Wintrust Financial (WTFC) 10-Q 9 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Entity Current Reporting Status	Yes
Trading Symbol	WTFC
Entity Registrant Name	WINTRUST FINANCIAL CORP
Entity Central Index Key	1,015,328
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		56,282,928

Consolidated Statements Of Cond

Consolidated Statements Of Condition - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Assets
Cash and due from banks	$ 231,407	$ 277,534	$ 214,102
Federal funds sold and securities purchased under resale agreements	57	57	3,046
Interest bearing deposits with banks	980,380	1,063,242	1,007,468
Available-for-sale securities, at fair value	1,895,688	1,803,666	1,803,733
Held-to-maturity securities, at amortized cost ($862.5 million, $812.5 million and $647.9 million fair value at March 31, 2018, December 31, 2017 and March 31, 2017 respectively)	892,937	826,449	667,764
Trading account securities	1,682	995	714
Equity securities with readily determinable fair value	37,832	0	0
Federal Home Loan Bank and Federal Reserve Bank stock	104,956	89,989	78,904
Brokerage customer receivables	24,531	26,431	23,171
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
Loans, net of unearned income, excluding covered loans	22,062,134	21,640,797	19,931,058
Covered loans	0	0	52,359
Total loans	22,062,134	21,640,797	19,983,417
Allowance for loan losses	(139,503)	(137,905)	(125,819)
Allowance for covered loan losses	0	0	(1,319)
Net loans	21,922,631	21,502,892	19,856,279
Premises and equipment, net	626,687	621,895	598,746
Lease investments, net	190,775	212,335	155,233
Accrued interest receivable and other assets	601,794	567,374	560,741
Trade date securities receivable	0	90,014	0
Goodwill	511,497	501,884	499,341
Other intangible assets	22,413	17,621	20,687
Total assets	28,456,772	27,915,970	25,778,893
Deposits:
Non-interest bearing	6,612,319	6,792,497	5,790,579
Interest bearing	16,667,008	16,390,850	15,939,862
Total deposits	23,279,327	23,183,347	21,730,441
Federal Home Loan Bank advances	915,000	559,663	227,585
Other borrowings	247,092	266,123	238,787
Subordinated notes	139,111	139,088	138,993
Junior subordinated debentures	253,566	253,566	253,566
Accrued interest payable and other liabilities	591,426	537,244	424,538
Total liabilities	25,425,522	24,939,031	23,013,910
Preferred stock, no par value; 20,000,000 shares authorized:
Common stock, no par value; $1.00 stated value; 100,000,000 shares authorized at March 31, 2018, December 31, 2017 and March 31, 2017; 56,363,786 shares issued at March 31, 2018, 56,068,220 shares issued at December 31, 2017 and 52,605,401 shares issued at March 31, 2017	56,364	56,068	52,605
Surplus	1,540,673	1,529,035	1,381,886
Treasury stock, at cost, 107,288 shares at March 31, 2018, 103,013 shares at December 31, 2017, and 101,738 shares at March 31, 2017	(5,355)	(4,986)	(4,884)
Retained earnings	1,387,663	1,313,657	1,143,943
Accumulated other comprehensive loss	(73,095)	(41,835)	(59,824)
Total shareholders’ equity	3,031,250	2,976,939	2,764,983
Total liabilities and shareholders’ equity	28,456,772	27,915,970	25,778,893
Series C - $1,000 liquidation value; no shares issued and outstanding at March 31, 2018 and December 31, 2017 and 126,257 shares issued and outstanding at March 31, 2017
Preferred stock, no par value; 20,000,000 shares authorized:
Preferred stock, Series C and Series D	0	0	126,257
Series D - $25 liquidation value; 5,000,000 shares issued and outstanding at March 31, 2018, December 31, 2017 and March 31, 2017
Preferred stock, no par value; 20,000,000 shares authorized:
Preferred stock, Series C and Series D	$ 125,000	$ 125,000	$ 125,000

Consolidated Statements Of Con3

Consolidated Statements Of Condition (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Held-to-maturity securities, at Fair value	$ 862,527	$ 812,516	$ 647,895
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000	20,000,000
Common stock, $1.00 stated value (usd per share)	$ 1	$ 1	$ 1
Common stock, 100,000,000 shares authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares)	56,363,786	56,068,220	52,605,401
Treasury stock, (in shares)	107,288	103,013	101,738
Series C Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 1,000	$ 1,000	$ 1,000
Preferred stock, shares outstanding (in shares)	0	0	126,257
Preferred stock, shares issued (in shares)	0	0	126,257
Series D Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 25	$ 25	$ 25
Preferred stock, shares outstanding (in shares)	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	5,000,000	5,000,000	5,000,000

Consolidated Statements Of Inco

Consolidated Statements Of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income
Interest and fees on loans	$ 234,994	$ 196,916
Mortgage loans held-for-sale	2,818	2,398
Interest bearing deposits with banks	2,796	1,623
Federal funds sold and securities purchased under resale agreements	0	1
Investment securities	19,128	13,573
Trading account securities	14	11
Federal Home Loan Bank and Federal Reserve Bank stock	1,298	1,070
Brokerage customer receivables	157	167
Total interest income	261,205	215,759
Interest expense
Interest on deposits	26,549	16,270
Interest on Federal Home Loan Bank advances	3,639	1,590
Interest on other borrowings	1,699	1,139
Interest on subordinated notes	1,773	1,772
Interest on junior subordinated debentures	2,463	2,408
Total interest expense	36,123	23,179
Net interest income	225,082	192,580
Provision for credit losses	8,346	5,209
Net interest income after provision for credit losses	216,736	187,371
Non-interest income
Wealth management	22,986	20,148
Mortgage banking	30,960	21,938
Service charges on deposit accounts	8,857	8,265
Losses on investment securities, net	(351)	(55)
Fees from covered call options	1,597	759
Trading gains (losses), net	103	(320)
Operating lease income, net	9,691	5,782
Other	11,836	12,248
Total non-interest income	85,679	68,765
Non-interest expense
Salaries and employee benefits	112,436	99,316
Equipment	10,072	9,002
Operating lease equipment depreciation	6,533	4,636
Occupancy, net	13,767	13,101
Data processing	8,493	7,925
Advertising and marketing	8,824	5,150
Professional fees	6,649	4,660
Amortization of other intangible assets	1,004	1,164
FDIC insurance	4,362	4,156
OREO expense, net	2,926	1,665
Other	19,283	17,343
Total non-interest expense	194,349	168,118
Income before taxes	108,066	88,018
Income tax expense	26,085	29,640
Net income	81,981	58,378
Preferred stock dividends	2,050	3,628
Net income applicable to common shares	$ 79,931	$ 54,750
Net income per common share-Basic (usd per share)	$ 1.42	$ 1.05
Net income per common share-Diluted (usd per share)	1.40	1
Cash dividends declared per common share (usd per share)	$ 0.19	$ 0.14
Weighted average common shares outstanding (in shares)	56,137	52,267
Dilutive potential common shares (in shares)	888	4,160
Average common shares and dilutive common shares (in shares)	57,025	56,427

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 81,981	$ 58,378
Unrealized (losses) gains on available-for-sale securities
Before tax	(36,184)	7,379
Tax effect	9,710	(2,900)
Net of tax	(26,474)	4,479
Reclassification of net losses on available-for-sale securities included in net income
Before tax	(975)	(55)
Tax effect	262	21
Net of tax	(713)	(34)
Reclassification of amortization of unrealized gains and losses on investment securities transferred to held-to-maturity from available-for-sale
Before tax	(4)	1,428
Tax effect	1	(561)
Net of tax	(3)	867
Net unrealized (losses) gains on available-for-sale securities	(25,758)	3,646
Unrealized gains on derivative instruments
Before tax	3,075	1,615
Tax effect	(826)	(634)
Net unrealized gains on derivative instruments	2,249	981
Foreign currency adjustment
Before tax	(3,853)	1,215
Tax effect	956	(338)
Net foreign currency adjustment	(2,897)	877
Total other comprehensive (loss) income	(26,406)	5,504
Comprehensive income	$ 55,575	$ 63,882

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred stock	Common stock	Surplus	Treasury stock	Retained earnings	Accumulated other comprehensive loss
Balance at the beginning at Dec. 31, 2016	$ 2,695,617	$ 251,257	$ 51,978	$ 1,365,781	$ (4,589)	$ 1,096,518	$ (65,328)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	58,378					58,378
Other comprehensive income, net of tax	5,504						5,504
Cash dividends declared on common stock	(7,325)					(7,325)
Dividends on preferred stock	(3,628)					(3,628)
Stock-based compensation	2,918			2,918
Common stock issued for:
Exercise of stock options and warrants	12,784		512	12,272
Restricted stock awards	(295)		74	(74)	(295)
Employee stock purchase plan	624		9	615
Director compensation plan	406		32	374
Balance at the end at Mar. 31, 2017	2,764,983	251,257	52,605	1,381,886	(4,884)	1,143,943	(59,824)
Balance at the beginning at Dec. 31, 2017	2,976,939	125,000	56,068	1,529,035	(4,986)	1,313,657	(41,835)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	81,981					81,981
Other comprehensive income, net of tax	(26,406)						(26,406)
Cash dividends declared on common stock	(10,663)					(10,663)
Dividends on preferred stock	(2,050)					(2,050)
Stock-based compensation	3,683			3,683
Common stock issued for:
Exercise of stock options and warrants	7,196		179	7,017
Restricted stock awards	(369)		90	(90)	(369)
Employee stock purchase plan	630		8	622
Director compensation plan	425		19	406
Balance at the end at Mar. 31, 2018	$ 3,031,250	$ 125,000	$ 56,364	$ 1,540,673	$ (5,355)	$ 1,387,663	$ (73,095)

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities:
Net income	$ 81,981	$ 58,378
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	8,346	5,209
Depreciation, amortization and accretion, net	15,883	14,437
Stock-based compensation expense	3,683	2,918
Net amortization of premium on securities	1,071	1,732
Accretion of discount on loans	(4,927)	(6,439)
Mortgage servicing rights fair value change, net	(2,931)	789
Originations and purchases of mortgage loans held-for-sale	(778,852)	(722,467)
Proceeds from sales of mortgage loans held-for-sale	696,336	867,924
Bank owned life insurance (BOLI) income	(714)	(985)
(Increase) decrease in trading securities, net	(687)	1,275
Net decrease in brokerage customer receivables	1,900	2,010
Gains on mortgage loans sold	(18,917)	(16,047)
Losses on investment securities, net	351	55
Losses (gains) on sales of premises and equipment, net	25	(163)
Net losses on sales and fair value adjustments of other real estate owned	2,387	828
Decrease in accrued interest receivable and other assets, net	4,566	3,635
Increase (decrease) in accrued interest payable and other liabilities, net	12,857	(82,290)
Net Cash Provided by Operating Activities	22,358	130,799
Investing Activities:
Proceeds from maturities of available-for-sale securities	47,463	43,688
Proceeds from maturities of held-to-maturity securities	129	258
Proceeds from sales and calls of available-for-sale securities	210,891	6,005
Proceeds from calls of held-to-maturity securities	4,141	51,060
Proceeds from sales of equity securities with readily determinable fair value	0	0
Proceeds from sales of equity securities without readily determinable fair value	0	0
Purchases of available-for-sale securities	(333,999)	(124,227)
Purchases of held-to-maturity securities	(70,988)	(84,890)
Purchases of equity securities with readily determinable fair value	0	0
Purchases of equity securities without readily determinable fair value	(1,801)	0
(Purchase) redemption of Federal Home Loan Bank and Federal Reserve Bank stock, net	(14,967)	54,590
Net cash paid in business combinations	(18,708)	(284)
Proceeds from sales of other real estate owned	3,679	3,961
Proceeds received from the FDIC related to reimbursements on covered assets	0	386
Net decrease (increase) in interest bearing deposits with banks	81,162	(27,011)
Net increase in loans	(394,433)	(219,047)
Purchases of premises and equipment, net	(11,580)	(10,823)
Net Cash Used for Investing Activities	(499,011)	(306,334)
Financing Activities:
Increase in deposit accounts	95,988	71,862
Decrease in subordinated notes and other borrowings, net	(15,631)	(23,732)
Increase in Federal Home Loan Bank advances, net	355,000	73,000
Cash payments to settle contingent consideration liabilities recognized in business combinations	0	(1,058)
Issuance of common shares resulting from the exercise of stock options, employee stock purchase plan and conversion of common stock warrants	8,251	13,814
Common stock repurchases for tax withholdings related to stock-based compensation	(369)	(295)
Dividends paid	(12,713)	(10,953)
Net Cash Provided by Financing Activities	430,526	122,638
Net Decrease in Cash and Cash Equivalents	(46,127)	(52,897)
Cash and Cash Equivalents at Beginning of Period	277,591	270,045
Cash and Cash Equivalents at End of Period	$ 231,464	$ 217,148

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements of Wintrust Financial Corporation and Subsidiaries (“Wintrust” or the “Company”) presented herein are unaudited, but in the opinion of management reflect all necessary adjustments of a normal or recurring nature for a fair presentation of results as of the dates and for the periods covered by the consolidated financial statements. The accompanying consolidated financial statements are unaudited and do not include information or footnotes necessary for a complete presentation of financial condition, results of operations or cash flows in accordance with U.S. generally accepted accounting principles ("GAAP"). The unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 (“ 2017 Form 10-K”). Operating results reported for the period are not necessarily indicative of the results which may be expected for the entire year. Reclassifications of certain prior period amounts have been made to conform to the current period presentation. The preparation of the financial statements requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities. Management believes that the estimates made are reasonable, however, changes in estimates may be required if economic or other conditions develop differently from management’s expectations. Certain policies and accounting principles inherently have a greater reliance on the use of estimates, assumptions and judgments and as such have a greater possibility of producing results that could be materially different than originally reported. Management views critical accounting policies to be those which are highly dependent on subjective or complex judgments, estimates and assumptions, and where changes in those estimates and assumptions could have a significant impact on the financial statements. Management currently views the determination of the allowance for loan losses, allowance for covered loan losses and the allowance for losses on lending-related commitments, loans acquired with evidence of credit quality deterioration since origination, estimations of fair value, the valuations required for impairment testing of goodwill, the valuation and accounting for derivative instruments and income taxes as the accounting areas that require the most subjective and complex judgments, and as such could be the most subject to revision as new information becomes available. Descriptions of the Company's significant accounting policies are included in Note 1 - “Summary of Significant Accounting Policies” of the 2017 Form 10-K.

Recent Accounting Developments

Recent Accounting Developments	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Developments	Recent Accounting Developments Revenue Recognition In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, which created “Revenue from Contracts with Customers (Topic 606),” to clarify the principles for recognizing revenue and develop a common revenue standard for customer contracts. This ASU provides guidance regarding how 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. The ASU also added a new subtopic to the codification, ASC 340-40, “Other Assets and Deferred Costs: Contracts with Customers” to provide guidance on costs related to obtaining and fulfilling a customer contract. Furthermore, the new standard requires disclosure of sufficient information to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. At the time ASU No. 2014-09 was issued, the guidance was effective for fiscal years beginning after December 15, 2016. In July 2015, the FASB approved a deferral of the effective date by one year, which resulted in the guidance becoming effective for the Company as of January 1, 2018. The FASB continued to issue various updates to clarify and improve specific areas of ASU No. 2014-09. In March 2016, the FASB issued ASU No. 2016-08, “Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net),” to clarify the implementation guidance within ASU No. 2014-09 surrounding principal versus agent considerations and its impact on revenue recognition. In April 2016, the FASB issued ASU No. 2016-10, “Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing,” to also clarify the implementation guidance within ASU No. 2014-09 related to these two topics. In May 2016, the FASB issued ASU No. 2016-11, “Revenue Recognition (Topic 605) and Derivative and Hedging (Topic 815): Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting,” to remove certain areas of SEC Staff Guidance from those specific Topics. In May 2016 and December 2016, the FASB issued ASU 2016-12, “Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients” and ASU 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers,” to clarify specific aspects of implementation, including the collectability criterion, exclusion of sales taxes collected from a transaction price, noncash consideration, contract modifications, completed contracts at transition, the applicability of loan guarantee fees, impairment of capitalized contract costs and certain disclosure requirements. In February 2017, the FASB issued ASU No. 2017-05, “Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets,” to clarify the implementation guidance within ASU No. 2014-09 surrounding transfers of nonfinancial assets, including partial sales of such assets, and its impact on revenue recognition. Like ASU No. 2014-09, this guidance became effective for the Company starting January 1, 2018. The Company adopted ASU No. 2014-09 and all subsequent updates issued to clarify and improve specific areas of this ASU as of January 1, 2018. As certain significant revenue sources related to financial instruments such as interest income are considered not in-scope, the new guidance did not have a significant impact on the Company's consolidated financial statements. Revenue sources impacted by the new guidance include brokerage and trust and asset management fees from the wealth management business unit, card-based fees, deposit-related fees and other non-interest income. During implementation, the Company reviewed specific contracts with customers across these various sources of revenue. Reviews of such contracts assisted in identifying any characteristics of such contracts that could result in a change in the Company's current practices for recognition of revenue and recognition of costs incurred to obtain or fulfill such contracts. After review of such contracts, the Company identified no indication within the terms of such contracts that a change in the Company's current practices and accounting policies was necessary. The Company elected to adopt the new guidance using the modified retrospective approach applied to all contracts as of the date of initial application at January 1, 2018. Electing the modified retrospective approach resulted in no cumulative effect adjustment to the opening balance of retained earnings at the date of initial application. Additional disclosures have been added in accordance with the new guidance. See Note 13 – Revenue from Contracts with Customers for discussion of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Financial Instruments In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities,” to improve the accounting for financial instruments. This ASU requires equity securities with readily determinable fair values to be measured at fair value with changes recognized in net income. Such equity securities with readily determinable fair values are no longer classified as available-for-sale securities or trading securities within the consolidated financial statements of an entity. For equity securities without a readily determinable fair value, the value of the equity securities may be elected to be measured at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer instead of fair value, unless a qualitative assessment indicates impairment. Additionally, this ASU requires the separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements. The Company adopted this guidance as of January 1, 2018. For equity securities with a readily determinable fair value, this guidance was applied under a modified retrospective approach with a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. As of January 1, 2018, the Company reclassified approximately $1.9 million from accumulated other comprehensive income, related to previously recognized unrealized gains, net of deferred taxes, from equity securities with readily determinable fair values, to retained earnings. Equity securities with readily determinable fair values are now prospectively presented separate from available-for-sale securities and trading securities within the Company's Consolidated Statements of Condition. Additionally, for the three months ended March 31, 2018, the Company recognized $1.0 million of unrealized gains from equity securities with readily determinable fair values directly to earnings. For equity securities without a readily determinable fair value, the Company elected to measure such investments at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer, unless a qualitative assessment indicates impairment, which was applied prospectively. Equity securities without readily determinable fair values are included within accrued interest receivable and other assets within the Company's Consolidated Statements of Condition. See Note 5 - Investment Securities for further discussion of equity securities with and without readily determinable fair values. In January 2018, the FASB issued ASU No. 2018-03, “Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities,” to clarify certain aspects of the guidance issued in ASU No. 2016-01, including aspects of equity securities without a readily determinable fair value. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years beginning after June 15, 2018. Early adoption is permitted. As these clarifications did not have a material impact on the Company's consolidated financial statements, the Company elected to early adopt this guidance as of January 1, 2018. Leases In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842),” to improve transparency and comparability across entities regarding leasing arrangements. This ASU requires the recognition of a separate lease liability representing the required discounted lease payments over the lease term and a separate lease asset representing the right to use the underlying asset during the same lease term. Further, this ASU provides clarification regarding the identification of certain components of contracts that would represent a lease as well as requires additional disclosures to the notes of the financial statements. Additionally, in January 2018, the FASB issued ASU No. 2018-01, "Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842," to permit an entity to elect an optional practical expedient to not evaluate under Topic 842 land easements that exist or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under existing accounting guidance. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied under a modified retrospective approach, including the option to apply certain practical expedients. The Company is currently evaluating the impact of adopting this new guidance on the consolidated financial statements. Excluding any impact from the clarification of contracts representing a lease, the Company expects to recognize separate lease liabilities and right to use assets for the amounts related to certain facilities under operating lease agreements disclosed in Note 15 - Minimum Lease Commitments in the 2017 Form 10-K . Additionally, the Company does not expect to significantly change operating lease agreements prior to adoption. The Company has established a committee consisting of individuals from various areas of the Company tasked with transitioning the Company to the new guidance requirements. Additionally, the Company has begun obtaining and reviewing lease agreements across its various business units to determine any additional potential impact. Derivatives In August 2017, the FASB issued ASU No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities,” to improve the financial reporting of hedging relationships to better align the economic results of an entity’s risk management activities and disclosures within its financial statements. In addition, this ASU makes certain targeted improvements to simplify the application of the hedge accounting, including to derivative instruments as well as allow a one-time election to reclassify fixed-rate, prepayable debt securities from a held-to-maturity classification to an available-for-sale classification. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Guidance related to existing cash flow hedges and, if elected, fair value hedges is to be applied under a modified retrospective approach and guidance related to amended presentation and disclosures is to be applied under a prospective approach. Early adoption is permitted as of the beginning of an annual period that has not been issued or made available for issuance. The Company elected to early adopt this guidance as of January 1, 2018. See Note 15 - Derivative Financial Instruments for further discussion of early adoption of this guidance. The impact of early adoption on the financial statements included the following: • As allowed under the guidance, for certain existing derivative instruments designated as fair value hedges, the Company transitioned the measurement methodology for the related hedged item (loans) to be in accordance with the guidance without dedesignation of the hedging relationship. This resulted in a negative cumulative basis adjustment to loans of $116,000 with a corresponding adjustment to retained earnings. • No fixed-rate, prepayable held-to-maturity securities were transferred to an available-for-sale classification. • The entire change in the hedging instrument included in the assessment of hedge effectiveness of fair value hedges is presented in the same income statement line as the current impact of the effective portion of such hedge, or interest income and interest expense for interest rate hedging. The Company has previously recognized this ineffectiveness within non-interest income. For the first quarter of 2018, the Company recognized $45,000 of such change in interest income related to hedge effectiveness. Allowance for Credit Losses In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” to replace the current incurred loss methodology for recognizing credit losses, which delays recognition until it is probable a loss has been incurred, with a methodology that reflects an estimate of all expected credit losses and considers additional reasonable and supportable forecasted information when determining credit loss estimates. This impacts the calculation of an allowance for credit losses for all financial assets measured under the amortized cost basis, including PCI loans at the time of and subsequent to acquisition. Additionally, credit losses related to available-for-sale debt securities would be recorded through the allowance for credit losses and not as a direct adjustment to the amortized cost of the securities. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and is to be applied under a modified retrospective approach. The Company is currently evaluating the impact of adopting this new guidance on the consolidated financial statements as well as the impact on current systems and processes. Specifically, the Company has established a committee consisting of individuals from the various areas of the Company tasked with transitioning to the new requirements. At this time, the Company is reviewing potential methodologies for estimating expected credit losses using reasonable and supportable forecast information, has identified certain historical data and system requirements and has reviewed options for platforms to build, store, execute and review the financial impact. Statement of Cash Flows In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the FASB Emerging Issues Task Force),” to clarify the presentation of specific types of cash flow receipts and payments, including the payment of debt prepayment or debt extinguishment costs, contingent consideration cash payments paid subsequent to the acquisition date and proceeds from settlement of BOLI policies. This guidance became effective as of January 1, 2018 and was applied under a retrospective approach resulting in additional disclosure, including cash payments made to settle contingent consideration liabilities recognized in prior business combinations. In November 2016, the FASB issued ASU No. 2016-18 “Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force),” to clarify the classification and presentation of changes in restricted cash on the statement of cash flows. This guidance became effective as of January 1, 2018 and did not have a material impact on the Company. Income Taxes In October 2016, the FASB issued ASU No. 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory,” to improve the accounting for intra-entity transfers of assets other than inventory. This ASU allows the recognition of current and deferred income taxes for such transfers prior to the subsequent sale of the transferred assets to an outside party. Initial recognition of current and deferred income taxes is currently prohibited for intra-entity transfers of assets other than inventory. This guidance became effective as of January 1, 2018 and did not have a material impact on the Company. The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017, and the Company recognized a provisional tax benefit of $7.6 million in 2017 to reflect the impact of the Tax Act, primarily reflecting estimated effects of a lower federal income tax rate on its net deferred tax liabilities and a transition tax due on the deferred earnings of the Company's Canadian subsidiary. Estimates were made in good faith and may change as additional information and interpretive guidance regarding provisions of the Tax Act become available. Staff Accounting Bulletin 118 provides a measurement period, not to extend beyond one year from the date of enactment, during which a company may complete the accounting for the impacts of the Tax Act. No adjustments were made to the provisional amounts in the first quarter of 2018 and the Company expects to complete the accounting for the impacts of the Tax Act in the fourth quarter of 2018. Business Combinations In January 2017, the FASB issued ASU No. 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business,” to improve such definition and, as a result, assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or as business combinations. The definition of a business impacts many areas of accounting including acquisitions, disposals, goodwill and consolidation. This guidance became effective as of January 1, 2018 and was applied under a prospective approach. See Note 3 - Business Combinations for further discussion of business combinations including the acquisition of certain assets and assumption of certain liabilities of the mortgage banking business of iFreedom Direct Corporation DBA Veterans First Mortgage ("Veterans First") during the current period. Goodwill In January 2017, the FASB issued ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” to simplify the subsequent measurement of goodwill. When the carrying amount of a reporting unit exceeds its fair value, an entity would no longer be required to determine goodwill impairment by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit was acquired in a business combination. Goodwill impairment would be recognized according to the excess of the carrying amount of the reporting unit over the calculated fair value of such unit. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and is to be applied under a prospective approach. The Company does not expect this guidance to have a material impact on the Company's consolidated financial statements. Compensation In March 2017, the FASB issued ASU No. 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” to improve the presentation of net periodic pension cost and net periodic post-retirement benefit cost. An entity will be required to report the service cost component of such costs in the same line item or items as other compensation costs related to services rendered. Additionally, only the service cost component will be eligible for capitalization when applicable. This guidance became effective as of January 1, 2018 and was applied under a retrospective approach related to presentation of the service cost component and a prospective approach related to capitalization of such costs. Adoption of this guidance did not have a material impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, “Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting,” to clarify when modification accounting is appropriate for changes to the terms and conditions of a share-based payment award. An entity will be required to account for such changes as a modification unless certain criteria is met. This guidance became effective as of January 1, 2018 and was applied under a prospective approach for awards modified on or after the adoption date. Adoption of this guidance did not have a material impact on the Company's consolidated financial statements. Amortization of Premium on Certain Debt Securities In March 2017, the FASB issued ASU No. 2017-08, “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities,” to amend the amortization period for certain purchased callable debt securities held at a premium. The amortization period for such securities will be shortened to the earliest call date. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied under a modified retrospective approach. Early adoption is permitted as of the beginning of an annual period that has not been issued or made available for issuance. The Company did not early adopt this guidance as of January 1, 2018. The Company is currently evaluating the impact of adopting this new guidance on the consolidated financial statements. Accumulated Other Comprehensive Income (Loss) In February 2018, the FASB issued ASU No. 2018-02, “Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” to allow a reclassification from accumulated other comprehensive income to retained earnings related to the stranded tax effects within other comprehensive income resulting from the Federal income tax rate reduction in the Tax Act. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied either in the period of adoption or retrospectively to each period or periods in which the effect of the Tax Act is recognized. Early adoption is permitted as of the beginning of an annual period that has not been issued or made available for issuance. The Company elected to early adopt this guidance as of January 1, 2018 and applied such reclassification in the current period (period of adoption). As of January 1, 2018, the Company reclassified a stranded credit of $3.0 million from accumulated other comprehensive income to retained earnings. The Company has a policy for releasing the income tax effects from accumulated other comprehensive income using an individual security approach.

Business Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Business Combinations	Business Combinations FDIC-Assisted Transactions From 2010 to 2012, the Company acquired the banking operations, including the acquisition of certain assets and the assumption of liabilities, of nine financial institutions in FDIC-assisted transactions. Loans comprised the majority of the assets acquired in nearly all of these FDIC-assisted transactions, of which eight such transactions were subject to loss sharing agreements with the FDIC whereby the FDIC agreed to reimburse the Company for 80% of losses incurred on the purchased loans, other real estate owned (“OREO”), and certain other assets. Additionally, clawback provisions within these loss share agreements with the FDIC required the Company to reimburse the FDIC for actual losses on covered assets that were lower than the original loss estimates agreed upon with the FDIC with respect of such assets in the loss share agreements. The Company refers to the loans subject to these loss sharing agreements as “covered loans” and uses the term “covered assets” to refer to covered loans, covered OREO and certain other covered assets during periods subject to such agreements. As of dates subject to such agreements, the loans covered by the loss share agreements were classified and presented as covered loans and the estimated reimbursable losses were recorded as an FDIC indemnification asset or liability in the Consolidated Statements of Condition. The Company recorded the acquired assets and liabilities at their estimated fair values at the acquisition date. The fair value for loans reflected expected credit losses at the acquisition date. Therefore, the Company only recognized a provision for credit losses and charge-offs on the acquired loans for any further credit deterioration subsequent to the acquisition date. See Note 7 — Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans for further discussion of the allowance on covered loans. The loss share agreements with the FDIC covered realized losses on loans, foreclosed real estate and certain other assets and required the Company to record loss share assets and liabilities that were measured separately from the loan portfolios because they were not contractually embedded in the loans and were not transferable with the loans had the Company chosen to dispose of them. Fair values at the acquisition dates were estimated based on projected cash flows available for loss share based on the credit adjustments estimated for each loan pool and the loss share percentages. The loss share assets and liabilities were recorded as FDIC indemnification assets and other liabilities, respectively, on the Consolidated Statements of Condition as of dates covered by loss share agreements. Subsequent to the acquisition date, reimbursements received from the FDIC for actual incurred losses reduced the FDIC indemnification assets. Reductions to expected losses, to the extent such reductions to expected losses were the result of an improvement to the actual or expected cash flows from the covered assets, also reduced the FDIC indemnification assets and, if necessary, increased any loss share liability when necessary reductions exceeded the current value of the FDIC indemnification assets. In accordance with the clawback provision noted above, the Company was required to reimburse the FDIC when actual losses were less than certain thresholds established for each loss share agreement. The balance of these estimated reimbursements in accordance with clawback provisions and any related amortization were adjusted periodically for changes in the expected losses on covered assets. On the Consolidated Statements of Condition as of dates subject to loss share agreements, estimated reimbursements from clawback provisions were recorded as a reduction to the FDIC indemnification asset or, if necessary, an increase to the loss share liability, which was included within accrued interest payable and other liabilities. In the second quarter of 2017, the Company recorded a $4.9 million reduction to the estimated loss share liability as a result of an adjustment related to such clawback provisions. Although these assets were contractual receivables from the FDIC and these liabilities were contractual payables to the FDIC, there were no contractual interest rates. Additional expected losses, to the extent such expected losses resulted in recognition of an allowance for covered loan losses, increased the FDIC indemnification asset or reduced the FDIC indemnification liability. The corresponding amortization was recorded as a component of non-interest income on the Consolidated Statements of Income during periods covered by loss share agreements. The following table summarizes the activity in the Company’s FDIC indemnification liability during the period indicated: Three Months Ended (Dollars in thousands) March 31, Balance at beginning of period $ 16,701 Reductions from reimbursable expenses (82 ) Amortization 244 Changes in expected reimbursements from the FDIC for changes in expected credit losses and reimbursable expenses 1,014 Payments received from the FDIC 386 Balance at end of period $ 18,263 On October 16, 2017, the Company entered into agreements with the FDIC that terminate all existing loss share agreements with the FDIC. Under the terms of the agreements, the Company made a net payment of $15.2 million to the FDIC as consideration for the early termination of the loss share agreements. The Company recorded a pre-tax gain of approximately $0.4 million in the fourth quarter of 2017 to write off the remaining loss share asset, relieve the claw-back liability and recognize the payment to the FDIC. Mortgage Banking Acquisitions On January 4, 2018, the Company acquired Veterans First. The Company also acquired mortgage-servicing-rights assets from Veterans First on approximately 10,000 loans, totaling an estimated $1.6 billion in unpaid principal balance. The Company recorded goodwill of $10.2 million on the acquisition. On February 14, 2017, the Company acquired certain assets and assumed certain liabilities of the mortgage banking business of American Homestead Mortgage, LLC ("AHM"). The Company recorded goodwill of $999,000 on the acquisition. Purchased Credit Impaired ("PCI") Loans Purchased loans acquired in a business combination are recorded at estimated fair value on their purchase date. For PCI loans, expected future cash flows at the purchase date in excess of the fair value of loans are recorded as interest income over the life of the loans if the timing and amount of the future cash flows is reasonably estimable (“accretable yield”). The difference between contractually required payments and the cash flows expected to be collected at acquisition is referred to as the non-accretable difference and represents probable losses in the portfolio. In determining the acquisition date fair value of PCI loans, and in subsequent accounting, the Company aggregates these purchased loans into pools of loans by common risk characteristics, such as credit risk rating and loan type. Subsequent to the purchase date, increases in cash flows over those expected at the purchase date are recognized as interest income prospectively. Subsequent decreases to the expected cash flows will result in a provision for loan losses. The Company purchased a portfolio of life insurance premium finance receivables in 2009. These purchased life insurance premium finance receivables are valued on an individual basis. If credit related conditions deteriorate, an allowance related to these loans will be established as part of the provision for credit losses. See Note 6—Loans, for additional information on PCI loans.

Cash and Cash Equivalents

Cash and Cash Equivalents	3 Months Ended
	Mar. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of the Consolidated Statements of Cash Flows, the Company considers cash and cash equivalents to include cash on hand, cash items in the process of collection, non-interest bearing amounts due from correspondent banks, federal funds sold and securities purchased under resale agreements with original maturities of three months or less.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2018
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Investment Securities	Investment Securities The following tables are a summary of the investment securities portfolios as of the dates shown: March 31, 2018 (Dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. Treasury $ 25,022 $ — $ (295 ) $ 24,727 U.S. Government agencies 149,899 — (563 ) 149,336 Municipal 120,396 2,218 (856 ) 121,758 Corporate notes: Financial issuers 100,294 16 (1,595 ) 98,715 Other 1,000 — (1 ) 999 Mortgage-backed: (1) Mortgage-backed securities 1,510,421 169 (64,077 ) 1,446,513 Collateralized mortgage obligations 55,836 7 (2,203 ) 53,640 Equity securities (2) — — — — Total available-for-sale securities $ 1,962,868 $ 2,410 $ (69,590 ) $ 1,895,688 Held-to-maturity securities U.S. Government agencies $ 639,442 $ — $ (25,891 ) $ 613,551 Municipal 253,495 939 (5,458 ) 248,976 Total held-to-maturity securities $ 892,937 $ 939 $ (31,349 ) $ 862,527 Equity securities with readily determinable fair value (2) $ 34,230 $ 4,670 $ (1,068 ) $ 37,832 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 144,904 $ — $ (1,082 ) $ 143,822 U.S. Government agencies 157,638 2 (725 ) 156,915 Municipal 113,197 2,712 (557 ) 115,352 Corporate notes: Financial issuers 30,309 43 (301 ) 30,051 Other 1,000 — (1 ) 999 Mortgage-backed: (1) Mortgage-backed securities 1,291,695 446 (31,955 ) 1,260,186 Collateralized mortgage obligations 60,092 64 (617 ) 59,539 Equity securities (2) 34,234 3,357 (789 ) 36,802 Total available-for-sale securities $ 1,833,069 $ 6,624 $ (36,027 ) $ 1,803,666 Held-to-maturity securities U.S. Government agencies $ 579,062 $ 23 $ (14,066 ) $ 565,019 Municipal 247,387 2,668 (2,558 ) 247,497 Total held-to-maturity securities $ 826,449 $ 2,691 $ (16,624 ) $ 812,516 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. (2) As a result of the adoption of ASU No. 2016-01 effective January 1, 2018, equity securities with readily determinable fair value are no longer presented within available-for-sale securities and are now presented as equity securities with readily determinable fair values in the Company's Consolidated Statements of Condition for the current period. March 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 142,772 $ — $ (616 ) $ 142,156 U.S. Government agencies 178,475 31 (677 ) 177,829 Municipal 125,061 2,878 (376 ) 127,563 Corporate notes: Financial issuers 65,306 107 (986 ) 64,427 Other 1,000 — (3 ) 997 Mortgage-backed: (1) Mortgage-backed securities 1,256,497 302 (46,423 ) 1,210,376 Collateralized mortgage obligations 46,035 78 (445 ) 45,668 Equity securities (2) 32,634 3,106 (1,023 ) 34,717 Total available-for-sale securities $ 1,847,780 $ 6,502 $ (50,549 ) $ 1,803,733 Held-to-maturity securities U.S. Government agencies $ 465,891 $ 115 $ (18,664 ) $ 447,342 Municipal 201,873 1,114 (2,434 ) 200,553 Total held-to-maturity securities $ 667,764 $ 1,229 $ (21,098 ) $ 647,895 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. (2) As a result of the adoption of ASU No. 2016-01 effective January 1, 2018, equity securities with readily determinable fair value are no longer presented within available-for-sale securities and are now presented as equity securities with readily determinable fair values in the Company's Consolidated Statements of Condition for the current period. Equity securities without readily determinable fair values totaled $25.2 million as of March 31, 2018 . Equity securities without readily determinable fair values are included as part of accrued interest receivable and other assets in the Company's Consolidated Statements of Condition. In accordance with the adoption of ASU No. 2016-01, in the first quarter of 2018, the Company recorded an upward adjustment on such securities of $131,000 related to observable price changes in orderly transactions for the identical or a similar investment of the same issuer. No downward adjustment of equity securities without readily determinable fair values was recorded during the current period. The Company monitors its equity investments without a readily determinable fair values to identify potential transactions that may indicate an observable price change requiring adjustment to its carrying amount. The following table presents the portion of the Company’s available-for-sale and held-to-maturity investment securities portfolios which has gross unrealized losses, reflecting the length of time that individual securities have been in a continuous unrealized loss position at March 31, 2018 : Continuous unrealized losses existing for less than 12 months Continuous unrealized losses existing for greater than 12 months Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale securities U.S. Treasury $ 24,727 $ (295 ) $ — $ — $ 24,727 $ (295 ) U.S. Government agencies 14,742 (104 ) 134,594 (459 ) 149,336 (563 ) Municipal 35,225 (494 ) 13,794 (362 ) 49,019 (856 ) Corporate notes: Financial issuers 73,037 (1,294 ) 5,665 (301 ) 78,702 (1,595 ) Other — — 999 (1 ) 999 (1 ) Mortgage-backed: Mortgage-backed securities 495,082 (12,177 ) 945,641 (51,900 ) 1,440,723 (64,077 ) Collateralized mortgage obligations 39,939 (1,672 ) 12,342 (531 ) 52,281 (2,203 ) Total available-for-sale securities $ 682,752 $ (16,036 ) $ 1,113,035 $ (53,554 ) $ 1,795,787 $ (69,590 ) Held-to-maturity securities U.S. Government agencies $ 311,150 $ (7,688 ) $ 292,800 $ (18,203 ) $ 603,950 $ (25,891 ) Municipal 160,027 (3,563 ) 49,129 (1,895 ) 209,156 (5,458 ) Total held-to-maturity securities $ 471,177 $ (11,251 ) $ 341,929 $ (20,098 ) $ 813,106 $ (31,349 ) The Company conducts a regular assessment of its available-for-sale and held-to-maturity investment securities to determine whether securities are other-than-temporarily impaired considering, among other factors, the nature of the securities, credit ratings or financial condition of the issuer, the extent and duration of the unrealized loss, expected cash flows, market conditions and the Company’s ability to hold the securities through the anticipated recovery period. The Company does not consider available-for-sale and held-to-maturity securities with unrealized losses at March 31, 2018 to be other-than-temporarily impaired. The Company does not intend to sell these investments and it is more likely than not that the Company will not be required to sell these investments before recovery of the amortized cost bases, which may be the maturity dates of the securities. The unrealized losses within each category have occurred as a result of changes in interest rates, market spreads and market conditions subsequent to purchase. Securities with continuous unrealized losses existing for more than twelve months were primarily mortgage-backed securities, U.S. government agency securities and municipal securities. The following table provides information as to the amount of gross gains and losses, adjustments and impairment on investment securities and proceeds received through the sale or call of investment securities: Three months ended March 31, (Dollars in thousands) 2018 2017 Realized gains on available-for-sale debt securities $ — $ — Realized losses on available-for-sale debt securities (975 ) (55 ) Net realized losses on available-for-sale debt securities (975 ) $ (55 ) Unrealized gains on equity securities with readily determinable fair value 1,873 — Unrealized losses on equity securities with readily determinable fair value (843 ) — Net unrealized gains on equity securities with readily determinable fair value 1,030 — Upward adjustments of equity securities without readily determinable fair values 131 — Downward adjustments of equity securities without readily determinable fair values — — Impairment of equity securities without readily determinable fair values (537 ) — Adjustment and impairment, net, of equity securities without readily determinable fair values (406 ) — Other than temporary impairment charges — — Losses on investment securities, net $ (351 ) $ (55 ) Proceeds from sales and calls of available-for-sale securities $ 210,891 $ 6,005 Proceeds from calls of held-to-maturity securities 4,141 51,060 Proceeds from sales of equity securities with readily determinable fair value — — Proceeds from sales of equity securities without readily determinable fair value — — During the three months ending March 31, 2018, the Company recorded impairment of equity securities without readily determinable fair values totaling $537,000 . The Company conducts a quarterly assessment of its equity securities without a readily determinable fair values to determine whether impairment exists in such securities, considering, among other factors, the nature of the securities, financial condition of the issuer and expected future cash flows. The amortized cost and fair value of available-for-sale and held-to-maturity investment securities as of March 31, 2018 , December 31, 2017 and March 31, 2017 , by contractual maturity, are shown in the following table. Contractual maturities may differ from actual maturities as borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Mortgage-backed securities are not included in the maturity categories in the following maturity summary as actual maturities may differ from contractual maturities because the underlying mortgages may be called or prepaid without penalties: March 31, 2018 December 31, 2017 March 31, 2017 (Dollars in thousands) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Available-for-sale securities Due in one year or less $ 180,899 $ 180,333 $ 300,833 $ 299,285 $ 142,323 $ 142,001 Due in one to five years 90,073 89,953 97,019 97,326 320,945 320,278 Due in five to ten years 116,909 116,517 33,947 35,029 39,520 40,519 Due after ten years 8,730 8,732 15,249 15,499 9,826 10,174 Mortgage-backed 1,566,257 1,500,153 1,351,787 1,319,725 1,302,532 1,256,044 Equity securities (1) — — 34,234 36,802 32,634 34,717 Total available-for-sale securities $ 1,962,868 $ 1,895,688 $ 1,833,069 $ 1,803,666 $ 1,847,780 $ 1,803,733 Held-to-maturity securities Due in one year or less $ 3,786 $ 3,775 $ 170 $ 171 $ — $ — Due in one to five years 34,495 33,994 38,392 38,012 32,771 32,525 Due in five to ten years 210,705 205,823 205,227 203,680 70,533 69,348 Due after ten years 643,951 618,935 582,660 570,653 564,460 546,022 Total held-to-maturity securities $ 892,937 $ 862,527 $ 826,449 $ 812,516 $ 667,764 $ 647,895 (1) As a result of the adoption of ASU No. 2016-01 effective January 1, 2018, equity securities with readily determinable fair value are no longer presented within available-for-sale securities and are now presented as equity securities with readily determinable fair values in the Company's Consolidated Statements of Condition for the current period. Securities having a fair value of $1.5 billion at March 31, 2018 as well as securities having a fair value of $1.7 billion and $1.3 billion at December 31, 2017 and March 31, 2017 , respectively, were pledged as collateral for public deposits, trust deposits, Federal Home Loan Bank ("FHLB") advances, securities sold under repurchase agreements and derivatives. At March 31, 2018 , there were no securities of a single issuer, other than U.S. Government-sponsored agency securities, which exceeded 10% of shareholders’ equity.

