrial Consumer Total (in thousands) 2017 Beginning Balance $ 20,852 $ 28,593 $ 4,838 $ 76,734 $ 794 $ 131,811 Charge-offs — 175 — 2,921 61 3,157 Recoveries (226 ) (1,781 ) (108 ) (619 ) (33 ) (2,767 ) Provision (619 ) (1,474 ) (141 ) 7,192 42 5,000 Ending Balance $ 20,459 $ 28,725 $ 4,805 $ 81,624 $ 808 $ 136,421 2016 Beginning Balance $ 21,386 $ 24,867 $ 4,546 $ 70,547 $ 758 $ 122,104 Charge-offs — 72 79 2,558 — 2,709 Recoveries (302 ) (521 ) (179 ) (466 ) (21 ) (1,489 ) Provision (347 ) (450 ) (513 ) 3,406 (96 ) 2,000 Ending Balance $ 21,341 $ 24,866 $ 4,133 $ 71,861 $ 683 $ 122,884 Nine Months Ended September 30, Construction and Land Development Commercial Real Estate Residential Real Estate Commercial and Industrial Consumer Total (in thousands) 2017 Beginning Balance $ 21,175 $ 25,673 $ 3,851 $ 73,333 $ 672 $ 124,704 Charge-offs — 1,994 447 6,166 103 8,710 Recoveries (1,011 ) (2,719 ) (1,659 ) (2,705 ) (83 ) (8,177 ) Provision (1,727 ) 2,327 (258 ) 11,752 156 12,250 Ending Balance $ 20,459 $ 28,725 $ 4,805 $ 81,624 $ 808 $ 136,421 2016 Beginning Balance $ 18,976 $ 23,160 $ 5,278 $ 71,181 $ 473 $ 119,068 Charge-offs — 726 105 11,210 120 12,161 Recoveries (455 ) (4,956 ) (589 ) (2,846 ) (131 ) (8,977 ) Provision 1,910 (2,524 ) (1,629 ) 9,044 199 7,000 Ending Balance $ 21,341 $ 24,866 $ 4,133 $ 71,861 $ 683 $ 122,884 The following table presents impairment method information related to loans and allowance for credit losses by loan portfolio segment: Commercial Real Estate-Owner Occupied Commercial Real Estate-Non-Owner Occupied Commercial and Industrial Residential Real Estate Construction and Land Development Commercial Leases Consumer Total Loans (in thousands) Loans as of September 30, 2017: Recorded Investment: Impaired loans with an allowance recorded $ — $ — $ 8,773 $ — $ — $ — $ — $ 8,773 Impaired loans with no allowance recorded 16,936 19,010 48,807 15,794 11,503 336 197 112,583 Total loans individually evaluated for impairment 16,936 19,010 57,580 15,794 11,503 336 197 121,356 Loans collectively evaluated for impairment 2,014,282 3,496,683 6,603,572 360,315 1,660,049 74,514 50,545 14,259,960 Loans acquired with deteriorated credit quality 11,044 112,722 — 607 — — — 124,373 Total recorded investment $ 2,042,262 $ 3,628,415 $ 6,661,152 $ 376,716 $ 1,671,552 $ 74,850 $ 50,742 $ 14,505,689 Unpaid Principal Balance Impaired loans with an allowance recorded $ — $ — $ 8,977 $ — $ — $ — $ — $ 8,977 Impaired loans with no allowance recorded 23,966 27,418 80,622 25,017 28,369 1,539 10,813 197,744 Total loans individually evaluated for impairment 23,966 27,418 89,599 25,017 28,369 1,539 10,813 206,721 Loans collectively evaluated for impairment 2,014,282 3,496,683 6,603,572 360,315 1,660,049 74,514 50,545 14,259,960 Loans acquired with deteriorated credit quality 14,378 139,473 4,812 725 — — — 159,388 Total unpaid principal balance $ 2,052,626 $ 3,663,574 $ 6,697,983 $ 386,057 $ 1,688,418 $ 76,053 $ 61,358 $ 14,626,069 Related Allowance for Credit Losses Impaired loans with an allowance recorded $ — $ — $ 4,394 $ — $ — $ — $ — $ 4,394 Impaired loans with no allowance recorded — — — — — — — — Total loans individually evaluated for impairment — — 4,394 — — — — 4,394 Loans collectively evaluated for impairment 12,865 14,172 77,228 4,805 20,459 — 808 130,337 Loans acquired with deteriorated credit quality — 1,688 2 — — — — 1,690 Total allowance for credit losses $ 12,865 $ 15,860 $ 81,624 $ 4,805 $ 20,459 $ — $ 808 $ 136,421 Commercial Real Estate-Owner Occupied Commercial Real Estate-Non-Owner Occupied Commercial and Industrial Residential Real Estate Construction and Land Development Commercial Leases Consumer Total Loans (in thousands) Loans as of December 31, 2016: Recorded Investment: Impaired loans with an allowance recorded $ 3,125 $ — $ 7,766 $ — $ — $ — $ 18 $ 10,909 Impaired loans with no allowance recorded 17,624 25,524 13,340 16,391 14,838 355 228 88,300 Total loans individually evaluated for impairment 20,749 25,524 21,106 16,391 14,838 355 246 99,209 Loans collectively evaluated for impairment 1,981,176 3,383,585 5,733,915 242,409 1,443,952 100,410 38,717 12,924,164 Loans acquired with deteriorated credit quality 11,351 134,847 — 632 19,324 — — 166,154 Total recorded investment $ 2,013,276 $ 3,543,956 $ 5,755,021 $ 259,432 $ 1,478,114 $ 100,765 $ 38,963 $ 13,189,527 Unpaid Principal Balance Impaired loans with an allowance recorded $ 3,125 $ — $ 8,019 $ — $ — $ — $ 18 $ 11,162 Impaired loans with no allowance recorded 26,336 33,632 43,176 26,225 33,487 507 1,358 164,721 Total loans individually evaluated for impairment 29,461 33,632 51,195 26,225 33,487 507 1,376 175,883 Loans collectively evaluated for impairment 1,981,176 3,383,585 5,733,915 242,409 1,443,952 100,410 38,717 12,924,164 Loans acquired with deteriorated credit quality 14,878 165,275 925 738 19,858 — — 201,674 Total unpaid principal balance $ 2,025,515 $ 3,582,492 $ 5,786,035 $ 269,372 $ 1,497,297 $ 100,917 $ 40,093 $ 13,301,721 Related Allowance for Credit Losses Impaired loans with an allowance recorded $ 937 $ — $ 3,301 $ — $ — $ — $ 1 $ 4,239 Impaired loans with no allowance recorded — — — — — — — — Total loans individually evaluated for impairment 937 — 3,301 — — — 1 4,239 Loans collectively evaluated for impairment 11,403 12,646 69,673 3,851 20,398 — 671 118,642 Loans acquired with deteriorated credit quality — 687 359 — 777 — — 1,823 Total allowance for credit losses $ 12,340 $ 13,333 $ 73,333 $ 3,851 $ 21,175 $ — $ 672 $ 124,704

Other Assets Acquired Through28

Other Assets Acquired Through Foreclosure (Tables)	9 Months Ended
	Sep. 30, 2017
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]
Changes in Other Assets Acquired Through Foreclosure	The following table represents the changes in other assets acquired through foreclosure: Three Months Ended September 30, 2017 Gross Balance Valuation Allowance Net Balance (in thousands) Balance, beginning of period $ 35,037 $ (4,049 ) $ 30,988 Transfers to other assets acquired through foreclosure, net 430 — 430 Proceeds from sale of other real estate owned and repossessed assets, net (2,491 ) 330 (2,161 ) Valuation adjustments, net — (343 ) (343 ) Gains (losses), net (1) 78 — 78 Balance, end of period $ 33,054 $ (4,062 ) $ 28,992 Three Months Ended September 30, 2016 Balance, beginning of period $ 56,467 $ (6,623 ) $ 49,844 Transfers to other assets acquired through foreclosure, net 1,162 — 1,162 Proceeds from sale of other real estate owned and repossessed assets, net (1,260 ) 32 (1,228 ) Valuation adjustments, net — (184 ) (184 ) Gains (losses), net (1) 25 — 25 Balance, end of period $ 56,394 $ (6,775 ) $ 49,619 Nine Months Ended September 30, 2017 Gross Balance Valuation Allowance Net Balance (in thousands) Balance, beginning of period $ 54,138 $ (6,323 ) $ 47,815 Transfers to other assets acquired through foreclosure, net 1,812 — 1,812 Proceeds from sale of other real estate owned and repossessed assets, net (23,129 ) 2,381 (20,748 ) Valuation adjustments, net — (120 ) (120 ) (Losses) gains, net (1) 233 — 233 Balance, end of period $ 33,054 $ (4,062 ) $ 28,992 Nine Months Ended September 30, 2016 Balance, beginning of period $ 52,984 $ (9,042 ) $ 43,942 Transfers to other assets acquired through foreclosure, net 11,888 — 11,888 Proceeds from sale of other real estate owned and repossessed assets, net (8,174 ) 2,140 (6,034 ) Valuation adjustments, net — 127 127 (Losses) gains, net (1) (304 ) — (304 ) Balance, end of period $ 56,394 $ (6,775 ) $ 49,619 (1) There were zero net gains related to initial transfers to other assets during the three months ended September 30, 2017 and 2016 and $0.1 million and zero net gains related to initial transfers to other assets during the nine months ended September 30, 2017 and 2016 , respectively.

Other Borrowings (Tables)

Other Borrowings (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Company's Borrowings	The following table summarizes the Company’s borrowings as of September 30, 2017 and December 31, 2016 : September 30, 2017 December 31, 2016 (in thousands) Short-Term: FHLB advances $ — $ 80,000 Total short-term borrowings $ — $ 80,000

Accumulated Other Comprehensi30

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income	The following table summarizes the changes in accumulated other comprehensive income (loss) by component, net of tax, for the periods indicated: Three Months Ended September 30, Unrealized holding gains (losses) on AFS Unrealized holding gains (losses) on SERP Unrealized holding gains (losses) on junior subordinated debt Impairment loss on securities Total (in thousands) Balance, June 30, 2017 $ (449 ) $ 157 $ 6,638 $ 144 $ 6,490 Other comprehensive income (loss) before reclassifications 1,116 114 641 — 1,871 Amounts reclassified from accumulated other comprehensive income (197 ) — — — (197 ) Net current-period other comprehensive income (loss) 919 114 641 — 1,674 Balance, September 30, 2017 $ 470 $ 271 $ 7,279 $ 144 $ 8,164 Balance, June 30, 2016 $ 33,013 $ 102 $ 13,367 $ 144 $ 46,626 Other comprehensive (loss) income before reclassifications (7,415 ) 6 (2,825 ) — (10,234 ) Amounts reclassified from accumulated other comprehensive income — — — — — Net current-period other comprehensive (loss) income (7,415 ) 6 (2,825 ) — (10,234 ) Balance, September 30, 2016 $ 25,598 $ 108 $ 10,542 $ 144 $ 36,392 Nine Months Ended September 30, Unrealized holding gains (losses) on AFS Unrealized holding gains (losses) on SERP Unrealized holding gains (losses) on junior subordinated debt Impairment loss on securities Total (in thousands) Balance, December 31, 2016 $ (14,916 ) $ 121 $ 9,956 $ 144 $ (4,695 ) Other comprehensive income (loss) before reclassifications 15,947 150 (2,677 ) 13,420 Amounts reclassified from accumulated other comprehensive income (561 ) — — — (561 ) Net current-period other comprehensive income (loss) 15,386 150 (2,677 ) — 12,859 Balance, September 30, 2017 $ 470 $ 271 $ 7,279 $ 144 $ 8,164 Balance, December 31, 2015 $ 9,993 $ 90 $ 12,033 $ 144 $ 22,260 Other comprehensive income (loss) before reclassifications 16,316 18 (1,491 ) — 14,843 Amounts reclassified from accumulated other comprehensive income (711 ) — — — (711 ) Net current-period other comprehensive income (loss) 15,605 18 (1,491 ) — 14,132 Balance, September 30, 2016 $ 25,598 $ 108 $ 10,542 $ 144 $ 36,392
Schedule of Reclassifications Out of Accumulated Other Comprehensive Income	The following table presents reclassifications out of accumulated other comprehensive income: Three Months Ended September 30, Nine Months Ended September 30, Income Statement Classification 2017 2016 2017 2016 (in thousands) Gain (loss) on sales of investment securities, net $ 319 $ — $ 907 $ 1,001 Income tax (expense) benefit (122 ) — (346 ) (290 ) Net of tax $ 197 $ — $ 561 $ 711

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position	The fair value of derivative contracts, after taking into account the effects of master netting agreements, is included in other assets or other liabilities in the Consolidated Balance Sheets, as indicated in the following table: September 30, 2017 December 31, 2016 September 30, 2016 Fair Value Fair Value Fair Value Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities (in thousands) Derivatives designated as hedging instruments: Fair value hedges Interest rate swaps $ 1,016,694 $ 1,656 $ 59,346 $ 993,485 $ 4,220 $ 65,749 $ 988,337 $ 4,350 $ 100,067 Total 1,016,694 1,656 59,346 993,485 4,220 65,749 988,337 4,350 100,067 Netting adjustments (1) — 1,588 1,588 — 1,869 1,869 — — — Net derivatives in the balance sheet $ 1,016,694 $ 68 $ 57,758 $ 993,485 $ 2,351 $ 63,880 $ 988,337 $ 4,350 $ 100,067 (1) Netting adjustments represent the amounts recorded to convert the Company's derivative balances from a gross basis to a net basis in accordance with the applicable accounting guidance.
Gain (Loss) on Derivative Instruments	The following table summarizes the gains (losses) on fair value hedges for the three and nine months ended September 30, 2017 and 2016 , all of which are recorded in non-interest income. Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Hedge of Fixed Rate Loans (1) Gain (loss) on "pay fixed" swap $ 4,437 $ 7,225 $ 3,820 $ (35,087 ) (Loss) gain on receive fixed rate loans (4,423 ) (7,206 ) (3,780 ) 35,113 Net ineffectiveness $ 14 $ 19 $ 40 $ 26 Hedge of Fixed Rate Subordinated Debt Issuances (1) (Loss) gain on "receive fixed" swap $ (1,767 ) $ (3,793 ) $ 19 $ 395 Gain (loss) on subordinated debt 1,767 3,793 (19 ) (395 ) Net ineffectiveness $ — $ — $ — $ — (1) The fair value of derivatives contracts are carried as other assets and other liabilities in the Consolidated Balance Sheets. The effective portion of hedging gains (losses) is recorded as basis adjustments to the underlying hedged asset or liability. Gains and losses on both the hedging derivative and hedged item are recorded through non-interest income with a resulting net income impact for the amount of ineffectiveness.
Largest Exposure To Individual Counterparty	The following table summarizes the Company's largest exposure to an individual counterparty at the dates indicated: September 30, 2017 December 31, 2016 September 30, 2016 (in thousands) Largest gross exposure (derivative asset) to an individual counterparty $ 945 $ 2,351 $ 4,159 Collateral posted by this counterparty — 1,691 4,131 Derivative liability with this counterparty 44,053 — — Collateral pledged to this counterparty 65,051 — — Net exposure after netting adjustments and collateral $ — $ 660 $ 28

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table presents the calculation of basic and diluted EPS: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands, except per share amounts) Weighted average shares - basic 104,221 103,768 104,124 102,791 Dilutive effect of stock awards 721 796 817 741 Weighted average shares - diluted 104,942 104,564 104,941 103,532 Net income $ 82,858 $ 67,052 $ 236,186 $ 189,998 Earnings per share - basic 0.80 0.65 2.27 1.85 Earnings per share - diluted 0.79 0.64 2.25 1.84