Loans

Loans	3 Months Ended
	Mar. 31, 2018
Loans and Leases Receivable Disclosure [Abstract]
Loans	Loans The following table shows the Company’s loan portfolio by category as of the dates shown: March 31, December 31, March 31, (Dollars in thousands) 2018 2017 2017 Balance: Commercial $ 7,060,871 $ 6,787,677 $ 6,081,489 Commercial real estate 6,633,520 6,580,618 6,261,682 Home equity 626,547 663,045 708,258 Residential real estate 869,104 832,120 720,608 Premium finance receivables—commercial 2,576,150 2,634,565 2,446,946 Premium finance receivables—life insurance 4,189,961 4,035,059 3,593,563 Consumer and other 105,981 107,713 118,512 Total loans, net of unearned income, excluding covered loans $ 22,062,134 $ 21,640,797 $ 19,931,058 Covered loans — — 52,359 Total loans $ 22,062,134 $ 21,640,797 $ 19,983,417 Mix: Commercial 32 % 31 % 30 % Commercial real estate 30 30 31 Home equity 3 3 4 Residential real estate 4 4 4 Premium finance receivables—commercial 12 12 12 Premium finance receivables—life insurance 19 19 18 Consumer and other — 1 1 Total loans, net of unearned income, excluding covered loans 100 % 100 % 100 % Covered loans — — — Total loans 100 % 100 % 100 % The Company’s loan portfolio is generally comprised of loans to consumers and small to medium-sized businesses located within the geographic market areas that the banks serve. The premium finance receivables portfolios are made to customers throughout the United States and Canada. The Company strives to maintain a loan portfolio that is diverse in terms of loan type, industry, borrower and geographic concentrations. Such diversification reduces the exposure to economic downturns that may occur in different segments of the economy or in different industries. Certain premium finance receivables are recorded net of unearned income. The unearned income portions of such premium finance receivables were $85.4 million at March 31, 2018 , $87.0 million at December 31, 2017 and $72.4 million at March 31, 2017 . Total loans, excluding PCI loans, include net deferred loan fees and costs and fair value purchase accounting adjustments totaling $9.4 million at March 31, 2018 , $9.3 million at December 31, 2017 and $4.6 million at March 31, 2017 . PCI loans are recorded net of credit discounts. See “Acquired Loan Information at Acquisition - PCI Loans” below. It is the policy of the Company to review each prospective credit in order to determine the appropriateness and, when required, the adequacy of security or collateral necessary to obtain when making a loan. The type of collateral, when required, will vary from liquid assets to real estate. The Company seeks to ensure access to collateral, in the event of default, through adherence to state lending laws and the Company’s credit monitoring procedures. Acquired Loan Information at Acquisition—PCI Loans As part of the Company's previous acquisitions, the Company acquired loans for which there was evidence of credit quality deterioration since origination (PCI loans) and determined that it was probable that the Company would be unable to collect all contractually required principal and interest payments. The following table presents the unpaid principal balance and carrying value for these acquired loans: March 31, 2018 December 31, 2017 (Dollars in thousands) Unpaid Principal Balance Carrying Value Unpaid Carrying PCI loans $ 348,102 $ 325,745 $ 375,237 $ 350,690 See Note 7—Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans for further discussion regarding the allowance for loan losses associated with PCI loans at March 31, 2018 . Accretable Yield Activity - PCI Loans Changes in expected cash flows may vary from period to period as the Company periodically updates its cash flow model assumptions for PCI loans. The factors that most significantly affect the estimates of gross cash flows expected to be collected, and accordingly the accretable yield, include changes in the benchmark interest rate indices for variable-rate products and changes in prepayment assumptions and loss estimates. The following table provides activity for the accretable yield of PCI loans: Three Months Ended (Dollars in thousands) March 31, March 31, Accretable yield, beginning balance $ 36,565 $ 49,408 Acquisitions — 531 Accretable yield amortized to interest income (4,619 ) (5,599 ) Accretable yield amortized to indemnification asset/liability (1) — (354 ) Reclassification from non-accretable difference (2) 1,556 2,535 Increases (decreases) in interest cash flows due to payments and changes in interest rates 2,190 (759 ) Accretable yield, ending balance $ 35,692 $ 45,762 (1) Represents the portion of the current period accreted yield, resulting from lower expected losses, applied to reduce the loss share indemnification asset or increase the loss share indemnification liability. (2) Reclassification is the result of subsequent increases in expected principal cash flows. Accretion to interest income accounted for under ASC 310-30 totaled $4.6 million and $5.6 million in the first quarter of 2018 and 2017 , respectively. These amounts include accretion from both covered and non-covered loans, and are both included within interest and fees on loans in the Consolidated Statements of Income.

Allowance for Loan Losses, Allo

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans	Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans The tables below show the aging of the Company’s loan portfolio at March 31, 2018 , December 31, 2017 and March 31, 2017 : As of March 31, 2018 90+ days and still accruing 60-89 days past due 30-59 days past due (Dollars in thousands) Nonaccrual Current Total Loans Loan Balances: Commercial Commercial, industrial and other $ 10,051 $ — $ 594 $ 31,475 $ 4,518,760 $ 4,560,880 Franchise 2,401 — 44 1,203 931,710 935,358 Mortgage warehouse lines of credit — — — 5,771 157,699 163,470 Asset-based lending 1,194 — 47 12,611 963,883 977,735 Leases 361 — — 3,170 410,667 414,198 PCI - commercial (1) — 856 86 3 8,285 9,230 Total commercial 14,007 856 771 54,233 6,991,004 7,060,871 Commercial real estate: Construction 3,139 — — 9,576 802,921 815,636 Land 182 — — 4,527 117,981 122,690 Office 474 — 925 11,466 878,206 891,071 Industrial 1,427 — 823 5,027 898,867 906,144 Retail 12,274 — — 4,785 878,563 895,622 Multi-family 19 — — 328 931,008 931,355 Mixed use and other 4,310 — 192 13,626 1,937,328 1,955,456 PCI - commercial real estate (1) — 3,107 1,623 9,134 101,682 115,546 Total commercial real estate 21,825 3,107 3,563 58,469 6,546,556 6,633,520 Home equity 9,828 — 1,505 4,033 611,181 626,547 Residential real estate, including PCI 17,214 1,437 229 8,808 841,416 869,104 Premium finance receivables Commercial insurance loans 17,342 8,547 6,543 17,756 2,525,962 2,576,150 Life insurance loans — — 5,125 11,420 3,986,181 4,002,726 PCI - life insurance loans (1) — — — — 187,235 187,235 Consumer and other, including PCI 720 269 216 291 104,485 105,981 Total loans, net of unearned income $ 80,936 $ 14,216 $ 17,952 $ 155,010 $ 21,794,020 $ 22,062,134 As of December 31, 2017 90+ days and still accruing 60-89 days past due 30-59 days past due (Dollars in thousands) Nonaccrual Current Total Loans Loan Balances: Commercial Commercial, industrial and other $ 11,260 $ — $ 3,746 $ 13,392 $ 4,314,107 $ 4,342,505 Franchise 2,447 — — — 845,150 847,597 Mortgage warehouse lines of credit — — — 4,000 190,523 194,523 Asset-based lending 1,550 — 283 10,057 968,576 980,466 Leases 439 — 3 1,958 410,772 413,172 PCI - commercial (1) — 877 186 — 8,351 9,414 Total commercial 15,696 877 4,218 29,407 6,737,479 6,787,677 Commercial real estate Construction 3,143 — — 200 742,171 745,514 Land 188 — — 5,156 121,140 126,484 Office 2,438 — — 4,458 887,937 894,833 Industrial 811 — — 2,412 879,796 883,019 Retail 12,328 — 668 148 938,383 951,527 Multi-family — — — 1,034 914,610 915,644 Mixed use and other 3,140 — 1,423 9,641 1,921,501 1,935,705 PCI - commercial real estate (1) — 7,135 2,255 6,277 112,225 127,892 Total commercial real estate 22,048 7,135 4,346 29,326 6,517,763 6,580,618 Home equity 8,978 — 518 4,634 648,915 663,045 Residential real estate, including PCI 17,977 5,304 1,303 8,378 799,158 832,120 Premium finance receivables Commercial insurance loans 12,163 9,242 17,796 15,849 2,579,515 2,634,565 Life insurance loans — — 4,837 10,017 3,820,936 3,835,790 PCI - life insurance loans (1) — — — — 199,269 199,269 Consumer and other, including PCI 740 101 242 727 105,903 107,713 Total loans, net of unearned income $ 77,602 $ 22,659 $ 33,260 $ 98,338 $ 21,408,938 $ 21,640,797 (1) PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. Loan agings are based upon contractually required payments. As of March 31, 2017 90+ days and still accruing 60-89 days past due 30-59 days past due (Dollars in thousands) Nonaccrual Current Total Loans Loan Balances: Commercial Commercial, industrial and other $ 12,036 $ 100 $ 19 $ 23,780 $ 3,855,140 $ 3,891,075 Franchise 323 — — 987 822,424 823,734 Mortgage warehouse lines of credit — — — 9,111 145,069 154,180 Asset-based lending 1,378 — — 3,744 875,882 881,004 Leases 570 — — 874 318,566 320,010 PCI - commercial (1) — 1,368 — 944 9,174 11,486 Total commercial 14,307 1,468 19 39,440 6,026,255 6,081,489 Commercial real estate: Construction 2,408 — 391 4,356 648,178 655,333 Land 350 — — 3,274 101,455 105,079 Office 3,513 — 953 7,155 859,045 870,666 Industrial 7,004 — — 2,656 783,302 792,962 Retail 589 — — 4,727 906,470 911,786 Multi-family 668 — 203 4,813 799,092 804,776 Mixed use and other 6,277 — 3,207 14,166 1,940,094 1,963,744 PCI - commercial real estate (1) — 12,559 672 15,565 128,540 157,336 Total commercial real estate 20,809 12,559 5,426 56,712 6,166,176 6,261,682 Home equity 11,722 — 430 4,884 691,222 708,258 Residential real estate, including PCI 11,943 900 3,410 5,262 699,093 720,608 Premium finance receivables Commercial insurance loans 12,629 4,991 6,383 23,775 2,399,168 2,446,946 Life insurance loans — 2,024 2,535 32,208 3,316,090 3,352,857 PCI - life insurance loans (1) — — — — 240,706 240,706 Consumer and other, including PCI 350 167 323 543 117,129 118,512 Total loans, net of unearned income, excluding covered loans $ 71,760 $ 22,109 $ 18,526 $ 162,824 $ 19,655,839 $ 19,931,058 Covered loans 1,592 2,808 268 1,570 46,121 52,359 Total loans, net of unearned income $ 73,352 $ 24,917 $ 18,794 $ 164,394 $ 19,701,960 $ 19,983,417 (1) PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. Loan agings are based upon contractually required payments. The Company's ability to manage credit risk depends in large part on our ability to properly identify and manage problem loans. To do so, the Company operates a credit risk rating system under which our credit management personnel assign a credit risk rating (1 to 10 rating) to each loan at the time of origination and review loans on a regular basis. Each loan officer is responsible for monitoring his or her loan portfolio, recommending a credit risk rating for each loan in his or her portfolio and ensuring the credit risk ratings are appropriate. These credit risk ratings are then ratified by the bank’s chief credit officer and/or concurrence credit officer. Credit risk ratings are determined by evaluating a number of factors including: a borrower’s financial strength, cash flow coverage, collateral protection and guarantees. The Company’s Problem Loan Reporting system automatically includes all loans with credit risk ratings of 6 through 9. This system is designed to provide an on-going detailed tracking mechanism for each problem loan. Once management determines that a loan has deteriorated to a point where it has a credit risk rating of 6 or worse, the Company’s Managed Asset Division performs an overall credit and collateral review. As part of this review, all underlying collateral is identified and the valuation methodology is analyzed and tracked. As a result of this initial review by the Company’s Managed Asset Division, the credit risk rating is reviewed and a portion of the outstanding loan balance may be deemed uncollectible or an impairment reserve may be established. The Company’s impairment analysis utilizes an independent re-appraisal of the collateral (unless such a third-party evaluation is not possible due to the unique nature of the collateral, such as a closely-held business or thinly traded securities). In the case of commercial real estate collateral, an independent third party appraisal is ordered by the Company’s Real Estate Services Group to determine if there has been any change in the underlying collateral value. These independent appraisals are reviewed by the Real Estate Services Group and sometimes by independent third party valuation experts and may be adjusted depending upon market conditions. Through the credit risk rating process, loans are reviewed to determine if they are performing in accordance with the original contractual terms. If the borrower has failed to comply with the original contractual terms, further action may be required by the Company, including a downgrade in the credit risk rating, movement to non-accrual status, a charge-off or the establishment of a specific impairment reserve. If a loan amount, or portion thereof, is determined to be uncollectible, the loan’s credit risk rating is immediately downgraded to an 8 or 9 and the uncollectible amount is charged-off. Any loan that has a partial charge-off continues to be assigned a credit risk rating of an 8 or 9 for the duration of time that a balance remains outstanding. The Company undertakes a thorough and ongoing analysis to determine if additional impairment and/or charge-offs are appropriate and to begin a workout plan for the credit to minimize actual losses. If, based on current information and events, it is probable that the Company will be unable to collect all amounts due to it according to the contractual terms of the loan agreement, a specific impairment reserve is established. In determining the appropriate charge-off for collateral-dependent loans, the Company considers the results of appraisals for the associated collateral. Non-performing loans include all non-accrual loans (8 and 9 risk ratings) as well as loans 90 days past due and still accruing interest, excluding PCI and covered loans. The remainder of the portfolio is considered performing under the contractual terms of the loan agreement. The following table presents the recorded investment based on performance of loans by class, excluding covered loans, per the most recent analysis at March 31, 2018 , December 31, 2017 and March 31, 2017 : Performing Non-performing Total (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, March 31, December 31, March 31, Loan Balances: Commercial Commercial, industrial and other $ 4,550,829 $ 4,331,245 $ 3,878,939 $ 10,051 $ 11,260 $ 12,136 $ 4,560,880 $ 4,342,505 $ 3,891,075 Franchise 932,957 845,150 823,411 2,401 2,447 323 935,358 847,597 823,734 Mortgage warehouse lines of credit 163,470 194,523 154,180 — — — 163,470 194,523 154,180 Asset-based lending 976,541 978,916 879,626 1,194 1,550 1,378 977,735 980,466 881,004 Leases 413,837 412,733 319,440 361 439 570 414,198 413,172 320,010 PCI - commercial (1) 9,230 9,414 11,486 — — — 9,230 9,414 11,486 Total commercial 7,046,864 6,771,981 6,067,082 14,007 15,696 14,407 7,060,871 6,787,677 6,081,489 Commercial real estate Construction 812,497 742,371 652,925 3,139 3,143 2,408 815,636 745,514 655,333 Land 122,508 126,296 104,729 182 188 350 122,690 126,484 105,079 Office 890,597 892,395 867,153 474 2,438 3,513 891,071 894,833 870,666 Industrial 904,717 882,208 785,958 1,427 811 7,004 906,144 883,019 792,962 Retail 883,348 939,199 911,197 12,274 12,328 589 895,622 951,527 911,786 Multi-family 931,336 915,644 804,108 19 — 668 931,355 915,644 804,776 Mixed use and other 1,951,146 1,932,565 1,957,467 4,310 3,140 6,277 1,955,456 1,935,705 1,963,744 PCI - commercial real estate (1) 115,546 127,892 157,336 — — — 115,546 127,892 157,336 Total commercial real estate 6,611,695 6,558,570 6,240,873 21,825 22,048 20,809 6,633,520 6,580,618 6,261,682 Home equity 616,719 654,067 696,536 9,828 8,978 11,722 626,547 663,045 708,258 Residential real estate, including PCI 851,890 810,865 708,665 17,214 21,255 11,943 869,104 832,120 720,608 Premium finance receivables Commercial insurance loans 2,550,261 2,613,160 2,429,326 25,889 21,405 17,620 2,576,150 2,634,565 2,446,946 Life insurance loans 4,002,726 3,835,790 3,350,833 — — 2,024 4,002,726 3,835,790 3,352,857 PCI - life insurance loans (1) 187,235 199,269 240,706 — — — 187,235 199,269 240,706 Consumer and other, including PCI 105,054 106,933 118,058 927 780 454 105,981 107,713 118,512 Total loans, net of unearned income, excluding covered loans $ 21,972,444 $ 21,550,635 $ 19,852,079 $ 89,690 $ 90,162 $ 78,979 $ 22,062,134 $ 21,640,797 $ 19,931,058 (1) PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. See Note 6 - Loans for further discussion of these purchased loans. A summary of activity in the allowance for credit losses by loan portfolio (excluding covered loans) for the three months ended March 31, 2018 and 2017 is as follows: Three months ended March 31, 2018 Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total, Excluding Covered Loans (Dollars in thousands) Commercial Allowance for credit losses Allowance for loan losses at beginning of period $ 57,811 $ 55,227 $ 10,493 $ 6,688 $ 6,846 $ 840 $ 137,905 Other adjustments (1 ) (24 ) — (3 ) (12 ) — (40 ) Reclassification from allowance for unfunded lending-related commitments — 26 — — — — 26 Charge-offs (2,687 ) (813 ) (357 ) (571 ) (4,721 ) (129 ) (9,278 ) Recoveries 262 1,687 123 40 385 47 2,544 Provision for credit losses 2,251 1,378 (399 ) 124 4,835 157 8,346 Allowance for loan losses at period end $ 57,636 $ 57,481 $ 9,860 $ 6,278 $ 7,333 $ 915 $ 139,503 Allowance for unfunded lending-related commitments at period end $ — $ 1,243 $ — $ — $ — $ — $ 1,243 Allowance for credit losses at period end $ 57,636 $ 58,724 $ 9,860 $ 6,278 $ 7,333 $ 915 $ 140,746 Individually evaluated for impairment $ 2,344 $ 3,611 $ 749 $ 148 $ — $ 25 $ 6,877 Collectively evaluated for impairment 54,789 55,042 9,111 6,029 7,333 890 133,194 Loans acquired with deteriorated credit quality 503 71 — 101 — — 675 Loans at period end Individually evaluated for impairment $ 33,810 $ 38,237 $ 10,102 $ 20,558 $ — $ 748 $ 103,455 Collectively evaluated for impairment 7,017,831 6,479,737 616,445 768,859 6,578,876 103,224 21,564,972 Loans acquired with deteriorated credit quality 9,230 115,546 — 11,725 187,235 2,009 325,745 Loans held at fair value — — — 67,962 — — 67,962 Three months ended March 31, 2017 Commercial Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total, Excluding Covered Loans (Dollars in thousands) Allowance for credit losses Allowance for loan losses at beginning of period $ 44,493 $ 51,422 $ 11,774 $ 5,714 $ 7,625 $ 1,263 $ 122,291 Other adjustments (19 ) (36 ) — (4 ) 3 — (56 ) Reclassification from allowance for unfunded lending-related commitments (92 ) (46 ) — — — — (138 ) Charge-offs (641 ) (261 ) (625 ) (329 ) (1,427 ) (134 ) (3,417 ) Recoveries 273 554 65 178 612 141 1,823 Provision for credit losses 2,568 1,000 989 (29 ) 746 42 5,316 Allowance for loan losses at period end $ 46,582 $ 52,633 $ 12,203 $ 5,530 $ 7,559 $ 1,312 $ 125,819 Allowance for unfunded lending-related commitments at period end $ 592 $ 1,219 $ — $ — $ — $ — $ 1,811 Allowance for credit losses at period end $ 47,174 $ 53,852 $ 12,203 $ 5,530 $ 7,559 $ 1,312 $ 127,630 Individually evaluated for impairment $ 2,845 $ 3,198 $ 1,979 $ 666 $ — $ 92 $ 8,780 Collectively evaluated for impairment 43,687 50,594 10,224 4,802 7,559 1,219 118,085 Loans acquired with deteriorated credit quality 642 60 — 62 — 1 765 Loans at period end Individually evaluated for impairment $ 19,319 $ 40,107 $ 11,878 $ 16,594 $ — $ 405 $ 88,303 Collectively evaluated for impairment 6,050,684 6,064,239 696,380 671,765 5,799,803 116,966 19,399,837 Loans acquired with deteriorated credit quality 11,486 157,336 — 3,701 240,706 1,141 414,370 Loans held at fair value — — — 28,548 — — 28,548 A summary of activity in the allowance for covered loan losses for the three months ended March 31, 2017 is as follows: Three Months Ended March 31, (Dollars in thousands) 2017 Balance at beginning of period $ 1,322 Provision for covered loan losses before benefit attributable to FDIC loss share agreements (535 ) Benefit attributable to FDIC loss share agreements 428 Net provision for covered loan losses (107 ) Increase in FDIC indemnification liability (428 ) Loans charged-off (216 ) Recoveries of loans charged-off 748 Net (charge-offs) recoveries 532 Balance at end of period $ 1,319 In conjunction with FDIC-assisted transactions, the Company entered into loss share agreements with the FDIC. Additional expected losses, to the extent such expected losses resulted in the recognition of an allowance for loan losses, increased the FDIC loss share asset or reduced any FDIC loss share liability. The allowance for loan losses for loans acquired in FDIC-assisted transactions was determined without giving consideration to the amounts recoverable through loss share agreements (since the loss share agreements were separately accounted for and thus presented “gross” on the balance sheet). On the Consolidated Statements of Income, the provision for credit losses was reported net of changes in the amount recoverable under the loss share agreements. Reductions to expected losses, to the extent such reductions to expected losses were the result of an improvement to the actual or expected cash flows from the covered assets, reduced the FDIC loss share asset or increased any FDIC loss share liability. Additions to expected losses required an increase to the allowance for covered loan losses, and a corresponding increase to the FDIC loss share asset or reduction to any FDIC loss share liability. See “FDIC-Assisted Transactions” within Note 3 – Business Combinations for more detail. On October 16, 2017, the Company entered into agreements with the FDIC that terminated all existing loss share agreements with the FDIC. As a result, the allowance for covered loan losses previously measured is included within the allowance for credit losses, excluding covered loans, presented above for subsequent periods. See Note 3 - Business Combinations for further discussion of the termination of FDIC loss share agreements. Impaired Loans A summary of impaired loans, including troubled debt restructurings ("TDRs"), is as follows: March 31, December 31, March 31, (Dollars in thousands) 2018 2017 2017 Impaired loans (included in non-performing and TDRs): Impaired loans with an allowance for loan loss required (1) $ 37,572 $ 36,084 $ 39,968 Impaired loans with no allowance for loan loss required 65,559 69,004 47,554 Total impaired loans (2) $ 103,131 $ 105,088 $ 87,522 Allowance for loan losses related to impaired loans $ 6,863 $ 8,023 $ 8,165 TDRs $ 47,676 $ 49,786 $ 39,669 (1) These impaired loans require an allowance for loan losses because the estimated fair value of the loans or related collateral is less than the recorded investment in the loans. (2) Impaired loans are considered by the Company to be non-accrual loans, TDRs or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest. The following tables present impaired loans by loan class, excluding covered loans, for the periods ended as follows: For the Three Months Ended As of March 31, 2018 March 31, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized (Dollars in thousands) Impaired loans with a related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 5,521 $ 5,587 $ 1,738 $ 5,607 $ 83 Franchise — — — — — Asset-based lending 1,107 1,107 475 1,166 20 Leases 2,213 2,221 131 2,247 27 Commercial real estate Construction 3,097 3,897 599 3,097 50 Land 1,500 1,500 3 1,567 17 Office 1,479 2,078 73 1,483 24 Industrial 63 172 1 63 2 Retail 15,347 15,415 2,512 15,315 166 Multi-family 1,234 1,277 21 1,254 12 Mixed use and other 2,036 2,281 388 2,054 30 Home equity 1,697 1,889 749 1,699 19 Residential real estate 2,253 2,956 148 2,258 33 Consumer and other 25 27 25 25 — Impaired loans with no related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 5,480 $ 6,777 $ — $ 5,650 $ 109 Franchise 18,657 18,661 — 18,675 239 Asset-based lending 86 231 — 182 3 Leases 746 746 — 754 11 Commercial real estate Construction 1,363 1,364 — 1,364 15 Land 2,329 2,434 — 2,339 31 Office 59 754 — 61 11 Industrial 1,427 1,485 — 1,430 20 Retail 2,695 2,992 — 2,710 58 Multi-family — 84 — — 1 Mixed use and other 5,284 5,981 — 5,340 80 Home equity 8,405 12,535 — 8,255 151 Residential real estate 18,305 20,983 — 18,630 222 Consumer and other 723 870 — 726 12 Total impaired loans, net of unearned income $ 103,131 $ 116,304 $ 6,863 $ 103,951 $ 1,446 For the Twelve Months Ended As of December 31, 2017 December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized (Dollars in thousands) Impaired loans with a related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 6,233 $ 7,323 $ 3,951 $ 7,220 $ 452 Franchise — — — — — Asset-based lending 948 949 355 1,302 72 Leases 2,331 2,337 158 2,463 117 Commercial real estate Construction 3,097 3,897 403 3,690 197 Land — — — — — Office 471 471 5 481 24 Industrial 408 408 40 414 25 Retail 15,599 15,657 1,336 15,736 624 Multi-family — — — — — Mixed use and other 1,567 1,586 379 1,599 77 Home equity 1,606 1,869 784 1,626 81 Residential real estate 3,798 3,910 586 3,790 146 Consumer and other 26 28 26 27 2 Impaired loans with no related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 8,460 $ 12,259 $ — $ 10,170 $ 683 Franchise 16,256 16,256 — 17,089 780 Asset-based lending 602 602 — 688 40 Leases 782 782 — 845 49 Commercial real estate Construction 1,367 1,678 — 1,555 84 Land 3,961 4,192 — 4,129 182 Office 2,438 6,140 — 3,484 330 Industrial 403 2,010 — 1,849 174 Retail 2,393 3,538 — 2,486 221 Multi-family 1,231 2,078 — 1,246 76 Mixed use and other 5,275 6,731 — 5,559 351 Home equity 7,648 11,648 — 9,114 603 Residential real estate 17,455 20,327 — 17,926 860 Consumer and other 733 890 — 773 48 Total impaired loans, net of unearned income $ 105,088 $ 127,566 $ 8,023 $ 115,261 $ 6,298 For the Three Months Ended As of March 31, 2017 March 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized (Dollars in thousands) Impaired loans with a related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 3,804 $ 3,830 $ 1,568 $ 3,856 $ 50 Franchise — — — — — Asset-based lending 1,378 1,380 378 1,279 12 Leases 2,616 2,619 304 2,689 36 Commercial real estate Construction 5,262 5,262 74 5,276 53 Land 3,033 3,033 13 3,033 28 Office 1,512 1,522 310 1,513 18 Industrial 4,831 5,554 1,703 4,854 71 Retail 1,733 1,843 156 1,739 23 Multi-family 1,256 1,256 20 1,256 11 Mixed use and other 5,472 5,561 902 5,486 67 Home equity 3,863 3,891 1,979 3,866 35 Residential real estate 5,116 5,652 666 5,166 57 Consumer and other 92 94 92 95 1 Impaired loans with no related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 10,270 $ 11,307 $ — $ 10,668 $ 185 Franchise — — — — — Leases 846 846 — 852 13 Commercial real estate Construction 3,912 3,912 — 3,973 46 Land 1,240 1,631 — 1,321 15 Office 2,487 3,803 — 2,432 56 Industrial 2,172 2,487 — 2,152 57 Retail — — — — — Multi-family 668 752 — 652 11 Mixed use and other 6,153 6,961 — 6,234 91 Home equity 8,015 10,420 — 8,176 123 Residential real estate 11,478 12,673 — 11,522 151 Consumer and other 313 401 — 315 5 Total impaired loans, net of unearned income $ 87,522 $ 96,690 $ 8,165 $ 88,405 $ 1,215 TDRs At March 31, 2018 , the Company had $47.7 million in loans modified in TDRs. The $47.7 million in TDRs represents 85 credits in which economic concessions were granted to certain borrowers to better align the terms of their loans with their current ability to pay. The Company’s approach to restructuring loans, excluding PCI loans, is built on its credit risk rating system which requires credit management personnel to assign a credit risk rating to each loan. In each case, the loan officer is responsible for recommending a credit risk rating for each loan and ensuring the credit risk ratings are appropriate. These credit risk ratings are then reviewed and approved by the bank’s chief credit officer and/or concurrence credit officer. Credit risk ratings are determined by evaluating a number of factors including a borrower’s financial strength, cash flow coverage, collateral protection and guarantees. The Company’s credit risk rating scale is one through ten with higher scores indicating higher risk. In the case of loans rated six or worse following modification, the Company’s Managed Assets Division evaluates the loan and the credit risk rating and determines that the loan has been restructured to be reasonably assured of repayment and of performance according to the modified terms and is supported by a current, well-documented credit assessment of the borrower’s financial condition and prospects for repayment under the revised terms. A modification of a loan, excluding PCI loans, with an existing credit risk rating of 6 or worse or a modification of any other credit, which will result in a restructured credit risk rating of six or worse, must be reviewed for possible TDR classification. In that event, our Managed Assets Division conducts an overall credit and collateral review. A modification of these loans is considered to be a TDR if both (1) the borrower is experiencing financial difficulty and (2) for economic or legal reasons, the bank grants a concession to a borrower that it would not otherwise consider. The modification of a loan, excluding PCI loans, where the credit risk rating is 5 or better both before and after such modification is not considered to be a TDR. Based on the Company’s credit risk rating system, it considers that borrowers whose credit risk rating is 5 or better are not experiencing financial difficulties and therefore, are not considered TDRs. All credits determined to be a TDR will continue to be classified as a TDR in all subsequent periods, unless the borrower has been in compliance with the loan’s modified terms for a period of six months (including over a calendar year-end) and the current interest rate represents a market rate at the time of restructuring. The Managed Assets Division, in consultation with the respective loan officer, determines whether the modified interest rate represented a current market rate at the time of restructuring. Using knowledge of current market conditions and rates, competitive pricing on recent loan originations, and an assessment of various characteristics of the modified loan (including collateral position and payment history), an appropriate market rate for a new borrower with similar risk is determined. If the modified interest rate meets or exceeds this market rate for a new borrower with similar risk, the modified interest rate represents a market rate at the time of restructuring. Additionally, before removing a loan from TDR classification, a review of the current or previously measured impairment on the loan and any concerns related to future performance by the borrower is conducted. If concerns exist about the future ability of the borrower to meet its obligations under the loans based on a credit review by the Managed Assets Division, the TDR classification is not removed from the loan. TDRs are reviewed at the time of the modification and on a quarterly basis to determine if a specific reserve is necessary. The carrying amount of the loan is compared to the expected payments to be received, discounted at the loan's original rate, or for collateral dependent loans, to the fair value of the collateral. Any shortfall is recorded as a specific reserve. The Company, in accordance with ASC 310-10, continues to individually measure impairment of these loans after the TDR classification is removed. Each TDR was reviewed for impairment at March 31, 2018 and approximately $1.1 million of impairment was present and appropriately reserved for through the Company’s normal reserving methodology in the Company’s allowance for loan losses. For TDRs in which impairment is calculated by the present value of future cash flows, the Company records interest income representing the decrease in impairment resulting from the passage of time during the respective period, which differs from interest income from contractually required interest on these specific loans. During the three months ended March 31, 2018 and 2017 , the Company recorded $21,000 and $55,000 , respectively, of interest income, which was reflected as a decrease in impairment. TDRs may arise in which, due to financial difficulties experienced by the borrower, the Company obtains through physical possession one or more collateral assets in satisfaction of all or part of an existing credit. Once possession is obtained, the Company reclassifies the appropriate portion of the remaining balance of the credit from loans to OREO, which is included within other assets in the Consolidated Statements of Condition. For any residential real estate property collateralizing a consumer mortgage loan, the Company is considered to possess the related collateral only if legal title is obtained upon completion of foreclosure, or the borrower conveys all interest in the residential real estate property to the Company through completion of a deed in lieu of foreclosure or similar legal agreement. At March 31, 2018 , the Company had $8.6 million of foreclosed residential real estate properties included within OREO. Furthermore, the recorded investment in residential mortgage loans secured by residential real estate properties for which foreclosure proceedings are in process totaled $11.4 million and $13.5 million at March 31, 2018 and 2017, respectively. The tables below present a summary of the post-modification balance of loans restructured during the three months ended March 31, 2018 and 2017 , respectively, which represent TDRs: Three months ended March 31, 2018 (Dollars in thousands) Total (1)(2) Extension at Below Market (2) Reduction of Interest Rate (2) Modification to Interest-only Payments (2) Forgiveness of Debt (2) Count Balance Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 1 $ 96 1 $ 96 — $ — — $ — — $ — Commercial real estate Office 1 59 1 59 — — — — — — Industrial — — — — — — — — — — Mixed use and other — — — — — — — — — — Residential real estate and other 5 835 5 835 2 111 — — — — Total loans 7 $ 990 7 $ 990 2 $ 111 — $ — — $ — Three months ended March 31, 2017 (Dollars in thousands) Total (1)(2) Extension at Below Market Terms (2) Reduction of Interest Rate (2) Modification to Interest-only Payments (2) Forgiveness of Debt (2) Count Balance Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 1 $ 95 1 $ 95 — $ — — $ — — $ — Commercial real estate Office — — — — — — — — — — Industrial — — — — — — — — — — Mixed use and other 1 1,245 1 1,245 — — — — — — Residential real estate and other 2 173 2 173 2 173 — — — — Total loans 4 $ 1,513 4 $ 1,513 2 $ 173 — $ — — $ — (1) TDRs may have more than one modification representing a concession. As such, TDRs during the period may be represented in more than one of the categories noted above. (2) Balances represent the recorded investment in the loan at the time of the restructuring. During the three months ended March 31, 2018 , seven loans totaling $1.0 million were determined to be TDRs, compared to four loans totaling $1.5 million during the three months ended March 31, 2017 . Of these loans extended at below market terms, the weighted average extension had a term of approximately 74 months during the quarter ended March 31, 2018 compared to 10 months for the quarter ended March 31, 2017 . Further, the weighted average decrease in the stated interest rate for loans with a reduction of interest rate during the period was approximately 287 basis points and 48 basis points during the three months ended March 31, 2018 and 2017 , respectively. Additionally, no principal balances were forgiven in the first quarter of 2018 and 2017. The following table presents a summary of all loans restructured in TDRs during the twelve months ended March 31, 2018 and 2017 , and such loans which were in payment default under the restructured terms during the respective periods below: (Dollars in thousands) As of March 31, 2018 Three Months Ended March 31, 2018 As of March 31, 2017 Three Months Ended March 31, 2017 Total (1)(3) Payments in Default (2)(3) Total (1)(3) Payments in Default (2)(3) Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 5 $ 3,776 5 $ 3,776 3 398 1 $ 28 Leases 3 16,256 — — 2 2,949 — — Commercial real estate Office 1 59 — — — — — — Industrial — — — — — — — — Mixed use and other — — — — 1 1,245 — — Residential real estate and other 15 3,711 5 2,551 8 1,095 1 232 Total loans 24 $ 23,802 10 $ 6,327 14 5,687 2 $ 260 (1) Total TDRs represent all loans restructured in TDRs during the previous twelve months from the date indicated. (2) TDRs considered to

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets A summary of the Company’s goodwill assets by business segment is presented in the following table: (Dollars in thousands) January 1, 2018 Goodwill Acquired Impairment Loss Goodwill Adjustments March 31, Community banking $ 429,520 $ 10,229 $ — $ — $ 439,749 Specialty finance 40,250 — — (616 ) 39,634 Wealth management 32,114 — — — 32,114 Total $ 501,884 $ 10,229 $ — $ (616 ) $ 511,497 The community banking segment's goodwill increased $10.2 million in the first three months of 2018 primarily as a result of the acquisition of Veterans First. The specialty finance segment's goodwill decreased $616,000 in the first three months of 2018 as a result of foreign currency translation adjustments related to the Canadian acquisitions. At June 30, 2017, the Company utilized a quantitative approach for its annual goodwill impairment test of the community banking segment and determined that no impairment existed at that time. At December 31, 2017, the Company utilized a quantitative approach for its annual goodwill impairment tests of the specialty finance and wealth management segments and determined that no impairment existed at that time. At each reporting date between annual goodwill impairment tests, the Company considers potential indicators of impairment. As of March 31, 2018 , the Company identified no such indicators of goodwill impairment for each business segment. A summary of intangible assets as of the dates shown and the expected amortization of finite-lived intangible assets as of March 31, 2018 is as follows: (Dollars in thousands) March 31, December 31, March 31, Community banking segment: Core deposit intangibles with finite lives: Gross carrying amount $ 37,272 $ 37,272 $ 37,272 Accumulated amortization (26,280 ) (25,427 ) (22,634 ) Net carrying amount $ 10,992 $ 11,845 $ 14,638 Trademark with indefinite lives: Carrying amount 5,800 — — Total net carrying amount $ 16,792 $ 11,845 $ 14,638 Specialty finance segment: Customer list intangibles with finite lives: Gross carrying amount $ 1,967 $ 1,972 $ 1,800 Accumulated amortization (1,335 ) (1,298 ) (1,191 ) Net carrying amount $ 632 $ 674 $ 609 Wealth management segment: Customer list and other intangibles with finite lives: Gross carrying amount $ 7,940 $ 7,940 $ 7,940 Accumulated amortization (2,951 ) (2,838 ) (2,500 ) Net carrying amount $ 4,989 $ 5,102 $ 5,440 Total other intangible assets, net $ 22,413 $ 17,621 $ 20,687 Estimated amortization Actual in three months ended March 31, 2018 $ 1,004 Estimated remaining in 2018 2,792 Estimated—2019 3,223 Estimated—2020 2,597 Estimated—2021 2,056 Estimated—2022 1,556 The core deposit intangibles recognized in connection with prior bank acquisitions are amortized over a ten -year period on an accelerated basis. The customer list intangibles recognized in connection with the purchase of life insurance premium finance assets in 2009 are being amortized over an 18 -year period on an accelerated basis while the customer list intangibles recognized in connection with prior acquisitions within the wealth management segment are being amortized over a ten -year period on a straight-line basis. Indefinite-lived intangible assets consist of certain trade and domain names recognized in connection with the Veterans First acquisition. As indefinite-lived intangible assets are not amortized, the Company assesses impairment on at least an annual basis. Total amortization expense associated with finite-lived intangibles totaled approximately $1.0 million and $1.2 million for the three months ended March 31, 2018 and 2017 , respectively.