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Summary of Contractual Amounts for Unfunded Commitments and Letters of Credit	A summary of the contractual amounts for unfunded commitments and letters of credit are as follows: September 30, 2017 December 31, 2016 (in thousands) Commitments to extend credit, including unsecured loan commitments of $322,991 at September 30, 2017 and $360,840 at December 31, 2016 $ 5,378,255 $ 4,428,495 Credit card commitments and financial guarantees 140,728 115,536 Standby letters of credit, including unsecured letters of credit of $11,383 at September 30, 2017 and $6,431 at December 31, 2016 129,489 78,576 Total $ 5,648,472 $ 4,622,607

Fair Value Accounting (Tables)

Fair Value Accounting (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Gains and Losses from Fair Value Changes Included in Consolidated Statement of Operations	For the three and nine months ended September 30, 2017 and 2016 , gains and losses from fair value changes on securities and junior subordinated debt were as follows: Changes in Fair Values for Items Measured at Fair Value Unrealized Gain/(Loss) on Assets and Liabilities Measured at Fair Value, Net Interest Income on Securities Interest Expense on Junior Subordinated Debt Total Changes Included in Current-Period Earnings Total Changes Included in OCI (in thousands) Three Months Ended September 30, 2017 Securities measured at fair value $ — $ — $ — $ — $ — Junior subordinated debt 1,035 — (835 ) (835 ) 641 Total $ 1,035 $ — $ (835 ) $ (835 ) $ 641 Nine Months Ended September 30, 2017 Securities measured at fair value $ — $ 9 $ — $ 9 $ — Junior subordinated debt (4,327 ) — (2,376 ) (2,376 ) (2,677 ) Total $ (4,327 ) $ 9 $ (2,376 ) $ (2,367 ) $ (2,677 ) Three Months Ended September 30, 2016 Securities measured at fair value $ (12 ) $ 11 $ — $ (1 ) $ — Junior subordinated debt (4,604 ) — (702 ) (625 ) (2,825 ) Total $ (4,616 ) $ 11 $ (702 ) $ (626 ) $ (2,825 ) Nine Months Ended September 30, 2016 Securities measured at fair value $ (18 ) $ 33 $ — $ 15 $ — Junior subordinated debt (2,386 ) — (2,075 ) (1,843 ) (1,491 ) Total $ (2,404 ) $ 33 $ (2,075 ) $ (1,828 ) $ (1,491 )
Fair Value of Assets and Liabilities	The fair value of assets and liabilities measured at fair value on a recurring basis was determined using the following inputs as of the periods presented: Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Fair Value (in thousands) September 30, 2017 Assets: Available-for-sale CDO $ — $ 15,553 $ — $ 15,553 Commercial MBS issued by GSEs — 113,794 — 113,794 Corporate debt securities — 104,014 — 104,014 CRA investments 50,648 — — 50,648 Preferred stock 96,100 — — 96,100 Private label residential MBS — 797,615 — 797,615 Residential MBS issued by GSEs — 1,819,006 — 1,819,006 Tax-exempt — 462,773 — 462,773 Trust preferred securities — 29,208 — 29,208 U.S. government sponsored agency securities — 61,636 — 61,636 U.S. treasury securities — 2,497 — 2,497 Total AFS securities $ 146,748 $ 3,406,096 $ — $ 3,552,844 Loans - HFS $ — $ 16,347 $ — $ 16,347 Derivative assets (1) — 1,656 — 1,656 Liabilities: Junior subordinated debt (2) $ — $ — $ 54,737 $ 54,737 Derivative liabilities (1) — 59,346 — 59,346 (1) Derivative assets and liabilities relate to interest rate swaps, see " Note 9. Derivatives and Hedging Activities ." In addition, the carrying value of loans is increased by $44,721 and the net carrying value of subordinated debt is decreased by $12,307 as of September 30, 2017 , which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment. Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value (in thousands) December 31, 2016 Assets: Measured at fair value Residential MBS issued by GSEs $ — $ 1,053 $ — $ 1,053 Available-for-sale CDO — 13,490 — 13,490 Commercial MBS issued by GSEs — 117,792 — 117,792 Corporate debt securities 20,000 44,144 — 64,144 CRA investments 37,113 — — 37,113 Preferred stock 94,662 — — 94,662 Private label residential MBS — 433,685 — 433,685 Residential MBS issued by GSEs — 1,355,205 — 1,355,205 Tax-exempt — 408,233 — 408,233 Trust preferred securities — 26,532 — 26,532 U.S. government sponsored agency securities — 56,022 — 56,022 U.S. treasury securities — 2,502 — 2,502 Total AFS securities $ 151,775 $ 2,457,605 $ — $ 2,609,380 Loans - HFS $ — $ 18,909 $ — $ 18,909 Derivative assets (1) — 4,220 — 4,220 Liabilities: Junior subordinated debt (2) $ — $ — $ 50,410 $ 50,410 Derivative liabilities (1) — 65,749 — 65,749 (1) Derivative assets and liabilities relate to interest rate swaps, see " Note 9. Derivatives and Hedging Activities ." In addition, the carrying value of loans is increased by $48,161 and the net carrying value of subordinated debt is decreased by $12,325 as of December 31, 2016 , which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment.
Change in Level 3 Liabilities Measured at Fair Value on Recurring Basis	For the three and nine months ended September 30, 2017 and 2016 , the change in Level 3 assets and liabilities measured at fair value on a recurring basis was as follows: Junior Subordinated Debt Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Beginning balance $ 55,772 $ 44,710 $ 50,410 $ 46,928 Transfers into Level 3 — — — — Total gains (losses) for the period Included in other comprehensive income (1,035 ) 4,604 4,327 2,386 Ending balance $ 54,737 $ 49,314 $ 54,737 $ 49,314 CDO Securities Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (in thousands) Beginning balance $ — $ 10,183 $ — $ 10,060 Transfers into Level 3 — — — — Total gains (losses) for the period Included in other comprehensive income — 369 — 492 Ending balance $ — $ 10,552 $ — $ 10,552 The Company transferred all CDO securities from Level 3 to Level 2 during the year ended December 31, 2016 as a result of an increase in the availability and reliability of the observable inputs utilized in the securities' fair value measurement. The Company recognized this transfer between levels on October 31, 2016, in accordance with its policy to recognize transfers between levels in the fair value hierarchy as of the end of the month following the event or change in circumstance that caused the transfer.
Assets Measured at Fair Value on Nonrecurring Basis	The following table presents such assets carried on the balance sheet by caption and by level within the ASC 825 hierarchy: Fair Value Measurements at the End of the Reporting Period Using Total Quoted Prices in Active Markets for Identical Assets (Level 1) Active Markets for Similar Assets (Level 2) Unobservable Inputs (Level 3) (in thousands) As of September 30, 2017: Impaired loans with specific valuation allowance $ 4,379 $ — $ — $ 4,379 Impaired loans without specific valuation allowance (1) 70,170 — — 70,170 Other assets acquired through foreclosure 28,992 — — 28,992 As of December 31, 2016: Impaired loans with specific valuation allowance $ 6,670 $ — $ — $ 6,670 Impaired loans without specific valuation allowance (1) 60,738 — — 60,738 Other assets acquired through foreclosure 47,815 — — 47,815 (1) Net of loan balances with charge-offs of $42.4 million and $27.6 million as of September 30, 2017 and December 31, 2016 , respectively.
Estimated Fair Value of Financial Instruments	The estimated fair value of the Company’s financial instruments is as follows: September 30, 2017 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in thousands) Financial assets: Investment securities: HTM $ 154,920 $ — $ 160,582 $ — $ 160,582 AFS 3,552,844 146,748 3,406,096 — 3,552,844 Derivative assets 1,656 — 1,656 — 1,656 Loans, net 14,385,615 — 13,999,391 74,549 14,073,940 Accrued interest receivable 72,374 — 72,374 — 72,374 Financial liabilities: Deposits $ 16,904,783 $ — $ 16,911,392 $ — $ 16,911,392 Customer repurchase agreements 26,066 — 26,066 — 26,066 Qualifying debt 372,851 — — 399,855 399,855 Derivative liabilities 59,346 — 59,346 — 59,346 Accrued interest payable 10,958 — 10,958 — 10,958 December 31, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in thousands) Financial assets: Investment securities: HTM $ 92,079 $ — $ 91,966 $ — $ 91,966 AFS 2,609,380 151,775 2,457,605 — 2,609,380 Trading 1,053 — 1,053 — 1,053 Derivative assets 4,220 — 4,220 — 4,220 Loans, net 13,083,732 — 12,736,336 67,408 12,803,744 Accrued interest receivable 70,320 — 70,320 — 70,320 Financial liabilities: Deposits $ 14,549,863 $ — $ 14,553,931 $ — $ 14,553,931 Customer repurchase agreements 41,728 — 41,728 — 41,728 FHLB advances 80,000 — 80,000 — 80,000 Qualifying debt 367,937 — — 375,626 375,626 Derivative liabilities 65,749 — 65,749 — 65,749 Accrued interest payable 15,354 — 15,354 — 15,354

Segments (Tables)

Segments (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Operating Segment Information	The following is a summary of operating segment information for the periods indicated: Regional Segments Balance Sheet: Consolidated Company Arizona Nevada Southern California Northern California At September 30, 2017 (in millions) Assets: Cash, cash equivalents, and investment securities $ 4,424.0 $ 1.9 $ 7.7 $ 1.9 $ 1.7 Loans, net of deferred loan fees and costs 14,521.9 3,131.2 1,685.6 1,873.5 1,260.7 Less: allowance for credit losses (136.4 ) (30.7 ) (16.8 ) (20.4 ) (12.6 ) Total loans 14,385.5 3,100.5 1,668.8 1,853.1 1,248.1 Other assets acquired through foreclosure, net 29.0 2.3 13.7 — 0.2 Goodwill and other intangible assets, net 301.2 — 23.2 — 156.8 Other assets 782.5 45.8 58.4 13.9 17.4 Total assets $ 19,922.2 $ 3,150.5 $ 1,771.8 $ 1,868.9 $ 1,424.2 Liabilities: Deposits $ 16,904.8 $ 5,198.1 $ 3,950.5 $ 2,512.2 $ 1,535.6 Borrowings and qualifying debt 372.9 — — — — Other liabilities 498.9 13.4 23.3 3.6 11.1 Total liabilities 17,776.6 5,211.5 3,973.8 2,515.8 1,546.7 Allocated equity: 2,145.6 390.4 251.5 216.6 299.2 Total liabilities and stockholders' equity $ 19,922.2 $ 5,601.9 $ 4,225.3 $ 2,732.4 $ 1,845.9 Excess funds provided (used) — 2,451.4 2,453.5 863.5 421.7 Income Statement: Three Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 201,583 $ 52,637 $ 36,310 $ 26,811 $ 21,932 Provision for credit losses 5,000 (289 ) (2,044 ) (58 ) 3,144 Net interest income (expense) after provision for credit losses 196,583 52,926 38,354 26,869 18,788 Non-interest income 10,288 1,265 2,354 971 1,796 Non-interest expense (89,114 ) (18,844 ) (14,748 ) (12,340 ) (11,317 ) Income (loss) before income taxes 117,757 35,347 25,960 15,500 9,267 Income tax expense (benefit) 34,899 13,857 9,086 6,517 3,897 Net income (loss) $ 82,858 $ 21,490 $ 16,874 $ 8,983 $ 5,370 Nine Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 573,635 $ 145,839 $ 108,028 $ 81,087 $ 63,686 Provision for (recovery of) credit losses 12,250 109 (5,378 ) (20 ) 4,238 Net interest income (expense) after provision for credit losses 561,385 145,730 113,406 81,107 59,448 Non-interest income 31,281 3,567 6,800 2,602 5,839 Non-interest expense (265,128 ) (55,388 ) (45,733 ) (38,063 ) (36,188 ) Income (loss) before income taxes 327,538 93,909 74,473 45,646 29,099 Income tax expense (benefit) 91,352 36,831 26,066 19,194 12,236 Net income (loss) $ 236,186 $ 57,078 $ 48,407 $ 26,452 $ 16,863 National Business Lines Balance Sheet: HOA Public & Nonprofit Finance Technology & Innovation Hotel Franchise Finance Other NBLs Corporate & Other At September 30, 2017 Assets: (in millions) Cash, cash equivalents, and investment securities $ — $ — $ — $ — $ — $ 4,410.8 Loans, net of deferred loan fees and costs 157.3 1,574.5 1,049.2 1,272.5 2,513.0 4.4 Less: allowance for credit losses (1.6 ) (16.1 ) (9.9 ) (2.7 ) (25.5 ) (0.1 ) Total loans 155.7 1,558.4 1,039.3 1,269.8 2,487.5 4.3 Other assets acquired through foreclosure, net — — — — — 12.8 Goodwill and other intangible assets, net — — 121.1 0.1 — — Other assets 0.4 12.2 5.3 5.2 10.1 613.8 Total assets $ 156.1 $ 1,570.6 $ 1,165.7 $ 1,275.1 $ 2,497.6 $ 5,041.7 Liabilities: Deposits $ 2,153.3 $ — $ 1,459.5 $ — $ — $ 95.6 Borrowings and qualifying debt — — — — — 372.9 Other liabilities 1.1 46.4 0.7 0.4 136.1 262.8 Total liabilities 2,154.4 46.4 1,460.2 0.4 136.1 731.3 Allocated equity: 57.4 126.0 234.6 104.3 207.2 258.4 Total liabilities and stockholders' equity $ 2,211.8 $ 172.4 $ 1,694.8 $ 104.7 $ 343.3 $ 989.7 Excess funds provided (used) 2,055.7 (1,398.2 ) 529.1 (1,170.4 ) (2,154.3 ) (4,052.0 ) Income Statement: Three Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 13,746 $ 7,269 $ 20,415 $ 15,346 $ 16,933 $ (9,816 ) Provision for credit losses 40 91 (83 ) 1,116 4,416 (1,333 ) Net interest income (expense) after provision for credit losses 13,706 7,178 20,498 14,230 12,517 (8,483 ) Non-interest income 136 15 1,855 — 379 1,517 Non-interest expense (7,011 ) (1,871 ) (8,824 ) (1,905 ) (5,286 ) (6,968 ) Income (loss) before income taxes 6,831 5,322 13,529 12,325 7,610 (13,934 ) Income tax expense (benefit) 2,562 1,028 5,075 4,622 2,853 (14,598 ) Net income (loss) $ 4,269 $ 4,294 $ 8,454 $ 7,703 $ 4,757 $ 664 Nine Months Ended September 30, 2017: (in thousands) Net interest income (expense) $ 40,275 $ 21,242 $ 59,610 $ 42,337 $ 46,380 $ (34,849 ) Provision for (recovery of) credit losses 332 796 816 2,924 10,265 (1,832 ) Net interest income (expense) after provision for credit losses 39,943 20,446 58,794 39,413 36,115 (33,017 ) Non-interest income 417 40 5,689 — 1,632 4,695 Non-interest expense (21,416 ) (6,107 ) (26,685 ) (7,949 ) (14,573 ) (13,026 ) Income (loss) before income taxes 18,944 14,379 37,798 31,464 23,174 (41,348 ) Income tax expense (benefit) 7,104 4,424 14,175 11,799 8,690 (49,167 ) Net income (loss) $ 11,840 $ 9,955 $ 23,623 $ 19,665 $ 14,484 $ 7,819 Regional Segments Balance Sheet: Consolidated Company Arizona Nevada Southern California Northern California At December 31, 2016 (in millions) Assets: Cash, cash equivalents, and investment securities $ 3,052.3 $ 1.9 $ 10.1 $ 2.1 $ 1.9 Loans, net of deferred loan fees and costs 13,208.5 2,955.9 1,725.5 1,766.8 1,095.4 Less: allowance for credit losses (124.7 ) (30.1 ) (18.5 ) (19.4 ) (8.8 ) Total loans 13,083.8 2,925.8 1,707.0 1,747.4 1,086.6 Other assets acquired through foreclosure, net 47.8 6.2 18.0 — 0.3 Goodwill and other intangible assets, net 302.9 — 23.7 — 157.5 Other assets 714.0 42.9 58.8 14.5 14.3 Total assets $ 17,200.8 $ 2,976.8 $ 1,817.6 $ 1,764.0 $ 1,260.6 Liabilities: Deposits $ 14,549.8 $ 3,843.4 $ 3,731.5 $ 2,382.6 $ 1,543.6 Borrowings and qualifying debt 447.9 — — — — Other liabilities 311.6 12.8 28.3 12.9 12.4 Total liabilities 15,309.3 3,856.2 3,759.8 2,395.5 1,556.0 Allocated equity: 1,891.5 346.6 250.7 201.6 283.7 Total liabilities and stockholders' equity $ 17,200.8 $ 4,202.8 $ 4,010.5 $ 2,597.1 $ 1,839.7 Excess funds provided (used) — 1,226.0 2,192.9 833.1 579.1 Income Statement: Three Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 172,547 $ 45,531 $ 35,977 $ 26,488 $ 22,181 Provision for (recovery of) credit losses 2,000 2,399 (1,009 ) (105 ) 144 Net interest income (expense) after provision for credit losses 170,547 43,132 36,986 26,593 22,037 Non-interest income 10,683 1,180 2,264 686 2,916 Non-interest expense (85,007 ) (16,084 ) (14,801 ) (11,532 ) (12,706 ) Income (loss) before income taxes 96,223 28,228 24,449 15,747 12,247 Income tax expense (benefit) 29,171 11,074 8,557 6,621 5,150 Net income (loss) $ 67,052 $ 17,154 $ 15,892 $ 9,126 $ 7,097 Nine Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 481,944 $ 125,191 $ 102,016 $ 76,719 $ 67,272 Provision for (recovery of) credit losses 7,000 10,875 (3,526 ) 145 2,112 Net interest income (expense) after provision for credit losses 474,944 114,316 105,542 76,574 65,160 Non-interest income 32,375 5,749 6,420 1,907 7,858 Non-interest expense (242,304 ) (45,090 ) (44,371 ) (33,401 ) (40,154 ) Income (loss) before income taxes 265,015 74,975 67,591 45,080 32,864 Income tax expense (benefit) 75,017 29,413 23,657 18,956 13,819 Net income (loss) $ 189,998 $ 45,562 $ 43,934 $ 26,124 $ 19,045 National Business Lines Balance Sheet: HOA Public & Nonprofit Finance Technology & Innovation Hotel Franchise Finance Other NBLs Corporate & Other At December 31, 2016 Assets: (in millions) Cash, cash equivalents, and investment securities $ — $ — $ — $ — $ — $ 3,036.3 Loans, net of deferred loan fees and costs 116.8 1,454.3 1,011.4 1,292.1 1,776.9 13.4 Less: allowance for credit losses (1.3 ) (15.6 ) (10.6 ) (0.8 ) (19.0 ) (0.6 ) Total loans 115.5 1,438.7 1,000.8 1,291.3 1,757.9 12.8 Other assets acquired through foreclosure, net — — — — — 23.3 Goodwill and other intangible assets, net — — 121.5 0.2 — — Other assets 0.3 15.6 7.2 5.3 11.1 544.0 Total assets $ 115.8 $ 1,454.3 $ 1,129.5 $ 1,296.8 $ 1,769.0 $ 3,616.4 Liabilities: Deposits $ 1,890.3 $ — $ 1,038.2 $ — $ — $ 120.2 Borrowings and qualifying debt — — — — — 447.9 Other liabilities 0.7 50.5 2.0 1.4 17.5 173.1 Total liabilities 1,891.0 50.5 1,040.2 1.4 17.5 741.2 Allocated equity: 65.6 117.1 224.1 107.1 145.5 149.5 Total liabilities and stockholders' equity $ 1,956.6 $ 167.6 $ 1,264.3 $ 108.5 $ 163.0 $ 890.7 Excess funds provided (used) 1,840.8 (1,286.7 ) 134.8 (1,188.3 ) (1,606.0 ) (2,725.7 ) Income Statement: Three Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 11,312 $ 5,012 $ 18,143 $ 13,370 $ 12,060 $ (17,527 ) Provision for (recovery of) credit losses 72 (315 ) (557 ) — 1,372 (1) Net interest income (expense) after provision for credit losses 11,240 5,327 18,700 13,370 10,688 (17,526 ) Non-interest income 125 19 1,871 — 728 894 Non-interest expense (6,062 ) (1,974 ) (8,837 ) (3,207 ) (3,972 ) (5,832 ) Income (loss) before income taxes 5,303 3,372 11,734 10,163 7,444 (22,464 ) Income tax expense (benefit) 1,989 1,265 4,400 3,811 2,791 (16,487 ) Net income (loss) $ 3,314 $ 2,107 $ 7,334 $ 6,352 $ 4,653 $ (5,977 ) Nine Months Ended September 30, 2016: (in thousands) Net interest income (expense) $ 29,853 $ 15,259 $ 51,083 $ 25,438 $ 35,220 $ (46,107 ) Provision for (recovery of) credit losses 160 (509 ) (2,336 ) — 3,309 (3,230 ) Net interest income (expense) after provision for credit losses 29,693 15,768 53,419 25,438 31,911 (42,877 ) Non-interest income 340 22 4,623 — 1,598 3,858 Non-interest expense (17,423 ) (5,927 ) (23,177 ) (5,764 ) (11,007 ) (15,990 ) Income (loss) before income taxes 12,610 9,863 34,865 19,674 22,502 (55,009 ) Income tax expense (benefit) 4,729 3,699 13,074 7,378 8,438 (48,146 ) Net income (loss) $ 7,881 $ 6,164 $ 21,791 $ 12,296 $ 14,064 $ (6,863 )