Mortgage Servicing Rights ("MSR

Mortgage Servicing Rights ("MSRs")	3 Months Ended
	Mar. 31, 2018
Disclosures Pertaining to Servicing Assets and Servicing Liabilities [Abstract]
Mortgage Servicing Rights (MSRs)	Mortgage Servicing Rights ( “ MSRs”) The following is a summary of the changes in the carrying value of MSRs, accounted for at fair value, for the periods indicated: Three Months Ended March 31, March 31, (Dollars in thousands) 2018 2017 Balance at beginning of the period $ 33,676 $ 19,103 Additions from loans sold with servicing retained 4,159 2,766 Additions from acquisitions 13,806 — Estimate of changes in fair value due to: Payoffs and paydowns (1,202 ) (429 ) Changes in valuation inputs or assumptions 4,133 156 Fair value at end of the period $ 54,572 $ 21,596 Unpaid principal balance of mortgage loans serviced for others $ 4,795,335 $ 1,972,592 The Company recognizes MSR assets upon the sale of residential real estate loans to external third parties when it retains the obligation to service the loans and the servicing fee is more than adequate compensation. The initial recognition of MSR assets from loans sold with servicing retained and subsequent changes in fair value of all MSRs are recognized in mortgage banking revenue. MSRs are subject to changes in value from actual and expected prepayment of the underlying loans. The Company does not specifically hedge the value of its MSRs. Fair values are determined by using a discounted cash flow model that incorporates the objective characteristics of the portfolio as well as subjective valuation parameters that purchasers of servicing would apply to such portfolios sold into the secondary market. The subjective factors include loan prepayment speeds, discount rates, servicing costs and other economic factors. The Company uses a third party to assist in the valuation of MSRs.

Deposits

Deposits	3 Months Ended
	Mar. 31, 2018
Deposits [Abstract]
Deposits	Deposits The following table is a summary of deposits as of the dates shown: (Dollars in thousands) March 31, December 31, March 31, Balance: Non-interest bearing $ 6,612,319 $ 6,792,497 $ 5,790,579 NOW and interest bearing demand deposits 2,315,122 2,315,055 2,484,676 Wealth management deposits 2,495,134 2,323,699 2,390,464 Money market 4,617,122 4,515,353 4,555,752 Savings 2,901,504 2,829,373 2,287,958 Time certificates of deposit 4,338,126 4,407,370 4,221,012 Total deposits $ 23,279,327 $ 23,183,347 $ 21,730,441 Mix: Non-interest bearing 28 % 29 % 27 % NOW and interest bearing demand deposits 10 10 11 Wealth management deposits 11 10 11 Money market 20 20 21 Savings 12 12 11 Time certificates of deposit 19 19 19 Total deposits 100 % 100 % 100 % Wealth management deposits represent deposit balances (primarily money market accounts) at the Company’s subsidiary banks from brokerage customers of Wayne Hummer Investments, LLC ("WHI"), trust and asset management customers of Company and brokerage customers from unaffiliated companies.

FHLB Advances, Other Borrowings

FHLB Advances, Other Borrowings and Subordinated Notes	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
FHLB Advances, Other Borrowings and Subordinated Notes	FHLB Advances, Other Borrowings and Subordinated Notes The following table is a summary of FHLB advances, other borrowings and subordinated notes as of the dates shown: (Dollars in thousands) March 31, December 31, March 31, FHLB advances $ 915,000 $ 559,663 $ 227,585 Other borrowings: Notes payable 33,727 41,222 48,702 Short-term borrowings 17,977 17,209 39,246 Other 48,742 49,131 17,949 Secured borrowings 146,646 158,561 132,890 Total other borrowings 247,092 266,123 238,787 Subordinated notes 139,111 139,088 138,993 Total FHLB advances, other borrowings and subordinated notes $ 1,301,203 $ 964,874 $ 605,365 FHLB Advances FHLB advances consist of obligations of the banks and are collateralized by qualifying commercial and residential real estate and home equity loans and certain securities. FHLB advances are stated at par value of the debt adjusted for unamortized prepayment fees paid at the time of prior restructurings of FHLB advances and unamortized fair value adjustments recorded in connection with advances acquired through acquisitions. Notes Payable At March 31, 2018 , notes payable represented a $33.7 million term facility ("Term Facility"), which is part of a $150.0 million loan agreement ("Credit Agreement") with unaffiliated banks dated December 15, 2014 (as subsequently amended). The Credit Agreement consists of the Term Facility with an original outstanding balance of $75.0 million and a $75.0 million revolving credit facility ("Revolving Credit Facility"). At March 31, 2018 , the Company had a balance of $33.7 million compared to $41.2 million at December 31, 2017 and $48.7 million at March 31, 2017 under the Term Facility. The Term Facility is stated at par of the current outstanding balance of the debt adjusted for unamortized costs paid by the Company in relation to the debt issuance. The Company was contractually required to borrow the entire amount of the Term Facility on June 15, 2015 and all such borrowings must be repaid by June 15, 2020 . Beginning September 30, 2015 , the Company was required to make straight-line quarterly amortizing payments on the Term Facility. At March 31, 2018 , December 31, 2017 and March 31, 2017 , the Company had no outstanding balance under the Revolving Credit Facility. As no outstanding balance exists on the Revolving Credit Facility, unamortized costs paid by the Company in relation to the issuance of this debt are classified in other assets on the Consolidated Statements of Condition. In December 2017, the Company again amended the Credit Agreement, effectively extending the maturity date on the Revolving Credit Facility from December 11, 2017 to December 10, 2018. Borrowings under the Credit Agreement that are considered “Base Rate Loans” bear interest at a rate equal to the sum of (1) 50 basis points (in the case of a borrowing under the Revolving Credit Facility) or 75 basis points (in the case of a borrowing under the Term Facility) plus (2) the highest of (a) the federal funds rate plus 50 basis points , (b) the lender's prime rate, and (c) the Eurodollar Rate (as defined below) that would be applicable for an interest period of one month plus 100 basis points . Borrowings under the agreement that are considered “Eurodollar Rate Loans” bear interest at a rate equal to the sum of (1) 150 basis points (in the case of a borrowing under the Revolving Credit Facility) or 175 basis points (in the case of a borrowing under the Term Facility) plus (2) the LIBOR rate for the applicable period, as adjusted for statutory reserve requirements for eurocurrency liabilities (the “Eurodollar Rate”). A commitment fee is payable quarterly equal to 0.20% of the actual daily amount by which the lenders' commitment under the Revolving Credit Facility exceeded the amount outstanding under such facility. Borrowings under the Credit Agreement are secured by pledges of and first priority perfected security interests in the Company's equity interest in its bank subsidiaries and contain several restrictive covenants, including the maintenance of various capital adequacy levels, asset quality and profitability ratios, and certain restrictions on dividends and other indebtedness. At March 31, 2018 , the Company was in compliance with all such covenants. The Revolving Credit Facility and the Term Facility are available to be utilized, as needed, to provide capital to fund continued growth at the Company’s banks and to serve as an interim source of funds for acquisitions, common stock repurchases or other general corporate purposes. Short-term Borrowings Short-term borrowings include securities sold under repurchase agreements and federal funds purchased. These borrowings totaled $18.0 million at March 31, 2018 compared to $17.2 million at December 31, 2017 and $39.2 million at March 31, 2017 . At March 31, 2018 , December 31, 2017 and March 31, 2017 , securities sold under repurchase agreements represent $18.0 million , $17.2 million and $39.2 million , respectively, of customer sweep accounts in connection with master repurchase agreements at the banks. The Company records securities sold under repurchase agreements at their gross value and does not offset positions on the Consolidated Statements of Condition. As of March 31, 2018 , the Company had pledged securities related to its customer balances in sweep accounts of $43.4 million . Securities pledged for customer balances in sweep accounts and short-term borrowings from brokers are maintained under the Company’s control and consist of U.S. Government agency and mortgage-backed securities. These securities are included in the available-for-sale and held-to-maturity securities portfolios as reflected on the Company’s Consolidated Statements of Condition. The following is a summary of these securities pledged as of March 31, 2018 disaggregated by investment category and maturity of the related customer sweep account, and reconciled to the outstanding balance of securities sold under repurchase agreements: (Dollars in thousands) Overnight Sweep Collateral Available-for-sale securities pledged Mortgage-backed securities $ 21,499 Held-to-maturity securities pledged U.S. Government agencies 21,886 Total collateral pledged $ 43,385 Excess collateral 25,408 Securities sold under repurchase agreements $ 17,977 Other Borrowings Other borrowings at March 31, 2018 represent a fixed-rate promissory note issued by the Company in June 2017 ("Fixed-Rate Promissory Note") related to and secured by two office buildings owned by the Company, and non-recourse notes issued by the Company to other banks related to certain capital leases. At March 31, 2018 , the Fixed-Rate Promissory Note had a balance of $48.7 million compared to $49.0 million at December 31, 2017. Under the Fixed-Rate Promissory Note, the Company will make monthly principal payments and pay interest at a fixed rate of 3.36% until maturity on June 30, 2022 . The Fixed-Rate Promissory Note contains several restrictive covenants, including the maintenance of various capital adequacy levels, asset quality and profitability ratios, and certain restrictions on dividends and indebtedness. At March 31, 2018, the Company was in compliance with all such covenants. Under a previous fixed-rate promissory note with an unrelated creditor related to and secured by an office building owned by the Company, other borrowings totaled $17.6 million at March 31, 2017 . In June 2017, this previous fixed-rate promissory note was paid off upon the Company's issuance of the Fixed-Rate Promissory Note. At March 31, 2018 , the non-recourse notes related to certain capital leases totaled $75,000 compared to $151,000 and $374,000 at December 31, 2017 and March 31, 2017 , respectively. Secured Borrowings Secured borrowings at March 31, 2018 primarily represents transactions to sell an undivided co-ownership interest in all receivables owed to the Company's subsidiary, First Insurance Funding of Canada ("FIFC Canada"). In December 2014, FIFC Canada sold such interest to an unrelated third party in exchange for a cash payment of approximately C$150 million pursuant to a receivables purchase agreement (“Receivables Purchase Agreement”). The Receivables Purchase Agreement was amended in December 2015, effectively extending the maturity date from December 15, 2015 to December 15, 2017 . Additionally, at that time, the unrelated third party paid an additional C$10 million , which increased the total payments to C$160 million . The Receivables Purchase Agreement was again amended in December 2017, effectively extending the maturity date from December 15, 2017 to December 16, 2019. Additionally, in December 2017, the unrelated third party paid an additional C$10 million , which increased the total payments to C$170 million . These transactions were not considered sales of receivables and, as such, related proceeds received are reflected on the Company’s Consolidated Statements of Condition as a secured borrowing owed to the unrelated third party, net of unamortized debt issuance costs, and translated to the Company’s reporting currency as of the respective date. At March 31, 2018 , the translated balance of the secured borrowing totaled $131.7 million compared to $135.1 million at December 31, 2017 and $120.1 million at March 31, 2017 . Additionally, the interest rate under the Receivables Purchase Agreement at March 31, 2018 was 2.4253% . The remaining $15.0 million within secured borrowings at March 31, 2018 represents other sold interests in certain loans by the Company that were not considered sales and, as such, related proceeds received are reflected on the Company’s Consolidated Statements of Condition as a secured borrowing owed to the various unrelated third parties. Subordinated Notes At March 31, 2018 , the Company had outstanding subordinated notes totaling $139.1 million compared to $139.1 million and $139.0 million outstanding at December 31, 2017 and March 31, 2017 , respectively. The notes have a stated interest rate of 5.00% and mature in June 2024 . These notes are stated at par adjusted for unamortized costs paid related to the issuance of this debt.

Junior Subordinated Debentures

Junior Subordinated Debentures	3 Months Ended
	Mar. 31, 2018
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Junior Subordinated Debentures	Junior Subordinated Debentures As of March 31, 2018 , the Company owned 100% of the common securities of eleven trusts, Wintrust Capital Trust III, Wintrust Statutory Trust IV, Wintrust Statutory Trust V, Wintrust Capital Trust VII, Wintrust Capital Trust VIII, Wintrust Capital Trust IX, Northview Capital Trust I, Town Bankshares Capital Trust I, First Northwest Capital Trust I, Suburban Illinois Capital Trust II, and Community Financial Shares Statutory Trust II (the “Trusts”) set up to provide long-term financing. The Northview, Town, First Northwest, Suburban, and Community Financial Shares capital trusts were acquired as part of the acquisitions of Northview Financial Corporation, Town Bankshares, Ltd., First Northwest Bancorp, Inc., Suburban and CFIS, respectively. The Trusts were formed for purposes of issuing trust preferred securities to third-party investors and investing the proceeds from the issuance of the trust preferred securities and common securities solely in junior subordinated debentures issued by the Company (or assumed by the Company in connection with an acquisition), with the same maturities and interest rates as the trust preferred securities. The junior subordinated debentures are the sole assets of the Trusts. In each Trust, the common securities represent approximately 3% of the junior subordinated debentures and the trust preferred securities represent approximately 97% of the junior subordinated debentures. The Trusts are reported in the Company’s consolidated financial statements as unconsolidated subsidiaries. Accordingly, in the Consolidated Statements of Condition, the junior subordinated debentures issued by the Company to the Trusts are reported as liabilities and the common securities of the Trusts, all of which are owned by the Company, are included in available-for-sale securities. The following table provides a summary of the Company’s junior subordinated debentures as of March 31, 2018 . The junior subordinated debentures represent the par value of the obligations owed to the Trusts. (Dollars in thousands) Common Securities Trust Preferred Securities Junior Subordinated Debentures Rate Structure Contractual rate at 3/31/2018 Issue Date Maturity Date Earliest Redemption Date Wintrust Capital Trust III $ 774 $ 25,000 $ 25,774 L+3.25 4.97 % 04/2003 04/2033 04/2008 Wintrust Statutory Trust IV 619 20,000 20,619 L+2.80 5.11 % 12/2003 12/2033 12/2008 Wintrust Statutory Trust V 1,238 40,000 41,238 L+2.60 4.91 % 05/2004 05/2034 06/2009 Wintrust Capital Trust VII 1,550 50,000 51,550 L+1.95 4.07 % 12/2004 03/2035 03/2010 Wintrust Capital Trust VIII 1,238 25,000 26,238 L+1.45 3.76 % 08/2005 09/2035 09/2010 Wintrust Capital Trust IX 1,547 50,000 51,547 L+1.63 3.75 % 09/2006 09/2036 09/2011 Northview Capital Trust I 186 6,000 6,186 L+3.00 4.77 % 08/2003 11/2033 08/2008 Town Bankshares Capital Trust I 186 6,000 6,186 L+3.00 4.77 % 08/2003 11/2033 08/2008 First Northwest Capital Trust I 155 5,000 5,155 L+3.00 5.31 % 05/2004 05/2034 05/2009 Suburban Illinois Capital Trust II 464 15,000 15,464 L+1.75 3.87 % 12/2006 12/2036 12/2011 Community Financial Shares Statutory Trust II 109 3,500 3,609 L+1.62 3.74 % 06/2007 09/2037 06/2012 Total $ 253,566 4.33 % The junior subordinated debentures totaled $253.6 million at March 31, 2018 , December 31, 2017 and March 31, 2017 . The interest rates on the variable rate junior subordinated debentures are based on the three-month LIBOR rate and reset on a quarterly basis. At March 31, 2018 , the weighted average contractual interest rate on the junior subordinated debentures was 4.33% . Distributions on the common and preferred securities issued by the Trusts are payable quarterly at a rate per annum equal to the interest rates being earned by the Trusts on the junior subordinated debentures. Interest expense on the junior subordinated debentures is deductible for income tax purposes. The Company has guaranteed the payment of distributions and payments upon liquidation or redemption of the trust preferred securities, in each case to the extent of funds held by the Trusts. The Company and the Trusts believe that, taken together, the obligations of the Company under the guarantees, the junior subordinated debentures, and other related agreements provide, in the aggregate, a full, irrevocable and unconditional guarantee, on a subordinated basis, of all of the obligations of the Trusts under the trust preferred securities. Subject to certain limitations, the Company has the right to defer the payment of interest on the junior subordinated debentures at any time, or from time to time, for a period not to exceed 20 consecutive quarters. The trust preferred securities are subject to mandatory redemption, in whole or in part, upon repayment of the junior subordinated debentures at maturity or their earlier redemption. The junior subordinated debentures are redeemable in whole or in part prior to maturity at any time after the earliest redemption dates shown in the table, and earlier at the discretion of the Company if certain conditions are met, and, in any event, only after the Company has obtained Federal Reserve Bank ("FRB") approval, if then required under applicable guidelines or regulations. Prior to January 1, 2015, the junior subordinated debentures, subject to certain limitations, qualified as Tier 1 regulatory capital of the Company and the amount in excess of those certain limitations could, subject to other restrictions, be included in Tier 2 capital. Starting in 2015, a portion of these junior subordinated debentures still qualified as Tier 1 regulatory capital of the Company and the amount in excess of those certain limitations, subject to certain restrictions, was included in Tier 2 capital. Starting in 2016, none of the junior subordinated debentures qualified as Tier 1 regulatory capital of the Company resulting in $245.5 million of the junior subordinated debentures, net of common securities, being included in the Company's Tier 2 regulatory capital.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers As of January 1, 2018, the Company adopted ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” and all subsequent updates issued to clarify and improve specific areas of ASU 2014-09. The Company elected to adopt the new guidance using the modified retrospective approach applied to all contracts as of the date of initial application at January 1, 2018. Under the modified retrospective approach, the Company recognized no cumulative effect adjustment to the opening balance of retained earnings at the date of initial application. Disaggregation of Revenue As certain significant revenue sources related to financial instruments such as interest income are considered not in-scope, ASU 2014-09 did not have a significant impact on the Company's consolidated financial statements. The following table presents revenue from contracts with customers, considered in-scope under ASU 2014-09, disaggregated by the revenue source: (Dollars in thousands) Three Months Ended Revenue from contracts with customers Location in income statement March 31, March 31, Brokerage and insurance product commissions Wealth management $ 6,031 $ 6,220 Trust Wealth management 3,417 3,308 Asset management Wealth management 13,538 10,620 Total wealth management 22,986 20,148 Mortgage broker fees Mortgage banking 279 316 Service charges on deposit accounts Service charges on deposit accounts 8,857 8,265 Administrative services Other non-interest income 1,061 1,024 Card related fees Other non-interest income 2,139 1,415 Other deposit related fees Other non-interest income 2,858 2,358 Total revenue from contracts with customers $ 38,180 $ 33,526 Wealth Management Revenue Wealth management revenue is comprised of brokerage and insurance product commissions, managed money fees and trust and asset management revenue of the Company's three wealth management subsidiaries: WHI, Great Lakes Advisors, LLC ("GLA") and The Chicago Trust Company, N.A. ("CTC"). All wealth management revenue is recognized in the wealth management segment. Brokerage and insurance product commissions consists primarily of commissions earned from trade execution services on behalf of customers and from selling mutual funds, insurance and other investment products to customers. For trade execution services, the Company recognizes commissions and receives payment from the brokerage customers at the point of transaction execution. Commissions received from the investment or insurance product providers are recognized at the point of sale of the product. The Company also receives trail and other commissions from providers for certain plans. These are generally based on qualifying account values and are recognized once the performance obligation, specific to each provider, is satisfied on a monthly, quarterly or annual basis. Trust revenue is earned from trust and custody services that are generally performed over time. Revenue is determined periodically based on a schedule of fees applied to the value of each customer account using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Fees are typically billed on a calendar month or quarter basis in advance or in arrears depending upon the contract. Additional fees earned for certain extraordinary services performed on behalf of the customers are recognized when the service has been performed. Asset management revenue is earned from money management and advisory services that are performed over time. Revenue is based primarily on the market value of assets under management or administration using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Fees are typically billed on a calendar month or quarter basis in advance or in arrears depending upon the contract. Certain programs provide the customer with an option of paying fees as a percentage of the account value or incurring commission charges for each trade similar to brokerage and insurance product commissions. Trade commissions and any other fees received for additional services are recognized at a point in time once the performance obligation is satisfied. Mortgage Broker Fees For customers desiring a mortgage product not currently offered by the Company, the Company may refer such customers and, with permission, direct such customers' applications to certain third party mortgage brokers. Mortgage broker fees are received from these brokers for such customer referrals upon settlement of the underlying mortgage. The Company's entitlement to the consideration is contingent on the settlement of the mortgage which is highly susceptible to factors outside of the Company's influence, such as third party broker's underwriting requirements. Also, the uncertainty surrounding the consideration could be resolved in varying lengths of time, dependent upon the third party brokers. Therefore, mortgage broker fees are recognized at the settlement of the underlying mortgage when the consideration is received. Broker fees are recognized in the community banking segment. Service Charges on Deposit Accounts Service charges on deposit accounts include fees charged to deposit customers for various services, including account analysis services, and are based on factors such as the size and type of customer, type of product and number of transactions. The fees are based on a standard schedule of fees and, depending on the nature of the service performed, the service is performed at a point in time or over a period of a month. When the service is performed at a point in time, the Company recognizes and receives revenue when the service has been performed. When the service is performed over a period of a month, the Company recognizes and receives revenue in the month the service has been performed. Service charges on deposit accounts are recognized in the community banking segment. Administrative Services Administrative services revenue is earned from providing outsourced administrative services, such as data processing of payrolls, billing and cash management services, to temporary staffing service clients located throughout the United States. Fees are charged periodically (typically a payroll cycle) and computed in accordance with the contractually determined rate applied to the total gross billings administered for the period. The revenue is recognized over the period using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Other fees are charged on a per occurrence basis as the service is provided in the billing cycle. The Company has certain contracts with customers to perform outsourced administrative services and short-term accounts receivable financing. For these contracts, the total fee is allocated between the administrative services revenue and interest income during the client onboarding process based on the specific client and services provided. Administrative services revenue is recognized in the specialty finance segment. Card and Deposit Related Fees Card related fees include interchange and merchant revenue, and fees related to debit and credit cards. Interchange revenue is related to the Company issued debit cards. Other deposit related fees primarily include pay by phone processing fees, ATM and safe deposit box fees, check order charges and foreign currency related fees. Card and deposit related fees are generally based on volume of transactions and are recognized at the point in time when the service has been performed. For any consideration that is constrained, the revenue is recognized once the uncertainty is known. Upfront fees received from certain contracts are recognized on a straight line basis over the term of the contract. Card and deposit related fees are recognized in the community banking segment. Contract Balances The following table provides information about contract assets, contract liabilities and receivables from contracts with customers: (Dollars in thousands) March 31, December 31, March 31, Contract assets $ — $ — $ — Contract liabilities $ 1,614 $ 1,706 $ 1,983 Mortgage broker fees receivable $ 20 $ 69 $ 9 Wealth management receivable 8,111 8,102 7,484 Card related fees receivable 320 202 304 Total receivables from contracts with customer $ 8,451 $ 8,373 $ 7,797 Contract liabilities represent upfront fees that the Company received at inception of certain contracts. The revenue recognized that was included in the contract liability balance at beginning of the period totaled $92,000 and $82,000 for the three months ended March 31, 2018 and 2017 , respectively. Receivables are recognized in the period the Company provides services when the Company's right to consideration is unconditional. Card related fee receivable is the result of volume based fee that the Company receives from a customer on an annual basis in the second quarter of each year. Payment terms on other invoiced amounts are typically 30 days or less. Contract liabilities and receivables from contracts with customers are included within the accrued interest payable and other liabilities and accrued interest receivable and other assets line items, respectively, in the Consolidated Statements of Condition. Transaction price allocated to the remaining performance obligations For contracts with an original expected length of more than one year, the following table presents the estimated future timing of recognition of upfront fees related to card and deposit related fees. These upfront fees represent performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period. (Dollars in thousands) Estimated remaining in 2018 $ 277 Estimated—2019 369 Estimated—2020 369 Estimated—2021 303 Estimated—2022 153 Estimated—2023 143 Total $ 1,614 Practical Expedients and Exemptions The Company does not adjust the promised amount of consideration for the effects of a significant financing component if the Company expects, at contract inception, that the period between when the Company transfers a promised service to a customer and when the customer pays for that services is one year or less. The Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the entity otherwise would have recognized is one year or less.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The Company’s operations consist of three primary segments: community banking, specialty finance and wealth management. The three reportable segments are strategic business units that are separately managed as they offer different products and services and have different marketing strategies. In addition, each segment’s customer base has varying characteristics and each segment has a different regulatory environment. While the Company’s management monitors each of the fifteen bank subsidiaries’ operations and profitability separately, these subsidiaries have been aggregated into one reportable operating segment due to the similarities in products and services, customer base, operations, profitability measures, and economic characteristics. For purposes of internal segment profitability, management allocates certain intersegment and parent company balances. Management allocates a portion of revenues to the specialty finance segment related to loans and leases originated by the specialty finance segment and sold or assigned to the community banking segment. Similarly, for purposes of analyzing the contribution from the wealth management segment, management allocates a portion of the net interest income earned by the community banking segment on deposit balances of customers of the wealth management segment to the wealth management segment. See Note 10 — Deposits, for more information on these deposits. Finally, expenses incurred at the Wintrust parent company are allocated to each segment based on each segment's risk-weighted assets. The segment financial information provided in the following tables has been derived from the internal profitability reporting system used by management to monitor and manage the financial performance of the Company. The accounting policies of the segments are substantially similar to those described in “Summary of Significant Accounting Policies” in Note 1 of the Company’s 2017 Form 10-K. The Company evaluates segment performance based on after-tax profit or loss and other appropriate profitability measures common to each segment. The following is a summary of certain operating information for reportable segments: Three months ended $ Change in Contribution % Change in Contribution (Dollars in thousands) March 31, March 31, Net interest income: Community Banking $ 183,254 $ 156,280 $ 26,974 17 % Specialty Finance 32,912 26,812 6,100 23 Wealth Management 4,441 5,056 (615 ) (12 ) Total Operating Segments 220,607 188,148 32,459 17 Intersegment Eliminations 4,475 4,432 43 1 Consolidated net interest income $ 225,082 $ 192,580 $ 32,502 17 % Non-interest income: Community Banking $ 56,547 $ 42,716 $ 13,831 32 % Specialty Finance 15,725 14,156 1,569 11 Wealth Management 22,958 20,802 2,156 10 Total Operating Segments 95,230 77,674 17,556 23 Intersegment Eliminations (9,551 ) (8,909 ) (642 ) (7 ) Consolidated non-interest income $ 85,679 $ 68,765 $ 16,914 25 % Net revenue: Community Banking $ 239,801 $ 198,996 $ 40,805 21 % Specialty Finance 48,637 40,968 7,669 19 Wealth Management 27,399 25,858 1,541 6 Total Operating Segments 315,837 265,822 50,015 19 Intersegment Eliminations (5,076 ) (4,477 ) (599 ) (13 ) Consolidated net revenue $ 310,761 $ 261,345 $ 49,416 19 % Segment profit: Community Banking $ 57,280 $ 37,677 $ 19,603 52 % Specialty Finance 20,000 16,098 3,902 24 Wealth Management 4,701 4,603 98 2 Consolidated net income $ 81,981 $ 58,378 $ 23,603 40 % Segment assets: Community Banking $ 23,213,499 $ 21,164,041 $ 2,049,458 10 % Specialty Finance 4,568,906 3,966,542 602,364 15 Wealth Management 674,367 648,310 26,057 4 Consolidated total assets $ 28,456,772 $ 25,778,893 $ 2,677,879 10 %

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company primarily enters into derivative financial instruments as part of its strategy to manage its exposure to changes in interest rates. Derivative instruments represent contracts between parties that result in one party delivering cash to the other party based on a notional amount and an underlying term (such as a rate, security price or price index) as specified in the contract. The amount of cash delivered from one party to the other is determined based on the interaction of the notional amount of the contract with the underlying term. Derivatives are also implicit in certain contracts and commitments. The derivative financial instruments currently used by the Company to manage its exposure to interest rate risk include: (1) interest rate swaps to manage the interest rate risk of certain fixed and variable rate assets and variable rate liabilities; (2) interest rate lock commitments provided to customers to fund certain mortgage loans to be sold into the secondary market; (3) forward commitments for the future delivery of such mortgage loans to protect the Company from adverse changes in interest rates and corresponding changes in the value of mortgage loans held-for-sale; and (4) covered call options to economically hedge specific investment securities and receive fee income effectively enhancing the overall yield on such securities to compensate for net interest margin compression. The Company also enters into derivatives (typically interest rate swaps) with certain qualified borrowers to facilitate the borrowers’ risk management strategies and concurrently enters into mirror-image derivatives with a third party counterparty, effectively making a market in the derivatives for such borrowers. Additionally, the Company enters into foreign currency contracts to manage foreign exchange risk associated with certain foreign currency denominated assets. The Company recognizes derivative financial instruments in the consolidated financial statements at fair value regardless of the purpose or intent for holding the instrument. The Company records derivative assets and derivative liabilities on the Consolidated Statements of Condition within accrued interest receivable and other assets and accrued interest payable and other liabilities, respectively. Changes in the fair value of derivative financial instruments are either recognized in income or in shareholders’ equity as a component of other comprehensive income depending on whether the derivative financial instrument qualifies for hedge accounting and, if so, whether it qualifies as a fair value hedge or cash flow hedge. As of January 1, 2018, the Company elected to early adopt ASU No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” Generally, changes in fair values of derivatives accounted for as fair value hedges are recorded in income in the same period and in the same income statement line as changes in the fair values of the hedged items that relate to the hedged risk(s). Changes in fair values of derivative financial instruments accounted for as cash flow hedges are recorded as a component of other comprehensive income, net of deferred taxes, and reclassified to earnings when the hedged transaction affects earnings. Changes in fair values of derivative financial instruments not designated in a hedging relationship pursuant to ASC 815 are reported in non-interest income during the period of the change. Derivative financial instruments are valued by a third party and are corroborated by comparison with valuations provided by the respective counterparties. Fair values of certain mortgage banking derivatives (interest rate lock commitments and forward commitments to sell mortgage loans) are estimated based on changes in mortgage interest rates from the date of the loan commitment. The fair value of foreign currency derivatives is computed based on changes in foreign currency rates stated in the contract compared to those prevailing at the measurement date. The table below presents the fair value of the Company’s derivative financial instruments as of March 31, 2018 , December 31, 2017 and March 31, 2017 : Derivative Assets Derivative Liabilities (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, Derivatives designated as hedging instruments under ASC 815: Interest rate derivatives designated as Cash Flow Hedges $ 15,012 $ 11,914 $ 9,311 $ 35 $ 12 $ — Interest rate derivatives designated as Fair Value Hedges 4,962 2,932 2,381 — — — Total derivatives designated as hedging instruments under ASC 815 $ 19,974 $ 14,846 $ 11,692 $ 35 $ 12 $ — Derivatives not designated as hedging instruments under ASC 815: Interest rate derivatives $ 52,996 $ 34,139 $ 36,476 $ 52,408 $ 33,704 $ 35,459 Interest rate lock commitments 5,449 2,843 5,600 1,207 269 2,981 Forward commitments to sell mortgage loans 3 14 69 1,464 1,457 2,656 Foreign exchange contracts 538 227 436 585 229 435 Total derivatives not designated as hedging instruments under ASC 815 $ 58,986 $ 37,223 $ 42,581 $ 55,664 $ 35,659 $ 41,531 Total Derivatives $ 78,960 $ 52,069 $ 54,273 $ 55,699 $ 35,671 $ 41,531 Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to net interest income and to manage its exposure to interest rate movements. To accomplish these objectives, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without the exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of payments at the end of each period in which the interest rate specified in the contract exceeds the agreed upon strike price. As of March 31, 2018 , the Company had eight interest rate swap derivatives designated as cash flow hedges of variable rate deposits. When the relationship between the hedged item and hedging instrument is highly effective at achieving offsetting changes in cash flows attributable to the hedged risk, changes in the fair value of these cash flow hedges are recorded in accumulated other comprehensive income and are subsequently reclassified to interest expense as interest payments are made on such variable rate deposits. The changes in fair value (net of tax) are separately disclosed in the Consolidated Statements of Comprehensive Income. The table below provides details on each of these cash flow hedges as of March 31, 2018 : March 31, 2018 (Dollars in thousands) Notional Fair Value Maturity Date Amount Asset (Liability) Interest Rate Swaps: June 2019 $ 200,000 $ 1,496 July 2019 250,000 4,209 August 2019 275,000 5,347 January 2020 175,000 891 January 2020 25,000 127 April 2020 50,000 (7 ) April 2020 200,000 (28 ) June 2020 200,000 2,942 Total Cash Flow Hedges $ 1,375,000 $ 14,977 A rollforward of the amounts in accumulated other comprehensive loss related to interest rate derivatives designated as cash flow hedges follows: Three months ended (Dollars in thousands) March 31, March 31, Unrealized gain at beginning of period $ 11,902 $ 6,944 Amount reclassified from accumulated other comprehensive loss to interest expense on deposits and junior subordinated debentures (680 ) 356 Amount of gain recognized in other comprehensive income 3,755 1,259 Unrealized gain at end of period $ 14,977 $ 8,559 As of March 31, 2018 , the Company estimates that during the next twelve months $8.8 million will be reclassified from accumulated other comprehensive gain as an increase to interest expense. Fair Value Hedges of Interest Rate Risk Interest rate swaps designated as fair value hedges involve the payment of fixed amounts to a counterparty in exchange for the Company receiving variable payments over the life of the agreements without the exchange of the underlying notional amount. As of March 31, 2018 , the Company has eleven interest rate swaps with an aggregate notional amount of $125.3 million that were designated as fair value hedges associated with fixed rate commercial and industrial and commercial franchise loans as well as life insurance premium finance receivables. For derivatives designated and that qualify as fair value hedges, the net gain or loss from the entire change in the fair value of the derivative instrument is recognized in the same income statement line item as the earnings effect, including the net gain or loss, of the hedged item (interest income earned on fixed rate loans) when the hedged item affects earnings. The following table presents the carrying amount of the hedged assets/(liabilities) and the cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets/(liabilities) that are designated as a fair value hedge accounting relationship as of March 31, 2018 : March 31, 2018 (Dollars in thousands) Derivatives in Fair Value Hedging Relationships Location in the Statement of Condition Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued Interest rate swaps Loans, net of unearned income, excluding covered loans $ 115,092 $ (5,106 ) $ — The following table presents the gain or loss recognized related to derivative instruments that are designated as fair value hedges for the respective period: (Dollars in thousands) Derivatives in Fair Value Hedging Relationships Location of Gain/(Loss) Recognized in Income on Derivative Three Months Ended March 31, 2018 Interest rate swaps Interest and fees on loans $ (45 ) Non-Designated Hedges The Company does not use derivatives for speculative purposes. Derivatives not designated as accounting hedges are used to manage the Company’s economic exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of ASC 815. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings. Interest Rate Derivatives —The Company has interest rate derivatives, including swaps and option products, resulting from a service the Company provides to certain qualified borrowers. The Company’s banking subsidiaries execute certain derivative products (typically interest rate swaps) directly with qualified commercial borrowers to facilitate their respective risk management strategies. For example, these arrangements allow the Company’s commercial borrowers to effectively convert a variable rate loan to a fixed rate. In order to minimize the Company’s exposure on these transactions, the Company simultaneously executes offsetting derivatives with third parties. In most cases, the offsetting derivatives have mirror-image terms, which result in the positions’ changes in fair value substantially offsetting through earnings each period. However, to the extent that the derivatives are not a mirror-image and because of differences in counterparty credit risk, changes in fair value will not completely offset resulting in some earnings impact each period. Changes in the fair value of these derivatives are included in other non-interest income. At March 31, 2018 , the Company had interest rate derivative transactions with an aggregate notional amount of approximately $5.0 billion (all interest rate swaps and caps with customers and third parties) related to this program. These interest rate derivatives had maturity dates ranging from April 2018 to February 2045 . Mortgage Banking Derivatives— These derivatives include interest rate lock commitments provided to customers to fund certain mortgage loans to be sold into the secondary market and forward commitments for the future delivery of such loans. It is the Company’s practice to enter into forward commitments for the future delivery of a portion of our residential mortgage loan production when interest rate lock commitments are entered into in order to economically hedge the effect of future changes in interest rates on its commitments to fund the loans as well as on its portfolio of mortgage loans held-for-sale. The Company’s mortgage banking derivatives have not been designated as being in hedge relationships. At March 31, 2018 , the Company had forward commitments to sell mortgage loans with an aggregate notional amount of approximately $813.4 million and interest rate lock commitments with an aggregate notional amount of approximately $376.3 million . The fair values of these derivatives were estimated based on changes in mortgage rates from the dates of the commitments. Changes in the fair value of these mortgage banking derivatives are included in mortgage banking revenue. Foreign Currency Derivatives— These derivatives include foreign currency contracts used to manage the foreign exchange risk associated with foreign currency denominated assets and transactions. Foreign currency contracts, which include spot and forward contracts, represent agreements to exchange the currency of one country for the currency of another country at an agreed-upon price on an agreed-upon settlement date. As a result of fluctuations in foreign currencies, the U.S. dollar-equivalent value of the foreign currency denominated assets or forecasted transactions increase or decrease. Gains or losses on the derivative instruments related to these foreign currency denominated assets or forecasted transactions are expected to substantially offset this variability. As of March 31, 2018 the Company held foreign currency derivatives with an aggregate notional amount of approximately $38.1 million . Other Derivatives— Periodically, the Company will sell options to a bank or dealer for the right to purchase certain securities held within the banks’ investment portfolios (covered call options). These option transactions are designed primarily to mitigate overall interest rate risk and to increase the total return associated with the investment securities portfolio. These options do not qualify as accounting hedges pursuant to ASC 815, and, accordingly, changes in fair value of these contracts are recognized as other non-interest income. There were no covered call options outstanding as of March 31, 2018 , December 31, 2017 or March 31, 2017 . Amounts included in the Consolidated Statements of Income related to derivative instruments not designated in hedge relationships were as follows: (Dollars in thousands) Three Months Ended Derivative Location in income statement March 31, March 31, Interest rate swaps and caps Trading gains (losses), net $ 153 $ (303 ) Mortgage banking derivatives Mortgage banking revenue 1,418 738 Covered call options Fees from covered call options 1,597 759 Foreign exchange contracts Trading losses, net (43 ) (28 ) Credit Risk Derivative instruments have inherent risks, primarily market risk and credit risk. Market risk is associated with changes in interest rates and credit risk relates to the risk that the counterparty will fail to perform according to the terms of the agreement. The amounts potentially subject to market and credit risks are the streams of interest payments under the contracts and the market value of the derivative instrument and not the notional principal amounts used to express the volume of the transactions. Market and credit risks are managed and monitored as part of the Company's overall asset-liability management process, except that the credit risk related to derivatives entered into with certain qualified borrowers is managed through the Company's standard loan underwriting process since these derivatives are secured through collateral provided by the loan agreements. Actual exposures are monitored against various types of credit limits established to contain risk within parameters. When deemed necessary, appropriate types and amounts of collateral are obtained to minimize credit exposure. The Company has agreements with certain of its interest rate derivative counterparties that contain cross-default provisions, which provide that if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations. The Company also has agreements with certain of its derivative counterparties that contain a provision allowing the counterparty to terminate the derivative positions if the Company fails to maintain its status as a well or adequately capitalized institution, which would require the Company to settle its obligations under the agreements. As of March 31, 2018 , the fair value of interest rate derivatives in a net liability position that were subject to such agreements, which includes accrued interest related to these agreements, was $456,000 . If the Company had breached any of these provisions and the derivatives were terminated as a result, the Company would have been required to settle its obligations under the agreements at the termination value and would have been required to pay any additional amounts due in excess of amounts previously posted as collateral with the respective counterparty. The Company is also exposed to the credit risk of its commercial borrowers who are counterparties to interest rate derivatives with the banks. This counterparty risk related to the commercial borrowers is managed and monitored through the banks' standard underwriting process applicable to loans since these derivatives are secured through collateral provided by the loan agreement. The counterparty risk associated with the mirror-image swaps executed with third parties is monitored and managed in connection with the Company's overall asset liability management process. The Company records interest rate derivatives subject to master netting agreements at their gross value and does not offset derivative assets and liabilities on the Consolidated Statements of Condition. The tables below summarize the Company's interest rate derivatives and offsetting positions as of the dates shown. Derivative Assets Derivative Liabilities Fair Value Fair Value (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, Gross Amounts Recognized $ 72,970 $ 48,985 $ 48,168 $ 52,443 $ 33,716 $ 35,459 Less: Amounts offset in the Statements of Financial Condition — — — — — — Net amount presented in the Statements of Financial Condition $ 72,970 $ 48,985 $ 48,168 $ 52,443 $ 33,716 $ 35,459 Gross amounts not offset in the Statements of Financial Condition Offsetting Derivative Positions $ (9,627 ) (14,878 ) (16,529 ) $ (9,627 ) (14,878 ) (16,529 ) Collateral Posted (54,490 ) (18,060 ) (6,990 ) (340 ) (2,220 ) (12,300 ) Net Credit Exposure $ 8,853 $ 16,047 $ 24,649 $ 42,476 $ 16,618 $ 6,630

Fair Values of Assets and Liabi

Fair Values of Assets and Liabilities	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Values of Assets and Liabilities	Fair Values of Assets and Liabilities The Company measures, monitors and discloses certain of its assets and liabilities on a fair value basis. These financial assets and financial liabilities are measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the observability of the inputs used to determine fair value. These levels are: • Level 1—unadjusted quoted prices in active markets for identical 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 include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability or inputs that are derived principally from or corroborated by observable market data by correlation or other means. • Level 3—significant unobservable inputs that reflect the Company’s own assumptions that market participants would use in pricing the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. A financial instrument’s categorization within the above valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the assets or liabilities. The following is a description of the valuation methodologies used for the Company’s assets and liabilities measured at fair value on a recurring basis. Available-for-sale securities, trading account securities and equity securities with readily determinable fair value —Fair values for available-for-sale securities, trading account securities and equity securities with readily determinable fair value are typically based on prices obtained from independent pricing vendors. Securities measured with these valuation techniques are generally classified as Level 2 of the fair value hierarchy. Typically, standard inputs such as benchmark yields, reported trades for similar securities, issuer spreads, benchmark securities, bids, offers and reference data including market research publications are used to fair value a security. When these inputs are not available, broker/dealer quotes may be obtained by the vendor to determine the fair value of the security. We review the vendor’s pricing methodologies to determine if observable market information is being used, versus unobservable inputs. Fair value measurements using significant inputs that are unobservable in the market due to limited activity or a less liquid market are classified as Level 3 in the fair value hierarchy. The Company’s Investment Operations Department is responsible for the valuation of Level 3 available-for-sale securities. The methodology and variables used as inputs in pricing Level 3 securities are derived from a combination of observable and unobservable inputs. The unobservable inputs are determined through internal assumptions that may vary from period to period due to external factors, such as market movement and credit rating adjustments. At March 31, 2018 , the Company classified $84.6 million of municipal securities as Level 3. These municipal securities are bond issues for various municipal government entities primarily located in the Chicago metropolitan area and southern Wisconsin and are privately placed, non-rated bonds without CUSIP numbers. The Company also classified $3.6 million of U.S. government agencies as Level 3 at March 31, 2018 . The Company’s methodology for pricing these securities focuses on three distinct inputs: equivalent rating, yield and other pricing terms. To determine the rating for a given non-rated municipal bond, the Investment Operations Department references a publicly issued bond by the same issuer if available. A reduction is then applied to the rating obtained from the comparable bond, as the Company believes if liquidated, a non-rated bond would be valued less than a similar bond with a verifiable rating. The reduction applied by the Company is one complete rating grade (i.e. a “AA” rating for a comparable bond would be reduced to “A” for the Company’s valuation). In the first quarter of 2018 , all of the ratings derived in the above process by Investment Operations were BBB or better, for both bonds with and without comparable bond proxies. The fair value measurement of municipal bonds is sensitive to the rating input, as a higher rating typically results in an increased valuation. The remaining pricing inputs used in the bond valuation are observable. Based on the rating determined in the above process, Investment Operations obtains a corresponding current market yield curve available to market participants. Other terms including coupon, maturity date, redemption price, number of coupon payments per year, and accrual method are obtained from the individual bond term sheets. Certain municipal bonds held by the Company at March 31, 2018 have a call date that has passed, and are now continuously callable. When valuing these bonds, the fair value is capped at par value as the Company assumes a market participant would not pay more than par for a continuously callable bond. To determine the rating for the U.S. government agency securities, the Investment Operations Department assigned a AAA rating as it is guaranteed by the U.S. government. Mortgage loans held-for-sale —The fair value of mortgage loans held-for-sale is determined by reference to investor price sheets for loan products with similar characteristics. Loans held-for-investment —The fair value for loans in which the Company elected the fair value option is estimated by discounting future scheduled cash flows for the specific loan through maturity, adjusted for estimated credit losses and prepayments. The Company uses a discount rate based on the actual coupon rate of the underlying loan. At March 31, 2018 , the Company classified $26.6 million of loans held-for-investment as Level 3. The weighted average discount rate used as an input to value these loans at March 31, 2018 was 4.14% with discount rates applied ranging from 3% - 4% . The higher the rate utilized to discount estimated future cash flows, the lower the fair value measurement. As noted above, the fair value estimate also includes assumptions of prepayment speeds and credit losses. The Company included a prepayments speed assumption of 8.76% at March 31, 2018 . Prepayment speeds are inversely related to the fair value of these loans as an increase in prepayment speeds results in a decreased valuation. Additionally, the weighted average credit discount used as an input to value the specific loans was 1.88% with credit loss discount ranging from 0% - 11% at March 31, 2018 . MSRs —Fair value for MSRs is determined utilizing a valuation model which calculates the fair value of each servicing rights based on the present value of estimated future cash flows. The Company uses a discount rate commensurate with the risk associated with each servicing rights, given current market conditions. At March 31, 2018 , the Company classified $54.6 million of MSRs as Level 3. The weighted average discount rate used as an input to value the pool of MSRs at March 31, 2018 was 10.02% with discount rates applied ranging from 7% - 17% . The higher the rate utilized to discount estimated future cash flows, the lower the fair value measurement. The fair value of MSRs was also estimated based on other assumptions including prepayment speeds and the cost to service. Prepayment speeds used as an input to value the MSRs at March 31, 2018 ranged from 0% - 87% or a weighted average prepayment speed of 9.40% . Further, for current and delinquent loans, the Company assumed a weighted average cost of servicing of $78 and $368 , respectively, per loan. Prepayment speeds and the cost to service are both inversely related to the fair value of MSRs as an increase in prepayment speeds or the cost to service results in a decreased valuation. See Note 9 - Mortgage Servicing Rights (“MSRs”) for further discussion of MSRs. Derivative instruments —The Company’s derivative instruments include interest rate swaps and caps, commitments to fund mortgages for sale into the secondary market (interest rate locks), forward commitments to end investors for the sale of mortgage loans and foreign currency contracts. Interest rate swaps and caps are valued by a third party, using models that primarily use market observable inputs, such as yield curves, and are validated by comparison with valuations provided by the respective counterparties. The credit risk associated with derivative financial instruments that are subject to master netting agreements is measured on a net basis by counterparty portfolio. The fair value for mortgage-related derivatives is based on changes in mortgage rates from the date of the commitments. The fair value of foreign currency derivatives is computed based on change in foreign currency rates stated in the contract compared to those prevailing at the measurement date. At March 31, 2018 , the Company classified $4.6 million of derivative assets related to interest rate locks as Level 3. The fair value of interest rate locks is based on prices obtained for loans with similar characteristics from third parties, adjusted for the pull-through rate, which represents the Company’s best estimate of the likelihood that a committed loan will ultimately fund. The weighted-average pull-through rate at March 31, 2018 was 85.34% with pull-through rates applied ranging from 32% to 100% . Pull-through rates are directly related to the fair value of interest rate locks as an increase in the pull-through rate results in an increased valuation. Nonqualified deferred compensation assets —The underlying assets relating to the nonqualified deferred compensation plan are included in a trust and primarily consist of non-exchange traded institutional funds which are priced based by an independent third party service. The following tables present the balances of assets and liabilities measured at fair value on a recurring basis for the periods presented: March 31, 2018 (Dollars in thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 24,727 $ — $ 24,727 $ — U.S. Government agencies 149,336 — 145,720 3,616 Municipal 121,758 — 37,166 84,592 Corporate notes 99,714 — 99,714 — Mortgage-backed 1,500,153 — 1,500,153 — Trading account securities 1,682 — 1,682 — Equity securities with readily determinable fair value 37,832 — 37,832 — Mortgage loans held-for-sale 411,505 — 411,505 — Loans held-for-investment 67,962 — 41,342 26,620 MSRs 54,572 — — 54,572 Nonqualified deferred compensation assets 11,724 — 11,724 — Derivative assets 78,960 — 74,355 4,605 Total $ 2,559,925 $ — $ 2,385,920 $ 174,005 Derivative liabilities $ 55,699 $ — $ 55,699 $ — December 31, 2017 (Dollars in thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 143,822 $ — $ 143,822 $ — U.S. Government agencies 156,915 — 153,136 3,779 Municipal 115,352 — 38,171 77,181 Corporate notes 31,050 — 31,050 — Mortgage-backed 1,319,725 — 1,319,725 — Equity securities 36,802 — 36,802 — Trading account securities 995 — 995 — Mortgage loans held-for-sale 313,592 — 313,592 — Loans held-for-investment 33,717 — — 33,717 MSRs 33,676 — — 33,676 Nonqualified deferred compensation assets 11,065 — 11,065 — Derivative assets 52,069 — 49,912 2,157 Total $ 2,248,780 $ — $ 2,098,270 $ 150,510 Derivative liabilities $ 35,671 $ — $ 35,671 $ — March 31, 2017 (Dollars in thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 142,156 $ — $ 142,156 $ — U.S. Government agencies 177,829 — 173,546 4,283 Municipal 127,563 — 47,818 79,745 Corporate notes 65,424 — 65,424 — Mortgage-backed 1,256,044 — 1,256,044 — Equity securities 34,717 — 34,717 — Trading account securities 714 — 714 — Mortgage loans held-for-sale 288,964 — 288,964 — Loans held-for-investment 28,548 — — 28,548 MSRs 21,596 — — 21,596 Nonqualified deferred compensation assets 10,347 — 10,347 — Derivative assets 54,273 — 50,691 3,582 Total $ 2,208,175 $ — $ 2,070,421 $ 137,754 Derivative liabilities $ 41,531 $ — $ 41,531 $ — The aggregate remaining contractual principal balance outstanding as of March 31, 2018 , December 31, 2017 and March 31, 2017 for mortgage loans held-for-sale measured at fair value under ASC 825 was $396.9 million , $299.5 million and $277.3 million , respectively, while the aggregate fair value of mortgage loans held-for-sale was $411.5 million , $313.6 million and $289.0 million , for the same respective periods, as shown in the above tables. There were no nonaccrual loans or loans past due greater than 90 days and still accruing in the mortgage loans held-for-sale portfolio as of March 31, 2018 , December 31, 2017 and March 31, 2017 . The changes in Level 3 assets measured at fair value on a recurring basis during the three months ended March 31, 2018 and 2017 are summarized as follows: U.S. Government Agencies Loans held-for- investment Mortgage servicing rights Derivative Assets (Dollars in thousands) Municipal Balance at January 1, 2018 $ 77,181 $ 3,779 $ 33,717 $ 33,676 $ 2,157 Total net gains (losses) included in: Net income (1) — — (1,128 ) 7,090 2,448 Other comprehensive loss (2,190 ) (163 ) — — — Purchases (2) 12,270 — — 13,806 — Issuances — — — — — Sales — — — — — Settlements (2,669 ) — (6,255 ) — — Net transfers into/(out of) Level 3 — — 286 — — Balance at March 31, 2018 $ 84,592 $ 3,616 $ 26,620 $ 54,572 $ 4,605 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income. (2) Purchased as a part of the Veterans First business combination. See Note 3 - Business Combinations for further discussion. U.S. Government Agencies Loans held-for- investment Mortgage servicing rights Derivative Assets (Dollars in thousands) Municipal Balance at January 1, 2017 $ 79,626 $ — $ 22,137 $ 19,103 $ 2,291 Total net gains (losses) included in: Net income (1) — — (112 ) 2,493 1,291 Other comprehensive loss 457 — — — — Purchases 7,586 — — — — Issuances — — — — — Sales — — — — — Settlements (7,924 ) — (3,332 ) — — Net transfers into/(out of) Level 3 — 4,283 9,855 — — Balance at March 31, 2017 $ 79,745 $ 4,283 $ 28,548 $ 21,596 $ 3,582 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income. Also, the Company may be required, from time to time, to measure certain other financial assets at fair value on a nonrecurring basis in accordance with GAAP. These adjustments to fair value usually result from impairment charges on individual assets. For assets measured at fair value on a nonrecurring basis that were still held in the balance sheet at the end of the period, the following table provides the carrying value of the related individual assets or portfolios at March 31, 2018 . March 31, 2018 Three Months Ended March 31, 2018 Fair Value Losses Recognized, net (Dollars in thousands) Total Level 1 Level 2 Level 3 Impaired loans—collateral based $ 68,684 $ — $ — $ 68,684 $ 3,886 Other real estate owned (1) 36,598 — — 36,598 2,158 Total $ 105,282 $ — $ — $ 105,282 $ 6,044 (1) Fair value losses recognized, net on other real estate owned include valuation adjustments and charge-offs during the respective period. Impaired loans —A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due pursuant to the contractual terms of the loan agreement. A loan modified in a TDR is an impaired loan according to applicable accounting guidance. Impairment is measured by estimating the fair value of the loan based on the present value of expected cash flows, the market price of the loan, or the fair value of the underlying collateral. Impaired loans are considered a fair value measurement where an allowance is established based on the fair value of collateral. Appraised values, which may require adjustments to market-based valuation inputs, are generally used on real estate collateral-dependent impaired loans. The Company’s Managed Assets Division is primarily responsible for the valuation of Level 3 inputs of impaired loans. For more information on the Managed Assets Division review of impaired loans refer to Note 7 – Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans. At March 31, 2018 , the Company had $103.1 million of impaired loans classified as Level 3. Of the $103.1 million of impaired loans, $68.7 million were measured at fair value based on the underlying collateral of the loan as shown in the table above. The remaining $34.4 million were valued based on discounted cash flows in accordance with ASC 310. Other real estate owned —Other real estate owned is comprised of real estate acquired in partial or full satisfaction of loans and is included in other assets. Other real estate owned is recorded at its estimated fair value less estimated selling costs at the date of transfer, with any excess of the related loan balance over the fair value less expected selling costs charged to the allowance for loan losses. Subsequent changes in value are reported as adjustments to the carrying amount and are recorded in other non-interest expense. Gains and losses upon sale, if any, are also charged to other non-interest expense. Fair value is generally based on third party appraisals and internal estimates that are adjusted by a discount representing the estimated cost of sale and is therefore considered a Level 3 valuation. The Company’s Managed Assets Division is primarily responsible for the valuation of Level 3 inputs for other real estate owned. At March 31, 2018 , the Company had $36.6 million of other real estate owned classified as Level 3. The unobservable input applied to other real estate owned relates to the 10% reduction to the appraisal value representing the estimated cost of sale of the foreclosed property. A higher discount for the estimated cost of sale results in a decreased carrying value. The valuation techniques and significant unobservable inputs used to measure both recurring and non-recurring Level 3 fair value measurements at March 31, 2018 were as follows: (Dollars in thousands) Fair Value Valuation Methodology Significant Unobservable Input Range of Inputs Weighted Average of Inputs Impact to valuation from an increased or higher input value Measured at fair value on a recurring basis: Municipal Securities $ 84,592 Bond pricing Equivalent rating BBB-AA+ N/A Increase U.S. Government agencies 3,616 Bond pricing Equivalent rating AAA AAA Increase Loans held-for-investment 26,620 Discounted cash flows Discount rate 3%-4% 4.14% Decrease Credit discount 0%-11% 1.88% Decrease Constant prepayment rate (CPR) 8.76% 8.76% Decrease MSRs 54,572 Discounted cash flows Discount rate 7%-17% 10.02% Decrease Constant prepayment rate (CPR) 0%-87% 9.40% Decrease Cost of servicing $70-$200 $78 Decrease Cost of servicing - delinquent $200-$1,000 $368 Decrease Derivatives 4,605 Discounted cash flows Pull-through rate 32%-100% 85.34% Increase Measured at fair value on a non-recurring basis: Impaired loans—collateral based $ 68,684 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease Other real estate owned 36,598 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease The Company is required under applicable accounting guidance to report the fair value of all financial instruments on the consolidated statements of condition, including those financial instruments carried at cost. The table below presents the carrying amounts and estimated fair values of the Company’s financial instruments as of the dates shown: At March 31, 2018 At December 31, 2017 At March 31, 2017 Carrying Fair Carrying Fair Carrying Fair (Dollars in thousands) Value Value Value Value Value Value Financial Assets: Cash and cash equivalents $ 231,464 $ 231,464 $ 277,591 $ 277,591 $ 217,148 $ 217,148 Interest bearing deposits with banks 980,380 980,380 1,063,242 1,063,242 1,007,468 1,007,468 Available-for-sale securities 1,895,688 1,895,688 1,803,666 1,803,666 1,803,733 1,803,733 Held-to-maturity securities 892,937 862,527 826,449 812,516 667,764 647,895 Trading account securities 1,682 1,682 995 995 714 714 Equity securities with readily determinable fair value 37,832 37,832 — — — — FHLB and FRB stock, at cost 104,956 104,956 89,989 89,989 78,904 78,904 Brokerage customer receivables 24,531 24,531 26,431 26,431 23,171 23,171 Mortgage loans held-for-sale, at fair value 411,505 411,505 313,592 313,592 288,964 288,964 Loans held-for-investment, at fair value 67,962 67,962 33,717 33,717 28,548 28,548 Loans held-for-investment, at amortized cost 21,994,172 22,234,795 21,607,080 21,768,978 19,954,869 21,048,751 MSRs 54,572 54,572 33,676 33,676 21,596 21,596 Nonqualified deferred compensation assets 11,724 11,724 11,065 11,065 10,347 10,347 Derivative assets 78,960 78,960 52,069 52,069 54,273 54,273 Accrued interest receivable and other 236,131 236,131 227,649 227,649 209,623 209,623 Total financial assets $ 27,024,496 $ 27,234,709 $ 26,367,211 $ 26,515,176 $ 24,367,122 $ 25,441,135 Financial Liabilities Non-maturity deposits $ 18,941,201 $ 18,941,201 $ 18,775,977 $ 18,775,977 $ 17,509,429 $ 17,509,429 Deposits with stated maturities 4,338,126 4,344,584 4,407,370 4,350,004 4,221,012 4,210,294 FHLB advances 915,000 916,513 559,663 544,750 227,585 229,338 Other borrowings 247,092 247,092 266,123 266,123 238,787 238,787 Subordinated notes 139,111 140,889 139,088 144,266 138,993 141,180 Junior subordinated debentures 253,566 268,873 253,566 264,696 253,566 254,417 Derivative liabilities 55,699 55,699 35,671 35,671 41,531 41,531 FDIC indemnification liability — — — — 18,264 18,264 Accrued interest payable 11,442 11,442 8,030 8,030 7,944 7,944 Total financial liabilities $ 24,901,237 $ 24,926,293 $ 24,445,488 $ 24,389,517 $ 22,657,111 $ 22,651,184 Not all the financial instruments listed in the table above are subject to the disclosure provisions of ASC Topic 820, as certain assets and liabilities result in their carrying value approximating fair value. These include cash and cash equivalents, interest bearing deposits with banks, brokerage customer receivables, FHLB and FRB stock, FDIC indemnification liability, accrued interest receivable and accrued interest payable and non-maturity deposits. The following methods and assumptions were used by the Company in estimating fair values of financial instruments that were not previously disclosed. Held-to-maturity securities. Held-to-maturity securities include U.S. Government-sponsored agency securities and municipal bonds issued by various municipal government entities primarily located in the Chicago metropolitan area and southern Wisconsin. Fair values for held-to-maturity securities are typically based on prices obtained from independent pricing vendors. In accordance with ASC 820, the Company has categorized these held-to-maturity securities as a Level 2 fair value measurement. Fair values for certain other held-to-maturity securities are based on the bond pricing methodology discussed previously related to certain available-for-sale securities. In accordance with ASC 820, the Company has categorized these held-to-maturity securities as a Level 3 fair value measurement. Loans held-for-investment, at amortized cost. Fair values are estimated for portfolios of loans with similar financial characteristics. Loans are analyzed by type such as commercial, residential real estate, etc. Each category is further segmented by interest rate type (fixed and variable) and term. For variable-rate loans that reprice frequently, estimated fair values are based on carrying values. The fair value of residential loans is based on secondary market sources for securities backed by similar loans, adjusted for differences in loan characteristics. The fair value for other fixed rate loans is estimated by discounting scheduled cash flows through the estimated maturity using estimated market discount rates that reflect credit and interest rate risks inherent in the loan. The primary impact of credit risk on the present value of the loan portfolio, however, was assessed through the use of the allowance for loan losses, which is believed to represent the current fair value of probable incurred losses for purposes of the fair value calculation. In accordance with ASC 820, the Company has categorized loans as a Level 3 fair value measurement. Deposits with stated maturities. The fair value of certificates of deposit is based on the discounted value of contractual cash flows. The discount rate is estimated using the rates currently in effect for deposits of similar remaining maturities. In accordance with ASC 820, the Company has categorized deposits with stated maturities as a Level 3 fair value measurement. FHLB advances. The fair value of FHLB advances is obtained from the FHLB which uses a discounted cash flow analysis based on current market rates of similar maturity debt securities to discount cash flows. In accordance with ASC 820, the Company has categorized FHLB advances as a Level 3 fair value measurement. Subordinated notes. The fair value of the subordinated notes is based on a market price obtained from an independent pricing vendor. In accordance with ASC 820, the Company has categorized subordinated notes as a Level 2 fair value measurement. Junior subordinated debentures. The fair value of the junior subordinated debentures is based on the discounted value of contractual cash flows. In accordance with ASC 820, the Company has categorized junior subordinated debentures as a Level 3 fair value measurement.

Stock-Based Compensation Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 2018
Share-based Compensation [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans In May 2015, the Company’s shareholders approved the 2015 Stock Incentive Plan (“the 2015 Plan”) which provides for the issuance of up to 5,485,000 shares of common stock. The 2015 Plan replaced the 2007 Stock Incentive Plan (“the 2007 Plan”) which replaced the 1997 Stock Incentive Plan (“the 1997 Plan”). The 2015 Plan, the 2007 Plan and the 1997 Plan are collectively referred to as “the Plans.” The 2015 Plan has substantially similar terms to the 2007 Plan and the 1997 Plan. Outstanding awards under the Plans for which common shares are not issued by reason of cancellation, forfeiture, lapse of such award or settlement of such award in cash, are again available under the 2015 Plan. All grants made after the approval of the 2015 Plan are made pursuant to the 2015 Plan. As of March 31, 2018 , approximately 3.4 million shares were available for future grants assuming the maximum number of shares are issued for the performance awards outstanding. The Plans cover substantially all employees of Wintrust. The Compensation Committee of the Board of Directors administers all stock-based compensation programs and authorizes all awards granted pursuant to the Plans. The Plans permit the grant of incentive stock options, non-qualified stock options, stock appreciation rights, stock awards, restricted share or unit awards, performance awards and other incentive awards valued in whole or in part by reference to the Company’s common stock, all on a stand alone, combination or tandem basis. The Company historically awarded stock-based compensation in the form of time-vested non-qualified stock options and time-vested restricted share unit awards (“restricted shares”). The grants of options provide for the purchase of shares of the Company’s common stock at the fair market value of the stock on the date the options are granted. Stock options generally vest ratably over periods of three to five years and have a maximum term of seven years from the date of grant. Restricted shares entitle the holders to receive, at no cost, shares of the Company’s common stock. Restricted shares generally vest over periods of one to five years from the date of grant. Beginning in 2011, the Company has awarded annual grants under the Long-Term Incentive Program (“LTIP”), which is administered under the Plans. The LTIP is designed in part to align the interests of management with the interests of shareholders, foster retention, create a long-term focus based on sustainable results and provide participants with a target long-term incentive opportunity. It is anticipated that LTIP awards will continue to be granted annually. LTIP grants generally consist of a combination of time-vested non-qualified stock options, performance-based stock awards and performance-based cash awards. Performance-based stock and cash awards granted under the LTIP are contingent upon the achievement of pre-established long-term performance goals set in advance by the Compensation Committee over a three -year period starting at the beginning of each calendar year. These performance awards are granted at a target level, and based on the Company’s achievement of the pre-established long-term goals, the actual payouts can range from 0% to a maximum of 150% (for awards granted after 2014) or 200% (for awards granted prior to 2015) of the target award. The awards vest in the quarter after the end of the performance period upon certification of the payout by the Compensation Committee of the Board of Directors. Holders of performance-based stock awards are entitled to receive, at no cost, the shares earned based on the achievement of the pre-established long-term goals. Holders of restricted share awards and performance-based stock awards received under the Plans are not entitled to vote or receive cash dividends (or cash payments equal to the cash dividends) on the underlying common shares until the awards are vested and issued. Shares that are vested but not issuable pursuant to deferred compensation arrangements accrue additional shares based on the value of dividends otherwise paid. Except in limited circumstances, these awards are canceled upon termination of employment without any payment of consideration by the Company. Stock-based compensation is measured as the fair value of an award on the date of grant, and the measured cost is recognized over the period which the recipient is required to provide service in exchange for the award. The fair values of restricted share and performance-based stock awards are determined based on the average of the high and low trading prices on the grant date, and the fair value of stock options is estimated using a Black-Scholes option-pricing model that utilizes various assumptions. Option-pricing models require the input of highly subjective assumptions and are sensitive to changes in the option's expected life and the price volatility of the underlying stock, which can materially affect the fair value estimate. Options granted since the inception of the LTIP in 2011 were primarily granted as LTIP awards. Expected life of options granted since the inception of the LTIP awards has been based on the safe harbor rule of the SEC Staff Accounting Bulletin No. 107 “Share-Based Payment” as the Company believes historical exercise data may not provide a reasonable basis to estimate the expected term of these options. Expected stock price volatility is based on historical volatility of the Company's common stock, which correlates with the expected life of the options, and the risk-free interest rate is based on comparable U.S. Treasury rates. Management reviews and adjusts the assumptions used to calculate the fair value of an option on a periodic basis to better reflect expected trends. No options were granted in the three month periods ended March 31, 2018 and March 31, 2017 . Stock based compensation is recognized based upon the number of awards that are ultimately expected to vest, taking into account expected forfeitures. In addition, for performance-based awards, an estimate is made of the number of shares expected to vest as a result of actual performance against the performance criteria in the award to determine the amount of compensation expense to recognize. The estimate is reevaluated periodically and total compensation expense is adjusted for any change in estimate in the current period. Stock-based compensation expense recognized in the Consolidated Statements of Income was $3.7 million in the first quarter of 2018 and $2.9 million in the first quarter of 2017 . A summary of the Company's stock option activity for the three months ended March 31, 2018 and March 31, 2017 is presented below: Stock Options Common Shares Weighted Average Strike Price Remaining Contractual Term (1) Intrinsic Value (2) ($000) Outstanding at January 1, 2018 1,084,756 $ 41.98 Granted — — Exercised (169,387 ) 42.47 Forfeited or canceled (1,703 ) 40.87 Outstanding at March 31, 2018 913,666 $ 41.89 3.7 $ 40,351 Exercisable at March 31, 2018 712,535 $ 42.00 3.4 $ 31,391 Stock Options Common Shares Weighted Average Strike Price Remaining Contractual Term (1) Intrinsic Value (2) ($000) Outstanding at January 1, 2017 1,698,912 $ 41.50 Granted — — Exercised (319,802 ) 39.97 Forfeited or canceled (6,496 ) 42.65 Outstanding at March 31, 2017 1,372,614 $ 41.85 4.6 $ 37,436 Exercisable at March 31, 2017 819,955 $ 41.60 4.0 $ 22,568 (1) Represents the remaining weighted average contractual life in years. (2) Aggregate intrinsic value represents the total pre-tax intrinsic value (i.e., the difference between the Company's stock price on the last trading day of the quarter and the option exercise price, multiplied by the number of shares) that would have been received by the option holders if they had exercised their options on the last day of the quarter. Options with exercise prices above the stock price on the last trading day of the quarter are excluded from the calculation of intrinsic value. The intrinsic value will change based on the fair market value of the Company's stock. The aggregate intrinsic value of options exercised during the three months ended March 31, 2018 and March 31, 2017 , was $7.5 million and $10.2 million , respectively. Cash received from option exercises under the Plan for the three months ended March 31, 2018 and March 31, 2017 was $7.2 million and $12.8 million , respectively. A summary of the Plans' restricted share activity for the three months ended March 31, 2018 and March 31, 2017 is presented below: Three months ended March 31, 2018 Three months ended March 31, 2017 Restricted Shares Common Shares Weighted Average Grant-Date Fair Value Common Shares Weighted Average Grant-Date Fair Value Outstanding at January 1 127,787 $ 53.33 133,425 $ 49.94 Granted 20,700 86.42 8,425 72.52 Vested and issued (7,258 ) 53.47 (5,063 ) 42.71 Forfeited or canceled (982 ) 55.39 — — Outstanding at March 31 140,247 $ 58.20 136,787 $ 51.60 Vested, but not issuable at March 31 89,924 $ 51.71 89,215 $ 51.51 A summary of the Plans' performance-based stock award activity, based on the target level of the awards, for the three months ended March 31, 2018 and March 31, 2017 is presented below: Three months ended March 31, 2018 Three months ended March 31, 2017 Performance-based Stock Common Weighted Common Weighted Outstanding at January 1 359,196 $ 54.37 298,180 $ 43.64 Granted 127,419 88.20 141,399 72.55 Vested and issued (82,307 ) 44.39 (68,712 ) 46.85 Forfeited (6,580 ) 49.42 (7,731 ) 50.11 Outstanding at March 31 397,728 $ 67.35 363,136 $ 54.15 Vested, but deferred at March 31 21,388 $ 43.32 13,564 $ 42.55 The Company issues new shares to satisfy its obligation to issue shares granted pursuant to the Plans.