Mergers, Acquisitions and Dis36

Mergers, Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The recognized amounts of identifiable assets acquired and liabilities assumed, at their as adjusted acquisition date fair values, are as follows: April 20, 2016 (in thousands) Assets: Loans $ 1,280,997 Other assets 3,632 Total assets $ 1,284,629 Liabilities: Other liabilities $ 12,559 Total liabilities 12,559 Net assets acquired $ 1,272,070 Consideration paid Cash $ 1,272,187 Goodwill $ 117
Business Acquisition, Pro Forma Information [Table Text Block]	The following table presents pro forma information as if the acquisition was completed on January 1, 2015. The pro forma information includes adjustments for interest income on loans acquired and excludes acquisition / restructure expense. The pro forma information is not necessarily indicative of the results of operations as they would have been had the transactions been effected on the assumed dates. Three Months Ended September 30, 2016 Nine Months Ended September 30, 2016 (in thousands, except per share amounts) Interest income $ 180,335 $ 523,962 Non-interest income 10,683 32,375 Net income 65,349 194,095 Earnings per share - basic 0.63 1.89 Earnings per share - diluted 0.62 1.87

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017Subsidiary
Significant Of Accounting Policies [Line Items]
Number Of Wholly Owned Subsidiaries Non Bank Subsidiaries	1
Number of wholly-owned subsidiaries	10
Number Of Unconsolidated Subsidiaries	8

Investment Securities - Carryin

Investment Securities - Carrying Amounts and Fair Values of Investment Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	$ 154,920		$ 92,079
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	5,791		433
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(129)		(546)
Held-to-maturity Securities, Fair Value	160,582		91,966
Securities available for sale Total, Amortized Cost	3,551,770		2,633,298
Securities available-for-sale, Gross Unrealized Gains	36,509		26,355
Securities available-for-sale, Gross Unrealized (Losses)	(35,435)		(50,273)
Securities available for sale Total, Estimated Fair Value	3,552,844		2,609,380
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	64,000		59,000
Securities available-for-sale, Gross Unrealized Gains	0		0
Securities available-for-sale, Gross Unrealized (Losses)	(2,364)		(2,978)
Securities available for sale Total, Estimated Fair Value	61,636		56,022
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	2,496		2,496
Securities available-for-sale, Gross Unrealized Gains	3		6
Securities available-for-sale, Gross Unrealized (Losses)	(2)		0
Securities available for sale Total, Estimated Fair Value	2,497		2,502
Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	456,762		409,693
Securities available-for-sale, Gross Unrealized Gains	10,796		8,477
Securities available-for-sale, Gross Unrealized (Losses)	(4,785)		(9,937)
Securities available for sale Total, Estimated Fair Value	462,773		408,233
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	91,926		96,071
Securities available-for-sale, Gross Unrealized Gains	4,174		833
Securities available-for-sale, Gross Unrealized (Losses)	0		(2,242)
Securities available for sale Total, Estimated Fair Value	96,100		94,662
Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	1,831,411		1,369,289
Securities available-for-sale, Gross Unrealized Gains	3,484		3,046
Securities available-for-sale, Gross Unrealized (Losses)	(15,889)		(17,130)
Securities available for sale Total, Estimated Fair Value	1,819,006		1,355,205
Securities measured at fair value			1,053
Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	800,171		440,272
Securities available-for-sale, Gross Unrealized Gains	2,090		182
Securities available-for-sale, Gross Unrealized (Losses)	(4,646)		(6,769)
Securities available for sale Total, Estimated Fair Value	797,615		433,685
Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	32,000		32,000
Securities available-for-sale, Gross Unrealized Gains	0		0
Securities available-for-sale, Gross Unrealized (Losses)	(2,792)		(5,468)
Securities available for sale Total, Estimated Fair Value	29,208		26,532
Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	50		50
Securities available-for-sale, Gross Unrealized Gains	15,503		13,440
Securities available-for-sale, Gross Unrealized (Losses)	0		0
Securities available for sale Total, Estimated Fair Value	15,553		13,490
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	116,910		121,742
Securities available-for-sale, Gross Unrealized Gains	55		0
Securities available-for-sale, Gross Unrealized (Losses)	(3,171)		(3,950)
Securities available for sale Total, Estimated Fair Value	113,794		117,792
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	105,047		65,058
Securities available-for-sale, Gross Unrealized Gains	404		371
Securities available-for-sale, Gross Unrealized (Losses)	(1,437)		(1,285)
Securities available for sale Total, Estimated Fair Value	104,014		64,144
CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Amortized Cost	50,997		37,627
Securities available-for-sale, Gross Unrealized Gains	0		0
Securities available-for-sale, Gross Unrealized (Losses)	(349)		(514)
Securities available for sale Total, Estimated Fair Value	50,648		37,113
AAA [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	800,928	[1]	479,875	[2]
AAA [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Securities available for sale Total, Estimated Fair Value	63,991		80,862
AAA [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Securities measured at fair value			0
AAA [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	736,937		399,013
AAA [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AAA [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Split-rated AAA/AA Plus [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	2,047,578	[1]	1,531,521	[2]
Split-rated AAA/AA Plus [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	61,636		56,022
Split-rated AAA/AA Plus [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	2,497		2,502
Split-rated AAA/AA Plus [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Securities available for sale Total, Estimated Fair Value	25,264		0
Split-rated AAA/AA Plus [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Split-rated AAA/AA Plus [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	1,819,006		1,355,205
Securities measured at fair value			1,053
Split-rated AAA/AA Plus [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Split-rated AAA/AA Plus [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Split-rated AAA/AA Plus [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Split-rated AAA/AA Plus [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	113,794		117,792
Split-rated AAA/AA Plus [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Split-rated AAA/AA Plus [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	25,381		0
AA Plus to AA- [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	280,406	[1]	303,599	[2]
AA Plus to AA- [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AA Plus to AA- [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AA Plus to AA- [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Securities available for sale Total, Estimated Fair Value	224,235		268,249
AA Plus to AA- [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AA Plus to AA- [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Securities measured at fair value			0
AA Plus to AA- [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	56,171		29,921
AA Plus to AA- [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AA Plus to AA- [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AA Plus to AA- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
AA Plus to AA- [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		5,429
AA Plus to AA- [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
A Plus to A- [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	234,310	[1]	99,954	[2]
A Plus to A- [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
A Plus to A- [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
A Plus to A- [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Securities available for sale Total, Estimated Fair Value	147,407		59,122
A Plus to A- [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	10,575		0
A Plus to A- [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Securities measured at fair value			0
A Plus to A- [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	1,509		2,117
A Plus to A- [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
A Plus to A- [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
A Plus to A- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
A Plus to A- [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	74,819		38,715
A Plus to A- [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BBB Plus to BBB- [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	125,621	[1]	113,652	[2]
BBB Plus to BBB- [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BBB Plus to BBB- [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BBB Plus to BBB- [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Securities available for sale Total, Estimated Fair Value	0		0
BBB Plus to BBB- [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	66,193		64,486
BBB Plus to BBB- [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Securities measured at fair value			0
BBB Plus to BBB- [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	1,025		2,634
BBB Plus to BBB- [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	29,208		26,532
BBB Plus to BBB- [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BBB Plus to BBB- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BBB Plus to BBB- [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	29,195		20,000
BBB Plus to BBB- [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	21,841	[1]	28,148	[2]
BB Plus and below [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	4,315		14,658
BB Plus and below [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Securities measured at fair value			0
BB Plus and below [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	1,973		0
BB Plus and below [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	15,553		13,490
BB Plus and below [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
BB Plus and below [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	42,160	[1]	52,631	[2]
Corporate Credit Quality Indicator Unrated [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	154,920		92,079
Securities available for sale Total, Estimated Fair Value	1,876		0
Corporate Credit Quality Indicator Unrated [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	15,017		15,518
Corporate Credit Quality Indicator Unrated [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Securities measured at fair value			0
Corporate Credit Quality Indicator Unrated [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	0		0
Corporate Credit Quality Indicator Unrated [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	25,267		37,113
Rated Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	3,552,844	[1]	2,609,380	[2]
Rated Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	61,636		56,022
Rated Securities [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	2,497		2,502
Rated Securities [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	154,920		92,079
Securities available for sale Total, Estimated Fair Value	462,773		408,233
Rated Securities [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	96,100		94,662
Rated Securities [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	1,819,006		1,355,205
Securities measured at fair value			1,053
Rated Securities [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	797,615		433,685
Rated Securities [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	29,208		26,532
Rated Securities [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	15,553		13,490
Rated Securities [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	113,794		117,792
Rated Securities [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	104,014		64,144
Rated Securities [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale Total, Estimated Fair Value	$ 50,648		$ 37,113
[1]	he Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch
[2]	Where ratings differ, the Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch.