Shareholders' Equity and Earnin

Shareholders' Equity and Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Shareholders' Equity and Earnings Per Share	Shareholders’ Equity and Earnings Per Share Series D Preferred Stock In June 2015, the Company issued and sold 5,000,000 shares of fixed-to-floating non-cumulative perpetual preferred stock, Series D, liquidation preference $25 per share (the “Series D Preferred Stock”) for $125.0 million in a public offering. When, as and if declared, dividends on the Series D Preferred Stock are payable quarterly in arrears at a fixed rate of 6.50% per annum from the original issuance date to, but excluding, July 15, 2025 , and from (and including) that date at a floating rate equal to three-month LIBOR plus a spread of 4.06% per annum. Series C Preferred Stock In March 2012, the Company issued and sold 126,500 shares of non-cumulative perpetual convertible preferred stock, Series C, liquidation preference $1,000 per share (the “Series C Preferred Stock”) for $126.5 million in a public offering. When, as and if declared, dividends on the Series C Preferred Stock were payable quarterly in arrears at a rate of 5.00% per annum. The Series C Preferred Stock was convertible into common stock at the option of the holder subject to customary anti-dilution adjustments. Additionally, on and after April 15, 2017, the Company had the right under certain circumstances to cause the Series C Preferred Stock to be converted into common stock if the closing price of the Company’s common stock exceeded a certain amount. On April 25, 2017 , 2,073 shares of the Series C Preferred Stock were converted at the option of the respective holder into 51,244 shares of the Company's common stock, pursuant to the terms of the Series C Preferred Stock. On April 27, 2017 , the Company caused a mandatory conversion of its remaining 124,184 shares of Series C Preferred Stock into 3,069,828 shares of the Company's common stock at a conversion rate of 24.72 shares of common stock per share of Series C Preferred Stock. Cash was paid in lieu of fractional shares for an amount considered insignificant. Common Stock Warrant Pursuant to the U.S. Department of the Treasury’s (the “U.S. Treasury”) Capital Purchase Program, on December 19, 2008, the Company issued to the U.S. Treasury a warrant to exercise 1,643,295 warrant shares of Wintrust common stock with a term of 10 years. The exercise price, subject to customary anti-dilution, was $22.62 at March 31, 2018 . In February 2011, the U.S. Treasury sold all of its interest in the warrant issued to it in a secondary underwritten public offering. During the first three months of 2018 13,201 warrant shares were exercised, which resulted in 9,677 shares of common stock issued. At March 31, 2018 , all remaining holders of the interest in the warrant were able to exercise 10,160 warrant shares. Other At the January 2018 Board of Directors meeting, a quarterly cash dividend of $0.19 per share ( $0.76 on an annualized basis) was declared. It was paid on February 22, 2018 to shareholders of record as of February 8, 2018 . Accumulated Other Comprehensive Income (Loss) The following tables summarize the components of other comprehensive income (loss), including the related income tax effects, and the related amount reclassified to net income for the periods presented (in thousands). Accumulated Unrealized Gains (Losses) on Securities Accumulated Unrealized Losses on Derivative Instruments Accumulated Foreign Currency Translation Adjustments Total Accumulated Other Comprehensive Loss Balance at January 1, 2018 $ (15,813 ) $ 7,164 $ (33,186 ) $ (41,835 ) Cumulative effect adjustment from the adoption of: ASU 2016-01 (1,880 ) — — (1,880 ) ASU 2018-02 (4,517 ) 1,543 — (2,974 ) Other comprehensive (loss) income during the period, net of tax, before reclassifications (26,474 ) 2,746 (2,897 ) (26,625 ) Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax 713 (497 ) — 216 Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax 3 — — 3 Net other comprehensive (loss) income during the period, net of tax $ (25,758 ) $ 2,249 $ (2,897 ) $ (26,406 ) Balance at March 31, 2018 $ (47,968 ) $ 10,956 $ (36,083 ) $ (73,095 ) Balance at January 1, 2017 $ (29,309 ) $ 4,165 $ (40,184 ) $ (65,328 ) Other comprehensive income during the period, net of tax, before reclassifications 4,479 765 877 6,121 Amount reclassified from accumulated other comprehensive income into net income, net of tax 34 216 — 250 Amount reclassified from accumulated other comprehensive (loss) related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax (867 ) — — (867 ) Net other comprehensive income during the period, net of tax $ 3,646 $ 981 $ 877 $ 5,504 Balance at March 31, 2017 $ (25,663 ) $ 5,146 $ (39,307 ) $ (59,824 ) Amount Reclassified from Accumulated Other Comprehensive Income for the Details Regarding the Component of Accumulated Other Comprehensive Income Three Months Ended Impacted Line on the Consolidated Statements of Income March 31, 2018 2017 Accumulated unrealized losses on securities Losses included in net income $ (975 ) $ (55 ) Losses on investment securities, net (975 ) (55 ) Income before taxes Tax effect $ 262 $ 21 Income tax expense Net of tax $ (713 ) $ (34 ) Net income Accumulated unrealized losses on derivative instruments Amount reclassified to interest expense on deposits $ (680 ) $ 42 Interest on deposits Amount reclassified to interest expense on junior subordinated debentures — 314 Interest on junior subordinated debentures 680 (356 ) Income before taxes Tax effect $ (183 ) $ 140 Income tax expense Net of tax $ 497 $ (216 ) Net income Earnings per Share The following table shows the computation of basic and diluted earnings per share for the periods indicated: Three Months Ended (In thousands, except per share data) March 31, March 31, Net income $ 81,981 $ 58,378 Less: Preferred stock dividends 2,050 3,628 Net income applicable to common shares—Basic (A) 79,931 54,750 Add: Dividends on convertible preferred stock, if dilutive — 1,578 Net income applicable to common shares—Diluted (B) 79,931 56,328 Weighted average common shares outstanding (C) 56,137 52,267 Effect of dilutive potential common shares Common stock equivalents 888 1,060 Convertible preferred stock, if dilutive — 3,100 Total dilutive potential common shares 888 4,160 Weighted average common shares and effect of dilutive potential common shares (D) 57,025 56,427 Net income per common share: Basic (A/C) $ 1.42 $ 1.05 Diluted (B/D) $ 1.40 $ 1.00 Potentially dilutive common shares can result from stock options, restricted stock unit awards, stock warrants, the Company’s convertible preferred stock and shares to be issued under the Employee Stock Purchase Plan and the Directors Deferred Fee and Stock Plan, being treated as if they had been either exercised or issued, computed by application of the treasury stock method. While potentially dilutive common shares are typically included in the computation of diluted earnings per share, potentially dilutive common shares are excluded from this computation in periods in which the effect would reduce the loss per share or increase the income per share. For diluted earnings per share, net income applicable to common shares can be affected by the conversion of the Company’s convertible preferred stock. Where the effect of this conversion would reduce the loss per share or increase the income per share for a period, net income applicable to common shares is not adjusted by the associated preferred dividends.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Accounting	The consolidated financial statements of Wintrust Financial Corporation and Subsidiaries (“Wintrust” or the “Company”) presented herein are unaudited, but in the opinion of management reflect all necessary adjustments of a normal or recurring nature for a fair presentation of results as of the dates and for the periods covered by the consolidated financial statements. The accompanying consolidated financial statements are unaudited and do not include information or footnotes necessary for a complete presentation of financial condition, results of operations or cash flows in accordance with U.S. generally accepted accounting principles ("GAAP"). The unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 (“ 2017 Form 10-K”). Operating results reported for the period are not necessarily indicative of the results which may be expected for the entire year. Reclassifications of certain prior period amounts have been made to conform to the current period presentation. The preparation of the financial statements requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities. Management believes that the estimates made are reasonable, however, changes in estimates may be required if economic or other conditions develop differently from management’s expectations. Certain policies and accounting principles inherently have a greater reliance on the use of estimates, assumptions and judgments and as such have a greater possibility of producing results that could be materially different than originally reported. Management views critical accounting policies to be those which are highly dependent on subjective or complex judgments, estimates and assumptions, and where changes in those estimates and assumptions could have a significant impact on the financial statements. Management currently views the determination of the allowance for loan losses, allowance for covered loan losses and the allowance for losses on lending-related commitments, loans acquired with evidence of credit quality deterioration since origination, estimations of fair value, the valuations required for impairment testing of goodwill, the valuation and accounting for derivative instruments and income taxes as the accounting areas that require the most subjective and complex judgments, and as such could be the most subject to revision as new information becomes available. Descriptions of the Company's significant accounting policies are included in Note 1 - “Summary of Significant Accounting Policies” of the 2017 Form 10-K.
Recent Accounting Developments	Revenue Recognition In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, which created “Revenue from Contracts with Customers (Topic 606),” to clarify the principles for recognizing revenue and develop a common revenue standard for customer contracts. This ASU provides guidance regarding how 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. The ASU also added a new subtopic to the codification, ASC 340-40, “Other Assets and Deferred Costs: Contracts with Customers” to provide guidance on costs related to obtaining and fulfilling a customer contract. Furthermore, the new standard requires disclosure of sufficient information to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. At the time ASU No. 2014-09 was issued, the guidance was effective for fiscal years beginning after December 15, 2016. In July 2015, the FASB approved a deferral of the effective date by one year, which resulted in the guidance becoming effective for the Company as of January 1, 2018. The FASB continued to issue various updates to clarify and improve specific areas of ASU No. 2014-09. In March 2016, the FASB issued ASU No. 2016-08, “Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net),” to clarify the implementation guidance within ASU No. 2014-09 surrounding principal versus agent considerations and its impact on revenue recognition. In April 2016, the FASB issued ASU No. 2016-10, “Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing,” to also clarify the implementation guidance within ASU No. 2014-09 related to these two topics. In May 2016, the FASB issued ASU No. 2016-11, “Revenue Recognition (Topic 605) and Derivative and Hedging (Topic 815): Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting,” to remove certain areas of SEC Staff Guidance from those specific Topics. In May 2016 and December 2016, the FASB issued ASU 2016-12, “Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients” and ASU 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers,” to clarify specific aspects of implementation, including the collectability criterion, exclusion of sales taxes collected from a transaction price, noncash consideration, contract modifications, completed contracts at transition, the applicability of loan guarantee fees, impairment of capitalized contract costs and certain disclosure requirements. In February 2017, the FASB issued ASU No. 2017-05, “Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets,” to clarify the implementation guidance within ASU No. 2014-09 surrounding transfers of nonfinancial assets, including partial sales of such assets, and its impact on revenue recognition. Like ASU No. 2014-09, this guidance became effective for the Company starting January 1, 2018. The Company adopted ASU No. 2014-09 and all subsequent updates issued to clarify and improve specific areas of this ASU as of January 1, 2018. As certain significant revenue sources related to financial instruments such as interest income are considered not in-scope, the new guidance did not have a significant impact on the Company's consolidated financial statements. Revenue sources impacted by the new guidance include brokerage and trust and asset management fees from the wealth management business unit, card-based fees, deposit-related fees and other non-interest income. During implementation, the Company reviewed specific contracts with customers across these various sources of revenue. Reviews of such contracts assisted in identifying any characteristics of such contracts that could result in a change in the Company's current practices for recognition of revenue and recognition of costs incurred to obtain or fulfill such contracts. After review of such contracts, the Company identified no indication within the terms of such contracts that a change in the Company's current practices and accounting policies was necessary. The Company elected to adopt the new guidance using the modified retrospective approach applied to all contracts as of the date of initial application at January 1, 2018. Electing the modified retrospective approach resulted in no cumulative effect adjustment to the opening balance of retained earnings at the date of initial application. Additional disclosures have been added in accordance with the new guidance. See Note 13 – Revenue from Contracts with Customers for discussion of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Financial Instruments In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities,” to improve the accounting for financial instruments. This ASU requires equity securities with readily determinable fair values to be measured at fair value with changes recognized in net income. Such equity securities with readily determinable fair values are no longer classified as available-for-sale securities or trading securities within the consolidated financial statements of an entity. For equity securities without a readily determinable fair value, the value of the equity securities may be elected to be measured at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer instead of fair value, unless a qualitative assessment indicates impairment. Additionally, this ASU requires the separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements. The Company adopted this guidance as of January 1, 2018. For equity securities with a readily determinable fair value, this guidance was applied under a modified retrospective approach with a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. As of January 1, 2018, the Company reclassified approximately $1.9 million from accumulated other comprehensive income, related to previously recognized unrealized gains, net of deferred taxes, from equity securities with readily determinable fair values, to retained earnings. Equity securities with readily determinable fair values are now prospectively presented separate from available-for-sale securities and trading securities within the Company's Consolidated Statements of Condition. Additionally, for the three months ended March 31, 2018, the Company recognized $1.0 million of unrealized gains from equity securities with readily determinable fair values directly to earnings. For equity securities without a readily determinable fair value, the Company elected to measure such investments at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer, unless a qualitative assessment indicates impairment, which was applied prospectively. Equity securities without readily determinable fair values are included within accrued interest receivable and other assets within the Company's Consolidated Statements of Condition. See Note 5 - Investment Securities for further discussion of equity securities with and without readily determinable fair values. In January 2018, the FASB issued ASU No. 2018-03, “Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities,” to clarify certain aspects of the guidance issued in ASU No. 2016-01, including aspects of equity securities without a readily determinable fair value. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years beginning after June 15, 2018. Early adoption is permitted. As these clarifications did not have a material impact on the Company's consolidated financial statements, the Company elected to early adopt this guidance as of January 1, 2018. Leases In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842),” to improve transparency and comparability across entities regarding leasing arrangements. This ASU requires the recognition of a separate lease liability representing the required discounted lease payments over the lease term and a separate lease asset representing the right to use the underlying asset during the same lease term. Further, this ASU provides clarification regarding the identification of certain components of contracts that would represent a lease as well as requires additional disclosures to the notes of the financial statements. Additionally, in January 2018, the FASB issued ASU No. 2018-01, "Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842," to permit an entity to elect an optional practical expedient to not evaluate under Topic 842 land easements that exist or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under existing accounting guidance. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied under a modified retrospective approach, including the option to apply certain practical expedients. The Company is currently evaluating the impact of adopting this new guidance on the consolidated financial statements. Excluding any impact from the clarification of contracts representing a lease, the Company expects to recognize separate lease liabilities and right to use assets for the amounts related to certain facilities under operating lease agreements disclosed in Note 15 - Minimum Lease Commitments in the 2017 Form 10-K . Additionally, the Company does not expect to significantly change operating lease agreements prior to adoption. The Company has established a committee consisting of individuals from various areas of the Company tasked with transitioning the Company to the new guidance requirements. Additionally, the Company has begun obtaining and reviewing lease agreements across its various business units to determine any additional potential impact. Derivatives In August 2017, the FASB issued ASU No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities,” to improve the financial reporting of hedging relationships to better align the economic results of an entity’s risk management activities and disclosures within its financial statements. In addition, this ASU makes certain targeted improvements to simplify the application of the hedge accounting, including to derivative instruments as well as allow a one-time election to reclassify fixed-rate, prepayable debt securities from a held-to-maturity classification to an available-for-sale classification. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Guidance related to existing cash flow hedges and, if elected, fair value hedges is to be applied under a modified retrospective approach and guidance related to amended presentation and disclosures is to be applied under a prospective approach. Early adoption is permitted as of the beginning of an annual period that has not been issued or made available for issuance. The Company elected to early adopt this guidance as of January 1, 2018. See Note 15 - Derivative Financial Instruments for further discussion of early adoption of this guidance. The impact of early adoption on the financial statements included the following: • As allowed under the guidance, for certain existing derivative instruments designated as fair value hedges, the Company transitioned the measurement methodology for the related hedged item (loans) to be in accordance with the guidance without dedesignation of the hedging relationship. This resulted in a negative cumulative basis adjustment to loans of $116,000 with a corresponding adjustment to retained earnings. • No fixed-rate, prepayable held-to-maturity securities were transferred to an available-for-sale classification. • The entire change in the hedging instrument included in the assessment of hedge effectiveness of fair value hedges is presented in the same income statement line as the current impact of the effective portion of such hedge, or interest income and interest expense for interest rate hedging. The Company has previously recognized this ineffectiveness within non-interest income. For the first quarter of 2018, the Company recognized $45,000 of such change in interest income related to hedge effectiveness. Allowance for Credit Losses In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” to replace the current incurred loss methodology for recognizing credit losses, which delays recognition until it is probable a loss has been incurred, with a methodology that reflects an estimate of all expected credit losses and considers additional reasonable and supportable forecasted information when determining credit loss estimates. This impacts the calculation of an allowance for credit losses for all financial assets measured under the amortized cost basis, including PCI loans at the time of and subsequent to acquisition. Additionally, credit losses related to available-for-sale debt securities would be recorded through the allowance for credit losses and not as a direct adjustment to the amortized cost of the securities. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and is to be applied under a modified retrospective approach. The Company is currently evaluating the impact of adopting this new guidance on the consolidated financial statements as well as the impact on current systems and processes. Specifically, the Company has established a committee consisting of individuals from the various areas of the Company tasked with transitioning to the new requirements. At this time, the Company is reviewing potential methodologies for estimating expected credit losses using reasonable and supportable forecast information, has identified certain historical data and system requirements and has reviewed options for platforms to build, store, execute and review the financial impact. Statement of Cash Flows In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the FASB Emerging Issues Task Force),” to clarify the presentation of specific types of cash flow receipts and payments, including the payment of debt prepayment or debt extinguishment costs, contingent consideration cash payments paid subsequent to the acquisition date and proceeds from settlement of BOLI policies. This guidance became effective as of January 1, 2018 and was applied under a retrospective approach resulting in additional disclosure, including cash payments made to settle contingent consideration liabilities recognized in prior business combinations. In November 2016, the FASB issued ASU No. 2016-18 “Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force),” to clarify the classification and presentation of changes in restricted cash on the statement of cash flows. This guidance became effective as of January 1, 2018 and did not have a material impact on the Company. Income Taxes In October 2016, the FASB issued ASU No. 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory,” to improve the accounting for intra-entity transfers of assets other than inventory. This ASU allows the recognition of current and deferred income taxes for such transfers prior to the subsequent sale of the transferred assets to an outside party. Initial recognition of current and deferred income taxes is currently prohibited for intra-entity transfers of assets other than inventory. This guidance became effective as of January 1, 2018 and did not have a material impact on the Company. The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017, and the Company recognized a provisional tax benefit of $7.6 million in 2017 to reflect the impact of the Tax Act, primarily reflecting estimated effects of a lower federal income tax rate on its net deferred tax liabilities and a transition tax due on the deferred earnings of the Company's Canadian subsidiary. Estimates were made in good faith and may change as additional information and interpretive guidance regarding provisions of the Tax Act become available. Staff Accounting Bulletin 118 provides a measurement period, not to extend beyond one year from the date of enactment, during which a company may complete the accounting for the impacts of the Tax Act. No adjustments were made to the provisional amounts in the first quarter of 2018 and the Company expects to complete the accounting for the impacts of the Tax Act in the fourth quarter of 2018. Business Combinations In January 2017, the FASB issued ASU No. 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business,” to improve such definition and, as a result, assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or as business combinations. The definition of a business impacts many areas of accounting including acquisitions, disposals, goodwill and consolidation. This guidance became effective as of January 1, 2018 and was applied under a prospective approach. See Note 3 - Business Combinations for further discussion of business combinations including the acquisition of certain assets and assumption of certain liabilities of the mortgage banking business of iFreedom Direct Corporation DBA Veterans First Mortgage ("Veterans First") during the current period. Goodwill In January 2017, the FASB issued ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” to simplify the subsequent measurement of goodwill. When the carrying amount of a reporting unit exceeds its fair value, an entity would no longer be required to determine goodwill impairment by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit was acquired in a business combination. Goodwill impairment would be recognized according to the excess of the carrying amount of the reporting unit over the calculated fair value of such unit. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and is to be applied under a prospective approach. The Company does not expect this guidance to have a material impact on the Company's consolidated financial statements. Compensation In March 2017, the FASB issued ASU No. 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” to improve the presentation of net periodic pension cost and net periodic post-retirement benefit cost. An entity will be required to report the service cost component of such costs in the same line item or items as other compensation costs related to services rendered. Additionally, only the service cost component will be eligible for capitalization when applicable. This guidance became effective as of January 1, 2018 and was applied under a retrospective approach related to presentation of the service cost component and a prospective approach related to capitalization of such costs. Adoption of this guidance did not have a material impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, “Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting,” to clarify when modification accounting is appropriate for changes to the terms and conditions of a share-based payment award. An entity will be required to account for such changes as a modification unless certain criteria is met. This guidance became effective as of January 1, 2018 and was applied under a prospective approach for awards modified on or after the adoption date. Adoption of this guidance did not have a material impact on the Company's consolidated financial statements. Amortization of Premium on Certain Debt Securities In March 2017, the FASB issued ASU No. 2017-08, “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities,” to amend the amortization period for certain purchased callable debt securities held at a premium. The amortization period for such securities will be shortened to the earliest call date. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied under a modified retrospective approach. Early adoption is permitted as of the beginning of an annual period that has not been issued or made available for issuance. The Company did not early adopt this guidance as of January 1, 2018. The Company is currently evaluating the impact of adopting this new guidance on the consolidated financial statements. Accumulated Other Comprehensive Income (Loss) In February 2018, the FASB issued ASU No. 2018-02, “Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” to allow a reclassification from accumulated other comprehensive income to retained earnings related to the stranded tax effects within other comprehensive income resulting from the Federal income tax rate reduction in the Tax Act. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied either in the period of adoption or retrospectively to each period or periods in which the effect of the Tax Act is recognized. Early adoption is permitted as of the beginning of an annual period that has not been issued or made available for issuance. The Company elected to early adopt this guidance as of January 1, 2018 and applied such reclassification in the current period (period of adoption). As of January 1, 2018, the Company reclassified a stranded credit of $3.0 million from accumulated other comprehensive income to retained earnings. The Company has a policy for releasing the income tax effects from accumulated other comprehensive income using an individual security approach.
FDIC-Assisted Transactions	FDIC-Assisted Transactions From 2010 to 2012, the Company acquired the banking operations, including the acquisition of certain assets and the assumption of liabilities, of nine financial institutions in FDIC-assisted transactions. Loans comprised the majority of the assets acquired in nearly all of these FDIC-assisted transactions, of which eight such transactions were subject to loss sharing agreements with the FDIC whereby the FDIC agreed to reimburse the Company for 80% of losses incurred on the purchased loans, other real estate owned (“OREO”), and certain other assets. Additionally, clawback provisions within these loss share agreements with the FDIC required the Company to reimburse the FDIC for actual losses on covered assets that were lower than the original loss estimates agreed upon with the FDIC with respect of such assets in the loss share agreements. The Company refers to the loans subject to these loss sharing agreements as “covered loans” and uses the term “covered assets” to refer to covered loans, covered OREO and certain other covered assets during periods subject to such agreements. As of dates subject to such agreements, the loans covered by the loss share agreements were classified and presented as covered loans and the estimated reimbursable losses were recorded as an FDIC indemnification asset or liability in the Consolidated Statements of Condition. The Company recorded the acquired assets and liabilities at their estimated fair values at the acquisition date. The fair value for loans reflected expected credit losses at the acquisition date. Therefore, the Company only recognized a provision for credit losses and charge-offs on the acquired loans for any further credit deterioration subsequent to the acquisition date. See Note 7 — Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans for further discussion of the allowance on covered loans. The loss share agreements with the FDIC covered realized losses on loans, foreclosed real estate and certain other assets and required the Company to record loss share assets and liabilities that were measured separately from the loan portfolios because they were not contractually embedded in the loans and were not transferable with the loans had the Company chosen to dispose of them. Fair values at the acquisition dates were estimated based on projected cash flows available for loss share based on the credit adjustments estimated for each loan pool and the loss share percentages. The loss share assets and liabilities were recorded as FDIC indemnification assets and other liabilities, respectively, on the Consolidated Statements of Condition as of dates covered by loss share agreements. Subsequent to the acquisition date, reimbursements received from the FDIC for actual incurred losses reduced the FDIC indemnification assets. Reductions to expected losses, to the extent such reductions to expected losses were the result of an improvement to the actual or expected cash flows from the covered assets, also reduced the FDIC indemnification assets and, if necessary, increased any loss share liability when necessary reductions exceeded the current value of the FDIC indemnification assets. In accordance with the clawback provision noted above, the Company was required to reimburse the FDIC when actual losses were less than certain thresholds established for each loss share agreement. The balance of these estimated reimbursements in accordance with clawback provisions and any related amortization were adjusted periodically for changes in the expected losses on covered assets. On the Consolidated Statements of Condition as of dates subject to loss share agreements, estimated reimbursements from clawback provisions were recorded as a reduction to the FDIC indemnification asset or, if necessary, an increase to the loss share liability, which was included within accrued interest payable and other liabilities. In the second quarter of 2017, the Company recorded a $4.9 million reduction to the estimated loss share liability as a result of an adjustment related to such clawback provisions. Although these assets were contractual receivables from the FDIC and these liabilities were contractual payables to the FDIC, there were no contractual interest rates. Additional expected losses, to the extent such expected losses resulted in recognition of an allowance for covered loan losses, increased the FDIC indemnification asset or reduced the FDIC indemnification liability. The corresponding amortization was recorded as a component of non-interest income on the Consolidated Statements of Income during periods covered by loss share agreements.
PCI Loans	Purchased Credit Impaired ("PCI") Loans Purchased loans acquired in a business combination are recorded at estimated fair value on their purchase date. For PCI loans, expected future cash flows at the purchase date in excess of the fair value of loans are recorded as interest income over the life of the loans if the timing and amount of the future cash flows is reasonably estimable (“accretable yield”). The difference between contractually required payments and the cash flows expected to be collected at acquisition is referred to as the non-accretable difference and represents probable losses in the portfolio. In determining the acquisition date fair value of PCI loans, and in subsequent accounting, the Company aggregates these purchased loans into pools of loans by common risk characteristics, such as credit risk rating and loan type. Subsequent to the purchase date, increases in cash flows over those expected at the purchase date are recognized as interest income prospectively. Subsequent decreases to the expected cash flows will result in a provision for loan losses. The Company purchased a portfolio of life insurance premium finance receivables in 2009. These purchased life insurance premium finance receivables are valued on an individual basis. If credit related conditions deteriorate, an allowance related to these loans will be established as part of the provision for credit losses.
Cash and Cash Equivalents	For purposes of the Consolidated Statements of Cash Flows, the Company considers cash and cash equivalents to include cash on hand, cash items in the process of collection, non-interest bearing amounts due from correspondent banks, federal funds sold and securities purchased under resale agreements with original maturities of three months or less.
Investment Securities	During the three months ending March 31, 2018, the Company recorded impairment of equity securities without readily determinable fair values totaling $537,000 . The Company conducts a quarterly assessment of its equity securities without a readily determinable fair values to determine whether impairment exists in such securities, considering, among other factors, the nature of the securities, financial condition of the issuer and expected future cash flows. The Company conducts a regular assessment of its available-for-sale and held-to-maturity investment securities to determine whether securities are other-than-temporarily impaired considering, among other factors, the nature of the securities, credit ratings or financial condition of the issuer, the extent and duration of the unrealized loss, expected cash flows, market conditions and the Company’s ability to hold the securities through the anticipated recovery period. The Company does not consider available-for-sale and held-to-maturity securities with unrealized losses at March 31, 2018 to be other-than-temporarily impaired. The Company does not intend to sell these investments and it is more likely than not that the Company will not be required to sell these investments before recovery of the amortized cost bases, which may be the maturity dates of the securities. The unrealized losses within each category have occurred as a result of changes in interest rates, market spreads and market conditions subsequent to purchase. Securities with continuous unrealized losses existing for more than twelve months were primarily mortgage-backed securities, U.S. government agency securities and municipal securities. Equity securities without readily determinable fair values totaled $25.2 million as of March 31, 2018 . Equity securities without readily determinable fair values are included as part of accrued interest receivable and other assets in the Company's Consolidated Statements of Condition. In accordance with the adoption of ASU No. 2016-01, in the first quarter of 2018, the Company recorded an upward adjustment on such securities of $131,000 related to observable price changes in orderly transactions for the identical or a similar investment of the same issuer. No downward adjustment of equity securities without readily determinable fair values was recorded during the current period. The Company monitors its equity investments without a readily determinable fair values to identify potential transactions that may indicate an observable price change requiring adjustment to its carrying amount.
Finance, Loans and Leases Receivable	Certain premium finance receivables are recorded net of unearned income.
Receivables	These amounts include accretion from both covered and non-covered loans, and are both included within interest and fees on loans in the Consolidated Statements of Income.
Allowance and Nonperforming Loans, Allowance	As a result of this initial review by the Company’s Managed Asset Division, the credit risk rating is reviewed and a portion of the outstanding loan balance may be deemed uncollectible or an impairment reserve may be established. The Company’s impairment analysis utilizes an independent re-appraisal of the collateral (unless such a third-party evaluation is not possible due to the unique nature of the collateral, such as a closely-held business or thinly traded securities). In the case of commercial real estate collateral, an independent third party appraisal is ordered by the Company’s Real Estate Services Group to determine if there has been any change in the underlying collateral value. These independent appraisals are reviewed by the Real Estate Services Group and sometimes by independent third party valuation experts and may be adjusted depending upon market conditions. Through the credit risk rating process, loans are reviewed to determine if they are performing in accordance with the original contractual terms. If the borrower has failed to comply with the original contractual terms, further action may be required by the Company, including a downgrade in the credit risk rating, movement to non-accrual status, a charge-off or the establishment of a specific impairment reserve. If a loan amount, or portion thereof, is determined to be uncollectible, the loan’s credit risk rating is immediately downgraded to an 8 or 9 and the uncollectible amount is charged-off. Any loan that has a partial charge-off continues to be assigned a credit risk rating of an 8 or 9 for the duration of time that a balance remains outstanding. The Company undertakes a thorough and ongoing analysis to determine if additional impairment and/or charge-offs are appropriate and to begin a workout plan for the credit to minimize actual losses. If, based on current information and events, it is probable that the Company will be unable to collect all amounts due to it according to the contractual terms of the loan agreement, a specific impairment reserve is established. In determining the appropriate charge-off for collateral-dependent loans, the Company considers the results of appraisals for the associated collateral.
Loans and Leases Receivable, Nonperforming Loan and Lease	Non-performing loans include all non-accrual loans (8 and 9 risk ratings) as well as loans 90 days past due and still accruing interest, excluding PCI and covered loans. The remainder of the portfolio is considered performing under the contractual terms of the loan agreement.
Loans and Leases Receivable, Allowance for Loan Losses	In conjunction with FDIC-assisted transactions, the Company entered into loss share agreements with the FDIC. Additional expected losses, to the extent such expected losses resulted in the recognition of an allowance for loan losses, increased the FDIC loss share asset or reduced any FDIC loss share liability. The allowance for loan losses for loans acquired in FDIC-assisted transactions was determined without giving consideration to the amounts recoverable through loss share agreements (since the loss share agreements were separately accounted for and thus presented “gross” on the balance sheet). On the Consolidated Statements of Income, the provision for credit losses was reported net of changes in the amount recoverable under the loss share agreements. Reductions to expected losses, to the extent such reductions to expected losses were the result of an improvement to the actual or expected cash flows from the covered assets, reduced the FDIC loss share asset or increased any FDIC loss share liability. Additions to expected losses required an increase to the allowance for covered loan losses, and a corresponding increase to the FDIC loss share asset or reduction to any FDIC loss share liability.
Impaired Financing Receivable	Impaired loans are considered by the Company to be non-accrual loans, TDRs or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest. These impaired loans require an allowance for loan losses because the estimated fair value of the loans or related collateral is less than the recorded investment in the loans. A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due pursuant to the contractual terms of the loan agreement. A loan modified in a TDR is an impaired loan according to applicable accounting guidance. Impairment is measured by estimating the fair value of the loan based on the present value of expected cash flows, the market price of the loan, or the fair value of the underlying collateral. Impaired loans are considered a fair value measurement where an allowance is established based on the fair value of collateral. Appraised values, which may require adjustments to market-based valuation inputs, are generally used on real estate collateral-dependent impaired loans.
Loans and Leases Receivable, Troubled Debt Restructuring	The Company’s approach to restructuring loans, excluding PCI loans, is built on its credit risk rating system which requires credit management personnel to assign a credit risk rating to each loan. In each case, the loan officer is responsible for recommending a credit risk rating for each loan and ensuring the credit risk ratings are appropriate. These credit risk ratings are then reviewed and approved by the bank’s chief credit officer and/or concurrence credit officer. Credit risk ratings are determined by evaluating a number of factors including a borrower’s financial strength, cash flow coverage, collateral protection and guarantees. The Company’s credit risk rating scale is one through ten with higher scores indicating higher risk. In the case of loans rated six or worse following modification, the Company’s Managed Assets Division evaluates the loan and the credit risk rating and determines that the loan has been restructured to be reasonably assured of repayment and of performance according to the modified terms and is supported by a current, well-documented credit assessment of the borrower’s financial condition and prospects for repayment under the revised terms. A modification of a loan, excluding PCI loans, with an existing credit risk rating of 6 or worse or a modification of any other credit, which will result in a restructured credit risk rating of six or worse, must be reviewed for possible TDR classification. In that event, our Managed Assets Division conducts an overall credit and collateral review. A modification of these loans is considered to be a TDR if both (1) the borrower is experiencing financial difficulty and (2) for economic or legal reasons, the bank grants a concession to a borrower that it would not otherwise consider. The modification of a loan, excluding PCI loans, where the credit risk rating is 5 or better both before and after such modification is not considered to be a TDR. Based on the Company’s credit risk rating system, it considers that borrowers whose credit risk rating is 5 or better are not experiencing financial difficulties and therefore, are not considered TDRs. All credits determined to be a TDR will continue to be classified as a TDR in all subsequent periods, unless the borrower has been in compliance with the loan’s modified terms for a period of six months (including over a calendar year-end) and the current interest rate represents a market rate at the time of restructuring. The Managed Assets Division, in consultation with the respective loan officer, determines whether the modified interest rate represented a current market rate at the time of restructuring. Using knowledge of current market conditions and rates, competitive pricing on recent loan originations, and an assessment of various characteristics of the modified loan (including collateral position and payment history), an appropriate market rate for a new borrower with similar risk is determined. If the modified interest rate meets or exceeds this market rate for a new borrower with similar risk, the modified interest rate represents a market rate at the time of restructuring. Additionally, before removing a loan from TDR classification, a review of the current or previously measured impairment on the loan and any concerns related to future performance by the borrower is conducted. If concerns exist about the future ability of the borrower to meet its obligations under the loans based on a credit review by the Managed Assets Division, the TDR classification is not removed from the loan. TDRs are reviewed at the time of the modification and on a quarterly basis to determine if a specific reserve is necessary. The carrying amount of the loan is compared to the expected payments to be received, discounted at the loan's original rate, or for collateral dependent loans, to the fair value of the collateral. Any shortfall is recorded as a specific reserve. The Company, in accordance with ASC 310-10, continues to individually measure impairment of these loans after the TDR classification is removed. Each TDR was reviewed for impairment at March 31, 2018 and approximately $1.1 million of impairment was present and appropriately reserved for through the Company’s normal reserving methodology in the Company’s allowance for loan losses. For TDRs in which impairment is calculated by the present value of future cash flows, the Company records interest income representing the decrease in impairment resulting from the passage of time during the respective period, which differs from interest income from contractually required interest on these specific loans. During the three months ended March 31, 2018 and 2017 , the Company recorded $21,000 and $55,000 , respectively, of interest income, which was reflected as a decrease in impairment. TDRs may arise in which, due to financial difficulties experienced by the borrower, the Company obtains through physical possession one or more collateral assets in satisfaction of all or part of an existing credit. Once possession is obtained, the Company reclassifies the appropriate portion of the remaining balance of the credit from loans to OREO, which is included within other assets in the Consolidated Statements of Condition. For any residential real estate property collateralizing a consumer mortgage loan, the Company is considered to possess the related collateral only if legal title is obtained upon completion of foreclosure, or the borrower conveys all interest in the residential real estate property to the Company through completion of a deed in lieu of foreclosure or similar legal agreement.
Goodwill	At June 30, 2017, the Company utilized a quantitative approach for its annual goodwill impairment test of the community banking segment and determined that no impairment existed at that time. At December 31, 2017, the Company utilized a quantitative approach for its annual goodwill impairment tests of the specialty finance and wealth management segments and determined that no impairment existed at that time. At each reporting date between annual goodwill impairment tests, the Company considers potential indicators of impairment. As of March 31, 2018 , the Company identified no such indicators of goodwill impairment for each business segment.
Intangible Assets	The core deposit intangibles recognized in connection with prior bank acquisitions are amortized over a ten -year period on an accelerated basis. The customer list intangibles recognized in connection with the purchase of life insurance premium finance assets in 2009 are being amortized over an 18 -year period on an accelerated basis while the customer list intangibles recognized in connection with prior acquisitions within the wealth management segment are being amortized over a ten -year period on a straight-line basis. Indefinite-lived intangible assets consist of certain trade and domain names recognized in connection with the Veterans First acquisition. As indefinite-lived intangible assets are not amortized, the Company assesses impairment on at least an annual basis.
Transfers and Servicing of Financial Assets, Servicing of Financial Assets	The Company recognizes MSR assets upon the sale of residential real estate loans to external third parties when it retains the obligation to service the loans and the servicing fee is more than adequate compensation. The initial recognition of MSR assets from loans sold with servicing retained and subsequent changes in fair value of all MSRs are recognized in mortgage banking revenue. MSRs are subject to changes in value from actual and expected prepayment of the underlying loans. The Company does not specifically hedge the value of its MSRs. Fair values are determined by using a discounted cash flow model that incorporates the objective characteristics of the portfolio as well as subjective valuation parameters that purchasers of servicing would apply to such portfolios sold into the secondary market. The subjective factors include loan prepayment speeds, discount rates, servicing costs and other economic factors. The Company uses a third party to assist in the valuation of MSRs.
Offsetting Assets and Liabilities	The Company records securities sold under repurchase agreements at their gross value and does not offset positions on the Consolidated Statements of Condition.
Repurchase Agreements	Securities pledged for customer balances in sweep accounts and short-term borrowings from brokers are maintained under the Company’s control and consist of U.S. Government agency and mortgage-backed securities. These securities are included in the available-for-sale and held-to-maturity securities portfolios as reflected on the Company’s Consolidated Statements of Condition.
Debt	FHLB advances are stated at par value of the debt adjusted for unamortized prepayment fees paid at the time of prior restructurings of FHLB advances and unamortized fair value adjustments recorded in connection with advances acquired through acquisitions. As no outstanding balance exists on the Revolving Credit Facility, unamortized costs paid by the Company in relation to the issuance of this debt are classified in other assets on the Consolidated Statements of Condition. The Term Facility is stated at par of the current outstanding balance of the debt adjusted for unamortized costs paid by the Company in relation to the debt issuance. These notes are stated at par adjusted for unamortized costs paid related to the issuance of this debt. These transactions were not considered sales of receivables and, as such, related proceeds received are reflected on the Company’s Consolidated Statements of Condition as a secured borrowing owed to the unrelated third party, net of unamortized debt issuance costs, and translated to the Company’s reporting currency as of the respective date.
Transfers and Servicing of Financial Assets, Transfers of Financial Assets	The remaining $15.0 million within secured borrowings at March 31, 2018 represents other sold interests in certain loans by the Company that were not considered sales and, as such, related proceeds received are reflected on the Company’s Consolidated Statements of Condition as a secured borrowing owed to the various unrelated third parties.
Junior Subordinated Debentures	The Trusts are reported in the Company’s consolidated financial statements as unconsolidated subsidiaries. Accordingly, in the Consolidated Statements of Condition, the junior subordinated debentures issued by the Company to the Trusts are reported as liabilities and the common securities of the Trusts, all of which are owned by the Company, are included in available-for-sale securities.
Revenue Recognition	Contract liabilities represent upfront fees that the Company received at inception of certain contracts. The revenue recognized that was included in the contract liability balance at beginning of the period totaled $92,000 and $82,000 for the three months ended March 31, 2018 and 2017 , respectively. Receivables are recognized in the period the Company provides services when the Company's right to consideration is unconditional. Card related fee receivable is the result of volume based fee that the Company receives from a customer on an annual basis in the second quarter of each year. Payment terms on other invoiced amounts are typically 30 days or less. Contract liabilities and receivables from contracts with customers are included within the accrued interest payable and other liabilities and accrued interest receivable and other assets line items, respectively, in the Consolidated Statements of Condition. Wealth Management Revenue Wealth management revenue is comprised of brokerage and insurance product commissions, managed money fees and trust and asset management revenue of the Company's three wealth management subsidiaries: WHI, Great Lakes Advisors, LLC ("GLA") and The Chicago Trust Company, N.A. ("CTC"). All wealth management revenue is recognized in the wealth management segment. Brokerage and insurance product commissions consists primarily of commissions earned from trade execution services on behalf of customers and from selling mutual funds, insurance and other investment products to customers. For trade execution services, the Company recognizes commissions and receives payment from the brokerage customers at the point of transaction execution. Commissions received from the investment or insurance product providers are recognized at the point of sale of the product. The Company also receives trail and other commissions from providers for certain plans. These are generally based on qualifying account values and are recognized once the performance obligation, specific to each provider, is satisfied on a monthly, quarterly or annual basis. Trust revenue is earned from trust and custody services that are generally performed over time. Revenue is determined periodically based on a schedule of fees applied to the value of each customer account using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Fees are typically billed on a calendar month or quarter basis in advance or in arrears depending upon the contract. Additional fees earned for certain extraordinary services performed on behalf of the customers are recognized when the service has been performed. Asset management revenue is earned from money management and advisory services that are performed over time. Revenue is based primarily on the market value of assets under management or administration using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Fees are typically billed on a calendar month or quarter basis in advance or in arrears depending upon the contract. Certain programs provide the customer with an option of paying fees as a percentage of the account value or incurring commission charges for each trade similar to brokerage and insurance product commissions. Trade commissions and any other fees received for additional services are recognized at a point in time once the performance obligation is satisfied. Mortgage Broker Fees For customers desiring a mortgage product not currently offered by the Company, the Company may refer such customers and, with permission, direct such customers' applications to certain third party mortgage brokers. Mortgage broker fees are received from these brokers for such customer referrals upon settlement of the underlying mortgage. The Company's entitlement to the consideration is contingent on the settlement of the mortgage which is highly susceptible to factors outside of the Company's influence, such as third party broker's underwriting requirements. Also, the uncertainty surrounding the consideration could be resolved in varying lengths of time, dependent upon the third party brokers. Therefore, mortgage broker fees are recognized at the settlement of the underlying mortgage when the consideration is received. Broker fees are recognized in the community banking segment. Service Charges on Deposit Accounts Service charges on deposit accounts include fees charged to deposit customers for various services, including account analysis services, and are based on factors such as the size and type of customer, type of product and number of transactions. The fees are based on a standard schedule of fees and, depending on the nature of the service performed, the service is performed at a point in time or over a period of a month. When the service is performed at a point in time, the Company recognizes and receives revenue when the service has been performed. When the service is performed over a period of a month, the Company recognizes and receives revenue in the month the service has been performed. Service charges on deposit accounts are recognized in the community banking segment. Administrative Services Administrative services revenue is earned from providing outsourced administrative services, such as data processing of payrolls, billing and cash management services, to temporary staffing service clients located throughout the United States. Fees are charged periodically (typically a payroll cycle) and computed in accordance with the contractually determined rate applied to the total gross billings administered for the period. The revenue is recognized over the period using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Other fees are charged on a per occurrence basis as the service is provided in the billing cycle. The Company has certain contracts with customers to perform outsourced administrative services and short-term accounts receivable financing. For these contracts, the total fee is allocated between the administrative services revenue and interest income during the client onboarding process based on the specific client and services provided. Administrative services revenue is recognized in the specialty finance segment. Card and Deposit Related Fees Card related fees include interchange and merchant revenue, and fees related to debit and credit cards. Interchange revenue is related to the Company issued debit cards. Other deposit related fees primarily include pay by phone processing fees, ATM and safe deposit box fees, check order charges and foreign currency related fees. Card and deposit related fees are generally based on volume of transactions and are recognized at the point in time when the service has been performed. For any consideration that is constrained, the revenue is recognized once the uncertainty is known. Upfront fees received from certain contracts are recognized on a straight line basis over the term of the contract. Card and deposit related fees are recognized in the community banking segment. Practical Expedients and Exemptions The Company does not adjust the promised amount of consideration for the effects of a significant financing component if the Company expects, at contract inception, that the period between when the Company transfers a promised service to a customer and when the customer pays for that services is one year or less. The Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the entity otherwise would have recognized is one year or less.
Segment Reporting	The Company’s operations consist of three primary segments: community banking, specialty finance and wealth management. The three reportable segments are strategic business units that are separately managed as they offer different products and services and have different marketing strategies. In addition, each segment’s customer base has varying characteristics and each segment has a different regulatory environment. While the Company’s management monitors each of the fifteen bank subsidiaries’ operations and profitability separately, these subsidiaries have been aggregated into one reportable operating segment due to the similarities in products and services, customer base, operations, profitability measures, and economic characteristics. For purposes of internal segment profitability, management allocates certain intersegment and parent company balances. Management allocates a portion of revenues to the specialty finance segment related to loans and leases originated by the specialty finance segment and sold or assigned to the community banking segment. Similarly, for purposes of analyzing the contribution from the wealth management segment, management allocates a portion of the net interest income earned by the community banking segment on deposit balances of customers of the wealth management segment to the wealth management segment. See Note 10 — Deposits, for more information on these deposits. Finally, expenses incurred at the Wintrust parent company are allocated to each segment based on each segment's risk-weighted assets. The segment financial information provided in the following tables has been derived from the internal profitability reporting system used by management to monitor and manage the financial performance of the Company. The accounting policies of the segments are substantially similar to those described in “Summary of Significant Accounting Policies” in Note 1 of the Company’s 2017 Form 10-K. The Company evaluates segment performance based on after-tax profit or loss and other appropriate profitability measures common to each segment.
Derivatives	Periodically, the Company will sell options to a bank or dealer for the right to purchase certain securities held within the banks’ investment portfolios (covered call options). These option transactions are designed primarily to mitigate overall interest rate risk and to increase the total return associated with the investment securities portfolio. These options do not qualify as accounting hedges pursuant to ASC 815, and, accordingly, changes in fair value of these contracts are recognized as other non-interest income. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings. In most cases, the offsetting derivatives have mirror-image terms, which result in the positions’ changes in fair value substantially offsetting through earnings each period. However, to the extent that the derivatives are not a mirror-image and because of differences in counterparty credit risk, changes in fair value will not completely offset resulting in some earnings impact each period. Changes in the fair value of these derivatives are included in other non-interest income. When the relationship between the hedged item and hedging instrument is highly effective at achieving offsetting changes in cash flows attributable to the hedged risk, changes in the fair value of these cash flow hedges are recorded in accumulated other comprehensive income and are subsequently reclassified to interest expense as interest payments are made on such variable rate deposits. The changes in fair value (net of tax) are separately disclosed in the Consolidated Statements of Comprehensive Income. The fair values of these derivatives were estimated based on changes in mortgage rates from the dates of the commitments. Changes in the fair value of these mortgage banking derivatives are included in mortgage banking revenue. For derivatives designated and that qualify as fair value hedges, the net gain or loss from the entire change in the fair value of the derivative instrument is recognized in the same income statement line item as the earnings effect, including the net gain or loss, of the hedged item (interest income earned on fixed rate loans) when the hedged item affects earnings. The Company recognizes derivative financial instruments in the consolidated financial statements at fair value regardless of the purpose or intent for holding the instrument. The Company records derivative assets and derivative liabilities on the Consolidated Statements of Condition within accrued interest receivable and other assets and accrued interest payable and other liabilities, respectively. Changes in the fair value of derivative financial instruments are either recognized in income or in shareholders’ equity as a component of other comprehensive income depending on whether the derivative financial instrument qualifies for hedge accounting and, if so, whether it qualifies as a fair value hedge or cash flow hedge. As of January 1, 2018, the Company elected to early adopt ASU No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” Generally, changes in fair values of derivatives accounted for as fair value hedges are recorded in income in the same period and in the same income statement line as changes in the fair values of the hedged items that relate to the hedged risk(s). Changes in fair values of derivative financial instruments accounted for as cash flow hedges are recorded as a component of other comprehensive income, net of deferred taxes, and reclassified to earnings when the hedged transaction affects earnings. Changes in fair values of derivative financial instruments not designated in a hedging relationship pursuant to ASC 815 are reported in non-interest income during the period of the change. Derivative financial instruments are valued by a third party and are corroborated by comparison with valuations provided by the respective counterparties. Fair values of certain mortgage banking derivatives (interest rate lock commitments and forward commitments to sell mortgage loans) are estimated based on changes in mortgage interest rates from the date of the loan commitment. The fair value of foreign currency derivatives is computed based on changes in foreign currency rates stated in the contract compared to those prevailing at the measurement date. Interest rate swaps designated as fair value hedges involve the payment of fixed amounts to a counterparty in exchange for the Company receiving variable payments over the life of the agreements without the exchange of the underlying notional amount.
Derivatives, Offsetting Fair Value Amounts	The Company records interest rate derivatives subject to master netting agreements at their gross value and does not offset derivative assets and liabilities on the Consolidated Statements of Condition.
Fair Value of Financial Instruments	The Company measures, monitors and discloses certain of its assets and liabilities on a fair value basis. These financial assets and financial liabilities are measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the observability of the inputs used to determine fair value. These levels are: • Level 1—unadjusted quoted prices in active markets for identical 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 include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability or inputs that are derived principally from or corroborated by observable market data by correlation or other means. • Level 3—significant unobservable inputs that reflect the Company’s own assumptions that market participants would use in pricing the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. A financial instrument’s categorization within the above valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the assets or liabilities. The following is a description of the valuation methodologies used for the Company’s assets and liabilities measured at fair value on a recurring basis. Available-for-sale securities, trading account securities and equity securities with readily determinable fair value —Fair values for available-for-sale securities, trading account securities and equity securities with readily determinable fair value are typically based on prices obtained from independent pricing vendors. Securities measured with these valuation techniques are generally classified as Level 2 of the fair value hierarchy. Typically, standard inputs such as benchmark yields, reported trades for similar securities, issuer spreads, benchmark securities, bids, offers and reference data including market research publications are used to fair value a security. When these inputs are not available, broker/dealer quotes may be obtained by the vendor to determine the fair value of the security. We review the vendor’s pricing methodologies to determine if observable market information is being used, versus unobservable inputs. Fair value measurements using significant inputs that are unobservable in the market due to limited activity or a less liquid market are classified as Level 3 in the fair value hierarchy. The Company’s Investment Operations Department is responsible for the valuation of Level 3 available-for-sale securities. The methodology and variables used as inputs in pricing Level 3 securities are derived from a combination of observable and unobservable inputs. The unobservable inputs are determined through internal assumptions that may vary from period to period due to external factors, such as market movement and credit rating adjustments. At March 31, 2018 , the Company classified $84.6 million of municipal securities as Level 3. These municipal securities are bond issues for various municipal government entities primarily located in the Chicago metropolitan area and southern Wisconsin and are privately placed, non-rated bonds without CUSIP numbers. The Company also classified $3.6 million of U.S. government agencies as Level 3 at March 31, 2018 . The Company’s methodology for pricing these securities focuses on three distinct inputs: equivalent rating, yield and other pricing terms. To determine the rating for a given non-rated municipal bond, the Investment Operations Department references a publicly issued bond by the same issuer if available. A reduction is then applied to the rating obtained from the comparable bond, as the Company believes if liquidated, a non-rated bond would be valued less than a similar bond with a verifiable rating. The reduction applied by the Company is one complete rating grade (i.e. a “AA” rating for a comparable bond would be reduced to “A” for the Company’s valuation). In the first quarter of 2018 , all of the ratings derived in the above process by Investment Operations were BBB or better, for both bonds with and without comparable bond proxies. The fair value measurement of municipal bonds is sensitive to the rating input, as a higher rating typically results in an increased valuation. The remaining pricing inputs used in the bond valuation are observable. Based on the rating determined in the above process, Investment Operations obtains a corresponding current market yield curve available to market participants. Other terms including coupon, maturity date, redemption price, number of coupon payments per year, and accrual method are obtained from the individual bond term sheets. Certain municipal bonds held by the Company at March 31, 2018 have a call date that has passed, and are now continuously callable. When valuing these bonds, the fair value is capped at par value as the Company assumes a market participant would not pay more than par for a continuously callable bond. To determine the rating for the U.S. government agency securities, the Investment Operations Department assigned a AAA rating as it is guaranteed by the U.S. government. Mortgage loans held-for-sale —The fair value of mortgage loans held-for-sale is determined by reference to investor price sheets for loan products with similar characteristics. Loans held-for-investment —The fair value for loans in which the Company elected the fair value option is estimated by discounting future scheduled cash flows for the specific loan through maturity, adjusted for estimated credit losses and prepayments. The Company uses a discount rate based on the actual coupon rate of the underlying loan. At March 31, 2018 , the Company classified $26.6 million of loans held-for-investment as Level 3. The weighted average discount rate used as an input to value these loans at March 31, 2018 was 4.14% with discount rates applied ranging from 3% - 4% . The higher the rate utilized to discount estimated future cash flows, the lower the fair value measurement. As noted above, the fair value estimate also includes assumptions of prepayment speeds and credit losses. The Company included a prepayments speed assumption of 8.76% at March 31, 2018 . Prepayment speeds are inversely related to the fair value of these loans as an increase in prepayment speeds results in a decreased valuation. Additionally, the weighted average credit discount used as an input to value the specific loans was 1.88% with credit loss discount ranging from 0% - 11% at March 31, 2018 . MSRs —Fair value for MSRs is determined utilizing a valuation model which calculates the fair value of each servicing rights based on the present value of estimated future cash flows. The Company uses a discount rate commensurate with the risk associated with each servicing rights, given current market conditions. At March 31, 2018 , the Company classified $54.6 million of MSRs as Level 3. The weighted average discount rate used as an input to value the pool of MSRs at March 31, 2018 was 10.02% with discount rates applied ranging from 7% - 17% . The higher the rate utilized to discount estimated future cash flows, the lower the fair value measurement. The fair value of MSRs was also estimated based on other assumptions including prepayment speeds and the cost to service. Prepayment speeds used as an input to value the MSRs at March 31, 2018 ranged from 0% - 87% or a weighted average prepayment speed of 9.40% . Further, for current and delinquent loans, the Company assumed a weighted average cost of servicing of $78 and $368 , respectively, per loan. Prepayment speeds and the cost to service are both inversely related to the fair value of MSRs as an increase in prepayment speeds or the cost to service results in a decreased valuation. See Note 9 - Mortgage Servicing Rights (“MSRs”) for further discussion of MSRs. Derivative instruments —The Company’s derivative instruments include interest rate swaps and caps, commitments to fund mortgages for sale into the secondary market (interest rate locks), forward commitments to end investors for the sale of mortgage loans and foreign currency contracts. Interest rate swaps and caps are valued by a third party, using models that primarily use market observable inputs, such as yield curves, and are validated by comparison with valuations provided by the respective counterparties. The credit risk associated with derivative financial instruments that are subject to master netting agreements is measured on a net basis by counterparty portfolio. The fair value for mortgage-related derivatives is based on changes in mortgage rates from the date of the commitments. The fair value of foreign currency derivatives is computed based on change in foreign currency rates stated in the contract compared to those prevailing at the measurement date. At March 31, 2018 , the Company classified $4.6 million of derivative assets related to interest rate locks as Level 3. The fair value of interest rate locks is based on prices obtained for loans with similar characteristics from third parties, adjusted for the pull-through rate, which represents the Company’s best estimate of the likelihood that a committed loan will ultimately fund. The weighted-average pull-through rate at March 31, 2018 was 85.34% with pull-through rates applied ranging from 32% to 100% . Pull-through rates are directly related to the fair value of interest rate locks as an increase in the pull-through rate results in an increased valuation. Nonqualified deferred compensation assets —The underlying assets relating to the nonqualified deferred compensation plan are included in a trust and primarily consist of non-exchange traded institutional funds which are priced based by an independent third party service.
Foreclosed Assets	Other real estate owned is comprised of real estate acquired in partial or full satisfaction of loans and is included in other assets. Other real estate owned is recorded at its estimated fair value less estimated selling costs at the date of transfer, with any excess of the related loan balance over the fair value less expected selling costs charged to the allowance for loan losses. Subsequent changes in value are reported as adjustments to the carrying amount and are recorded in other non-interest expense. Gains and losses upon sale, if any, are also charged to other non-interest expense. Fair value is generally based on third party appraisals and internal estimates that are adjusted by a discount representing the estimated cost of sale and is therefore considered a Level 3 valuation.
Fair Value Measurement	Also, the Company may be required, from time to time, to measure certain other financial assets at fair value on a nonrecurring basis in accordance with GAAP. These adjustments to fair value usually result from impairment charges on individual assets. The following methods and assumptions were used by the Company in estimating fair values of financial instruments that were not previously disclosed. Held-to-maturity securities. Held-to-maturity securities include U.S. Government-sponsored agency securities and municipal bonds issued by various municipal government entities primarily located in the Chicago metropolitan area and southern Wisconsin. Fair values for held-to-maturity securities are typically based on prices obtained from independent pricing vendors. In accordance with ASC 820, the Company has categorized these held-to-maturity securities as a Level 2 fair value measurement. Fair values for certain other held-to-maturity securities are based on the bond pricing methodology discussed previously related to certain available-for-sale securities. In accordance with ASC 820, the Company has categorized these held-to-maturity securities as a Level 3 fair value measurement. Loans held-for-investment, at amortized cost. Fair values are estimated for portfolios of loans with similar financial characteristics. Loans are analyzed by type such as commercial, residential real estate, etc. Each category is further segmented by interest rate type (fixed and variable) and term. For variable-rate loans that reprice frequently, estimated fair values are based on carrying values. The fair value of residential loans is based on secondary market sources for securities backed by similar loans, adjusted for differences in loan characteristics. The fair value for other fixed rate loans is estimated by discounting scheduled cash flows through the estimated maturity using estimated market discount rates that reflect credit and interest rate risks inherent in the loan. The primary impact of credit risk on the present value of the loan portfolio, however, was assessed through the use of the allowance for loan losses, which is believed to represent the current fair value of probable incurred losses for purposes of the fair value calculation. In accordance with ASC 820, the Company has categorized loans as a Level 3 fair value measurement. Deposits with stated maturities. The fair value of certificates of deposit is based on the discounted value of contractual cash flows. The discount rate is estimated using the rates currently in effect for deposits of similar remaining maturities. In accordance with ASC 820, the Company has categorized deposits with stated maturities as a Level 3 fair value measurement. FHLB advances. The fair value of FHLB advances is obtained from the FHLB which uses a discounted cash flow analysis based on current market rates of similar maturity debt securities to discount cash flows. In accordance with ASC 820, the Company has categorized FHLB advances as a Level 3 fair value measurement. Subordinated notes. The fair value of the subordinated notes is based on a market price obtained from an independent pricing vendor. In accordance with ASC 820, the Company has categorized subordinated notes as a Level 2 fair value measurement. Junior subordinated debentures. The fair value of the junior subordinated debentures is based on the discounted value of contractual cash flows. In accordance with ASC 820, the Company has categorized junior subordinated debentures as a Level 3 fair value measurement. The Company is required under applicable accounting guidance to report the fair value of all financial instruments on the consolidated statements of condition, including those financial instruments carried at cost.
Stock-Based Compensation	Stock-based compensation is measured as the fair value of an award on the date of grant, and the measured cost is recognized over the period which the recipient is required to provide service in exchange for the award. The fair values of restricted share and performance-based stock awards are determined based on the average of the high and low trading prices on the grant date, and the fair value of stock options is estimated using a Black-Scholes option-pricing model that utilizes various assumptions. Option-pricing models require the input of highly subjective assumptions and are sensitive to changes in the option's expected life and the price volatility of the underlying stock, which can materially affect the fair value estimate. Options granted since the inception of the LTIP in 2011 were primarily granted as LTIP awards. Expected life of options granted since the inception of the LTIP awards has been based on the safe harbor rule of the SEC Staff Accounting Bulletin No. 107 “Share-Based Payment” as the Company believes historical exercise data may not provide a reasonable basis to estimate the expected term of these options. Expected stock price volatility is based on historical volatility of the Company's common stock, which correlates with the expected life of the options, and the risk-free interest rate is based on comparable U.S. Treasury rates. Management reviews and adjusts the assumptions used to calculate the fair value of an option on a periodic basis to better reflect expected trends.
Option and Incentive Plans	Stock based compensation is recognized based upon the number of awards that are ultimately expected to vest, taking into account expected forfeitures. In addition, for performance-based awards, an estimate is made of the number of shares expected to vest as a result of actual performance against the performance criteria in the award to determine the amount of compensation expense to recognize. The estimate is reevaluated periodically and total compensation expense is adjusted for any change in estimate in the current period.
Earnings Per Share	Potentially dilutive common shares can result from stock options, restricted stock unit awards, stock warrants, the Company’s convertible preferred stock and shares to be issued under the Employee Stock Purchase Plan and the Directors Deferred Fee and Stock Plan, being treated as if they had been either exercised or issued, computed by application of the treasury stock method. While potentially dilutive common shares are typically included in the computation of diluted earnings per share, potentially dilutive common shares are excluded from this computation in periods in which the effect would reduce the loss per share or increase the income per share. For diluted earnings per share, net income applicable to common shares can be affected by the conversion of the Company’s convertible preferred stock. Where the effect of this conversion would reduce the loss per share or increase the income per share for a period, net income applicable to common shares is not adjusted by the associated preferred dividends.