Investment Securities - Additio

Investment Securities - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017USD ($)positions	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)positions
Investment Identifier [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | positions	248		244
Amount of impairment losses reclassified out of accumulated other comprehensive income into earnings	$ 0	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	35,435,000		$ 50,273,000
Securities with carrying amounts were pledged	$ 975,100,000		$ 763,000,000

Investment Securities - Unreali

Investment Securities - Unrealized Losses and Fair Value of Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 129	$ 546
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	9,471	30,364
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	129	546
Held-to-maturity Securities, Fair Value	9,471	30,364
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	19,618	44,012
Available-for-sale securities, Less Than Twelve Months, Fair Value	1,662,248	1,789,692
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	15,817	6,261
Available-for-sale securities, Twelve Months or Longer, Fair Value	507,083	50,298
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	35,435	50,273
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	2,169,331	1,839,990
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	1,624	2,978
Available-for-sale securities, Less Than Twelve Months, Fair Value	42,376	56,022
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	740	0
Available-for-sale securities, Twelve Months or Longer, Fair Value	14,260	0
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	2,364	2,978
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	56,636	56,022
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	1,437	1,285
Available-for-sale securities, Less Than Twelve Months, Fair Value	78,563	38,716
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	0	0
Available-for-sale securities, Twelve Months or Longer, Fair Value	0	0
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	1,437	1,285
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	78,563	38,716
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses		2,188
Available-for-sale securities, Less Than Twelve Months, Fair Value		63,151
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses		54
Available-for-sale securities, Twelve Months or Longer, Fair Value		1,471
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total		2,242
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total		64,622
Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	11,994	16,990
Available-for-sale securities, Less Than Twelve Months, Fair Value	1,005,130	950,480
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	3,895	140
Available-for-sale securities, Twelve Months or Longer, Fair Value	184,589	5,326
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	15,889	17,130
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	1,189,719	955,806
Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	1,121	9,937
Available-for-sale securities, Less Than Twelve Months, Fair Value	120,904	148,780
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	3,664	0
Available-for-sale securities, Twelve Months or Longer, Fair Value	68,248	0
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	4,785	9,937
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	189,152	148,780
Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	2,295	6,170
Available-for-sale securities, Less Than Twelve Months, Fair Value	327,580	377,638
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	2,351	599
Available-for-sale securities, Twelve Months or Longer, Fair Value	134,429	16,969
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	4,646	6,769
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	462,009	394,607
Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	0	0
Available-for-sale securities, Less Than Twelve Months, Fair Value	0	0
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	2,792	5,468
Available-for-sale securities, Twelve Months or Longer, Fair Value	29,208	26,532
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	2,792	5,468
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	29,208	26,532
CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	349	514
Available-for-sale securities, Less Than Twelve Months, Fair Value	50,648	37,113
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	0	0
Available-for-sale securities, Twelve Months or Longer, Fair Value	0	0
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	349	514
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	50,648	37,113
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	796	3,950
Available-for-sale securities, Less Than Twelve Months, Fair Value	35,545	117,792
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	2,375	0
Available-for-sale securities, Twelve Months or Longer, Fair Value	76,349	0
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	3,171	3,950
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	111,894	$ 117,792
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less Than Twelve Months, Aggregate Losses	2
Available-for-sale securities, Less Than Twelve Months, Fair Value	1,502
Available-for-sale securities, Twelve Months or Longer, Aggregate Losses	0
Available-for-sale securities, Twelve Months or Longer, Fair Value	0
Available-for-sale securities, Continuous Unrealized Loss Position, Aggregate Losses, Total	2
Available-for-sale securities, Continuous Unrealized Loss Position, Fair Value, Total	$ 1,502

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Fair Value of Investment Securities by Contractual Maturities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	$ 100
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	101
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	15,116
Held-to-maturity Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	15,503
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	139,704
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	144,978
Held-to-maturity Securities	154,920	$ 92,079
Held-to-maturity Securities, Fair Value	160,582	91,966
Securities available for sale, Due in one year or less, Amortized Cost	50,997
Securities available for sale, After one year through five years, Amortized Cost	74,409
Securities available for sale, After five years through ten years, Amortized Cost	289,847
Securities available for sale, After ten years, Amortized Cost	388,025
Securities available for sale, Mortgage backed securities, Amortized Cost	2,748,492
Securities available for sale Total, Amortized Cost	3,551,770	2,633,298
Securities available for sale, Due in one year or less, Estimated Fair Value	50,648
Securities available for sale, After one year through five years, Estimated Fair Value	77,268
Securities available for sale, After five years through ten years, Estimated Fair Value	292,086
Securities available for sale, After ten years, Estimated Fair Value	402,427
Securities available for sale, Mortgage backed securities, Estimated Fair Value	2,730,415
Securities available for sale Total, Estimated Fair Value	$ 3,552,844	$ 2,609,380

Investment Securities - Investm

Investment Securities - Investment Securities by Credit Rating Type (Detail) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	$ 154,920		$ 92,079
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844		2,609,380
Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	462,773		408,233
Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,819,006		1,355,205
Securities measured at fair value			1,053
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	113,794		117,792
Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	797,615		433,685
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	61,636		56,022
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	2,497		2,502
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	96,100		94,662
Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	29,208		26,532
Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	15,553		13,490
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	104,014		64,144
CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	50,648		37,113
Rated Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844	[1]	2,609,380	[2]
Rated Securities [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	154,920		92,079
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	462,773		408,233
Rated Securities [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,819,006		1,355,205
Securities measured at fair value			1,053
Rated Securities [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	113,794		117,792
Rated Securities [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	797,615		433,685
Rated Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	61,636		56,022
Rated Securities [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	2,497		2,502
Rated Securities [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	96,100		94,662
Rated Securities [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	29,208		26,532
Rated Securities [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	15,553		13,490
Rated Securities [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	104,014		64,144
Rated Securities [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	50,648		37,113
AAA [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	800,928	[1]	479,875	[2]
AAA [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	63,991		80,862
AAA [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Securities measured at fair value			0
AAA [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	736,937		399,013
AAA [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AAA [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Split-rated AAA/AA Plus [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	2,047,578	[1]	1,531,521	[2]
Split-rated AAA/AA Plus [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	25,264		0
Split-rated AAA/AA Plus [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,819,006		1,355,205
Securities measured at fair value			1,053
Split-rated AAA/AA Plus [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	113,794		117,792
Split-rated AAA/AA Plus [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Split-rated AAA/AA Plus [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	61,636		56,022
Split-rated AAA/AA Plus [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	2,497		2,502
Split-rated AAA/AA Plus [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Split-rated AAA/AA Plus [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Split-rated AAA/AA Plus [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Split-rated AAA/AA Plus [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Split-rated AAA/AA Plus [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	25,381		0
AA Plus to AA- [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	280,406	[1]	303,599	[2]
AA Plus to AA- [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	224,235		268,249
AA Plus to AA- [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Securities measured at fair value			0
AA Plus to AA- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AA Plus to AA- [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	56,171		29,921
AA Plus to AA- [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AA Plus to AA- [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AA Plus to AA- [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AA Plus to AA- [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AA Plus to AA- [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
AA Plus to AA- [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		5,429
AA Plus to AA- [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
A Plus to A- [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	234,310	[1]	99,954	[2]
A Plus to A- [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	147,407		59,122
A Plus to A- [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Securities measured at fair value			0
A Plus to A- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
A Plus to A- [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,509		2,117
A Plus to A- [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
A Plus to A- [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
A Plus to A- [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	10,575		0
A Plus to A- [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
A Plus to A- [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
A Plus to A- [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	74,819		38,715
A Plus to A- [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BBB Plus to BBB- [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	125,621	[1]	113,652	[2]
BBB Plus to BBB- [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BBB Plus to BBB- [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Securities measured at fair value			0
BBB Plus to BBB- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BBB Plus to BBB- [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,025		2,634
BBB Plus to BBB- [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BBB Plus to BBB- [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BBB Plus to BBB- [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	66,193		64,486
BBB Plus to BBB- [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	29,208		26,532
BBB Plus to BBB- [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BBB Plus to BBB- [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	29,195		20,000
BBB Plus to BBB- [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	21,841	[1]	28,148	[2]
BB Plus and below [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	0		0
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Securities measured at fair value			0
BB Plus and below [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,973		0
BB Plus and below [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	4,315		14,658
BB Plus and below [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	15,553		13,490
BB Plus and below [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
BB Plus and below [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	42,160	[1]	52,631	[2]
Corporate Credit Quality Indicator Unrated [Member] | Municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities	154,920		92,079
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	1,876		0
Corporate Credit Quality Indicator Unrated [Member] | Residential mortgage-backed securities issued by GSEs
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Securities measured at fair value			0
Corporate Credit Quality Indicator Unrated [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | Private label residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	15,017		15,518
Corporate Credit Quality Indicator Unrated [Member] | Trust preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Corporate Credit Quality Indicator Unrated [Member] | CRA investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	$ 25,267		$ 37,113
[1]	he Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch
[2]	Where ratings differ, the Company uses an average of the available ratings by S&P, Moody’s, and/or Fitch.

Investment Securities - Gross G

Investment Securities - Gross Gains and (Losses) on Sales of Investments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Gross gains	$ 468	$ 0	$ 1,181	$ 2,057
Gross (losses)	(149)	0	(274)	(1,056)
Net (losses) gains	$ 319	$ 0	$ 907	$ 1,001

Loans, Leases and Allowance f44

Loans, Leases and Allowance for Credit Losses - Schedule of Held for Investment Loan Portfolio Composition of Loans, Leases and Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Credit Mark on Acquired Loans	$ 32,800	$ 47,300
Trade and Loans Receivables Held-for-sale, Net, Not Part of Disposal Group	16,347	18,909
Net deferred loan fees and costs	(21,600)	(22,300)
Receivable with Imputed Interest, Discount	(8,400)	5,200
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield	17,000	22,200
Loans, net of deferred loan fees and costs	14,505,689	13,189,527
Allowance for credit losses	(136,421)	(124,704)
Loans, net	14,369,268	13,064,823
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	6,661,152	5,755,021
Commercial Real Estate Non Owner Occupied Multi Family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	3,628,415	3,543,956
Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	2,042,262	2,013,276
Allowance for credit losses	(12,865)	(12,340)
Construction and land development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	1,671,552	1,478,114
Allowance for credit losses	(20,459)	(21,175)
Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	376,716	259,432
Allowance for credit losses	(4,805)	(3,851)
Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	74,850	100,765
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans, net of deferred loan fees and costs	50,742	38,963
Allowance for credit losses	$ (808)	$ (672)

Loans, Leases and Allowance f45

Loans, Leases and Allowance for Credit Losses - Contractual Aging of Loan Portfolio by Class of Loans Including Loans Held for Sale and Excluding Deferred Fees/Costs (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		$ 14,489,806	$ 13,166,460
Past Due		15,883	23,067
Total		14,505,689	13,189,527
Financing Receivable, Recorded Investment, Nonaccrual Status	[1]	54,994	40,272
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		44	1,067
Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		2,039,314	2,009,728
Past Due		2,948	3,548
Total		2,042,262	2,013,276
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	285
Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		3,431,099	3,339,121
Past Due		585	674
Total		3,431,684	3,339,795
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		196,731	204,161
Past Due		0	0
Total		196,731	204,161
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		6,657,204	5,747,368
Past Due		3,948	7,653
Total		6,661,152	5,755,021
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		44	775
Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		74,850	100,761
Past Due		0	4
Total		74,850	100,765
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		1,136,205	973,242
Past Due		2,230	0
Total		1,138,435	973,242
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		533,117	503,588
Past Due		0	1,284
Total		533,117	504,872
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		370,733	249,726
Past Due		5,983	9,706
Total		376,716	259,432
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		50,553	38,765
Past Due		189	198
Total		50,742	38,963
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	7
Non-accrual loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		44,918	24,421
Past Due		10,076	15,851
Financing Receivable, Recorded Investment, Nonaccrual Status		54,994	40,272
Non-accrual loans [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		5,102	5,084
Past Due		1,261	3,264
Financing Receivable, Recorded Investment, Nonaccrual Status		6,363	8,348
Non-accrual loans [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	8,317
Past Due		0	1
Financing Receivable, Recorded Investment, Nonaccrual Status		0	8,318
Non-accrual loans [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	0
Past Due		0	0
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
Non-accrual loans [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		38,875	10,893
Past Due		2,677	6,043
Financing Receivable, Recorded Investment, Nonaccrual Status		41,552	16,936
Non-accrual loans [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		15	28
Past Due		0	3
Financing Receivable, Recorded Investment, Nonaccrual Status		15	31
Non-accrual loans [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	0
Past Due		0	0
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
Non-accrual loans [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		887	0
Past Due		0	1,284
Financing Receivable, Recorded Investment, Nonaccrual Status		887	1,284
Non-accrual loans [Member] | Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		39	99
Past Due		5,983	5,093
Financing Receivable, Recorded Investment, Nonaccrual Status		6,022	5,192
Non-accrual loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	0
Past Due		155	163
Financing Receivable, Recorded Investment, Nonaccrual Status		155	163
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		4,990	5,651
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		1,687	71
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	672
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		1,066	549
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		2,230	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	4,333
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		7	26
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		189	869
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	2
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		162	584
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	281
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		27	2
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		10,704	16,547
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		1,261	3,477
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		585	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		2,720	6,520
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	4
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		0	1,284
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		5,983	5,092
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		$ 155	$ 170
[1]	Includes non-accrual TDR loans of $8.9 million and $7.1 million at September 30, 2017 and December 31, 2016, respectively.

Loans, Leases and Allowance f46

Loans, Leases and Allowance for Credit Losses - Summary of Recorded Investment in Nonaccrual Loans and Loans Past Due 90 Days Still Accruing Interest by Loan Class (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		$ 14,489,806	$ 13,166,460
Total Past Due		15,883	23,067
Total Non-accrual	[1]	54,994	40,272
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		44	1,067
Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		2,039,314	2,009,728
Total Past Due		2,948	3,548
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	285
Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		3,431,099	3,339,121
Total Past Due		585	674
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		196,731	204,161
Total Past Due		0	0
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		6,657,204	5,747,368
Total Past Due		3,948	7,653
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		44	775
Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		74,850	100,761
Total Past Due		0	4
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		1,136,205	973,242
Total Past Due		2,230	0
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		533,117	503,588
Total Past Due		0	1,284
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		370,733	249,726
Total Past Due		5,983	9,706
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	0
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		50,553	38,765
Total Past Due		189	198
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing		0	7
Non-accrual loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		44,918	24,421
Total Past Due		10,076	15,851
Total Non-accrual		54,994	40,272
Non-accrual loans [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		5,102	5,084
Total Past Due		1,261	3,264
Total Non-accrual		6,363	8,348
Non-accrual loans [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	8,317
Total Past Due		0	1
Total Non-accrual		0	8,318
Non-accrual loans [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	0
Total Past Due		0	0
Total Non-accrual		0	0
Non-accrual loans [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		38,875	10,893
Total Past Due		2,677	6,043
Total Non-accrual		41,552	16,936
Non-accrual loans [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		15	28
Total Past Due		0	3
Total Non-accrual		15	31
Non-accrual loans [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	0
Total Past Due		0	0
Total Non-accrual		0	0
Non-accrual loans [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		887	0
Total Past Due		0	1,284
Total Non-accrual		887	1,284
Non-accrual loans [Member] | Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		39	99
Total Past Due		5,983	5,093
Total Non-accrual		6,022	5,192
Non-accrual loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		0	0
Total Past Due		155	163
Total Non-accrual		$ 155	$ 163
[1]	Includes non-accrual TDR loans of $8.9 million and $7.1 million at September 30, 2017 and December 31, 2016, respectively.