Business Combinations (Tables)

Business Combinations (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Summary of FDIC Indemnification Liability	The following table summarizes the activity in the Company’s FDIC indemnification liability during the period indicated: Three Months Ended (Dollars in thousands) March 31, Balance at beginning of period $ 16,701 Reductions from reimbursable expenses (82 ) Amortization 244 Changes in expected reimbursements from the FDIC for changes in expected credit losses and reimbursable expenses 1,014 Payments received from the FDIC 386 Balance at end of period $ 18,263

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Marketable Securities	The following tables are a summary of the investment securities portfolios as of the dates shown: March 31, 2018 (Dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. Treasury $ 25,022 $ — $ (295 ) $ 24,727 U.S. Government agencies 149,899 — (563 ) 149,336 Municipal 120,396 2,218 (856 ) 121,758 Corporate notes: Financial issuers 100,294 16 (1,595 ) 98,715 Other 1,000 — (1 ) 999 Mortgage-backed: (1) Mortgage-backed securities 1,510,421 169 (64,077 ) 1,446,513 Collateralized mortgage obligations 55,836 7 (2,203 ) 53,640 Equity securities (2) — — — — Total available-for-sale securities $ 1,962,868 $ 2,410 $ (69,590 ) $ 1,895,688 Held-to-maturity securities U.S. Government agencies $ 639,442 $ — $ (25,891 ) $ 613,551 Municipal 253,495 939 (5,458 ) 248,976 Total held-to-maturity securities $ 892,937 $ 939 $ (31,349 ) $ 862,527 Equity securities with readily determinable fair value (2) $ 34,230 $ 4,670 $ (1,068 ) $ 37,832 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 144,904 $ — $ (1,082 ) $ 143,822 U.S. Government agencies 157,638 2 (725 ) 156,915 Municipal 113,197 2,712 (557 ) 115,352 Corporate notes: Financial issuers 30,309 43 (301 ) 30,051 Other 1,000 — (1 ) 999 Mortgage-backed: (1) Mortgage-backed securities 1,291,695 446 (31,955 ) 1,260,186 Collateralized mortgage obligations 60,092 64 (617 ) 59,539 Equity securities (2) 34,234 3,357 (789 ) 36,802 Total available-for-sale securities $ 1,833,069 $ 6,624 $ (36,027 ) $ 1,803,666 Held-to-maturity securities U.S. Government agencies $ 579,062 $ 23 $ (14,066 ) $ 565,019 Municipal 247,387 2,668 (2,558 ) 247,497 Total held-to-maturity securities $ 826,449 $ 2,691 $ (16,624 ) $ 812,516 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. (2) As a result of the adoption of ASU No. 2016-01 effective January 1, 2018, equity securities with readily determinable fair value are no longer presented within available-for-sale securities and are now presented as equity securities with readily determinable fair values in the Company's Consolidated Statements of Condition for the current period. March 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 142,772 $ — $ (616 ) $ 142,156 U.S. Government agencies 178,475 31 (677 ) 177,829 Municipal 125,061 2,878 (376 ) 127,563 Corporate notes: Financial issuers 65,306 107 (986 ) 64,427 Other 1,000 — (3 ) 997 Mortgage-backed: (1) Mortgage-backed securities 1,256,497 302 (46,423 ) 1,210,376 Collateralized mortgage obligations 46,035 78 (445 ) 45,668 Equity securities (2) 32,634 3,106 (1,023 ) 34,717 Total available-for-sale securities $ 1,847,780 $ 6,502 $ (50,549 ) $ 1,803,733 Held-to-maturity securities U.S. Government agencies $ 465,891 $ 115 $ (18,664 ) $ 447,342 Municipal 201,873 1,114 (2,434 ) 200,553 Total held-to-maturity securities $ 667,764 $ 1,229 $ (21,098 ) $ 647,895 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. (2) As a result of the adoption of ASU No. 2016-01 effective January 1, 2018, equity securities with readily determinable fair value are no longer presented within available-for-sale securities and are now presented as equity securities with readily determinable fair values in the Company's Consolidated Statements of Condition for the current period.
Investment Securities, Continuous Unrealized Loss Position, Fair Value	The following table presents the portion of the Company’s available-for-sale and held-to-maturity investment securities portfolios which has gross unrealized losses, reflecting the length of time that individual securities have been in a continuous unrealized loss position at March 31, 2018 : Continuous unrealized losses existing for less than 12 months Continuous unrealized losses existing for greater than 12 months Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale securities U.S. Treasury $ 24,727 $ (295 ) $ — $ — $ 24,727 $ (295 ) U.S. Government agencies 14,742 (104 ) 134,594 (459 ) 149,336 (563 ) Municipal 35,225 (494 ) 13,794 (362 ) 49,019 (856 ) Corporate notes: Financial issuers 73,037 (1,294 ) 5,665 (301 ) 78,702 (1,595 ) Other — — 999 (1 ) 999 (1 ) Mortgage-backed: Mortgage-backed securities 495,082 (12,177 ) 945,641 (51,900 ) 1,440,723 (64,077 ) Collateralized mortgage obligations 39,939 (1,672 ) 12,342 (531 ) 52,281 (2,203 ) Total available-for-sale securities $ 682,752 $ (16,036 ) $ 1,113,035 $ (53,554 ) $ 1,795,787 $ (69,590 ) Held-to-maturity securities U.S. Government agencies $ 311,150 $ (7,688 ) $ 292,800 $ (18,203 ) $ 603,950 $ (25,891 ) Municipal 160,027 (3,563 ) 49,129 (1,895 ) 209,156 (5,458 ) Total held-to-maturity securities $ 471,177 $ (11,251 ) $ 341,929 $ (20,098 ) $ 813,106 $ (31,349 )
Schedule of Gross Gains and Losses on Investment Securities	The following table provides information as to the amount of gross gains and losses, adjustments and impairment on investment securities and proceeds received through the sale or call of investment securities: Three months ended March 31, (Dollars in thousands) 2018 2017 Realized gains on available-for-sale debt securities $ — $ — Realized losses on available-for-sale debt securities (975 ) (55 ) Net realized losses on available-for-sale debt securities (975 ) $ (55 ) Unrealized gains on equity securities with readily determinable fair value 1,873 — Unrealized losses on equity securities with readily determinable fair value (843 ) — Net unrealized gains on equity securities with readily determinable fair value 1,030 — Upward adjustments of equity securities without readily determinable fair values 131 — Downward adjustments of equity securities without readily determinable fair values — — Impairment of equity securities without readily determinable fair values (537 ) — Adjustment and impairment, net, of equity securities without readily determinable fair values (406 ) — Other than temporary impairment charges — — Losses on investment securities, net $ (351 ) $ (55 ) Proceeds from sales and calls of available-for-sale securities $ 210,891 $ 6,005 Proceeds from calls of held-to-maturity securities 4,141 51,060 Proceeds from sales of equity securities with readily determinable fair value — — Proceeds from sales of equity securities without readily determinable fair value — —
Investments Classified by Contractual Maturity Date	The amortized cost and fair value of available-for-sale and held-to-maturity investment securities as of March 31, 2018 , December 31, 2017 and March 31, 2017 , by contractual maturity, are shown in the following table. Contractual maturities may differ from actual maturities as borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Mortgage-backed securities are not included in the maturity categories in the following maturity summary as actual maturities may differ from contractual maturities because the underlying mortgages may be called or prepaid without penalties: March 31, 2018 December 31, 2017 March 31, 2017 (Dollars in thousands) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Available-for-sale securities Due in one year or less $ 180,899 $ 180,333 $ 300,833 $ 299,285 $ 142,323 $ 142,001 Due in one to five years 90,073 89,953 97,019 97,326 320,945 320,278 Due in five to ten years 116,909 116,517 33,947 35,029 39,520 40,519 Due after ten years 8,730 8,732 15,249 15,499 9,826 10,174 Mortgage-backed 1,566,257 1,500,153 1,351,787 1,319,725 1,302,532 1,256,044 Equity securities (1) — — 34,234 36,802 32,634 34,717 Total available-for-sale securities $ 1,962,868 $ 1,895,688 $ 1,833,069 $ 1,803,666 $ 1,847,780 $ 1,803,733 Held-to-maturity securities Due in one year or less $ 3,786 $ 3,775 $ 170 $ 171 $ — $ — Due in one to five years 34,495 33,994 38,392 38,012 32,771 32,525 Due in five to ten years 210,705 205,823 205,227 203,680 70,533 69,348 Due after ten years 643,951 618,935 582,660 570,653 564,460 546,022 Total held-to-maturity securities $ 892,937 $ 862,527 $ 826,449 $ 812,516 $ 667,764 $ 647,895 (1) As a result of the adoption of ASU No. 2016-01 effective January 1, 2018, equity securities with readily determinable fair value are no longer presented within available-for-sale securities and are now presented as equity securities with readily determinable fair values in the Company's Consolidated Statements of Condition for the current period.

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2018
Loans and Leases Receivable Disclosure [Abstract]
Summary of Loan Portfolio	The following table shows the Company’s loan portfolio by category as of the dates shown: March 31, December 31, March 31, (Dollars in thousands) 2018 2017 2017 Balance: Commercial $ 7,060,871 $ 6,787,677 $ 6,081,489 Commercial real estate 6,633,520 6,580,618 6,261,682 Home equity 626,547 663,045 708,258 Residential real estate 869,104 832,120 720,608 Premium finance receivables—commercial 2,576,150 2,634,565 2,446,946 Premium finance receivables—life insurance 4,189,961 4,035,059 3,593,563 Consumer and other 105,981 107,713 118,512 Total loans, net of unearned income, excluding covered loans $ 22,062,134 $ 21,640,797 $ 19,931,058 Covered loans — — 52,359 Total loans $ 22,062,134 $ 21,640,797 $ 19,983,417 Mix: Commercial 32 % 31 % 30 % Commercial real estate 30 30 31 Home equity 3 3 4 Residential real estate 4 4 4 Premium finance receivables—commercial 12 12 12 Premium finance receivables—life insurance 19 19 18 Consumer and other — 1 1 Total loans, net of unearned income, excluding covered loans 100 % 100 % 100 % Covered loans — — — Total loans 100 % 100 % 100 %
Schedule of Unpaid Principal Balance and Carrying Value of Acquired Loans	The following table presents the unpaid principal balance and carrying value for these acquired loans: March 31, 2018 December 31, 2017 (Dollars in thousands) Unpaid Principal Balance Carrying Value Unpaid Carrying PCI loans $ 348,102 $ 325,745 $ 375,237 $ 350,690
Activity Related to Accretable Yield of PCI Loans	The following table provides activity for the accretable yield of PCI loans: Three Months Ended (Dollars in thousands) March 31, March 31, Accretable yield, beginning balance $ 36,565 $ 49,408 Acquisitions — 531 Accretable yield amortized to interest income (4,619 ) (5,599 ) Accretable yield amortized to indemnification asset/liability (1) — (354 ) Reclassification from non-accretable difference (2) 1,556 2,535 Increases (decreases) in interest cash flows due to payments and changes in interest rates 2,190 (759 ) Accretable yield, ending balance $ 35,692 $ 45,762 (1) Represents the portion of the current period accreted yield, resulting from lower expected losses, applied to reduce the loss share indemnification asset or increase the loss share indemnification liability. (2) Reclassification is the result of subsequent increases in expected principal cash flows.

Allowance for Loan Losses, Al30

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Schedule of Aging of the Company's Loan Portfolio	The tables below show the aging of the Company’s loan portfolio at March 31, 2018 , December 31, 2017 and March 31, 2017 : As of March 31, 2018 90+ days and still accruing 60-89 days past due 30-59 days past due (Dollars in thousands) Nonaccrual Current Total Loans Loan Balances: Commercial Commercial, industrial and other $ 10,051 $ — $ 594 $ 31,475 $ 4,518,760 $ 4,560,880 Franchise 2,401 — 44 1,203 931,710 935,358 Mortgage warehouse lines of credit — — — 5,771 157,699 163,470 Asset-based lending 1,194 — 47 12,611 963,883 977,735 Leases 361 — — 3,170 410,667 414,198 PCI - commercial (1) — 856 86 3 8,285 9,230 Total commercial 14,007 856 771 54,233 6,991,004 7,060,871 Commercial real estate: Construction 3,139 — — 9,576 802,921 815,636 Land 182 — — 4,527 117,981 122,690 Office 474 — 925 11,466 878,206 891,071 Industrial 1,427 — 823 5,027 898,867 906,144 Retail 12,274 — — 4,785 878,563 895,622 Multi-family 19 — — 328 931,008 931,355 Mixed use and other 4,310 — 192 13,626 1,937,328 1,955,456 PCI - commercial real estate (1) — 3,107 1,623 9,134 101,682 115,546 Total commercial real estate 21,825 3,107 3,563 58,469 6,546,556 6,633,520 Home equity 9,828 — 1,505 4,033 611,181 626,547 Residential real estate, including PCI 17,214 1,437 229 8,808 841,416 869,104 Premium finance receivables Commercial insurance loans 17,342 8,547 6,543 17,756 2,525,962 2,576,150 Life insurance loans — — 5,125 11,420 3,986,181 4,002,726 PCI - life insurance loans (1) — — — — 187,235 187,235 Consumer and other, including PCI 720 269 216 291 104,485 105,981 Total loans, net of unearned income $ 80,936 $ 14,216 $ 17,952 $ 155,010 $ 21,794,020 $ 22,062,134 As of December 31, 2017 90+ days and still accruing 60-89 days past due 30-59 days past due (Dollars in thousands) Nonaccrual Current Total Loans Loan Balances: Commercial Commercial, industrial and other $ 11,260 $ — $ 3,746 $ 13,392 $ 4,314,107 $ 4,342,505 Franchise 2,447 — — — 845,150 847,597 Mortgage warehouse lines of credit — — — 4,000 190,523 194,523 Asset-based lending 1,550 — 283 10,057 968,576 980,466 Leases 439 — 3 1,958 410,772 413,172 PCI - commercial (1) — 877 186 — 8,351 9,414 Total commercial 15,696 877 4,218 29,407 6,737,479 6,787,677 Commercial real estate Construction 3,143 — — 200 742,171 745,514 Land 188 — — 5,156 121,140 126,484 Office 2,438 — — 4,458 887,937 894,833 Industrial 811 — — 2,412 879,796 883,019 Retail 12,328 — 668 148 938,383 951,527 Multi-family — — — 1,034 914,610 915,644 Mixed use and other 3,140 — 1,423 9,641 1,921,501 1,935,705 PCI - commercial real estate (1) — 7,135 2,255 6,277 112,225 127,892 Total commercial real estate 22,048 7,135 4,346 29,326 6,517,763 6,580,618 Home equity 8,978 — 518 4,634 648,915 663,045 Residential real estate, including PCI 17,977 5,304 1,303 8,378 799,158 832,120 Premium finance receivables Commercial insurance loans 12,163 9,242 17,796 15,849 2,579,515 2,634,565 Life insurance loans — — 4,837 10,017 3,820,936 3,835,790 PCI - life insurance loans (1) — — — — 199,269 199,269 Consumer and other, including PCI 740 101 242 727 105,903 107,713 Total loans, net of unearned income $ 77,602 $ 22,659 $ 33,260 $ 98,338 $ 21,408,938 $ 21,640,797 (1) PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. Loan agings are based upon contractually required payments. As of March 31, 2017 90+ days and still accruing 60-89 days past due 30-59 days past due (Dollars in thousands) Nonaccrual Current Total Loans Loan Balances: Commercial Commercial, industrial and other $ 12,036 $ 100 $ 19 $ 23,780 $ 3,855,140 $ 3,891,075 Franchise 323 — — 987 822,424 823,734 Mortgage warehouse lines of credit — — — 9,111 145,069 154,180 Asset-based lending 1,378 — — 3,744 875,882 881,004 Leases 570 — — 874 318,566 320,010 PCI - commercial (1) — 1,368 — 944 9,174 11,486 Total commercial 14,307 1,468 19 39,440 6,026,255 6,081,489 Commercial real estate: Construction 2,408 — 391 4,356 648,178 655,333 Land 350 — — 3,274 101,455 105,079 Office 3,513 — 953 7,155 859,045 870,666 Industrial 7,004 — — 2,656 783,302 792,962 Retail 589 — — 4,727 906,470 911,786 Multi-family 668 — 203 4,813 799,092 804,776 Mixed use and other 6,277 — 3,207 14,166 1,940,094 1,963,744 PCI - commercial real estate (1) — 12,559 672 15,565 128,540 157,336 Total commercial real estate 20,809 12,559 5,426 56,712 6,166,176 6,261,682 Home equity 11,722 — 430 4,884 691,222 708,258 Residential real estate, including PCI 11,943 900 3,410 5,262 699,093 720,608 Premium finance receivables Commercial insurance loans 12,629 4,991 6,383 23,775 2,399,168 2,446,946 Life insurance loans — 2,024 2,535 32,208 3,316,090 3,352,857 PCI - life insurance loans (1) — — — — 240,706 240,706 Consumer and other, including PCI 350 167 323 543 117,129 118,512 Total loans, net of unearned income, excluding covered loans $ 71,760 $ 22,109 $ 18,526 $ 162,824 $ 19,655,839 $ 19,931,058 Covered loans 1,592 2,808 268 1,570 46,121 52,359 Total loans, net of unearned income $ 73,352 $ 24,917 $ 18,794 $ 164,394 $ 19,701,960 $ 19,983,417 (1) PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. Loan agings are based upon contractually required payments.
Summary of Performance by Loan Class	The following table presents the recorded investment based on performance of loans by class, excluding covered loans, per the most recent analysis at March 31, 2018 , December 31, 2017 and March 31, 2017 : Performing Non-performing Total (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, March 31, December 31, March 31, Loan Balances: Commercial Commercial, industrial and other $ 4,550,829 $ 4,331,245 $ 3,878,939 $ 10,051 $ 11,260 $ 12,136 $ 4,560,880 $ 4,342,505 $ 3,891,075 Franchise 932,957 845,150 823,411 2,401 2,447 323 935,358 847,597 823,734 Mortgage warehouse lines of credit 163,470 194,523 154,180 — — — 163,470 194,523 154,180 Asset-based lending 976,541 978,916 879,626 1,194 1,550 1,378 977,735 980,466 881,004 Leases 413,837 412,733 319,440 361 439 570 414,198 413,172 320,010 PCI - commercial (1) 9,230 9,414 11,486 — — — 9,230 9,414 11,486 Total commercial 7,046,864 6,771,981 6,067,082 14,007 15,696 14,407 7,060,871 6,787,677 6,081,489 Commercial real estate Construction 812,497 742,371 652,925 3,139 3,143 2,408 815,636 745,514 655,333 Land 122,508 126,296 104,729 182 188 350 122,690 126,484 105,079 Office 890,597 892,395 867,153 474 2,438 3,513 891,071 894,833 870,666 Industrial 904,717 882,208 785,958 1,427 811 7,004 906,144 883,019 792,962 Retail 883,348 939,199 911,197 12,274 12,328 589 895,622 951,527 911,786 Multi-family 931,336 915,644 804,108 19 — 668 931,355 915,644 804,776 Mixed use and other 1,951,146 1,932,565 1,957,467 4,310 3,140 6,277 1,955,456 1,935,705 1,963,744 PCI - commercial real estate (1) 115,546 127,892 157,336 — — — 115,546 127,892 157,336 Total commercial real estate 6,611,695 6,558,570 6,240,873 21,825 22,048 20,809 6,633,520 6,580,618 6,261,682 Home equity 616,719 654,067 696,536 9,828 8,978 11,722 626,547 663,045 708,258 Residential real estate, including PCI 851,890 810,865 708,665 17,214 21,255 11,943 869,104 832,120 720,608 Premium finance receivables Commercial insurance loans 2,550,261 2,613,160 2,429,326 25,889 21,405 17,620 2,576,150 2,634,565 2,446,946 Life insurance loans 4,002,726 3,835,790 3,350,833 — — 2,024 4,002,726 3,835,790 3,352,857 PCI - life insurance loans (1) 187,235 199,269 240,706 — — — 187,235 199,269 240,706 Consumer and other, including PCI 105,054 106,933 118,058 927 780 454 105,981 107,713 118,512 Total loans, net of unearned income, excluding covered loans $ 21,972,444 $ 21,550,635 $ 19,852,079 $ 89,690 $ 90,162 $ 78,979 $ 22,062,134 $ 21,640,797 $ 19,931,058 (1) PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. See Note 6 - Loans for further discussion of these purchased loans.
Summary of Activity in the Allowance for Credit Losses	A summary of activity in the allowance for credit losses by loan portfolio (excluding covered loans) for the three months ended March 31, 2018 and 2017 is as follows: Three months ended March 31, 2018 Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total, Excluding Covered Loans (Dollars in thousands) Commercial Allowance for credit losses Allowance for loan losses at beginning of period $ 57,811 $ 55,227 $ 10,493 $ 6,688 $ 6,846 $ 840 $ 137,905 Other adjustments (1 ) (24 ) — (3 ) (12 ) — (40 ) Reclassification from allowance for unfunded lending-related commitments — 26 — — — — 26 Charge-offs (2,687 ) (813 ) (357 ) (571 ) (4,721 ) (129 ) (9,278 ) Recoveries 262 1,687 123 40 385 47 2,544 Provision for credit losses 2,251 1,378 (399 ) 124 4,835 157 8,346 Allowance for loan losses at period end $ 57,636 $ 57,481 $ 9,860 $ 6,278 $ 7,333 $ 915 $ 139,503 Allowance for unfunded lending-related commitments at period end $ — $ 1,243 $ — $ — $ — $ — $ 1,243 Allowance for credit losses at period end $ 57,636 $ 58,724 $ 9,860 $ 6,278 $ 7,333 $ 915 $ 140,746 Individually evaluated for impairment $ 2,344 $ 3,611 $ 749 $ 148 $ — $ 25 $ 6,877 Collectively evaluated for impairment 54,789 55,042 9,111 6,029 7,333 890 133,194 Loans acquired with deteriorated credit quality 503 71 — 101 — — 675 Loans at period end Individually evaluated for impairment $ 33,810 $ 38,237 $ 10,102 $ 20,558 $ — $ 748 $ 103,455 Collectively evaluated for impairment 7,017,831 6,479,737 616,445 768,859 6,578,876 103,224 21,564,972 Loans acquired with deteriorated credit quality 9,230 115,546 — 11,725 187,235 2,009 325,745 Loans held at fair value — — — 67,962 — — 67,962 Three months ended March 31, 2017 Commercial Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total, Excluding Covered Loans (Dollars in thousands) Allowance for credit losses Allowance for loan losses at beginning of period $ 44,493 $ 51,422 $ 11,774 $ 5,714 $ 7,625 $ 1,263 $ 122,291 Other adjustments (19 ) (36 ) — (4 ) 3 — (56 ) Reclassification from allowance for unfunded lending-related commitments (92 ) (46 ) — — — — (138 ) Charge-offs (641 ) (261 ) (625 ) (329 ) (1,427 ) (134 ) (3,417 ) Recoveries 273 554 65 178 612 141 1,823 Provision for credit losses 2,568 1,000 989 (29 ) 746 42 5,316 Allowance for loan losses at period end $ 46,582 $ 52,633 $ 12,203 $ 5,530 $ 7,559 $ 1,312 $ 125,819 Allowance for unfunded lending-related commitments at period end $ 592 $ 1,219 $ — $ — $ — $ — $ 1,811 Allowance for credit losses at period end $ 47,174 $ 53,852 $ 12,203 $ 5,530 $ 7,559 $ 1,312 $ 127,630 Individually evaluated for impairment $ 2,845 $ 3,198 $ 1,979 $ 666 $ — $ 92 $ 8,780 Collectively evaluated for impairment 43,687 50,594 10,224 4,802 7,559 1,219 118,085 Loans acquired with deteriorated credit quality 642 60 — 62 — 1 765 Loans at period end Individually evaluated for impairment $ 19,319 $ 40,107 $ 11,878 $ 16,594 $ — $ 405 $ 88,303 Collectively evaluated for impairment 6,050,684 6,064,239 696,380 671,765 5,799,803 116,966 19,399,837 Loans acquired with deteriorated credit quality 11,486 157,336 — 3,701 240,706 1,141 414,370 Loans held at fair value — — — 28,548 — — 28,548
Summary Of Activity In Allowance For Covered Loan By FDIC Loss Table	A summary of activity in the allowance for covered loan losses for the three months ended March 31, 2017 is as follows: Three Months Ended March 31, (Dollars in thousands) 2017 Balance at beginning of period $ 1,322 Provision for covered loan losses before benefit attributable to FDIC loss share agreements (535 ) Benefit attributable to FDIC loss share agreements 428 Net provision for covered loan losses (107 ) Increase in FDIC indemnification liability (428 ) Loans charged-off (216 ) Recoveries of loans charged-off 748 Net (charge-offs) recoveries 532 Balance at end of period $ 1,319
Summary of Impaired Loans, Including Restructured Loans	A summary of impaired loans, including troubled debt restructurings ("TDRs"), is as follows: March 31, December 31, March 31, (Dollars in thousands) 2018 2017 2017 Impaired loans (included in non-performing and TDRs): Impaired loans with an allowance for loan loss required (1) $ 37,572 $ 36,084 $ 39,968 Impaired loans with no allowance for loan loss required 65,559 69,004 47,554 Total impaired loans (2) $ 103,131 $ 105,088 $ 87,522 Allowance for loan losses related to impaired loans $ 6,863 $ 8,023 $ 8,165 TDRs $ 47,676 $ 49,786 $ 39,669 (1) These impaired loans require an allowance for loan losses because the estimated fair value of the loans or related collateral is less than the recorded investment in the loans. (2) Impaired loans are considered by the Company to be non-accrual loans, TDRs or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest.
Summary of Impaired Loans by Loan Class	The following tables present impaired loans by loan class, excluding covered loans, for the periods ended as follows: For the Three Months Ended As of March 31, 2018 March 31, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized (Dollars in thousands) Impaired loans with a related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 5,521 $ 5,587 $ 1,738 $ 5,607 $ 83 Franchise — — — — — Asset-based lending 1,107 1,107 475 1,166 20 Leases 2,213 2,221 131 2,247 27 Commercial real estate Construction 3,097 3,897 599 3,097 50 Land 1,500 1,500 3 1,567 17 Office 1,479 2,078 73 1,483 24 Industrial 63 172 1 63 2 Retail 15,347 15,415 2,512 15,315 166 Multi-family 1,234 1,277 21 1,254 12 Mixed use and other 2,036 2,281 388 2,054 30 Home equity 1,697 1,889 749 1,699 19 Residential real estate 2,253 2,956 148 2,258 33 Consumer and other 25 27 25 25 — Impaired loans with no related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 5,480 $ 6,777 $ — $ 5,650 $ 109 Franchise 18,657 18,661 — 18,675 239 Asset-based lending 86 231 — 182 3 Leases 746 746 — 754 11 Commercial real estate Construction 1,363 1,364 — 1,364 15 Land 2,329 2,434 — 2,339 31 Office 59 754 — 61 11 Industrial 1,427 1,485 — 1,430 20 Retail 2,695 2,992 — 2,710 58 Multi-family — 84 — — 1 Mixed use and other 5,284 5,981 — 5,340 80 Home equity 8,405 12,535 — 8,255 151 Residential real estate 18,305 20,983 — 18,630 222 Consumer and other 723 870 — 726 12 Total impaired loans, net of unearned income $ 103,131 $ 116,304 $ 6,863 $ 103,951 $ 1,446 For the Twelve Months Ended As of December 31, 2017 December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized (Dollars in thousands) Impaired loans with a related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 6,233 $ 7,323 $ 3,951 $ 7,220 $ 452 Franchise — — — — — Asset-based lending 948 949 355 1,302 72 Leases 2,331 2,337 158 2,463 117 Commercial real estate Construction 3,097 3,897 403 3,690 197 Land — — — — — Office 471 471 5 481 24 Industrial 408 408 40 414 25 Retail 15,599 15,657 1,336 15,736 624 Multi-family — — — — — Mixed use and other 1,567 1,586 379 1,599 77 Home equity 1,606 1,869 784 1,626 81 Residential real estate 3,798 3,910 586 3,790 146 Consumer and other 26 28 26 27 2 Impaired loans with no related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 8,460 $ 12,259 $ — $ 10,170 $ 683 Franchise 16,256 16,256 — 17,089 780 Asset-based lending 602 602 — 688 40 Leases 782 782 — 845 49 Commercial real estate Construction 1,367 1,678 — 1,555 84 Land 3,961 4,192 — 4,129 182 Office 2,438 6,140 — 3,484 330 Industrial 403 2,010 — 1,849 174 Retail 2,393 3,538 — 2,486 221 Multi-family 1,231 2,078 — 1,246 76 Mixed use and other 5,275 6,731 — 5,559 351 Home equity 7,648 11,648 — 9,114 603 Residential real estate 17,455 20,327 — 17,926 860 Consumer and other 733 890 — 773 48 Total impaired loans, net of unearned income $ 105,088 $ 127,566 $ 8,023 $ 115,261 $ 6,298 For the Three Months Ended As of March 31, 2017 March 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized (Dollars in thousands) Impaired loans with a related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 3,804 $ 3,830 $ 1,568 $ 3,856 $ 50 Franchise — — — — — Asset-based lending 1,378 1,380 378 1,279 12 Leases 2,616 2,619 304 2,689 36 Commercial real estate Construction 5,262 5,262 74 5,276 53 Land 3,033 3,033 13 3,033 28 Office 1,512 1,522 310 1,513 18 Industrial 4,831 5,554 1,703 4,854 71 Retail 1,733 1,843 156 1,739 23 Multi-family 1,256 1,256 20 1,256 11 Mixed use and other 5,472 5,561 902 5,486 67 Home equity 3,863 3,891 1,979 3,866 35 Residential real estate 5,116 5,652 666 5,166 57 Consumer and other 92 94 92 95 1 Impaired loans with no related ASC 310 allowance recorded Commercial Commercial, industrial and other $ 10,270 $ 11,307 $ — $ 10,668 $ 185 Franchise — — — — — Leases 846 846 — 852 13 Commercial real estate Construction 3,912 3,912 — 3,973 46 Land 1,240 1,631 — 1,321 15 Office 2,487 3,803 — 2,432 56 Industrial 2,172 2,487 — 2,152 57 Retail — — — — — Multi-family 668 752 — 652 11 Mixed use and other 6,153 6,961 — 6,234 91 Home equity 8,015 10,420 — 8,176 123 Residential real estate 11,478 12,673 — 11,522 151 Consumer and other 313 401 — 315 5 Total impaired loans, net of unearned income $ 87,522 $ 96,690 $ 8,165 $ 88,405 $ 1,215
Summary of the Post-Modification Balance of TDRs	The tables below present a summary of the post-modification balance of loans restructured during the three months ended March 31, 2018 and 2017 , respectively, which represent TDRs: Three months ended March 31, 2018 (Dollars in thousands) Total (1)(2) Extension at Below Market (2) Reduction of Interest Rate (2) Modification to Interest-only Payments (2) Forgiveness of Debt (2) Count Balance Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 1 $ 96 1 $ 96 — $ — — $ — — $ — Commercial real estate Office 1 59 1 59 — — — — — — Industrial — — — — — — — — — — Mixed use and other — — — — — — — — — — Residential real estate and other 5 835 5 835 2 111 — — — — Total loans 7 $ 990 7 $ 990 2 $ 111 — $ — — $ — Three months ended March 31, 2017 (Dollars in thousands) Total (1)(2) Extension at Below Market Terms (2) Reduction of Interest Rate (2) Modification to Interest-only Payments (2) Forgiveness of Debt (2) Count Balance Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 1 $ 95 1 $ 95 — $ — — $ — — $ — Commercial real estate Office — — — — — — — — — — Industrial — — — — — — — — — — Mixed use and other 1 1,245 1 1,245 — — — — — — Residential real estate and other 2 173 2 173 2 173 — — — — Total loans 4 $ 1,513 4 $ 1,513 2 $ 173 — $ — — $ — (1) TDRs may have more than one modification representing a concession. As such, TDRs during the period may be represented in more than one of the categories noted above. (2) Balances represent the recorded investment in the loan at the time of the restructuring.
Schedule of Loans Restructured with Payments in Default	The following table presents a summary of all loans restructured in TDRs during the twelve months ended March 31, 2018 and 2017 , and such loans which were in payment default under the restructured terms during the respective periods below: (Dollars in thousands) As of March 31, 2018 Three Months Ended March 31, 2018 As of March 31, 2017 Three Months Ended March 31, 2017 Total (1)(3) Payments in Default (2)(3) Total (1)(3) Payments in Default (2)(3) Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 5 $ 3,776 5 $ 3,776 3 398 1 $ 28 Leases 3 16,256 — — 2 2,949 — — Commercial real estate Office 1 59 — — — — — — Industrial — — — — — — — — Mixed use and other — — — — 1 1,245 — — Residential real estate and other 15 3,711 5 2,551 8 1,095 1 232 Total loans 24 $ 23,802 10 $ 6,327 14 5,687 2 $ 260 (1) Total TDRs represent all loans restructured in TDRs during the previous twelve months from the date indicated. (2) TDRs considered to be in payment default are over 30 days past-due subsequent to the restructuring. (3) Balances represent the recorded investment in the loan at the time of the restructuring.