Loans, Leases and Allowance f47

Loans, Leases and Allowance for Credit Losses - Additional Information (Detail)		3 Months Ended		9 Months Ended
		Sep. 30, 2017USD ($)SecurityLoan	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)SecurityLoan	Sep. 30, 2016USD ($)SecurityLoan	Dec. 31, 2016USD ($)
Leases [Line Items]
Financing Receivable, Net		$ 14,505,689,000		$ 14,505,689,000		$ 13,189,527,000
Financing Receivable, Modifications, Number of Contracts | SecurityLoan		2		3
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 1,900,000		$ 6,800,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment			$ 0	$ 500,000	$ 5,714,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | SecurityLoan				3
Receivable with Imputed Interest, Discount		8,400,000		$ 8,400,000		(5,200,000)
Financing Receivable, Recorded Investment, Nonaccrual Status	[1]	54,994,000		54,994,000		40,272,000
Impaired Financing Receivable, Average Recorded Investment		108,033,000	106,357,000	106,456,000	112,901,000
Aggregate carrying amount of impaired loans	[2]	8,773,000		8,773,000		10,909,000
Reduction in interest income due to nonaccrual loans		700,000	600,000	1,800,000	1,500,000
Loans And Loans Receivable Purchases		216,800,000	163,700,000	666,800,000	262,000,000
Financing Receivable, Significant Sales		41,300,000		50,500,000	37,100,000
Impaired loans with no allowance recorded	[3]	112,583,000		112,583,000		88,300,000
Impaired loans with an allowance recorded		4,394,000		4,394,000		4,239,000
Loans and Leases Receivable, Gain (Loss) on Sales, Net				100,000	2,100,000
Troubled Debt Restructured Loans [Member]
Leases [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		8,900,000		8,900,000		7,100,000
Impaired Financing Receivable, Average Recorded Investment		52,000,000	63,900,000	56,600,000	71,400,000
Aggregate carrying amount of impaired loans		2,100,000		2,100,000		2,500,000
Loan commitments outstanding		0		0
Impaired loans with no allowance recorded		47,800,000		47,800,000		58,300,000
Impaired loans with an allowance recorded		1,300,000		1,300,000		600,000
Non-owner occupied [Member]
Leases [Line Items]
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 100,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | SecurityLoan		1
Aggregate carrying amount of impaired loans		$ 0		0		0
Impaired loans with no allowance recorded		19,010,000		19,010,000		25,524,000
Impaired loans with an allowance recorded		0		0		0
Construction and land development [Member]
Leases [Line Items]
Aggregate carrying amount of impaired loans		0		0		0
Impaired loans with no allowance recorded		11,503,000		11,503,000		14,838,000
Impaired loans with an allowance recorded		0		0		0
Residential real estate [Member]
Leases [Line Items]
Aggregate carrying amount of impaired loans		0		0		0
Loans And Loans Receivable Purchases				146,400,000
Impaired loans with no allowance recorded		15,794,000		15,794,000		16,391,000
Impaired loans with an allowance recorded		0		0		0
Commercial and industrial [Member]
Leases [Line Items]
Aggregate carrying amount of impaired loans		8,773,000		8,773,000		7,766,000
Loans And Loans Receivable Purchases				520,400,000
Impaired loans with no allowance recorded		48,807,000		48,807,000		13,340,000
Impaired loans with an allowance recorded		4,394,000		4,394,000		3,301,000
Consumer [Member]
Leases [Line Items]
Aggregate carrying amount of impaired loans		0		0		18,000
Impaired loans with no allowance recorded		197,000		197,000		228,000
Impaired loans with an allowance recorded		0		0		1,000
Commercial leases [Member]
Leases [Line Items]
Aggregate carrying amount of impaired loans		0		0		0
Impaired loans with no allowance recorded		336,000		336,000		355,000
Impaired loans with an allowance recorded		0		0		0
Commercial [Member] | Commercial and industrial [Member]
Leases [Line Items]
Financing Receivable, Net		6,661,152,000		6,661,152,000		5,755,021,000
Impaired Financing Receivable, Average Recorded Investment		39,736,000	25,662,000	33,009,000	$ 27,221,000
Non-owner occupied [Member]
Leases [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | SecurityLoan					2
Non-owner occupied [Member] | Commercial real estate [Member]
Leases [Line Items]
Financing Receivable, Net		3,431,684,000		3,431,684,000		$ 3,339,795,000
Impaired Financing Receivable, Average Recorded Investment		$ 20,789,000	$ 29,978,000	$ 22,446,000	$ 31,635,000
[1]	Includes non-accrual TDR loans of $8.9 million and $7.1 million at September 30, 2017 and December 31, 2016, respectively.
[2]	Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016, respectively.
[3]	Includes TDR loans of $47.8 million and $58.3 million at September 30, 2017 and December 31, 2016, respectively.

Loans, Leases and Allowance f48

Loans, Leases and Allowance for Credit Losses - Loans by Risk Rating (Detail) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	$ 14,505,689,000	$ 13,189,527,000
Current	14,489,806,000	13,166,460,000
Past Due	15,883,000	23,067,000
Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	376,716,000	259,432,000
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	50,742,000	38,963,000
Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	2,042,262,000	2,013,276,000
Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	3,431,684,000	3,339,795,000
Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	196,731,000	204,161,000
Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	6,661,152,000	5,755,021,000
Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	74,850,000	100,765,000
Construction and land development [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	1,138,435,000	973,242,000
Construction and land development [Member] | Land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	533,117,000	504,872,000
Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	14,130,913,000	12,893,422,000
Current	14,129,815,000	12,887,308,000
Pass [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	368,722,000	252,304,000
Pass [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	50,505,000	38,698,000
Pass [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	1,951,070,000	1,935,322,000
Pass [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	3,372,861,000	3,278,090,000
Pass [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	196,731,000	203,964,000
Pass [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	6,474,756,000	5,621,448,000
Pass [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	73,128,000	100,737,000
Pass [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	1,116,667,000	961,290,000
Pass [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	526,473,000	501,569,000
Watch [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	199,361,000	148,144,000
Current	197,067,000	147,838,000
Watch [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	1,350,000	929,000
Watch [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	80,000	64,000
Watch [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	40,730,000	53,634,000
Watch [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	42,619,000	22,972,000
Watch [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	197,000
Watch [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	100,449,000	70,011,000
Watch [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Watch [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	9,496,000	0
Watch [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	4,637,000	337,000
Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	150,438,000	140,731,000
Current	137,947,000	124,084,000
Substandard [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	6,644,000	6,199,000
Substandard [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	157,000	201,000
Substandard [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	48,847,000	22,090,000
Substandard [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	16,204,000	38,733,000
Substandard [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Substandard [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	62,585,000	58,562,000
Substandard [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	1,722,000	28,000
Substandard [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	12,272,000	11,952,000
Substandard [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	2,007,000	2,966,000
Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	24,977,000	7,230,000
Current	24,977,000	7,230,000
Doubtful [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Doubtful [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Doubtful [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	1,615,000	2,230,000
Doubtful [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Doubtful [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Doubtful [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	23,362,000	5,000,000
Doubtful [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Doubtful [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Doubtful [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Current	0	0
Loss [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Construction and land development [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Loss [Member] | Construction and land development [Member] | Land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Net	0	0
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	4,990,000	5,651,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	946,000	5,433,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Watch [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	2,257,000	96,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	1,787,000	122,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	189,000	869,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	152,000	410,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Watch [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	37,000	210,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	249,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	10,704,000	16,547,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	271,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Watch [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	10,704,000	16,276,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	$ 0	$ 0

Loans, Leases and Allowance f49

Loans, Leases and Allowance for Credit Losses - Impaired Loans by Loan Class (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	$ 121,356	$ 99,209
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	15,794	16,391
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	195	246
Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	16,937	20,748
Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	19,010	25,524
Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	0	0
Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	57,580	21,106
Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	57,581	21,107
Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	336	355
Construction and land development [Member] | Construction [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	0	0
Construction and land development [Member] | Land [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans by class	$ 11,503	$ 14,838

Loans, Leases and Allowance f50

Loans, Leases and Allowance for Credit Losses - Recorded Investment in Loans Classified as Impaired (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Receivables [Abstract]
Impaired loans with an allowance recorded	[1]	$ 8,773	$ 10,909
Impaired loans with no allowance recorded	[2]	112,583	88,300
Total impaired loans		121,356	99,209
Valuation allowance related to impaired loans		$ (4,394)	$ (4,239)
[1]	Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016, respectively.
[2]	Includes TDR loans of $47.8 million and $58.3 million at September 30, 2017 and December 31, 2016, respectively.

Loans, Leases and Allowance f51

Loans, Leases and Allowance for Credit Losses - Schedule of Average Investment in Impaired Loans and Income Recognized on Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Receivables [Abstract]
Impaired Financing Receivable, Average Recorded Investment	$ 108,033	$ 106,357	$ 106,456	$ 112,901
Interest income recognized on impaired loans	1,040	959	3,075	3,122
Interest recognized on nonaccrual loans, cash basis	$ 694	$ 245	$ 1,372	$ 642

Loans, Leases and Allowance f52

Loans, Leases and Allowance for Credit Losses - Average Investment in Impaired Loans by Loan Class (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	$ 108,033	$ 106,357	$ 106,456	$ 112,901
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	16,692	16,272	17,011	15,890
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	196	260	208	296
Troubled Debt Restructured Loans [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	52,000	63,900	56,600	71,400
Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	17,779	17,155	20,136	19,323
Commercial real estate [Member] | Non-owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	20,789	29,978	22,446	31,635
Commercial real estate [Member] | Multi-family [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	0	0	0	0
Commercial and industrial [Member] | Commercial [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	39,736	25,662	33,009	27,221
Commercial and industrial [Member] | Leases [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	338	331	349	904
Construction and land development [Member] | Construction [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	0	0	0	0
Construction and land development [Member] | Land [Member]
Financing Receivable, Impaired [Line Items]
Total average investment in impaired loans by loan class	$ 12,503	$ 16,699	$ 13,297	$ 17,632

Loans, Leases and Allowance f53

Loans, Leases and Allowance for Credit Losses - Interest Income on Impaired Loans by Loan Class (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	$ 1,040	$ 959	$ 3,075	$ 3,122
Owner occupied [Member] | Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	166	211	530	753
Non-owner occupied [Member] | Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	279	285	798	936
Multi-family [Member] | Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	0	0	0	0
Commercial [Member] | Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	303	90	777	319
Leases [Member] | Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	4	4	11	40
Construction [Member] | Construction and land development [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	0	0	0	0
Land [Member] | Construction and land development [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	163	240	551	686
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	124	128	406	384
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Total interest income on impaired loans by class	$ 1	$ 1	$ 2	$ 4

Loans, Leases and Allowance f54

Loans, Leases and Allowance for Credit Losses - Tabular Disclosure of Nonperforming Assets (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Nonaccrual Status	[1]	$ 54,994		$ 40,272
Loans past due 90 days or more on accrual status		44		1,067
Troubled debt restructured loans		40,922		53,637
Total nonperforming loans		95,960		94,976
Other assets acquired through foreclosure, net		28,992	$ 30,988	47,815	$ 49,619	$ 49,844	$ 43,942
Total nonperforming assets		124,952		142,791
Troubled Debt Restructured Loans [Member]
Financing Receivable, Recorded Investment, Nonaccrual Status		8,900		7,100
Receivables Acquired with Deteriorated Credit Quality [Member]
Loans past due 90 days or more on accrual status		$ 100		$ 100
[1]	Includes non-accrual TDR loans of $8.9 million and $7.1 million at September 30, 2017 and December 31, 2016, respectively.

Loans, Leases and Allowance f55

Loans, Leases and Allowance for Credit Losses - Changes in Accretable Discount for Loans Purchased with Credit Quality Deterioration (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period			$ 22,200
Balance at end of period	$ 17,000		17,000
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	14,247	$ 15,863	15,177		$ 15,925
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Additions	0	0	0		4,301
Reclassifications from non-accretable to accretable yield (1)	0	119	2,086	[1]	119	[1]
Accretion to interest income	(690)	(901)	(2,374)		(2,570)
Reversal of fair value adjustments upon disposition of loans	(2,199)	(578)	(3,531)		(3,272)
Balance at end of period	$ 11,358	$ 14,503	$ 11,358		$ 14,503
[1]	The primary drivers of reclassification from non-accretable to accretable yield resulted from changes in estimated cash flows.

Loans, Leases and Allowance f56

Loans, Leases and Allowance for Credit Losses - Allowances for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Valuation Allowance [Line Items]
Beginning Balance	$ 131,811	$ 122,104	$ 124,704	$ 119,068
Charge-offs	3,157	2,709	8,710	12,161
Recoveries	(2,767)	(1,489)	(8,177)	(8,977)
Provision for credit losses	5,000	2,000	12,250	7,000
Ending balance	136,421	122,884	136,421	122,884
Construction and land development [Member]
Valuation Allowance [Line Items]
Beginning Balance	20,852	21,386	21,175	18,976
Charge-offs	0	0	0	0
Recoveries	226	(302)	1,011	(455)
Provision for credit losses	(619)	(347)	(1,727)	1,910
Ending balance	20,459	21,341	20,459	21,341
Commercial real estate [Member]
Valuation Allowance [Line Items]
Beginning Balance	28,593	24,867	25,673	23,160
Charge-offs	175	72	1,994	726
Recoveries	1,781	(521)	2,719	(4,956)
Provision for credit losses	(1,474)	(450)	2,327	(2,524)
Ending balance	28,725	24,866	28,725	24,866
Residential real estate [Member]
Valuation Allowance [Line Items]
Beginning Balance	4,838	4,546	3,851	5,278
Charge-offs	0	79	447	105
Recoveries	108	(179)	1,659	(589)
Provision for credit losses	(141)	(513)	(258)	(1,629)
Ending balance	4,805	4,133	4,805	4,133
Commercial and industrial [Member]
Valuation Allowance [Line Items]
Beginning Balance	76,734	70,547	73,333	71,181
Charge-offs	2,921	2,558	6,166	11,210
Recoveries	619	(466)	2,705	(2,846)
Provision for credit losses	7,192	3,406	11,752	9,044
Ending balance	81,624	71,861	81,624	71,861
Consumer [Member]
Valuation Allowance [Line Items]
Beginning Balance	794	758	672	473
Charge-offs	61	0	103	120
Recoveries	33	(21)	83	(131)
Provision for credit losses	42	(96)	156	199
Ending balance	$ 808	$ 683	$ 808	$ 683

Loans, Leases and Allowance f57

Loans, Leases and Allowance for Credit Losses - Summary of Impairment Method Information Related to Loans and Allowance for Credit Losses (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded	[1]	$ 8,773	$ 10,909
Impaired loans with no allowance recorded	[2]	112,583	88,300
Total loans individually evaluated for impairment		121,356	99,209
Loans collectively evaluated for impairment		14,259,960	12,924,164
Impaired Financing Receivable, Recorded Investment		121,356	99,209
Total recorded investment		14,505,689	13,189,527
Impaired loans with an allowance recorded		8,977	11,162
Impaired loans with no allowance recorded		197,744	164,721
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		206,721	175,883
Loans collectively evaluated for impairment		14,259,960	12,924,164
Loans acquired with deteriorated credit quality		14,626,069	13,301,721
Impaired loans with an allowance recorded		4,394	4,239
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		4,394	4,239
Loans collectively evaluated for impairment		130,337	118,642
Total loans held for investment		136,421	124,704
Owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		0	3,125
Impaired loans with no allowance recorded		16,936	17,624
Total loans individually evaluated for impairment		16,936	20,749
Loans collectively evaluated for impairment		2,014,282	1,981,176
Total recorded investment		2,042,262	2,013,276
Impaired loans with an allowance recorded		0	3,125
Impaired loans with no allowance recorded		23,966	26,336
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		23,966	29,461
Loans collectively evaluated for impairment		2,014,282	1,981,176
Loans acquired with deteriorated credit quality		2,052,626	2,025,515
Impaired loans with an allowance recorded		0	937
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		0	937
Loans collectively evaluated for impairment		12,865	11,403
Total loans held for investment		12,865	12,340
Non-owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		19,010	25,524
Total loans individually evaluated for impairment		19,010	25,524
Loans collectively evaluated for impairment		3,496,683	3,383,585
Total recorded investment		3,628,415	3,543,956
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		27,418	33,632
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		27,418	33,632
Loans collectively evaluated for impairment		3,496,683	3,383,585
Loans acquired with deteriorated credit quality		3,663,574	3,582,492
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		0	0
Loans collectively evaluated for impairment		14,172	12,646
Total loans held for investment		15,860	13,333
Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		8,773	7,766
Impaired loans with no allowance recorded		48,807	13,340
Total loans individually evaluated for impairment		57,580	21,106
Loans collectively evaluated for impairment		6,603,572	5,733,915
Total recorded investment		6,661,152	5,755,021
Impaired loans with an allowance recorded		8,977	8,019
Impaired loans with no allowance recorded		80,622	43,176
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		89,599	51,195
Loans collectively evaluated for impairment		6,603,572	5,733,915
Loans acquired with deteriorated credit quality		6,697,983	5,786,035
Impaired loans with an allowance recorded		4,394	3,301
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		4,394	3,301
Loans collectively evaluated for impairment		77,228	69,673
Total loans held for investment		81,624	73,333
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		15,794	16,391
Total loans individually evaluated for impairment		15,794	16,391
Loans collectively evaluated for impairment		360,315	242,409
Total recorded investment		376,716	259,432
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		25,017	26,225
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		25,017	26,225
Loans collectively evaluated for impairment		360,315	242,409
Loans acquired with deteriorated credit quality		386,057	269,372
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		0	0
Loans collectively evaluated for impairment		4,805	3,851
Total loans held for investment		4,805	3,851
Construction and land development [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		11,503	14,838
Total loans individually evaluated for impairment		11,503	14,838
Loans collectively evaluated for impairment		1,660,049	1,443,952
Total recorded investment		1,671,552	1,478,114
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		28,369	33,487
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		28,369	33,487
Loans collectively evaluated for impairment		1,660,049	1,443,952
Loans acquired with deteriorated credit quality		1,688,418	1,497,297
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		0	0
Loans collectively evaluated for impairment		20,459	20,398
Total loans held for investment		20,459	21,175
Commercial leases [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		336	355
Total loans individually evaluated for impairment		336	355
Loans collectively evaluated for impairment		74,514	100,410
Total recorded investment		74,850	100,765
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		1,539	507
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		1,539	507
Loans collectively evaluated for impairment		74,514	100,410
Loans acquired with deteriorated credit quality		76,053	100,917
Impaired loans with an allowance recorded		0	0
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		0	0
Loans collectively evaluated for impairment		0	0
Total loans held for investment		0	0
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance recorded		0	18
Impaired loans with no allowance recorded		197	228
Total loans individually evaluated for impairment		197	246
Loans collectively evaluated for impairment		50,545	38,717
Total recorded investment		50,742	38,963
Impaired loans with an allowance recorded		0	18
Impaired loans with no allowance recorded		10,813	1,358
Impaired Financing Receivable Unpaid Principal Balance Individually Evaluated For Impairment		10,813	1,376
Loans collectively evaluated for impairment		50,545	38,717
Loans acquired with deteriorated credit quality		61,358	40,093
Impaired loans with an allowance recorded		0	1
Impaired loans with no allowance recorded		0	0
Total loans individually evaluated for impairment		0	1
Loans collectively evaluated for impairment		808	671
Total loans held for investment		808	672
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Impaired [Line Items]
Loans acquired with deteriorated credit quality		159,388	201,674
Impaired loans with an allowance recorded		1,690	1,823
Receivables Acquired with Deteriorated Credit Quality [Member] | Owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		11,044	11,351
Loans acquired with deteriorated credit quality		14,378	14,878
Impaired loans with an allowance recorded		0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		124,373	166,154
Receivables Acquired with Deteriorated Credit Quality [Member] | Non-owner occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		112,722	134,847
Loans acquired with deteriorated credit quality		139,473	165,275
Impaired loans with an allowance recorded		1,688	687
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		0	0
Loans acquired with deteriorated credit quality		4,812	925
Impaired loans with an allowance recorded		2	359
Receivables Acquired with Deteriorated Credit Quality [Member] | Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		607	632
Loans acquired with deteriorated credit quality		725	738
Impaired loans with an allowance recorded		0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Construction and land development [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		0	19,324
Loans acquired with deteriorated credit quality		0	19,858
Impaired loans with an allowance recorded		0	777
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial leases [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		0	0
Loans acquired with deteriorated credit quality		0	0
Impaired loans with an allowance recorded		0	0
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		0	0
Loans acquired with deteriorated credit quality		0	0
Impaired loans with an allowance recorded		$ 0	$ 0
[1]	Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016, respectively.
[2]	Includes TDR loans of $47.8 million and $58.3 million at September 30, 2017 and December 31, 2016, respectively.

Other Assets Acquired through58

Other Assets Acquired through Foreclosure - Changes in Other Assets Acquired through Foreclosure (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)Property	Sep. 30, 2016USD ($)Property	Sep. 30, 2017USD ($)Property	Sep. 30, 2016USD ($)Property	Dec. 31, 2016Property
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]
Balance, beginning of the period, Gross Balance	$ 35,037	$ 56,467	$ 54,138	$ 52,984
Transfers to other assets acquired through foreclosure, net, Gross Balance	430	1,162	1,812	11,888
Proceeds from sale of other real estate owned and repossessed assets, net, Gross Balance	(2,491)	(1,260)	(23,129)	(8,174)
Gains (losses), net, Gross Balance	78	25	233	(304)
Balance, end of period, Gross Balance	33,054	56,394	33,054	56,394
Balance, beginning of the period, Valuation Allowance	(4,049)	(6,623)	(6,323)	(9,042)
Proceeds from sale of other real estate owned and repossessed assets, net, Valuation Allowance	330	32	2,381	2,140
Valuation adjustments, net, Valuation Allowance	(343)	(184)	(120)	127
Balance, end of period, Valuation Allowance	(4,062)	(6,775)	(4,062)	(6,775)
Balance, beginning of the period, Net Balance	30,988	49,844	47,815	43,942
Transfers to other assets acquired through foreclosure, net, Net Balance	430	1,162	1,812	11,888
Proceeds from sale of other real estate owned and repossessed assets, net, Net Balance	(2,161)	(1,228)	(20,748)	(6,034)
Valuation adjustments of other repossessed assets, net	(343)	(184)	(120)	127
Gains (losses), net, Net Balance	78	25	233	(304)
Balance, end of period, Net Balance	28,992	$ 49,619	28,992	49,619
Gains Losses On Transfers To Other Real Estate And Foreclosed Assets	$ 0		$ 129	$ 0
Number of Real Estate Properties | Property	20	33	20	33	31

Other Borrowings - Additional I

Other Borrowings - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2017
Debt [Line Items]
FHLB advances	$ 80,000,000	$ 0
Short-term Debt	80,000,000	0
Revolving line of credit	$ 0	0
Weighted average interest rate of FHLB and FRB Short-term advances	0.55%
FRB [Member]
Debt [Line Items]
Additional available credit with the entity	$ 997,000,000	1,160,000,000
Other Credit Facilities [Member]
Debt [Line Items]
Secured borrowing credit line		167,500,000
Secured Credit Facility [Member]
Debt [Line Items]
Secured borrowing credit line		22,500,000
Unsecured Credit Facility [Member]
Debt [Line Items]
Secured borrowing credit line		145,000,000
FHLB [Member]
Debt [Line Items]
Additional available credit with the entity	$ 2,150,000,000	$ 2,290,000,000

Qualifying Debt (Details)

Qualifying Debt (Details)	9 Months Ended
	Sep. 30, 2017USD ($)Trust	Dec. 31, 2016USD ($)	Jun. 16, 2016USD ($)	Jun. 29, 2015USD ($)
Debt Instrument [Line Items]
Subordinated Debt	$ 306,100,000	$ 305,800,000
Number of Statutory Business Trusts Formed or Acquired | Trust	8
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	$ 66,721,000	$ 62,161,000
Subordinated Debt [Member] | Subordinated Debentures Maturing July 2056 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 175,000,000
Debt Issuance Cost			$ 5,530,000
Debt Instrument, Interest Rate, Stated Percentage			6.25%
Subordinated Debt [Member] | Subordinated Debentures Maturing July 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 150,000,000
Debt Issuance Cost				$ 1,800,000
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time	3.67%	3.34%

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury Stock, Shares, Acquired	64,705	8,328	266,883	301,495
Treasury Stock Acquired, Average Cost Per Share	$ 51.82	$ 34.30	$ 51.10	$ 30.95
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 1.9	$ 1.2	$ 4.5	$ 3.5
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Granted, Value, Share-based Compensation, Gross	2.7		18.9
Allocated Share-based Compensation Expense	2.7	2.7	11.3	10.2
Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Granted, Value, Share-based Compensation, Gross	5.2
Allocated Share-based Compensation Expense	$ 0.8	$ 0.3	$ 1.6	$ 0.8

Accumulated Other Comprehensi62

Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 6,490	$ 46,626	$ (4,695)	$ 22,260
Other comprehensive income before reclassifications	1,871	(10,234)	13,420	14,843
Amounts reclassified from accumulated other comprehensive income	(197)	0	(561)	(711)
Net other comprehensive income (loss)	1,674	(10,234)	12,859	14,132
Ending balance	8,164	36,392	8,164	36,392
Unrealized holding gains (losses) on AFS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(449)	33,013	(14,916)	9,993
Other comprehensive income before reclassifications	1,116	(7,415)	15,947	16,316
Amounts reclassified from accumulated other comprehensive income	(197)	0	(561)	(711)
Net other comprehensive income (loss)	919	(7,415)	15,386	15,605
Ending balance	470	25,598	470	25,598
Financial Liability Instruments, Fair Value Option [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	6,638	13,367	9,956	12,033
Other comprehensive income before reclassifications	641	(2,825)	(2,677)	(1,491)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Net other comprehensive income (loss)	641	(2,825)	(2,677)	(1,491)
Ending balance	7,279	10,542	7,279	10,542
Impairment loss on securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	144	144	144	144
Other comprehensive income before reclassifications	0	0		0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Net other comprehensive income (loss)	0	0	0	0
Ending balance	144	144	144	144
Supplemental Employee Retirement Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	157	102	121	90
Other comprehensive income before reclassifications	114	6	150	18
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Net other comprehensive income (loss)	114	6	150	18
Ending balance	$ 271	$ 108	$ 271	$ 108

Accumulated Other Comprehensi63

Accumulated Other Comprehensive Income - Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income	$ (122)	$ 0	$ (346)	$ (290)
Amount reclassified from accumulated other comprehensive income	197	0	561	711
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income	197	0	561	711
Realized Gain Loss On Sale Of Investment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Realized gains on sales of investment securities	319	0	907	1,001
Income Tax Expense [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income	$ (122)	$ 0	$ (346)	$ (290)

Derivatives and Hedging Fair Va

Derivatives and Hedging Fair Value of Derivative Contracts (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Derivatives, Fair Value [Line Items]
Notional Amount		$ 1,016,694	$ 993,485	$ 988,337
Derivative Asset, Fair Value		1,656	4,220	4,350
Derivative Liability, Fair Value		59,346	65,749	100,067
Notional Amount, Netting Adjustments	[1]	0	0	0
Derivative Netting Adjustments	[1]	1,588	1,869	0
Positive NPVs		68	2,351	4,350
Negative NPVs		57,758	63,880	100,067
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Amount		1,016,694	993,485	988,337
Derivative Asset, Fair Value		1,656	4,220	4,350
Derivative Liability, Fair Value		$ 59,346	$ 65,749	$ 100,067
[1]	Netting adjustments represent the amounts recorded to convert the Company's derivative balances from a gross basis to a net basis in accordance with the applicable accounting guidance.

Derivatives and Hedging Pre-Tax

Derivatives and Hedging Pre-Tax Net Gains (Losses) on Fair Value Hedges (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	$ 14	$ 19	$ 40	$ 26
Subordinated Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	0	0	0	0
Fixed Rate Loans [Member] | Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gain (Loss) on Derivatives	4,437	7,225	3,820	(35,087)
Increase (Decrease) to Basis of Hedged Assets	(4,423)	(7,206)	(3,780)	35,113
Fixed Rate Subordinated Debt [Member] | Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gain (Loss) on Derivatives	(1,767)	(3,793)	19	395
Increase (Decrease) to Basis of Hedged Assets	$ 1,767	$ 3,793	$ (19)	$ (395)

Derivatives and Hedging Largest

Derivatives and Hedging Largest Exposure to Individual Counterparty (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Largest gross exposure (positive derivative NPV) to an individual counterparty	$ 68	$ 2,351	$ 4,350
Largest individual counterparty [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Largest gross exposure (positive derivative NPV) to an individual counterparty	945	2,351	4,159
Collateral posted by this counterparty	0	1,691	4,131
Negative derivative NPV with this counterparty	44,053	0	0
Collateral pledged to this counterparty	65,051	0	0
Net exposure after netting adjustments and collateral	$ 0	$ 660	$ 28

Derivatives and Hedging Additio

Derivatives and Hedging Additional Information (Detail) - USD ($)	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 16, 2016	Jun. 29, 2015
Derivative [Line Items]
Collateral netted against derivative liabilities	$ 59,300,000	$ 65,700,000	$ 100,100,000
Negative NPVs	57,758,000	63,880,000	100,067,000
Over collateralization net position	25,100,000	$ 24,300,000	$ 23,100,000
Additional collateral held in securities	$ 84,400,000
Subordinated Debentures Maturing July 2025 [Member] | Subordinated Debt [Member]
Derivative [Line Items]
Debt Instrument, Face Amount					$ 150,000,000
Subordinated Debentures Maturing July 2056 [Member] | Subordinated Debt [Member]
Derivative [Line Items]
Debt Instrument, Face Amount				$ 175,000,000

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Basic	104,221,000	103,768,000	104,124,000	102,791,000
Dilutive Effect Of Stock Options Restricted Stock And Equity Settled Awards	721,000	796,000	817,000	741,000
Diluted	104,942,000	104,564,000	104,941,000	103,532,000
Net income available to common shareholders	$ 82,858	$ 67,052	$ 236,186	$ 189,998
Earnings (loss) per share - basic	$ 0.80	$ 0.65	$ 2.27	$ 1.85
Earnings (loss) per share - diluted	$ 0.79	$ 0.64	$ 2.25	$ 1.84
Anti-dilutive stock options outstanding that were not included in computation of diluted earnings per common share			0

Income Taxes Additional Informa

Income Taxes Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Percent	29.64%	30.32%	27.89%	28.31%
Deferred tax assets, net	$ 83,772		$ 83,772		$ 95,194
Operating Loss Carryforwards, Valuation Allowance					0
Amortization Method Qualified Affordable Housing Project Investments	252,900		252,900		187,400
Qualified Affordable Housing Project Investments, Commitment	149,400		149,400		84,400
Increase (Decrease) in Deferred Income Taxes			11,400
Amortization Method Qualified Affordable Housing Project Investments, Amortization	6,800	$ 5,500	19,500	$ 13,700
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 8,800		$ 8,800		$ 9,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Loss Contingencies [Line Items]
Letters of credit expiration period				1 year
Percentage of first liens initial loan to value ratio	75.00%
Percentage Of Commercial Real Estate Loans Occupied By Owners	36.00%	36.00%		36.00%
Operating Leases, Rent Expense, Net	$ 2.8		$ 2.8	$ 8.2	$ 8.1
Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Credit Concentration Risk [Member]
Loss Contingencies [Line Items]
Percent of commercial real estate related loans	51.00%	53.00%
Unfunded Loan Commitment [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 5.6	$ 7		$ 5.6

Commitments and Contingencies71

Commitments and Contingencies - Summary of Contractual Amounts for Unfunded Commitments and Letters of Credit (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Commitments [Line Items]
Total amount	$ 5,648,472	$ 4,622,607		$ 5,648,472
Percentage Of Commercial Real Estate Loans Occupied By Owners	36.00%	36.00%		36.00%
Operating Leases, Rent Expense, Net	$ 2,800		$ 2,800	$ 8,200	$ 8,100
Commitments to extend credit [Member]
Other Commitments [Line Items]
Unsecured Loan Commitments	322,991	$ 360,840		322,991
Total amount	5,378,255	4,428,495		5,378,255
Credit card guarantees [Member]
Other Commitments [Line Items]
Total amount	140,728	115,536		140,728
Standby letters of credit [Member]
Other Commitments [Line Items]
Total amount	129,489	78,576		129,489
Unsecured Letters Of Credit	$ 11,383	$ 6,431		$ 11,383
Commercial Real Estate Portfolio Segment [Member] | Credit Concentration Risk [Member] | Loans Receivable [Member]
Other Commitments [Line Items]
Concentration Risk, Percentage	51.00%	53.00%

Fair Value Accounting - Gains a

Fair Value Accounting - Gains and Losses from Fair Value Changes Included in Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016	Dec. 31, 2016
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 54,737	[1]		$ 54,737	[1]		$ 50,410
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1,035		$ (4,616)	(4,327)		$ (2,404)
Interest Income on Securities	0		11	9		33
Interest Expense on Junior Subordinated Debt	(835)		(702)	(2,376)		(2,075)
Total Changes Included in Current-Period Earnings	(835)		(626)	(2,367)		(1,828)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	641		(2,825)	(2,677)		(1,491)
Trading Securities [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0		(12)	0		(18)
Interest Income on Securities	0		11	9		33
Total Changes Included in Current-Period Earnings	0		(1)	9		15
Junior Subordinated Debt [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1,035		(4,604)	(4,327)		(2,386)
Interest Expense on Junior Subordinated Debt	(835)		(702)	(2,376)		(2,075)
Total Changes Included in Current-Period Earnings	(835)		(625)	(2,376)		(1,843)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	641		$ (2,825)	$ (2,677)		$ (1,491)
Junior subordinated debt, Input Value				5.42%			5.66%
Level 3 [Member] | Junior Subordinated Debt [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 54,737			$ 54,737			$ 50,410
Junior subordinated debt, Valuation Technique				Discounted cash flow			Discounted cash flow
Junior subordinated debt, Significant Unobservable Inputs				Implied credit rating of the Company			Implied credit rating of the Company
[1]	Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment.