Goodwill and Other Intangible31

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill Assets by Business Segment	A summary of the Company’s goodwill assets by business segment is presented in the following table: (Dollars in thousands) January 1, 2018 Goodwill Acquired Impairment Loss Goodwill Adjustments March 31, Community banking $ 429,520 $ 10,229 $ — $ — $ 439,749 Specialty finance 40,250 — — (616 ) 39,634 Wealth management 32,114 — — — 32,114 Total $ 501,884 $ 10,229 $ — $ (616 ) $ 511,497
Summary of Intangible Assets	A summary of intangible assets as of the dates shown and the expected amortization of finite-lived intangible assets as of March 31, 2018 is as follows: (Dollars in thousands) March 31, December 31, March 31, Community banking segment: Core deposit intangibles with finite lives: Gross carrying amount $ 37,272 $ 37,272 $ 37,272 Accumulated amortization (26,280 ) (25,427 ) (22,634 ) Net carrying amount $ 10,992 $ 11,845 $ 14,638 Trademark with indefinite lives: Carrying amount 5,800 — — Total net carrying amount $ 16,792 $ 11,845 $ 14,638 Specialty finance segment: Customer list intangibles with finite lives: Gross carrying amount $ 1,967 $ 1,972 $ 1,800 Accumulated amortization (1,335 ) (1,298 ) (1,191 ) Net carrying amount $ 632 $ 674 $ 609 Wealth management segment: Customer list and other intangibles with finite lives: Gross carrying amount $ 7,940 $ 7,940 $ 7,940 Accumulated amortization (2,951 ) (2,838 ) (2,500 ) Net carrying amount $ 4,989 $ 5,102 $ 5,440 Total other intangible assets, net $ 22,413 $ 17,621 $ 20,687
Summary of Intangible Assets	A summary of intangible assets as of the dates shown and the expected amortization of finite-lived intangible assets as of March 31, 2018 is as follows: (Dollars in thousands) March 31, December 31, March 31, Community banking segment: Core deposit intangibles with finite lives: Gross carrying amount $ 37,272 $ 37,272 $ 37,272 Accumulated amortization (26,280 ) (25,427 ) (22,634 ) Net carrying amount $ 10,992 $ 11,845 $ 14,638 Trademark with indefinite lives: Carrying amount 5,800 — — Total net carrying amount $ 16,792 $ 11,845 $ 14,638 Specialty finance segment: Customer list intangibles with finite lives: Gross carrying amount $ 1,967 $ 1,972 $ 1,800 Accumulated amortization (1,335 ) (1,298 ) (1,191 ) Net carrying amount $ 632 $ 674 $ 609 Wealth management segment: Customer list and other intangibles with finite lives: Gross carrying amount $ 7,940 $ 7,940 $ 7,940 Accumulated amortization (2,951 ) (2,838 ) (2,500 ) Net carrying amount $ 4,989 $ 5,102 $ 5,440 Total other intangible assets, net $ 22,413 $ 17,621 $ 20,687
Estimated Amortization	Estimated amortization Actual in three months ended March 31, 2018 $ 1,004 Estimated remaining in 2018 2,792 Estimated—2019 3,223 Estimated—2020 2,597 Estimated—2021 2,056 Estimated—2022 1,556

Mortgage Servicing Rights ("M32

Mortgage Servicing Rights ("MSRs") (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosures Pertaining to Servicing Assets and Servicing Liabilities [Abstract]
Schedule of Servicing Assets at Fair Value	The following is a summary of the changes in the carrying value of MSRs, accounted for at fair value, for the periods indicated: Three Months Ended March 31, March 31, (Dollars in thousands) 2018 2017 Balance at beginning of the period $ 33,676 $ 19,103 Additions from loans sold with servicing retained 4,159 2,766 Additions from acquisitions 13,806 — Estimate of changes in fair value due to: Payoffs and paydowns (1,202 ) (429 ) Changes in valuation inputs or assumptions 4,133 156 Fair value at end of the period $ 54,572 $ 21,596 Unpaid principal balance of mortgage loans serviced for others $ 4,795,335 $ 1,972,592

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2018
Deposits [Abstract]
Summary of Deposits	The following table is a summary of deposits as of the dates shown: (Dollars in thousands) March 31, December 31, March 31, Balance: Non-interest bearing $ 6,612,319 $ 6,792,497 $ 5,790,579 NOW and interest bearing demand deposits 2,315,122 2,315,055 2,484,676 Wealth management deposits 2,495,134 2,323,699 2,390,464 Money market 4,617,122 4,515,353 4,555,752 Savings 2,901,504 2,829,373 2,287,958 Time certificates of deposit 4,338,126 4,407,370 4,221,012 Total deposits $ 23,279,327 $ 23,183,347 $ 21,730,441 Mix: Non-interest bearing 28 % 29 % 27 % NOW and interest bearing demand deposits 10 10 11 Wealth management deposits 11 10 11 Money market 20 20 21 Savings 12 12 11 Time certificates of deposit 19 19 19 Total deposits 100 % 100 % 100 %

Federal Home Loan Bank Advances

Federal Home Loan Bank Advances, Other Borrowings and Subordinated Notes (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Summary of Debt	The following table is a summary of FHLB advances, other borrowings and subordinated notes as of the dates shown: (Dollars in thousands) March 31, December 31, March 31, FHLB advances $ 915,000 $ 559,663 $ 227,585 Other borrowings: Notes payable 33,727 41,222 48,702 Short-term borrowings 17,977 17,209 39,246 Other 48,742 49,131 17,949 Secured borrowings 146,646 158,561 132,890 Total other borrowings 247,092 266,123 238,787 Subordinated notes 139,111 139,088 138,993 Total FHLB advances, other borrowings and subordinated notes $ 1,301,203 $ 964,874 $ 605,365
Summary of Pledged Securities Related to Securities Sold Under Repurchase Agreements	The following is a summary of these securities pledged as of March 31, 2018 disaggregated by investment category and maturity of the related customer sweep account, and reconciled to the outstanding balance of securities sold under repurchase agreements: (Dollars in thousands) Overnight Sweep Collateral Available-for-sale securities pledged Mortgage-backed securities $ 21,499 Held-to-maturity securities pledged U.S. Government agencies 21,886 Total collateral pledged $ 43,385 Excess collateral 25,408 Securities sold under repurchase agreements $ 17,977

Junior Subordinated Debentures

Junior Subordinated Debentures (Tables)	3 Months Ended
	Mar. 31, 2018
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Summary of Junior Subordinated Debentures	The following table provides a summary of the Company’s junior subordinated debentures as of March 31, 2018 . The junior subordinated debentures represent the par value of the obligations owed to the Trusts. (Dollars in thousands) Common Securities Trust Preferred Securities Junior Subordinated Debentures Rate Structure Contractual rate at 3/31/2018 Issue Date Maturity Date Earliest Redemption Date Wintrust Capital Trust III $ 774 $ 25,000 $ 25,774 L+3.25 4.97 % 04/2003 04/2033 04/2008 Wintrust Statutory Trust IV 619 20,000 20,619 L+2.80 5.11 % 12/2003 12/2033 12/2008 Wintrust Statutory Trust V 1,238 40,000 41,238 L+2.60 4.91 % 05/2004 05/2034 06/2009 Wintrust Capital Trust VII 1,550 50,000 51,550 L+1.95 4.07 % 12/2004 03/2035 03/2010 Wintrust Capital Trust VIII 1,238 25,000 26,238 L+1.45 3.76 % 08/2005 09/2035 09/2010 Wintrust Capital Trust IX 1,547 50,000 51,547 L+1.63 3.75 % 09/2006 09/2036 09/2011 Northview Capital Trust I 186 6,000 6,186 L+3.00 4.77 % 08/2003 11/2033 08/2008 Town Bankshares Capital Trust I 186 6,000 6,186 L+3.00 4.77 % 08/2003 11/2033 08/2008 First Northwest Capital Trust I 155 5,000 5,155 L+3.00 5.31 % 05/2004 05/2034 05/2009 Suburban Illinois Capital Trust II 464 15,000 15,464 L+1.75 3.87 % 12/2006 12/2036 12/2011 Community Financial Shares Statutory Trust II 109 3,500 3,609 L+1.62 3.74 % 06/2007 09/2037 06/2012 Total $ 253,566 4.33 %

Revenue from Contracts with C36

Revenue from Contracts with Customers Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue by Source	The following table presents revenue from contracts with customers, considered in-scope under ASU 2014-09, disaggregated by the revenue source: (Dollars in thousands) Three Months Ended Revenue from contracts with customers Location in income statement March 31, March 31, Brokerage and insurance product commissions Wealth management $ 6,031 $ 6,220 Trust Wealth management 3,417 3,308 Asset management Wealth management 13,538 10,620 Total wealth management 22,986 20,148 Mortgage broker fees Mortgage banking 279 316 Service charges on deposit accounts Service charges on deposit accounts 8,857 8,265 Administrative services Other non-interest income 1,061 1,024 Card related fees Other non-interest income 2,139 1,415 Other deposit related fees Other non-interest income 2,858 2,358 Total revenue from contracts with customers $ 38,180 $ 33,526
Contract Assets, Contract Liabilities and Receivables from Contracts with Customers	The following table provides information about contract assets, contract liabilities and receivables from contracts with customers: (Dollars in thousands) March 31, December 31, March 31, Contract assets $ — $ — $ — Contract liabilities $ 1,614 $ 1,706 $ 1,983 Mortgage broker fees receivable $ 20 $ 69 $ 9 Wealth management receivable 8,111 8,102 7,484 Card related fees receivable 320 202 304 Total receivables from contracts with customer $ 8,451 $ 8,373 $ 7,797
Performance Obligations Unsatisfied at End of Period	These upfront fees represent performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period. (Dollars in thousands) Estimated remaining in 2018 $ 277 Estimated—2019 369 Estimated—2020 369 Estimated—2021 303 Estimated—2022 153 Estimated—2023 143 Total $ 1,614

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Summary of Segment Information	The following is a summary of certain operating information for reportable segments: Three months ended $ Change in Contribution % Change in Contribution (Dollars in thousands) March 31, March 31, Net interest income: Community Banking $ 183,254 $ 156,280 $ 26,974 17 % Specialty Finance 32,912 26,812 6,100 23 Wealth Management 4,441 5,056 (615 ) (12 ) Total Operating Segments 220,607 188,148 32,459 17 Intersegment Eliminations 4,475 4,432 43 1 Consolidated net interest income $ 225,082 $ 192,580 $ 32,502 17 % Non-interest income: Community Banking $ 56,547 $ 42,716 $ 13,831 32 % Specialty Finance 15,725 14,156 1,569 11 Wealth Management 22,958 20,802 2,156 10 Total Operating Segments 95,230 77,674 17,556 23 Intersegment Eliminations (9,551 ) (8,909 ) (642 ) (7 ) Consolidated non-interest income $ 85,679 $ 68,765 $ 16,914 25 % Net revenue: Community Banking $ 239,801 $ 198,996 $ 40,805 21 % Specialty Finance 48,637 40,968 7,669 19 Wealth Management 27,399 25,858 1,541 6 Total Operating Segments 315,837 265,822 50,015 19 Intersegment Eliminations (5,076 ) (4,477 ) (599 ) (13 ) Consolidated net revenue $ 310,761 $ 261,345 $ 49,416 19 % Segment profit: Community Banking $ 57,280 $ 37,677 $ 19,603 52 % Specialty Finance 20,000 16,098 3,902 24 Wealth Management 4,701 4,603 98 2 Consolidated net income $ 81,981 $ 58,378 $ 23,603 40 % Segment assets: Community Banking $ 23,213,499 $ 21,164,041 $ 2,049,458 10 % Specialty Finance 4,568,906 3,966,542 602,364 15 Wealth Management 674,367 648,310 26,057 4 Consolidated total assets $ 28,456,772 $ 25,778,893 $ 2,677,879 10 %

Derivative Financial Instrume38

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Fair Value Of Derivative Financial Instruments	The table below presents the fair value of the Company’s derivative financial instruments as of March 31, 2018 , December 31, 2017 and March 31, 2017 : Derivative Assets Derivative Liabilities (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, Derivatives designated as hedging instruments under ASC 815: Interest rate derivatives designated as Cash Flow Hedges $ 15,012 $ 11,914 $ 9,311 $ 35 $ 12 $ — Interest rate derivatives designated as Fair Value Hedges 4,962 2,932 2,381 — — — Total derivatives designated as hedging instruments under ASC 815 $ 19,974 $ 14,846 $ 11,692 $ 35 $ 12 $ — Derivatives not designated as hedging instruments under ASC 815: Interest rate derivatives $ 52,996 $ 34,139 $ 36,476 $ 52,408 $ 33,704 $ 35,459 Interest rate lock commitments 5,449 2,843 5,600 1,207 269 2,981 Forward commitments to sell mortgage loans 3 14 69 1,464 1,457 2,656 Foreign exchange contracts 538 227 436 585 229 435 Total derivatives not designated as hedging instruments under ASC 815 $ 58,986 $ 37,223 $ 42,581 $ 55,664 $ 35,659 $ 41,531 Total Derivatives $ 78,960 $ 52,069 $ 54,273 $ 55,699 $ 35,671 $ 41,531
Schedule Of Cash Flow Hedging Instruments	The table below provides details on each of these cash flow hedges as of March 31, 2018 : March 31, 2018 (Dollars in thousands) Notional Fair Value Maturity Date Amount Asset (Liability) Interest Rate Swaps: June 2019 $ 200,000 $ 1,496 July 2019 250,000 4,209 August 2019 275,000 5,347 January 2020 175,000 891 January 2020 25,000 127 April 2020 50,000 (7 ) April 2020 200,000 (28 ) June 2020 200,000 2,942 Total Cash Flow Hedges $ 1,375,000 $ 14,977
Rollforward Of Amounts In Accumulated Other Comprehensive Income Related To Interest Rate Swaps Designated As Cash Flow Hedges	A rollforward of the amounts in accumulated other comprehensive loss related to interest rate derivatives designated as cash flow hedges follows: Three months ended (Dollars in thousands) March 31, March 31, Unrealized gain at beginning of period $ 11,902 $ 6,944 Amount reclassified from accumulated other comprehensive loss to interest expense on deposits and junior subordinated debentures (680 ) 356 Amount of gain recognized in other comprehensive income 3,755 1,259 Unrealized gain at end of period $ 14,977 $ 8,559
Schedule of Carrying Amount of Hedged Assets/(Liabilities)	The following table presents the carrying amount of the hedged assets/(liabilities) and the cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets/(liabilities) that are designated as a fair value hedge accounting relationship as of March 31, 2018 : March 31, 2018 (Dollars in thousands) Derivatives in Fair Value Hedging Relationships Location in the Statement of Condition Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued Interest rate swaps Loans, net of unearned income, excluding covered loans $ 115,092 $ (5,106 ) $ — The following table presents the gain or loss recognized related to derivative instruments that are designated as fair value hedges for the respective period: (Dollars in thousands) Derivatives in Fair Value Hedging Relationships Location of Gain/(Loss) Recognized in Income on Derivative Three Months Ended March 31, 2018 Interest rate swaps Interest and fees on loans $ (45 )
Summary Amounts Included In Consolidated Statement Of Income Related To Derivatives	Amounts included in the Consolidated Statements of Income related to derivative instruments not designated in hedge relationships were as follows: (Dollars in thousands) Three Months Ended Derivative Location in income statement March 31, March 31, Interest rate swaps and caps Trading gains (losses), net $ 153 $ (303 ) Mortgage banking derivatives Mortgage banking revenue 1,418 738 Covered call options Fees from covered call options 1,597 759 Foreign exchange contracts Trading losses, net (43 ) (28 )
Offsetting Assets	The tables below summarize the Company's interest rate derivatives and offsetting positions as of the dates shown. Derivative Assets Derivative Liabilities Fair Value Fair Value (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, Gross Amounts Recognized $ 72,970 $ 48,985 $ 48,168 $ 52,443 $ 33,716 $ 35,459 Less: Amounts offset in the Statements of Financial Condition — — — — — — Net amount presented in the Statements of Financial Condition $ 72,970 $ 48,985 $ 48,168 $ 52,443 $ 33,716 $ 35,459 Gross amounts not offset in the Statements of Financial Condition Offsetting Derivative Positions $ (9,627 ) (14,878 ) (16,529 ) $ (9,627 ) (14,878 ) (16,529 ) Collateral Posted (54,490 ) (18,060 ) (6,990 ) (340 ) (2,220 ) (12,300 ) Net Credit Exposure $ 8,853 $ 16,047 $ 24,649 $ 42,476 $ 16,618 $ 6,630
Offsetting Liabilities	The tables below summarize the Company's interest rate derivatives and offsetting positions as of the dates shown. Derivative Assets Derivative Liabilities Fair Value Fair Value (Dollars in thousands) March 31, December 31, March 31, March 31, December 31, March 31, Gross Amounts Recognized $ 72,970 $ 48,985 $ 48,168 $ 52,443 $ 33,716 $ 35,459 Less: Amounts offset in the Statements of Financial Condition — — — — — — Net amount presented in the Statements of Financial Condition $ 72,970 $ 48,985 $ 48,168 $ 52,443 $ 33,716 $ 35,459 Gross amounts not offset in the Statements of Financial Condition Offsetting Derivative Positions $ (9,627 ) (14,878 ) (16,529 ) $ (9,627 ) (14,878 ) (16,529 ) Collateral Posted (54,490 ) (18,060 ) (6,990 ) (340 ) (2,220 ) (12,300 ) Net Credit Exposure $ 8,853 $ 16,047 $ 24,649 $ 42,476 $ 16,618 $ 6,630

Fair Values of Assets and Lia39

Fair Values of Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Summary Of Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following tables present the balances of assets and liabilities measured at fair value on a recurring basis for the periods presented: March 31, 2018 (Dollars in thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 24,727 $ — $ 24,727 $ — U.S. Government agencies 149,336 — 145,720 3,616 Municipal 121,758 — 37,166 84,592 Corporate notes 99,714 — 99,714 — Mortgage-backed 1,500,153 — 1,500,153 — Trading account securities 1,682 — 1,682 — Equity securities with readily determinable fair value 37,832 — 37,832 — Mortgage loans held-for-sale 411,505 — 411,505 — Loans held-for-investment 67,962 — 41,342 26,620 MSRs 54,572 — — 54,572 Nonqualified deferred compensation assets 11,724 — 11,724 — Derivative assets 78,960 — 74,355 4,605 Total $ 2,559,925 $ — $ 2,385,920 $ 174,005 Derivative liabilities $ 55,699 $ — $ 55,699 $ — December 31, 2017 (Dollars in thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 143,822 $ — $ 143,822 $ — U.S. Government agencies 156,915 — 153,136 3,779 Municipal 115,352 — 38,171 77,181 Corporate notes 31,050 — 31,050 — Mortgage-backed 1,319,725 — 1,319,725 — Equity securities 36,802 — 36,802 — Trading account securities 995 — 995 — Mortgage loans held-for-sale 313,592 — 313,592 — Loans held-for-investment 33,717 — — 33,717 MSRs 33,676 — — 33,676 Nonqualified deferred compensation assets 11,065 — 11,065 — Derivative assets 52,069 — 49,912 2,157 Total $ 2,248,780 $ — $ 2,098,270 $ 150,510 Derivative liabilities $ 35,671 $ — $ 35,671 $ — March 31, 2017 (Dollars in thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 142,156 $ — $ 142,156 $ — U.S. Government agencies 177,829 — 173,546 4,283 Municipal 127,563 — 47,818 79,745 Corporate notes 65,424 — 65,424 — Mortgage-backed 1,256,044 — 1,256,044 — Equity securities 34,717 — 34,717 — Trading account securities 714 — 714 — Mortgage loans held-for-sale 288,964 — 288,964 — Loans held-for-investment 28,548 — — 28,548 MSRs 21,596 — — 21,596 Nonqualified deferred compensation assets 10,347 — 10,347 — Derivative assets 54,273 — 50,691 3,582 Total $ 2,208,175 $ — $ 2,070,421 $ 137,754 Derivative liabilities $ 41,531 $ — $ 41,531 $ —
Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis	The changes in Level 3 assets measured at fair value on a recurring basis during the three months ended March 31, 2018 and 2017 are summarized as follows: U.S. Government Agencies Loans held-for- investment Mortgage servicing rights Derivative Assets (Dollars in thousands) Municipal Balance at January 1, 2018 $ 77,181 $ 3,779 $ 33,717 $ 33,676 $ 2,157 Total net gains (losses) included in: Net income (1) — — (1,128 ) 7,090 2,448 Other comprehensive loss (2,190 ) (163 ) — — — Purchases (2) 12,270 — — 13,806 — Issuances — — — — — Sales — — — — — Settlements (2,669 ) — (6,255 ) — — Net transfers into/(out of) Level 3 — — 286 — — Balance at March 31, 2018 $ 84,592 $ 3,616 $ 26,620 $ 54,572 $ 4,605 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income. (2) Purchased as a part of the Veterans First business combination. See Note 3 - Business Combinations for further discussion. U.S. Government Agencies Loans held-for- investment Mortgage servicing rights Derivative Assets (Dollars in thousands) Municipal Balance at January 1, 2017 $ 79,626 $ — $ 22,137 $ 19,103 $ 2,291 Total net gains (losses) included in: Net income (1) — — (112 ) 2,493 1,291 Other comprehensive loss 457 — — — — Purchases 7,586 — — — — Issuances — — — — — Sales — — — — — Settlements (7,924 ) — (3,332 ) — — Net transfers into/(out of) Level 3 — 4,283 9,855 — — Balance at March 31, 2017 $ 79,745 $ 4,283 $ 28,548 $ 21,596 $ 3,582 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income.
Summary Of Assets Measured At Fair Value On A Nonrecurring Basis	For assets measured at fair value on a nonrecurring basis that were still held in the balance sheet at the end of the period, the following table provides the carrying value of the related individual assets or portfolios at March 31, 2018 . March 31, 2018 Three Months Ended March 31, 2018 Fair Value Losses Recognized, net (Dollars in thousands) Total Level 1 Level 2 Level 3 Impaired loans—collateral based $ 68,684 $ — $ — $ 68,684 $ 3,886 Other real estate owned (1) 36,598 — — 36,598 2,158 Total $ 105,282 $ — $ — $ 105,282 $ 6,044 (1) Fair value losses recognized, net on other real estate owned include valuation adjustments and charge-offs during the respective period.
Schedule Of Valuation Techniques And Significant Unobservable Inputs Used To Measure Both Recurring And Non-Recurring	The valuation techniques and significant unobservable inputs used to measure both recurring and non-recurring Level 3 fair value measurements at March 31, 2018 were as follows: (Dollars in thousands) Fair Value Valuation Methodology Significant Unobservable Input Range of Inputs Weighted Average of Inputs Impact to valuation from an increased or higher input value Measured at fair value on a recurring basis: Municipal Securities $ 84,592 Bond pricing Equivalent rating BBB-AA+ N/A Increase U.S. Government agencies 3,616 Bond pricing Equivalent rating AAA AAA Increase Loans held-for-investment 26,620 Discounted cash flows Discount rate 3%-4% 4.14% Decrease Credit discount 0%-11% 1.88% Decrease Constant prepayment rate (CPR) 8.76% 8.76% Decrease MSRs 54,572 Discounted cash flows Discount rate 7%-17% 10.02% Decrease Constant prepayment rate (CPR) 0%-87% 9.40% Decrease Cost of servicing $70-$200 $78 Decrease Cost of servicing - delinquent $200-$1,000 $368 Decrease Derivatives 4,605 Discounted cash flows Pull-through rate 32%-100% 85.34% Increase Measured at fair value on a non-recurring basis: Impaired loans—collateral based $ 68,684 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease Other real estate owned 36,598 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease
Summary Of Carrying Amounts And Estimated Fair Values Of Financial Instruments	The table below presents the carrying amounts and estimated fair values of the Company’s financial instruments as of the dates shown: At March 31, 2018 At December 31, 2017 At March 31, 2017 Carrying Fair Carrying Fair Carrying Fair (Dollars in thousands) Value Value Value Value Value Value Financial Assets: Cash and cash equivalents $ 231,464 $ 231,464 $ 277,591 $ 277,591 $ 217,148 $ 217,148 Interest bearing deposits with banks 980,380 980,380 1,063,242 1,063,242 1,007,468 1,007,468 Available-for-sale securities 1,895,688 1,895,688 1,803,666 1,803,666 1,803,733 1,803,733 Held-to-maturity securities 892,937 862,527 826,449 812,516 667,764 647,895 Trading account securities 1,682 1,682 995 995 714 714 Equity securities with readily determinable fair value 37,832 37,832 — — — — FHLB and FRB stock, at cost 104,956 104,956 89,989 89,989 78,904 78,904 Brokerage customer receivables 24,531 24,531 26,431 26,431 23,171 23,171 Mortgage loans held-for-sale, at fair value 411,505 411,505 313,592 313,592 288,964 288,964 Loans held-for-investment, at fair value 67,962 67,962 33,717 33,717 28,548 28,548 Loans held-for-investment, at amortized cost 21,994,172 22,234,795 21,607,080 21,768,978 19,954,869 21,048,751 MSRs 54,572 54,572 33,676 33,676 21,596 21,596 Nonqualified deferred compensation assets 11,724 11,724 11,065 11,065 10,347 10,347 Derivative assets 78,960 78,960 52,069 52,069 54,273 54,273 Accrued interest receivable and other 236,131 236,131 227,649 227,649 209,623 209,623 Total financial assets $ 27,024,496 $ 27,234,709 $ 26,367,211 $ 26,515,176 $ 24,367,122 $ 25,441,135 Financial Liabilities Non-maturity deposits $ 18,941,201 $ 18,941,201 $ 18,775,977 $ 18,775,977 $ 17,509,429 $ 17,509,429 Deposits with stated maturities 4,338,126 4,344,584 4,407,370 4,350,004 4,221,012 4,210,294 FHLB advances 915,000 916,513 559,663 544,750 227,585 229,338 Other borrowings 247,092 247,092 266,123 266,123 238,787 238,787 Subordinated notes 139,111 140,889 139,088 144,266 138,993 141,180 Junior subordinated debentures 253,566 268,873 253,566 264,696 253,566 254,417 Derivative liabilities 55,699 55,699 35,671 35,671 41,531 41,531 FDIC indemnification liability — — — — 18,264 18,264 Accrued interest payable 11,442 11,442 8,030 8,030 7,944 7,944 Total financial liabilities $ 24,901,237 $ 24,926,293 $ 24,445,488 $ 24,389,517 $ 22,657,111 $ 22,651,184

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Share-based Compensation [Abstract]
Summary Of Stock Option Activity	A summary of the Company's stock option activity for the three months ended March 31, 2018 and March 31, 2017 is presented below: Stock Options Common Shares Weighted Average Strike Price Remaining Contractual Term (1) Intrinsic Value (2) ($000) Outstanding at January 1, 2018 1,084,756 $ 41.98 Granted — — Exercised (169,387 ) 42.47 Forfeited or canceled (1,703 ) 40.87 Outstanding at March 31, 2018 913,666 $ 41.89 3.7 $ 40,351 Exercisable at March 31, 2018 712,535 $ 42.00 3.4 $ 31,391 Stock Options Common Shares Weighted Average Strike Price Remaining Contractual Term (1) Intrinsic Value (2) ($000) Outstanding at January 1, 2017 1,698,912 $ 41.50 Granted — — Exercised (319,802 ) 39.97 Forfeited or canceled (6,496 ) 42.65 Outstanding at March 31, 2017 1,372,614 $ 41.85 4.6 $ 37,436 Exercisable at March 31, 2017 819,955 $ 41.60 4.0 $ 22,568 (1) Represents the remaining weighted average contractual life in years. (2) Aggregate intrinsic value represents the total pre-tax intrinsic value (i.e., the difference between the Company's stock price on the last trading day of the quarter and the option exercise price, multiplied by the number of shares) that would have been received by the option holders if they had exercised their options on the last day of the quarter. Options with exercise prices above the stock price on the last trading day of the quarter are excluded from the calculation of intrinsic value. The intrinsic value will change based on the fair market value of the Company's stock.
Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity	A summary of the Plans' restricted share activity for the three months ended March 31, 2018 and March 31, 2017 is presented below: Three months ended March 31, 2018 Three months ended March 31, 2017 Restricted Shares Common Shares Weighted Average Grant-Date Fair Value Common Shares Weighted Average Grant-Date Fair Value Outstanding at January 1 127,787 $ 53.33 133,425 $ 49.94 Granted 20,700 86.42 8,425 72.52 Vested and issued (7,258 ) 53.47 (5,063 ) 42.71 Forfeited or canceled (982 ) 55.39 — — Outstanding at March 31 140,247 $ 58.20 136,787 $ 51.60 Vested, but not issuable at March 31 89,924 $ 51.71 89,215 $ 51.51 A summary of the Plans' performance-based stock award activity, based on the target level of the awards, for the three months ended March 31, 2018 and March 31, 2017 is presented below: Three months ended March 31, 2018 Three months ended March 31, 2017 Performance-based Stock Common Weighted Common Weighted Outstanding at January 1 359,196 $ 54.37 298,180 $ 43.64 Granted 127,419 88.20 141,399 72.55 Vested and issued (82,307 ) 44.39 (68,712 ) 46.85 Forfeited (6,580 ) 49.42 (7,731 ) 50.11 Outstanding at March 31 397,728 $ 67.35 363,136 $ 54.15 Vested, but deferred at March 31 21,388 $ 43.32 13,564 $ 42.55