Fair Value Accounting - Fair Va

Fair Value Accounting - Fair Value of Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016		Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 3,552,844		$ 2,609,380
Derivative Liability	57,758		63,880		$ 100,067
Derivative Asset	68		2,351		$ 4,350
Subordinated Debt Obligations, Fair Value Disclosure	54,737	[1]	50,410
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	3,552,844		2,609,380
Loans Held-for-sale, Fair Value Disclosure	16,347		18,909
Derivative Liability	59,346	[2]	65,749	[3]
Derivative Asset	1,656	[2]	4,220	[3]
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	146,748		151,775
Loans Held-for-sale, Fair Value Disclosure	0		0
Derivative Liability	0	[2]	0	[3]
Derivative Asset	0	[2]	0	[3]
Subordinated Debt Obligations, Fair Value Disclosure	0	[1]	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	3,406,096		2,457,605
Loans Held-for-sale, Fair Value Disclosure	16,347		18,909
Derivative Liability	59,346	[2]	65,749	[3]
Derivative Asset	1,656	[2]	4,220	[3]
Subordinated Debt Obligations, Fair Value Disclosure	0	[1]	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Loans Held-for-sale, Fair Value Disclosure	0		0
Derivative Liability	0	[2]	0	[3]
Derivative Asset	0	[2]	0	[3]
Subordinated Debt Obligations, Fair Value Disclosure	54,737	[1]	50,410
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities issued by GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities measured at fair value			1,053
Securities available for sale	1,819,006		1,355,205
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities issued by GSEs | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities measured at fair value			0
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities issued by GSEs | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities measured at fair value			1,053
Securities available for sale	1,819,006		1,355,205
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities issued by GSEs | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities measured at fair value			0
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Private label residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	797,615		433,685
Fair Value, Measurements, Recurring [Member] | Private label residential mortgage-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Private label residential mortgage-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	797,615		433,685
Fair Value, Measurements, Recurring [Member] | Private label residential mortgage-backed securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	113,794		117,792
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	113,794		117,792
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	104,014		64,144
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		20,000
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	104,014		44,144
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Municipal obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	462,773		408,233
Fair Value, Measurements, Recurring [Member] | Municipal obligations [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Municipal obligations [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	462,773		408,233
Fair Value, Measurements, Recurring [Member] | Municipal obligations [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Preferred Stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	96,100		94,662
Fair Value, Measurements, Recurring [Member] | Preferred Stock [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	96,100		94,662
Fair Value, Measurements, Recurring [Member] | Preferred Stock [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Preferred Stock [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | CRA investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	50,648		37,113
Fair Value, Measurements, Recurring [Member] | CRA investments [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	50,648		37,113
Fair Value, Measurements, Recurring [Member] | CRA investments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | CRA investments [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	15,553		13,490
Fair Value, Measurements, Recurring [Member] | Collateralized debt obligations [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Collateralized debt obligations [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	15,553		13,490
Fair Value, Measurements, Recurring [Member] | Collateralized debt obligations [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	29,208		26,532
Fair Value, Measurements, Recurring [Member] | Trust preferred securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | Trust preferred securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	29,208		26,532
Fair Value, Measurements, Recurring [Member] | Trust preferred securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	61,636		56,022
Fair Value, Measurements, Recurring [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	61,636		56,022
Fair Value, Measurements, Recurring [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,497		2,502
Fair Value, Measurements, Recurring [Member] | US Treasury Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Fair Value, Measurements, Recurring [Member] | US Treasury Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,497		2,502
Fair Value, Measurements, Recurring [Member] | US Treasury Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0		0
Reported Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	3,552,844		2,609,380
Derivative Liability	59,346		65,749
Derivative Asset	1,656		4,220
Fixed Rate Loans [Member] | Reported Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	44,721		48,161
Fixed Rate Subordinated Debt [Member] | Reported Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ 12,307		$ 12,325
[1]	Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment.
[2]	Derivative assets and liabilities relate to interest rate swaps, see "Note 9. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $44,721 and the net carrying value of subordinated debt is decreased by $12,307 as of September 30, 2017, which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates.
[3]	Derivative assets and liabilities relate to interest rate swaps, see "Note 9. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $48,161 and the net carrying value of subordinated debt is decreased by $12,325 as of December 31, 2016, which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates.

Fair Value Accounting - Change

Fair Value Accounting - Change in Level 3 Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016	Dec. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 0		$ 0	$ 0		$ 0
Junior subordinated debt	54,737	[1]		54,737	[1]		$ 50,410
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt	54,737	[1]		$ 54,737	[1]		$ 50,410
Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Discounted cash flow method			Discounted cash flow method
Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0		10,552	$ 0		10,552	$ 0	$ 0	$ 10,183	$ 10,060
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0		369	$ 0		492
Other Assets [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Collateral method			Collateral method
Junior Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	1,035		(4,604)	$ (4,327)		(2,386)
Junior subordinated debt, Input Value				5.42%			5.66%
Junior Subordinated Debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt	54,737			$ 54,737			$ 50,410
Junior subordinated debt, Valuation Technique				Discounted cash flow			Discounted cash flow
Junior subordinated debt, Significant Unobservable Inputs				Implied credit rating of the Company			Implied credit rating of the Company
Junior Subordinated Debt [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	55,772		44,710	$ 50,410		46,928	$ 46,928
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	0		0	0		0
Closing balance	$ 54,737		$ 49,314	$ 54,737		$ 49,314	$ 50,410
Collateral Method [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Collateral method			Collateral method
Third Party Appraisal [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Third party appraisal or valuation			Third party appraisal
Third Party Appraisal [Member] | Other Assets [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Third party appraisal			Third party appraisal
Discount Rate [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Discount rate			Discount rate
Scheduled Cash Collections [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Scheduled cash collections			Scheduled cash collections
Proceeds from Non-Real Estate Collateral [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique				Proceeds from non-real estate collateral			Proceeds from non-real estate collateral
[1]	Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment.

Fair Value Accounting - Assets

Fair Value Accounting - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded	[1]	$ 8,773	$ 10,909
Impaired loans without specific valuation allowance	[2]	112,583	88,300
Other Repossessed Assets		29,000	47,800
Impaired Financing Receivables, With No related Allowance, Balances with Charge-offs		42,400	27,600
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded		4,379	6,670
Impaired loans without specific valuation allowance	[3]	70,170	60,738
Other Repossessed Assets		28,992	47,815
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded		0	0
Impaired loans without specific valuation allowance	[3]	0	0
Other Repossessed Assets		0	0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded		0	0
Impaired loans without specific valuation allowance	[3]	0	0
Other Repossessed Assets		0	0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded		4,379	6,670
Impaired loans without specific valuation allowance	[3]	70,170	60,738
Other Repossessed Assets		$ 28,992	$ 47,815
[1]	Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016, respectively.
[2]	Includes TDR loans of $47.8 million and $58.3 million at September 30, 2017 and December 31, 2016, respectively.
[3]	Net of loan balances with charge-offs of $42.4 million and $27.6 million as of September 30, 2017 and December 31, 2016, respectivel

Fair Value Accounting - Estimat

Fair Value Accounting - Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017		Dec. 31, 2016		Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 121,356		$ 99,209
Other Repossessed Assets	29,000		47,800
Financial assets
Held-to-maturity Securities	154,920		92,079
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844		2,609,380
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016	0		1,053
Derivative Asset	68		2,351		$ 4,350
Loans, net	14,369,268		13,064,823
Financial liabilities
Deposits	16,904,783		14,549,863
Customer repurchase agreements	26,066		41,728
Junior subordinated debt	54,737	[1]	50,410
Derivative Liability	57,758		63,880		$ 100,067
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Repossessed Assets	28,992		47,815
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Repossessed Assets	0		0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Repossessed Assets	0		0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Recorded Investment	74,549		67,408
Other Repossessed Assets	28,992		47,815
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Financial assets
Held-to-maturity Securities	154,920		92,079
Loans, net	14,385,615		13,083,732
Financial liabilities
Deposits	16,904,783		14,549,863
Junior subordinated debt	372,851		367,937
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member]
Financial assets
Held-to-maturity Securities	160,582		91,966
Loans, net	14,073,940		12,803,744
Financial liabilities
Deposits	16,911,392		14,553,931
Junior subordinated debt	399,855		375,626
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member] | Level 1 [Member]
Financial assets
Held-to-maturity Securities	0		0
Loans, net	0		0
Financial liabilities
Deposits	0		0
Junior subordinated debt	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member] | Level 2 [Member]
Financial assets
Held-to-maturity Securities	160,582		91,966
Loans, net	13,999,391		12,736,336
Financial liabilities
Deposits	16,911,392		14,553,931
Junior subordinated debt	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member] | Level 3 [Member]
Financial assets
Held-to-maturity Securities	0		0
Loans, net	74,549		67,408
Financial liabilities
Deposits	0		0
Junior subordinated debt	399,855		375,626
Fair Value, Measurements, Recurring [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844		2,609,380
Derivative Asset	1,656	[2]	4,220	[3]
Financial liabilities
Derivative Liability	59,346	[2]	65,749	[3]
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	146,748		151,775
Derivative Asset	0	[2]	0	[3]
Financial liabilities
Junior subordinated debt	0	[1]	0
Derivative Liability	0	[2]	0	[3]
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,406,096		2,457,605
Derivative Asset	1,656	[2]	4,220	[3]
Financial liabilities
Junior subordinated debt	0	[1]	0
Derivative Liability	59,346	[2]	65,749	[3]
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Derivative Asset	0	[2]	0	[3]
Financial liabilities
Junior subordinated debt	54,737	[1]	50,410
Derivative Liability	0	[2]	0	[3]
Fair Value, Measurements, Recurring [Member] | Reported Value Measurement [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844		2,609,380
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016			1,053
Derivative Asset	1,656		4,220
Accrued Investment Income Receivable	72,374		70,320
Financial liabilities
Customer repurchase agreements	26,066		41,728
Federal Home Loan Bank Borrowings, Fair Value Disclosure			80,000
Derivative Liability	59,346		65,749
Interest Payable, Current	10,958		15,354
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,552,844		2,609,380
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016			1,053
Derivative Asset	1,656		4,220
Accrued Investment Income Receivable	72,374		70,320
Financial liabilities
Customer repurchase agreements	26,066		41,728
Federal Home Loan Bank Borrowings, Fair Value Disclosure			80,000
Derivative Liability	59,346		65,749
Interest Payable, Current	10,958		15,354
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Level 1 [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	146,748		151,775
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016			0
Derivative Asset	0		0
Accrued Investment Income Receivable	0		0
Financial liabilities
Customer repurchase agreements	0		0
Federal Home Loan Bank Borrowings, Fair Value Disclosure			0
Derivative Liability	0		0
Interest Payable, Current	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Level 2 [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	3,406,096		2,457,605
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016			1,053
Derivative Asset	1,656		4,220
Accrued Investment Income Receivable	72,374		70,320
Financial liabilities
Customer repurchase agreements	26,066		41,728
Federal Home Loan Bank Borrowings, Fair Value Disclosure			80,000
Derivative Liability	59,346		65,749
Interest Payable, Current	10,958		15,354
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Level 3 [Member]
Financial assets
Investment securities - AFS, at fair value; amortized cost of $3,551,770 at September 30, 2017 and $2,633,298 at December 31, 2016	0		0
Investment securities - measured at fair value; amortized cost of $0 at September 30, 2017 and $1,055 at December 31, 2016			0
Derivative Asset	0		0
Accrued Investment Income Receivable	0		0
Financial liabilities
Customer repurchase agreements	0		0
Federal Home Loan Bank Borrowings, Fair Value Disclosure			0
Derivative Liability	0		0
Interest Payable, Current	$ 0		$ 0
Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Discounted cash flow method		Discounted cash flow method
Other Assets [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Collateral method		Collateral method
Collateral Method [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Collateral method		Collateral method
Third Party Appraisal [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Third party appraisal or valuation		Third party appraisal
Fair Value Measurements, Significant Assumptions	Costs to sell		Costs to sell
Third Party Appraisal [Member] | Other Assets [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Third party appraisal		Third party appraisal
Fair Value Measurements, Significant Assumptions	Costs to sell		Costs to sell
Discount Rate [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Discount rate		Discount rate
Fair Value Measurements, Significant Assumptions	Contractual loan rate		Contractual loan rate
Scheduled Cash Collections [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Scheduled cash collections		Scheduled cash collections
Fair Value Measurements, Significant Assumptions	Probability of default		Probability of default
Proceeds from Non-Real Estate Collateral [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Valuation Technique	Proceeds from non-real estate collateral		Proceeds from non-real estate collateral
Fair Value Measurements, Significant Assumptions	Loss given default		Loss given default
[1]	Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment.
[2]	Derivative assets and liabilities relate to interest rate swaps, see "Note 9. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $44,721 and the net carrying value of subordinated debt is decreased by $12,307 as of September 30, 2017, which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates.
[3]	Derivative assets and liabilities relate to interest rate swaps, see "Note 9. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $48,161 and the net carrying value of subordinated debt is decreased by $12,325 as of December 31, 2016, which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates.

Fair Value Accounting - Additio

Fair Value Accounting - Additional Information (Detail) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Recorded Investment		$ 121,356	$ 99,209
Aggregate carrying amount of impaired loans	[1]	8,773	10,909
Impaired loans with an allowance recorded		(4,394)	(4,239)
Other assets acquired through foreclosure		29,000	47,800
Goodwill		$ 289,895	$ 289,967
Common Stock, Shares, Issued		107,060,702	106,371,093
Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities contained credit losses		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded		$ (4,400)	$ (4,200)
Junior Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Input Value		5.42%	5.66%
Period of basis point spread		4.09%	4.66%
Percentage of LIBOR		1.33389%	1.00%
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate carrying amount of impaired loans		$ 4,379	$ 6,670
Other assets acquired through foreclosure		28,992	47,815
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Recorded Investment		74,549	67,408
Aggregate carrying amount of impaired loans		4,379	6,670
Other assets acquired through foreclosure		$ 28,992	$ 47,815
[1]	Includes TDR loans of $2.1 million and $2.5 million at September 30, 2017 and December 31, 2016, respectively.

Segments - Operating Segment In

Segments - Operating Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	$ 4,424,000		$ 4,424,000		$ 3,052,300
Loans, net of deferred loan fees and costs	14,521,900		14,521,900		13,208,500
Less: Allowance for credit losses	(136,421)		(136,421)		(124,704)
Total loans held for investment	14,385,500		14,385,500		13,083,800
Other Repossessed Assets	29,000		29,000		47,800
Intangible Assets, Net (Including Goodwill)	301,200		301,200		302,900
Other Assets Segment	782,500		782,500		714,000
Assets	19,922,221		19,922,221		17,200,842
Deposits	16,904,783		16,904,783		14,549,863
Other borrowings	372,900		372,900		447,900
Other Liabilities Segment	498,900		498,900		311,600
Liabilities	17,776,594		17,776,594		15,309,313
Stockholders' equity	2,145,627	$ 1,857,354	2,145,627	$ 1,857,354	1,891,529	$ 1,591,502
Liabilities and Equity	19,922,221		19,922,221		17,200,842
Excess Funds Provided by (Used in) Segment Basis	0		0		0
Net interest income	201,583	172,547	573,635	481,944
Provision for Loan, Lease, and Other Losses	5,000	2,000	12,250	7,000
Net interest income (loss) after provision for credit losses	196,583	170,547	561,385	474,944
Non-interest income	10,288	10,683	31,281	32,375
Non-interest expense	(89,114)	(85,007)	(265,128)	(242,304)
Income from continuing operations before income taxes	117,757	96,223	327,538	265,015
Income tax expense (benefit)	34,899	29,171	91,352	75,017
Net income	82,858	67,052	236,186	189,998
Operating Segments [Member] | HOA Services [Member]
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	0		0		0
Loans, net of deferred loan fees and costs	157,300		157,300		116,800
Less: Allowance for credit losses	(1,600)		(1,600)		(1,300)
Total loans held for investment	155,700		155,700		115,500
Other Repossessed Assets	0		0		0
Intangible Assets, Net (Including Goodwill)	0		0		0
Other Assets Segment	400		400		300
Assets	156,100		156,100		115,800
Deposits	2,153,300		2,153,300		1,890,300
Other borrowings	0		0		0
Other Liabilities Segment	1,100		1,100		700
Liabilities	2,154,400		2,154,400		1,891,000
Stockholders' equity	57,400		57,400		65,600
Liabilities and Equity	2,211,800		2,211,800		1,956,600
Excess Funds Provided by (Used in) Segment Basis	2,055,700		2,055,700		1,840,800
Net interest income	13,746	11,312	40,275	29,853
Provision for Loan, Lease, and Other Losses	40	72	332	160
Net interest income (loss) after provision for credit losses	13,706	11,240	39,943	29,693
Non-interest income	136	125	417	340
Non-interest expense	(7,011)	(6,062)	(21,416)	(17,423)
Income from continuing operations before income taxes	6,831	5,303	18,944	12,610
Income tax expense (benefit)	2,562	1,989	7,104	4,729
Net income	4,269	3,314	11,840	7,881
Operating Segments [Member] | Public and Non-Profit Finance [Member]
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	0		0		0
Loans, net of deferred loan fees and costs	1,574,500		1,574,500		1,454,300
Less: Allowance for credit losses	(16,100)		(16,100)		(15,600)
Total loans held for investment	1,558,400		1,558,400		1,438,700
Other Repossessed Assets	0		0		0
Intangible Assets, Net (Including Goodwill)	0		0		0
Other Assets Segment	12,200		12,200		15,600
Assets	1,570,600		1,570,600		1,454,300
Deposits	0		0		0
Other borrowings	0		0		0
Other Liabilities Segment	46,400		46,400		50,500
Liabilities	46,400		46,400		50,500
Stockholders' equity	126,000		126,000		117,100
Liabilities and Equity	172,400		172,400		167,600
Excess Funds Provided by (Used in) Segment Basis	(1,398,200)		(1,398,200)		(1,286,700)
Net interest income	7,269	5,012	21,242	15,259
Provision for Loan, Lease, and Other Losses	91	(315)	796	(509)
Net interest income (loss) after provision for credit losses	7,178	5,327	20,446	15,768
Non-interest income	15	19	40	22
Non-interest expense	(1,871)	(1,974)	(6,107)	(5,927)
Income from continuing operations before income taxes	5,322	3,372	14,379	9,863
Income tax expense (benefit)	1,028	1,265	4,424	3,699
Net income	4,294	2,107	9,955	6,164
Operating Segments [Member] | Technology and Innovation [Member]
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	0		0		0
Loans, net of deferred loan fees and costs	1,049,200		1,049,200		1,011,400
Less: Allowance for credit losses	(9,900)		(9,900)		(10,600)
Total loans held for investment	1,039,300		1,039,300		1,000,800
Other Repossessed Assets	0		0		0
Intangible Assets, Net (Including Goodwill)	121,100		121,100		121,500
Other Assets Segment	5,300		5,300		7,200
Assets	1,165,700		1,165,700		1,129,500
Deposits	1,459,500		1,459,500		1,038,200
Other borrowings	0		0		0
Other Liabilities Segment	700		700		2,000
Liabilities	1,460,200		1,460,200		1,040,200
Stockholders' equity	234,600		234,600		224,100
Liabilities and Equity	1,694,800		1,694,800		1,264,300
Excess Funds Provided by (Used in) Segment Basis	529,100		529,100		134,800
Net interest income	20,415	18,143	59,610	51,083
Provision for Loan, Lease, and Other Losses	(83)	(557)	816	(2,336)
Net interest income (loss) after provision for credit losses	20,498	18,700	58,794	53,419
Non-interest income	1,855	1,871	5,689	4,623
Non-interest expense	(8,824)	(8,837)	(26,685)	(23,177)
Income from continuing operations before income taxes	13,529	11,734	37,798	34,865
Income tax expense (benefit)	5,075	4,400	14,175	13,074
Net income	8,454	7,334	23,623	21,791
Operating Segments [Member] | HFF Loan Portfolio [Member]
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	0		0		0
Loans, net of deferred loan fees and costs	1,272,500		1,272,500		1,292,100
Less: Allowance for credit losses	(2,700)		(2,700)		(800)
Total loans held for investment	1,269,800		1,269,800		1,291,300
Other Repossessed Assets	0		0		0
Intangible Assets, Net (Including Goodwill)	100		100		200
Other Assets Segment	5,200		5,200		5,300
Assets	1,275,100		1,275,100		1,296,800
Deposits	0		0		0
Other borrowings	0		0		0
Other Liabilities Segment	400		400		1,400
Liabilities	400		400		1,400
Stockholders' equity	104,300		104,300		107,100
Liabilities and Equity	104,700		104,700		108,500
Excess Funds Provided by (Used in) Segment Basis	(1,170,400)		(1,170,400)		(1,188,300)
Net interest income	15,346	13,370	42,337	25,438
Provision for Loan, Lease, and Other Losses	1,116	0	2,924	0
Net interest income (loss) after provision for credit losses	14,230	13,370	39,413	25,438
Non-interest income	0	0	0	0
Non-interest expense	(1,905)	(3,207)	(7,949)	(5,764)
Income from continuing operations before income taxes	12,325	10,163	31,464	19,674
Income tax expense (benefit)	4,622	3,811	11,799	7,378
Net income	7,703	6,352	19,665	12,296
Operating Segments [Member] | Other National Business Lines [Member]
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	0		0		0
Loans, net of deferred loan fees and costs	2,513,000		2,513,000		1,776,900
Less: Allowance for credit losses	(25,500)		(25,500)		(19,000)
Total loans held for investment	2,487,500		2,487,500		1,757,900
Other Repossessed Assets	0		0		0
Intangible Assets, Net (Including Goodwill)	0		0		0
Other Assets Segment	10,100		10,100		11,100
Assets	2,497,600		2,497,600		1,769,000
Deposits	0		0		0
Other borrowings	0		0		0
Other Liabilities Segment	136,100		136,100		17,500
Liabilities	136,100		136,100		17,500
Stockholders' equity	207,200		207,200		145,500
Liabilities and Equity	343,300		343,300		163,000
Excess Funds Provided by (Used in) Segment Basis	(2,154,300)		(2,154,300)		(1,606,000)
Net interest income	16,933	12,060	46,380	35,220
Provision for Loan, Lease, and Other Losses	4,416	1,372	10,265	3,309
Net interest income (loss) after provision for credit losses	12,517	10,688	36,115	31,911
Non-interest income	379	728	1,632	1,598
Non-interest expense	(5,286)	(3,972)	(14,573)	(11,007)
Income from continuing operations before income taxes	7,610	7,444	23,174	22,502
Income tax expense (benefit)	2,853	2,791	8,690	8,438
Net income	4,757	4,653	14,484	14,064
Corporate & Other
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	4,410,800		4,410,800		3,036,300
Loans, net of deferred loan fees and costs	4,400		4,400		13,400
Less: Allowance for credit losses	(100)		(100)		(600)
Total loans held for investment	4,300		4,300		12,800
Other Repossessed Assets	12,800		12,800		23,300
Intangible Assets, Net (Including Goodwill)	0		0		0
Other Assets Segment	613,800		613,800		544,000
Assets	5,041,700		5,041,700		3,616,400
Deposits	95,600		95,600		120,200
Other borrowings	372,900		372,900		447,900
Other Liabilities Segment	262,800		262,800		173,100
Liabilities	731,300		731,300		741,200
Stockholders' equity	258,400		258,400		149,500
Liabilities and Equity	989,700		989,700		890,700
Excess Funds Provided by (Used in) Segment Basis	(4,052,000)		(4,052,000)		(2,725,700)
Net interest income	(9,816)	(17,527)	(34,849)	(46,107)
Provision for Loan, Lease, and Other Losses	(1,333)	(1)	(1,832)	(3,230)
Net interest income (loss) after provision for credit losses	(8,483)	(17,526)	(33,017)	(42,877)
Non-interest income	1,517	894	4,695	3,858
Non-interest expense	(6,968)	(5,832)	(13,026)	(15,990)
Income from continuing operations before income taxes	(13,934)	(22,464)	(41,348)	(55,009)
Income tax expense (benefit)	(14,598)	(16,487)	(49,167)	(48,146)
Net income	664	(5,977)	7,819	(6,863)
Reportable Geographical Components [Member] | ARIZONA
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	1,900		1,900		1,900
Loans, net of deferred loan fees and costs	3,131,200		3,131,200		2,955,900
Less: Allowance for credit losses	(30,700)		(30,700)		(30,100)
Total loans held for investment	3,100,500		3,100,500		2,925,800
Other Repossessed Assets	2,300		2,300		6,200
Intangible Assets, Net (Including Goodwill)	0		0		0
Other Assets Segment	45,800		45,800		42,900
Assets	3,150,500		3,150,500		2,976,800
Deposits	5,198,100		5,198,100		3,843,400
Other borrowings	0		0		0
Other Liabilities Segment	13,400		13,400		12,800
Liabilities	5,211,500		5,211,500		3,856,200
Stockholders' equity	390,400		390,400		346,600
Liabilities and Equity	5,601,900		5,601,900		4,202,800
Excess Funds Provided by (Used in) Segment Basis	2,451,400		2,451,400		1,226,000
Net interest income	52,637	45,531	145,839	125,191
Provision for Loan, Lease, and Other Losses	(289)	2,399	109	10,875
Net interest income (loss) after provision for credit losses	52,926	43,132	145,730	114,316
Non-interest income	1,265	1,180	3,567	5,749
Non-interest expense	(18,844)	(16,084)	(55,388)	(45,090)
Income from continuing operations before income taxes	35,347	28,228	93,909	74,975
Income tax expense (benefit)	13,857	11,074	36,831	29,413
Net income	21,490	17,154	57,078	45,562
Reportable Geographical Components [Member] | NEVADA
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	7,700		7,700		10,100
Loans, net of deferred loan fees and costs	1,685,600		1,685,600		1,725,500
Less: Allowance for credit losses	(16,800)		(16,800)		(18,500)
Total loans held for investment	1,668,800		1,668,800		1,707,000
Other Repossessed Assets	13,700		13,700		18,000
Intangible Assets, Net (Including Goodwill)	23,200		23,200		23,700
Other Assets Segment	58,400		58,400		58,800
Assets	1,771,800		1,771,800		1,817,600
Deposits	3,950,500		3,950,500		3,731,500
Other borrowings	0		0		0
Other Liabilities Segment	23,300		23,300		28,300
Liabilities	3,973,800		3,973,800		3,759,800
Stockholders' equity	251,500		251,500		250,700
Liabilities and Equity	4,225,300		4,225,300		4,010,500
Excess Funds Provided by (Used in) Segment Basis	2,453,500		2,453,500		2,192,900
Net interest income	36,310	35,977	108,028	102,016
Provision for Loan, Lease, and Other Losses	(2,044)	(1,009)	(5,378)	(3,526)
Net interest income (loss) after provision for credit losses	38,354	36,986	113,406	105,542
Non-interest income	2,354	2,264	6,800	6,420
Non-interest expense	(14,748)	(14,801)	(45,733)	(44,371)
Income from continuing operations before income taxes	25,960	24,449	74,473	67,591
Income tax expense (benefit)	9,086	8,557	26,066	23,657
Net income	16,874	15,892	48,407	43,934
Reportable Geographical Components [Member] | CALIFORNIA
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	1,900		1,900		2,100
Loans, net of deferred loan fees and costs	1,873,500		1,873,500		1,766,800
Less: Allowance for credit losses	(20,400)		(20,400)		(19,400)
Total loans held for investment	1,853,100		1,853,100		1,747,400
Other Repossessed Assets	0		0		0
Intangible Assets, Net (Including Goodwill)	0		0		0
Other Assets Segment	13,900		13,900		14,500
Assets	1,868,900		1,868,900		1,764,000
Deposits	2,512,200		2,512,200		2,382,600
Other borrowings	0		0		0
Other Liabilities Segment	3,600		3,600		12,900
Liabilities	2,515,800		2,515,800		2,395,500
Stockholders' equity	216,600		216,600		201,600
Liabilities and Equity	2,732,400		2,732,400		2,597,100
Excess Funds Provided by (Used in) Segment Basis	863,500		863,500		833,100
Net interest income	26,811	26,488	81,087	76,719
Provision for Loan, Lease, and Other Losses	(58)	(105)	(20)	145
Net interest income (loss) after provision for credit losses	26,869	26,593	81,107	76,574
Non-interest income	971	686	2,602	1,907
Non-interest expense	(12,340)	(11,532)	(38,063)	(33,401)
Income from continuing operations before income taxes	15,500	15,747	45,646	45,080
Income tax expense (benefit)	6,517	6,621	19,194	18,956
Net income	8,983	9,126	26,452	26,124
Reportable Geographical Components [Member] | Northern California
Operating Statistics [Line Items]
Cash, Cash Equivalents and Investment Securities	1,700		1,700		1,900
Loans, net of deferred loan fees and costs	1,260,700		1,260,700		1,095,400
Less: Allowance for credit losses	(12,600)		(12,600)		(8,800)
Total loans held for investment	1,248,100		1,248,100		1,086,600
Other Repossessed Assets	200		200		300
Intangible Assets, Net (Including Goodwill)	156,800		156,800		157,500
Other Assets Segment	17,400		17,400		14,300
Assets	1,424,200		1,424,200		1,260,600
Deposits	1,535,600		1,535,600		1,543,600
Other borrowings	0		0		0
Other Liabilities Segment	11,100		11,100		12,400
Liabilities	1,546,700		1,546,700		1,556,000
Stockholders' equity	299,200		299,200		283,700
Liabilities and Equity	1,845,900		1,845,900		1,839,700
Excess Funds Provided by (Used in) Segment Basis	421,700		421,700		$ 579,100
Net interest income	21,932	22,181	63,686	67,272
Provision for Loan, Lease, and Other Losses	3,144	144	4,238	2,112
Net interest income (loss) after provision for credit losses	18,788	22,037	59,448	65,160
Non-interest income	1,796	2,916	5,839	7,858
Non-interest expense	(11,317)	(12,706)	(36,188)	(40,154)
Income from continuing operations before income taxes	9,267	12,247	29,099	32,864
Income tax expense (benefit)	3,897	5,150	12,236	13,819
Net income	$ 5,370	$ 7,097	$ 16,863	$ 19,045

Mergers, Acquisitions and Dis79

Mergers, Acquisitions and Dispositions Assets Acquired and Liabilities Assumed in Acquisition (Details) - USD ($) $ in Thousands	Apr. 20, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Merger Restructure Expense		$ 0	$ 2,729	$ 0	$ 6,391
Goodwill		$ 289,895		289,895		$ 289,967
GE Capital US Holdings, Inc. [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 1,272,187
Merger Restructure Expense			$ 1,700	$ 0	$ 3,600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	1,280,997
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	3,632
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	1,284,629
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	12,559
Non-cash liabilities acquired in acquisition	12,559
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	1,272,070
Goodwill	$ 117

Mergers, Acquisitions and Dis80

Mergers, Acquisitions and Dispositions Business Combination, Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Merger Restructure Expense	$ 0	$ 2,729	$ 0	$ 6,391
GE Capital US Holdings, Inc. [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Merger Restructure Expense		1,700	$ 0	3,600
Business Acquisition, Pro Forma Interest Income		180,335		523,962
Business Acquisition, Pro Forma Non-Interest Income		10,683		32,375
Business Acquisition, Pro Forma Net Income (Loss)		$ 65,349		$ 194,095
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.63		$ 1.89
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.62		$ 1.87

Related Party Transactions (Det

Related Party Transactions (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Related Party Transactions [Abstract]
Related Party Transactions	$ 3