Shareholders' Equity and Earn41

Shareholders' Equity and Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Components Of Other Comprehensive Income (Loss)	The following tables summarize the components of other comprehensive income (loss), including the related income tax effects, and the related amount reclassified to net income for the periods presented (in thousands). Accumulated Unrealized Gains (Losses) on Securities Accumulated Unrealized Losses on Derivative Instruments Accumulated Foreign Currency Translation Adjustments Total Accumulated Other Comprehensive Loss Balance at January 1, 2018 $ (15,813 ) $ 7,164 $ (33,186 ) $ (41,835 ) Cumulative effect adjustment from the adoption of: ASU 2016-01 (1,880 ) — — (1,880 ) ASU 2018-02 (4,517 ) 1,543 — (2,974 ) Other comprehensive (loss) income during the period, net of tax, before reclassifications (26,474 ) 2,746 (2,897 ) (26,625 ) Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax 713 (497 ) — 216 Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax 3 — — 3 Net other comprehensive (loss) income during the period, net of tax $ (25,758 ) $ 2,249 $ (2,897 ) $ (26,406 ) Balance at March 31, 2018 $ (47,968 ) $ 10,956 $ (36,083 ) $ (73,095 ) Balance at January 1, 2017 $ (29,309 ) $ 4,165 $ (40,184 ) $ (65,328 ) Other comprehensive income during the period, net of tax, before reclassifications 4,479 765 877 6,121 Amount reclassified from accumulated other comprehensive income into net income, net of tax 34 216 — 250 Amount reclassified from accumulated other comprehensive (loss) related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax (867 ) — — (867 ) Net other comprehensive income during the period, net of tax $ 3,646 $ 981 $ 877 $ 5,504 Balance at March 31, 2017 $ (25,663 ) $ 5,146 $ (39,307 ) $ (59,824 )
Other Comprehensive Income Reclassified from AOCI	Amount Reclassified from Accumulated Other Comprehensive Income for the Details Regarding the Component of Accumulated Other Comprehensive Income Three Months Ended Impacted Line on the Consolidated Statements of Income March 31, 2018 2017 Accumulated unrealized losses on securities Losses included in net income $ (975 ) $ (55 ) Losses on investment securities, net (975 ) (55 ) Income before taxes Tax effect $ 262 $ 21 Income tax expense Net of tax $ (713 ) $ (34 ) Net income Accumulated unrealized losses on derivative instruments Amount reclassified to interest expense on deposits $ (680 ) $ 42 Interest on deposits Amount reclassified to interest expense on junior subordinated debentures — 314 Interest on junior subordinated debentures 680 (356 ) Income before taxes Tax effect $ (183 ) $ 140 Income tax expense Net of tax $ 497 $ (216 ) Net income
Computation Of Basic And Diluted Earnings Per Common Share	The following table shows the computation of basic and diluted earnings per share for the periods indicated: Three Months Ended (In thousands, except per share data) March 31, March 31, Net income $ 81,981 $ 58,378 Less: Preferred stock dividends 2,050 3,628 Net income applicable to common shares—Basic (A) 79,931 54,750 Add: Dividends on convertible preferred stock, if dilutive — 1,578 Net income applicable to common shares—Diluted (B) 79,931 56,328 Weighted average common shares outstanding (C) 56,137 52,267 Effect of dilutive potential common shares Common stock equivalents 888 1,060 Convertible preferred stock, if dilutive — 3,100 Total dilutive potential common shares 888 4,160 Weighted average common shares and effect of dilutive potential common shares (D) 57,025 56,427 Net income per common share: Basic (A/C) $ 1.42 $ 1.05 Diluted (B/D) $ 1.40 $ 1.00

Recent Accounting Developments

Recent Accounting Developments (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrealized gain from securities	$ 1,030	$ 0
Change in interest income hedge effectiveness	$ 45
Provisional tax benefit recognized			$ 7,600
ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				$ 0
ASU 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(116)
ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				0
Retained earnings | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				1,880
Retained earnings | ASU 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(116)
Retained earnings | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				2,974
Accumulated other comprehensive loss | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(1,880)
Accumulated other comprehensive loss | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(2,974)
New Accounting Pronouncement, Early Adoption, Effect | Retained earnings | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				3,000
New Accounting Pronouncement, Early Adoption, Effect | Accumulated other comprehensive loss | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				$ (3,000)

Business Combinations (Narrativ

Business Combinations (Narrative) (Detail) $ in Thousands	Jan. 04, 2018USD ($)Loan	Oct. 16, 2017USD ($)	Feb. 14, 2017USD ($)	Mar. 31, 2018USD ($)financial_institutionLoan	Dec. 31, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)
Business Acquisition [Line Items]
FDIC loss sharing percentage on purchased loans, OREO, and certain other assets				80.00%
Reduction in estimated loss share liability						$ 4,900
Payments received from the FDIC		$ 15,200					$ 386
Gain contract termination					$ 400
Goodwill recorded on acquisition				$ 10,229
FDIC Assisted
Business Acquisition [Line Items]
Number of FDIC assisted banks acquired | financial_institution				9
Loans subject to loss share agreements with FDIC | Loan				8
Veterans First Mortgage
Business Acquisition [Line Items]
Number of loans acquired | Loan	10,000
Unpaid principal balance	$ 1,600,000
Goodwill recorded on acquisition	$ 10,200
American Homestead Mortgage, LLC (AHM)
Business Acquisition [Line Items]
Goodwill recorded on acquisition			$ 999

Business Combinations (Summary

Business Combinations (Summary of FDIC Indemnification Asset) (Detail) - USD ($) $ in Thousands	Oct. 16, 2017	Mar. 31, 2017
FDIC Indemnification Asset [Roll Forward]
Balance at beginning of period		$ 16,701
Reductions from reimbursable expenses		(82)
Amortization		244
Changes in expected reimbursements from the FDIC for changes in expected credit losses and reimbursable expenses		1,014
Payments received from the FDIC	$ 15,200	386
Balance at end of period		$ 18,263

Investment Securities (Marketab

Investment Securities (Marketable Securities) (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Available-for-sale securities
Amortized Cost	$ 1,962,868,000	$ 1,833,069,000	$ 1,847,780,000
Gross Unrealized Gains	2,410,000	6,624,000	6,502,000
Gross Unrealized Losses	(69,590,000)	(36,027,000)	(50,549,000)
Available-for-sale securities, at fair value	1,895,688,000	1,803,666,000	1,803,733,000
Held-to-maturity securities
Amortized Cost	892,937,000	826,449,000	667,764,000
Gross Unrealized Gains	939,000	2,691,000	1,229,000
Gross Unrealized Losses	(31,349,000)	(16,624,000)	(21,098,000)
Held-to-maturity securities, at Fair value	862,527,000	812,516,000	647,895,000
Equity securities with readily determinable fair value
Amortized Cost	34,230,000
Gross Unrealized Gains	4,670,000
Gross Unrealized Losses	(1,068,000)
Fair Value	37,832,000	0	0
U.S. Treasury
Available-for-sale securities
Amortized Cost	25,022,000	144,904,000	142,772,000
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(295,000)	(1,082,000)	(616,000)
Available-for-sale securities, at fair value	24,727,000	143,822,000	142,156,000
U.S. Government agencies
Available-for-sale securities
Amortized Cost	149,899,000	157,638,000	178,475,000
Gross Unrealized Gains	0	2,000	31,000
Gross Unrealized Losses	(563,000)	(725,000)	(677,000)
Available-for-sale securities, at fair value	149,336,000	156,915,000	177,829,000
Held-to-maturity securities
Amortized Cost	639,442,000	579,062,000	465,891,000
Gross Unrealized Gains	0	23,000	115,000
Gross Unrealized Losses	(25,891,000)	(14,066,000)	(18,664,000)
Held-to-maturity securities, at Fair value	613,551,000	565,019,000	447,342,000
Municipal Securities
Available-for-sale securities
Amortized Cost	120,396,000	113,197,000	125,061,000
Gross Unrealized Gains	2,218,000	2,712,000	2,878,000
Gross Unrealized Losses	(856,000)	(557,000)	(376,000)
Available-for-sale securities, at fair value	121,758,000	115,352,000	127,563,000
Held-to-maturity securities
Amortized Cost	253,495,000	247,387,000	201,873,000
Gross Unrealized Gains	939,000	2,668,000	1,114,000
Gross Unrealized Losses	(5,458,000)	(2,558,000)	(2,434,000)
Held-to-maturity securities, at Fair value	248,976,000	247,497,000	200,553,000
Corporate notes, Financial issuers
Available-for-sale securities
Amortized Cost	100,294,000	30,309,000	65,306,000
Gross Unrealized Gains	16,000	43,000	107,000
Gross Unrealized Losses	(1,595,000)	(301,000)	(986,000)
Available-for-sale securities, at fair value	98,715,000	30,051,000	64,427,000
Corporate notes, Other
Available-for-sale securities
Amortized Cost	1,000,000	1,000,000	1,000,000
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(1,000)	(1,000)	(3,000)
Available-for-sale securities, at fair value	999,000	999,000	997,000
Mortgage-backed securities
Available-for-sale securities
Amortized Cost	1,510,421,000	1,291,695,000	1,256,497,000
Gross Unrealized Gains	169,000	446,000	302,000
Gross Unrealized Losses	(64,077,000)	(31,955,000)	(46,423,000)
Available-for-sale securities, at fair value	1,446,513,000	1,260,186,000	1,210,376,000
Collateralized mortgage obligations
Available-for-sale securities
Amortized Cost	55,836,000	60,092,000	46,035,000
Gross Unrealized Gains	7,000	64,000	78,000
Gross Unrealized Losses	(2,203,000)	(617,000)	(445,000)
Available-for-sale securities, at fair value	53,640,000	59,539,000	45,668,000
Equity securities
Available-for-sale securities
Amortized Cost	0	34,234,000	32,634,000
Gross Unrealized Gains	0	3,357,000	3,106,000
Gross Unrealized Losses	0	(789,000)	(1,023,000)
Available-for-sale securities, at fair value	0	36,802,000	34,717,000
Mortgage-backed securities, subprime
Available-for-sale securities
Available-for-sale securities, at fair value	$ 0	$ 0	$ 0

Investment Securities (Investme

Investment Securities (Investment Securities, Continuous Unrealized Loss Position, Fair Value) (Detail) $ in Thousands	Mar. 31, 2018USD ($)
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	$ 682,752
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(16,036)
Continuous unrealized losses existing for greater than 12 months, Fair value	1,113,035
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(53,554)
Total, Fair value	1,795,787
Total, Unrealized losses	(69,590)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	471,177
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(11,251)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	341,929
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(20,098)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	813,106
Held-to-maturity Securities, Continuous Unrealized Loss Position, Unrealized Losses	(31,349)
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	24,727
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(295)
Continuous unrealized losses existing for greater than 12 months, Fair value	0
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	0
Total, Fair value	24,727
Total, Unrealized losses	(295)
U.S. Government agencies
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	14,742
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(104)
Continuous unrealized losses existing for greater than 12 months, Fair value	134,594
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(459)
Total, Fair value	149,336
Total, Unrealized losses	(563)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	311,150
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(7,688)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	292,800
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(18,203)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	603,950
Held-to-maturity Securities, Continuous Unrealized Loss Position, Unrealized Losses	(25,891)
Municipal Securities
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	35,225
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(494)
Continuous unrealized losses existing for greater than 12 months, Fair value	13,794
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(362)
Total, Fair value	49,019
Total, Unrealized losses	(856)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	160,027
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(3,563)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	49,129
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(1,895)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	209,156
Held-to-maturity Securities, Continuous Unrealized Loss Position, Unrealized Losses	(5,458)
Corporate notes, Financial issuers
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	73,037
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(1,294)
Continuous unrealized losses existing for greater than 12 months, Fair value	5,665
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(301)
Total, Fair value	78,702
Total, Unrealized losses	(1,595)
Corporate notes, Other
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	0
Continuous unrealized losses existing for less than 12 months, Unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, Fair value	999
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(1)
Total, Fair value	999
Total, Unrealized losses	(1)
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	495,082
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(12,177)
Continuous unrealized losses existing for greater than 12 months, Fair value	945,641
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(51,900)
Total, Fair value	1,440,723
Total, Unrealized losses	(64,077)
Collateralized mortgage obligations
Schedule of Available-for-sale Securities [Line Items]
Continuous unrealized losses existing for less than 12 months, Fair value	39,939
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(1,672)
Continuous unrealized losses existing for greater than 12 months, Fair value	12,342
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(531)
Total, Fair value	52,281
Total, Unrealized losses	$ (2,203)

Investment Securities (Schedule

Investment Securities (Schedule of Realized Gain (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Realized gains on available-for-sale debt securities	$ 0	$ 0
Realized losses on available-for-sale debt securities	(975)	(55)
Net realized losses on available-for-sale debt securities	(975)	(55)
Unrealized gains on equity securities with readily determinable fair value	1,873	0
Unrealized losses on equity securities with readily determinable fair value	(843)	0
Net unrealized gains on equity securities with readily determinable fair value	1,030	0
Upward adjustments of equity securities without readily determinable fair values	131	0
Downward adjustments of equity securities without readily determinable fair values	0	0
Impairment of equity securities without readily determinable fair values	(537)	0
Adjustment and impairment, net, of equity securities without readily determinable fair values	(406)	0
Other than temporary impairment charges	0	0
Losses on investment securities, net	(351)	(55)
Proceeds from sales and calls of available-for-sale securities	210,891	6,005
Proceeds from calls of held-to-maturity securities	4,141	51,060
Proceeds from sales of equity securities with readily determinable fair value	0	0
Proceeds from sales of equity securities without readily determinable fair value	$ 0	$ 0

Investment Securities (Invest48

Investment Securities (Investments Classified by Contractual Maturity Date) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	$ 180,899	$ 300,833	$ 142,323
Due in one to five years, Amortized Cost	90,073	97,019	320,945
Due in five to ten years, Amortized Cost	116,909	33,947	39,520
Due after ten years, Amortized Cost	8,730	15,249	9,826
Amortized Cost	1,962,868	1,833,069	1,847,780
Due in one year or less, Fair Value	180,333	299,285	142,001
Due in one to five years, Fair Value	89,953	97,326	320,278
Due in five to ten years, Fair Value	116,517	35,029	40,519
Due after ten years, Fair Value	8,732	15,499	10,174
Available-for-sale securities	1,895,688	1,803,666	1,803,733
Held-to-maturity securities, Due in one year or less, Amortized Cost	3,786	170	0
Held-to-maturity securities, Due in one to five years, Amortized Cost	34,495	38,392	32,771
Held-to-maturity securities, Due in five to ten years, Amortized Cost	210,705	205,227	70,533
Held-to-maturity securities, Due after ten years, Amortized Cost	643,951	582,660	564,460
Amortized Cost	892,937	826,449	667,764
Held-to-maturity securities, Due in one year or less, Fair Value	3,775	171	0
Held-to-maturity securities, Due in one to five years, Fair Value	33,994	38,012	32,525
Held-to-maturity securities, Due in five to ten years, Fair Value	205,823	203,680	69,348
Held-to-maturity securities, Due after ten years, Fair Value	618,935	570,653	546,022
Held-to-maturity securities, Fair Value	862,527	812,516	647,895
Mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,566,257	1,351,787	1,302,532
Available-for-sale securities	1,500,153	1,319,725	1,256,044
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	34,234	32,634
Available-for-sale securities	$ 0	$ 36,802	$ 34,717

Investment Securities (Narrativ

Investment Securities (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)security	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Equity securities with readily determinable fair value	$ 25,200,000
Upward adjustments of equity securities without readily determinable fair values	131,000	$ 0
Downward adjustments of equity securities without readily determinable fair values	0
Impairment of equity securities without readily determinable fair values	(537,000)	0
Pledged Securities, carrying value	$ 1,500,000,000	$ 1,300,000,000	$ 1,700,000,000
Number of securities by a single non-government sponsored issuer exceeding 10% of shareholders' equity | security	0

Loans (Summary of Loan Portfoli

Loans (Summary of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 22,062,134	$ 21,640,797	$ 19,931,058
Covered loans	0	0	52,359
Total loans	$ 22,062,134	$ 21,640,797	$ 19,983,417
Total loans, net of unearned income, excluding covered loans	100.00%	100.00%	100.00%
Covered loans	0.00%	0.00%	0.00%
Total loans	100.00%	100.00%	100.00%
Commercial
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 7,060,871	$ 6,787,677	$ 6,081,489
Total loans, net of unearned income, excluding covered loans	32.00%	31.00%	30.00%
Commercial real estate
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 6,633,520	$ 6,580,618	$ 6,261,682
Total loans, net of unearned income, excluding covered loans	30.00%	30.00%	31.00%
Home equity
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 626,547	$ 663,045	$ 708,258
Total loans, net of unearned income, excluding covered loans	3.00%	3.00%	4.00%
Residential real estate
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 869,104	$ 832,120	$ 720,608
Total loans, net of unearned income, excluding covered loans	4.00%	4.00%	4.00%
Premium finance receivables—commercial | Commercial insurance loans
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 2,576,150	$ 2,634,565	$ 2,446,946
Total loans, net of unearned income, excluding covered loans	12.00%	12.00%	12.00%
Premium finance receivables—commercial | Life insurance
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 4,189,961	$ 4,035,059	$ 3,593,563
Total loans, net of unearned income, excluding covered loans	19.00%	19.00%	18.00%
Consumer and other
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 105,981	$ 107,713	$ 118,512
Total loans, net of unearned income, excluding covered loans	0.00%	1.00%	1.00%

Loans (Schedule of Unpaid Princ

Loans (Schedule of Unpaid Principal Balance And Carrying Value Of Acquired Loans) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Abstract]
Unpaid Principal Balance	$ 348,102	$ 375,237
Carrying Value	$ 325,745	$ 350,690

Loans (Activity Related to Accr

Loans (Activity Related to Accretable Yield of Loans Acquired With Evidence of Credit Quality Deterioration Since Origination) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Accretable yield, beginning balance	$ 36,565	$ 49,408
Acquisitions	0	531
Accretable yield amortized to interest income	(4,619)	(5,599)
Accretable yield amortized to indemnification asset/liability	0	(354)
Reclassification from non-accretable difference	1,556	2,535
Increases (decreases) in interest cash flows due to payments and changes in interest rates	2,190	(759)
Accretable yield, ending balance	$ 35,692	$ 45,762

Loans (Narrative) (Detail)

Loans (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule Of Accretable Yield Activity Related to Loans Acquired With Evidence Of Credit Quality Deterioration Since Origination Table [Line Items]
Net deferred loan fees and costs and fair value accounting adjustments	$ 9,400	$ 4,600	$ 9,300
Accretable yield amortized to interest income	4,619	5,599
Premium finance receivables
Schedule Of Accretable Yield Activity Related to Loans Acquired With Evidence Of Credit Quality Deterioration Since Origination Table [Line Items]
Unearned income portion of premium finance receivables	$ 85,400	$ 72,400	$ 87,000

Allowance for Loan Losses, Al54

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Schedule of Aging of the Company's Loan Portfolio) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	$ 80,936	$ 77,602	$ 73,352
90+ days and still accruing	14,216	22,659	24,917
Current	21,794,020	21,408,938	19,701,960
Loans, net of unearned income, excluding covered loans	22,062,134	21,640,797	19,931,058
Total loans, nonaccrual status, excluding covered loans			71,760
Total loans, 90 plus days, excluding covered loans			22,109
Total loans, current, excluding covered loans			19,655,839
Covered loans, Nonaccrual			1,592
Covered loans, 90 plus days and still accruing			2,808
Covered loans, Current			46,121
Covered loans	0	0	52,359
Total loans	22,062,134	21,640,797	19,983,417
60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	17,952	33,260	18,794
Total loans, 60-89 days past due, excluding covered loans			18,526
Covered loans, 60-89 days past due			268
30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	155,010	98,338	164,394
Total loans, 30-59 days past due, excluding covered loans			162,824
Covered loans, 30-59 days past due			1,570
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	14,007	15,696	14,307
90+ days and still accruing	856	877	1,468
Current	6,991,004	6,737,479	6,026,255
Loans, net of unearned income, excluding covered loans	7,060,871	6,787,677	6,081,489
Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	771	4,218	19
Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	54,233	29,407	39,440
Commercial | Commercial, industrial and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	10,051	11,260	12,036
90+ days and still accruing	0	0	100
Current	4,518,760	4,314,107	3,855,140
Loans, net of unearned income, excluding covered loans	4,560,880	4,342,505	3,891,075
Commercial | Commercial, industrial and other | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	594	3,746	19
Commercial | Commercial, industrial and other | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	31,475	13,392	23,780
Commercial | Franchise
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	2,401	2,447	323
90+ days and still accruing	0	0	0
Current	931,710	845,150	822,424
Loans, net of unearned income, excluding covered loans	935,358	847,597	823,734
Commercial | Franchise | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	44	0	0
Commercial | Franchise | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,203	0	987
Commercial | Mortgage warehouse lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	0	0	0
Current	157,699	190,523	145,069
Loans, net of unearned income, excluding covered loans	163,470	194,523	154,180
Commercial | Mortgage warehouse lines of credit | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0	0
Commercial | Mortgage warehouse lines of credit | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,771	4,000	9,111
Commercial | Asset-based lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,194	1,550	1,378
90+ days and still accruing	0	0	0
Current	963,883	968,576	875,882
Loans, net of unearned income, excluding covered loans	977,735	980,466	881,004
Commercial | Asset-based lending | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	47	283	0
Commercial | Asset-based lending | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	12,611	10,057	3,744
Commercial | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	361	439	570
90+ days and still accruing	0	0	0
Current	410,667	410,772	318,566
Loans, net of unearned income, excluding covered loans	414,198	413,172	320,010
Commercial | Leases | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	3	0
Commercial | Leases | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,170	1,958	874
Commercial | PCI - commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	856	877	1,368
Current	8,285	8,351	9,174
Loans, net of unearned income, excluding covered loans	9,230	9,414	11,486
Commercial | PCI - commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	86	186	0
Commercial | PCI - commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3	0	944
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	21,825	22,048	20,809
90+ days and still accruing	3,107	7,135	12,559
Current	6,546,556	6,517,763	6,166,176
Loans, net of unearned income, excluding covered loans	6,633,520	6,580,618	6,261,682
Commercial real estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,563	4,346	5,426
Commercial real estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	58,469	29,326	56,712
Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	3,139	3,143	2,408
90+ days and still accruing	0	0	0
Current	802,921	742,171	648,178
Loans, net of unearned income, excluding covered loans	815,636	745,514	655,333
Commercial real estate | Construction | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0	391
Commercial real estate | Construction | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	9,576	200	4,356
Commercial real estate | Land
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	182	188	350
90+ days and still accruing	0	0	0
Current	117,981	121,140	101,455
Loans, net of unearned income, excluding covered loans	122,690	126,484	105,079
Commercial real estate | Land | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0	0
Commercial real estate | Land | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,527	5,156	3,274
Commercial real estate | Office
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	474	2,438	3,513
90+ days and still accruing	0	0	0
Current	878,206	887,937	859,045
Loans, net of unearned income, excluding covered loans	891,071	894,833	870,666
Commercial real estate | Office | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	925	0	953
Commercial real estate | Office | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	11,466	4,458	7,155
Commercial real estate | Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,427	811	7,004
90+ days and still accruing	0	0	0
Current	898,867	879,796	783,302
Loans, net of unearned income, excluding covered loans	906,144	883,019	792,962
Commercial real estate | Industrial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	823	0	0
Commercial real estate | Industrial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,027	2,412	2,656
Commercial real estate | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	12,274	12,328	589
90+ days and still accruing	0	0	0
Current	878,563	938,383	906,470
Loans, net of unearned income, excluding covered loans	895,622	951,527	911,786
Commercial real estate | Retail | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	668	0
Commercial real estate | Retail | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,785	148	4,727
Commercial real estate | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	19	0	668
90+ days and still accruing	0	0	0
Current	931,008	914,610	799,092
Loans, net of unearned income, excluding covered loans	931,355	915,644	804,776
Commercial real estate | Multi-family | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0	203
Commercial real estate | Multi-family | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	328	1,034	4,813
Commercial real estate | Mixed use and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	4,310	3,140	6,277
90+ days and still accruing	0	0	0
Current	1,937,328	1,921,501	1,940,094
Loans, net of unearned income, excluding covered loans	1,955,456	1,935,705	1,963,744
Commercial real estate | Mixed use and other | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	192	1,423	3,207
Commercial real estate | Mixed use and other | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	13,626	9,641	14,166
Commercial real estate | PCI - commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	3,107	7,135	12,559
Current	101,682	112,225	128,540
Loans, net of unearned income, excluding covered loans	115,546	127,892	157,336
Commercial real estate | PCI - commercial real estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,623	2,255	672
Commercial real estate | PCI - commercial real estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	9,134	6,277	15,565
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	9,828	8,978	11,722
90+ days and still accruing	0	0	0
Current	611,181	648,915	691,222
Loans, net of unearned income, excluding covered loans	626,547	663,045	708,258
Home equity | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,505	518	430
Home equity | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,033	4,634	4,884
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	17,214	17,977	11,943
90+ days and still accruing	1,437	5,304	900
Current	841,416	799,158	699,093
Loans, net of unearned income, excluding covered loans	869,104	832,120	720,608
Residential real estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	229	1,303	3,410
Residential real estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	8,808	8,378	5,262
Premium finance receivables | Commercial insurance loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	17,342	12,163	12,629
90+ days and still accruing	8,547	9,242	4,991
Current	2,525,962	2,579,515	2,399,168
Loans, net of unearned income, excluding covered loans	2,576,150	2,634,565	2,446,946
Premium finance receivables | Commercial insurance loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	6,543	17,796	6,383
Premium finance receivables | Commercial insurance loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	17,756	15,849	23,775
Premium finance receivables | Life insurance loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	0	0	2,024
Current	3,986,181	3,820,936	3,316,090
Loans, net of unearned income, excluding covered loans	4,002,726	3,835,790	3,352,857
Premium finance receivables | Life insurance loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,125	4,837	2,535
Premium finance receivables | Life insurance loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	11,420	10,017	32,208
Premium finance receivables | PCI - life insurance loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	0	0	0
Current	187,235	199,269	240,706
Loans, net of unearned income, excluding covered loans	187,235	199,269	240,706
Premium finance receivables | PCI - life insurance loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0	0
Premium finance receivables | PCI - life insurance loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0	0
Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	720	740	350
90+ days and still accruing	269	101	167
Current	104,485	105,903	117,129
Loans, net of unearned income, excluding covered loans	105,981	107,713	118,512
Consumer and other | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	216	242	323
Consumer and other | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 291	$ 727	$ 543

Allowance for Loan Losses, Al55

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Performance by Loan Class) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	$ 22,062,134	$ 21,640,797	$ 19,931,058
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	7,060,871	6,787,677	6,081,489
Commercial | Commercial, industrial and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,560,880	4,342,505	3,891,075
Commercial | Franchise
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	935,358	847,597	823,734
Commercial | Mortgage warehouse lines of credit
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	163,470	194,523	154,180
Commercial | Asset-based lending
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	977,735	980,466	881,004
Commercial | Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	414,198	413,172	320,010
Commercial | PCI - commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	9,230	9,414	11,486
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	6,633,520	6,580,618	6,261,682
Commercial real estate | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	815,636	745,514	655,333
Commercial real estate | Land
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	122,690	126,484	105,079
Commercial real estate | Office
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	891,071	894,833	870,666
Commercial real estate | Industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	906,144	883,019	792,962
Commercial real estate | Retail
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	895,622	951,527	911,786
Commercial real estate | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	931,355	915,644	804,776
Commercial real estate | Mixed use and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,955,456	1,935,705	1,963,744
Commercial real estate | PCI - commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	115,546	127,892	157,336
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	626,547	663,045	708,258
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	869,104	832,120	720,608
Premium finance receivables | Commercial insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,576,150	2,634,565	2,446,946
Premium finance receivables | Life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,002,726	3,835,790	3,352,857
Premium finance receivables | PCI - life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	187,235	199,269	240,706
Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	105,981	107,713	118,512
Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	21,972,444	21,550,635	19,852,079
Performing | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	7,046,864	6,771,981	6,067,082
Performing | Commercial | Commercial, industrial and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,550,829	4,331,245	3,878,939
Performing | Commercial | Franchise
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	932,957	845,150	823,411
Performing | Commercial | Mortgage warehouse lines of credit
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	163,470	194,523	154,180
Performing | Commercial | Asset-based lending
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	976,541	978,916	879,626
Performing | Commercial | Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	413,837	412,733	319,440
Performing | Commercial | PCI - commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	9,230	9,414	11,486
Performing | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	6,611,695	6,558,570	6,240,873
Performing | Commercial real estate | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	812,497	742,371	652,925
Performing | Commercial real estate | Land
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	122,508	126,296	104,729
Performing | Commercial real estate | Office
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	890,597	892,395	867,153
Performing | Commercial real estate | Industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	904,717	882,208	785,958
Performing | Commercial real estate | Retail
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	883,348	939,199	911,197
Performing | Commercial real estate | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	931,336	915,644	804,108
Performing | Commercial real estate | Mixed use and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,951,146	1,932,565	1,957,467
Performing | Commercial real estate | PCI - commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	115,546	127,892	157,336
Performing | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	616,719	654,067	696,536
Performing | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	851,890	810,865	708,665
Performing | Premium finance receivables | Commercial insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,550,261	2,613,160	2,429,326
Performing | Premium finance receivables | Life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,002,726	3,835,790	3,350,833
Performing | Premium finance receivables | PCI - life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	187,235	199,269	240,706
Performing | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	105,054	106,933	118,058
Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	89,690	90,162	78,979
Non-performing | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	14,007	15,696	14,407
Non-performing | Commercial | Commercial, industrial and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	10,051	11,260	12,136
Non-performing | Commercial | Franchise
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,401	2,447	323
Non-performing | Commercial | Mortgage warehouse lines of credit
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	0	0
Non-performing | Commercial | Asset-based lending
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,194	1,550	1,378
Non-performing | Commercial | Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	361	439	570
Non-performing | Commercial | PCI - commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	0	0
Non-performing | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	21,825	22,048	20,809
Non-performing | Commercial real estate | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	3,139	3,143	2,408
Non-performing | Commercial real estate | Land
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	182	188	350
Non-performing | Commercial real estate | Office
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	474	2,438	3,513
Non-performing | Commercial real estate | Industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,427	811	7,004
Non-performing | Commercial real estate | Retail
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	12,274	12,328	589
Non-performing | Commercial real estate | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	19	0	668
Non-performing | Commercial real estate | Mixed use and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,310	3,140	6,277
Non-performing | Commercial real estate | PCI - commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	0	0
Non-performing | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	9,828	8,978	11,722
Non-performing | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	17,214	21,255	11,943
Non-performing | Premium finance receivables | Commercial insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	25,889	21,405	17,620
Non-performing | Premium finance receivables | Life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	0	2,024
Non-performing | Premium finance receivables | PCI - life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	0	0
Non-performing | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	$ 927	$ 780	$ 454

Allowance for Loan Losses, Al56

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Activity in the Allowance for Credit Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	$ 137,905	$ 122,291
Other adjustments	(40)	(56)
Reclassification from allowance for unfunded lending-related commitments	26	(138)
Charge-offs	(9,278)	(3,417)
Recoveries	2,544	1,823
Provision for credit losses	8,346	5,316
Allowance for loan losses at period end	139,503	125,819
Allowance for unfunded lending-related commitments at period end	1,243	1,811
Allowance for credit losses at period end	140,746	127,630
Individually evaluated for impairment	6,877	8,780
Collectively evaluated for impairment	133,194	118,085
Loans at period end, Individually evaluated for impairment	103,455	88,303
Loans at period end, Collectively evaluated for impairment	21,564,972	19,399,837
Loans held at fair value	67,962	28,548
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	675	765
Loans at period end, Loans acquired with deteriorated credit quality	325,745	414,370
Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	57,811	44,493
Other adjustments	(1)	(19)
Reclassification from allowance for unfunded lending-related commitments	0	(92)
Charge-offs	(2,687)	(641)
Recoveries	262	273
Provision for credit losses	2,251	2,568
Allowance for loan losses at period end	57,636	46,582
Allowance for unfunded lending-related commitments at period end	0	592
Allowance for credit losses at period end	57,636	47,174
Individually evaluated for impairment	2,344	2,845
Collectively evaluated for impairment	54,789	43,687
Loans at period end, Individually evaluated for impairment	33,810	19,319
Loans at period end, Collectively evaluated for impairment	7,017,831	6,050,684
Loans held at fair value	0	0
Commercial | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	503	642
Loans at period end, Loans acquired with deteriorated credit quality	9,230	11,486
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	55,227	51,422
Other adjustments	(24)	(36)
Reclassification from allowance for unfunded lending-related commitments	26	(46)
Charge-offs	(813)	(261)
Recoveries	1,687	554
Provision for credit losses	1,378	1,000
Allowance for loan losses at period end	57,481	52,633
Allowance for unfunded lending-related commitments at period end	1,243	1,219
Allowance for credit losses at period end	58,724	53,852
Individually evaluated for impairment	3,611	3,198
Collectively evaluated for impairment	55,042	50,594
Loans at period end, Individually evaluated for impairment	38,237	40,107
Loans at period end, Collectively evaluated for impairment	6,479,737	6,064,239
Loans held at fair value	0	0
Commercial real estate | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	71	60
Loans at period end, Loans acquired with deteriorated credit quality	115,546	157,336
Home equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	10,493	11,774
Other adjustments	0	0
Reclassification from allowance for unfunded lending-related commitments	0	0
Charge-offs	(357)	(625)
Recoveries	123	65
Provision for credit losses	(399)	989
Allowance for loan losses at period end	9,860	12,203
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	9,860	12,203
Individually evaluated for impairment	749	1,979
Collectively evaluated for impairment	9,111	10,224
Loans at period end, Individually evaluated for impairment	10,102	11,878
Loans at period end, Collectively evaluated for impairment	616,445	696,380
Loans held at fair value	0	0
Home equity | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	0	0
Loans at period end, Loans acquired with deteriorated credit quality	0	0
Residential real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	6,688	5,714
Other adjustments	(3)	(4)
Reclassification from allowance for unfunded lending-related commitments	0	0
Charge-offs	(571)	(329)
Recoveries	40	178
Provision for credit losses	124	(29)
Allowance for loan losses at period end	6,278	5,530
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	6,278	5,530
Individually evaluated for impairment	148	666
Collectively evaluated for impairment	6,029	4,802
Loans at period end, Individually evaluated for impairment	20,558	16,594
Loans at period end, Collectively evaluated for impairment	768,859	671,765
Loans held at fair value	67,962	28,548
Residential real estate | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	101	62
Loans at period end, Loans acquired with deteriorated credit quality	11,725	3,701
Premium finance receivables
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	6,846	7,625
Other adjustments	(12)	3
Reclassification from allowance for unfunded lending-related commitments	0	0
Charge-offs	(4,721)	(1,427)
Recoveries	385	612
Provision for credit losses	4,835	746
Allowance for loan losses at period end	7,333	7,559
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	7,333	7,559
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	7,333	7,559
Loans at period end, Individually evaluated for impairment	0	0
Loans at period end, Collectively evaluated for impairment	6,578,876	5,799,803
Loans held at fair value	0	0
Premium finance receivables | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	0	0
Loans at period end, Loans acquired with deteriorated credit quality	187,235	240,706
Consumer and other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	840	1,263
Other adjustments	0	0
Reclassification from allowance for unfunded lending-related commitments	0	0
Charge-offs	(129)	(134)
Recoveries	47	141
Provision for credit losses	157	42
Allowance for loan losses at period end	915	1,312
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	915	1,312
Individually evaluated for impairment	25	92
Collectively evaluated for impairment	890	1,219
Loans at period end, Individually evaluated for impairment	748	405
Loans at period end, Collectively evaluated for impairment	103,224	116,966
Loans held at fair value	0	0
Consumer and other | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses at period end	0	1
Loans at period end, Loans acquired with deteriorated credit quality	$ 2,009	$ 1,141

Allowance for Loan Losses, Al57

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Activity in the Allowance for Covered Loan Losses) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Allowance for Covered Loan Losses [Roll Forward]
Balance at beginning of period	$ 1,322
Provision for covered loan losses before benefit attributable to FDIC loss share agreements	(535)
Benefit attributable to FDIC loss share agreements	428
Net provision for covered loan losses	(107)
Increase in FDIC indemnification liability	(428)
Loans charged-off	(216)
Recoveries of loans charged-off	748
Net (charge-offs) recoveries	532
Balance at end of period	$ 1,319

Allowance for Loan Losses, Al58

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Impaired Loans, Including Restructured Loans) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance for loan loss required	$ 37,572	$ 36,084	$ 39,968
Impaired loans with no allowance for loan loss required	65,559	69,004	47,554
Total impaired loans	103,131	105,088	87,522
Allowance for loan losses related to impaired loans	6,863	8,023	8,165
Financing Receivable
Financing Receivable, Impaired [Line Items]
Allowance for loan losses related to impaired loans	1,100
TDRs	$ 47,676	$ 49,786	$ 39,669

Allowance for Loan Losses, Al59

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Impaired Loans by Loan Class) (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 37,572	$ 39,968	$ 36,084
Impaired Financing Receivable, Related Allowance	6,863	8,165	8,023
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	65,559	47,554	69,004
Total impaired loans	103,131	87,522	105,088
Impaired Financing Receivable, Unpaid Principal Balance	116,304	96,690	127,566
Impaired Financing Receivable, Average Recorded Investment	103,951	88,405	115,261
Impaired Financing Receivable, Interest Income Recognized	1,446	1,215	6,298
Commercial
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance		0
Impaired Financing Receivable, Related Allowance		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		0
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized		0
Commercial | Commercial, industrial and other
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,521	3,804	6,233
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,587	3,830	7,323
Impaired Financing Receivable, Related Allowance	1,738	1,568	3,951
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	5,607	3,856	7,220
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	83	50	452
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	5,480	10,270	8,460
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	6,777	11,307	12,259
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	5,650	10,668	10,170
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	109	185	683
Commercial | Franchise
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	18,657		16,256
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	18,661		16,256
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	18,675		17,089
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	239		780
Commercial | Asset-based lending
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,107	1,378	948
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,107	1,380	949
Impaired Financing Receivable, Related Allowance	475	378	355
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,166	1,279	1,302
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	20	12	72
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	86		602
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	231		602
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	182		688
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	3		40
Commercial | Leases
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,213	2,616	2,331
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,221	2,619	2,337
Impaired Financing Receivable, Related Allowance	131	304	158
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,247	2,689	2,463
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	27	36	117
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	746	846	782
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	746	846	782
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	754	852	845
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	11	13	49
Commercial real estate | Construction
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	3,097	5,262	3,097
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	3,897	5,262	3,897
Impaired Financing Receivable, Related Allowance	599	74	403
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	3,097	5,276	3,690
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	50	53	197
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,363	3,912	1,367
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,364	3,912	1,678
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,364	3,973	1,555
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	15	46	84
Commercial real estate | Land
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,500	3,033	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,500	3,033	0
Impaired Financing Receivable, Related Allowance	3	13	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,567	3,033	0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	17	28	0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,329	1,240	3,961
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,434	1,631	4,192
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,339	1,321	4,129
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	31	15	182
Commercial real estate | Office
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,479	1,512	471
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,078	1,522	471
Impaired Financing Receivable, Related Allowance	73	310	5
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,483	1,513	481
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	24	18	24
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	59	2,487	2,438
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	754	3,803	6,140
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	61	2,432	3,484
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	11	56	330
Commercial real estate | Industrial
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	63	4,831	408
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	172	5,554	408
Impaired Financing Receivable, Related Allowance	1	1,703	40
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	63	4,854	414
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	2	71	25
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,427	2,172	403
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,485	2,487	2,010
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,430	2,152	1,849
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	20	57	174
Commercial real estate | Retail
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	15,347	1,733	15,599
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	15,415	1,843	15,657
Impaired Financing Receivable, Related Allowance	2,512	156	1,336
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	15,315	1,739	15,736
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	166	23	624
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,695	0	2,393
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,992	0	3,538
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,710	0	2,486
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	58	0	221
Commercial real estate | Multi-family
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,234	1,256	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,277	1,256	0
Impaired Financing Receivable, Related Allowance	21	20	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,254	1,256	0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	12	11	0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	668	1,231
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	84	752	2,078
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	0	652	1,246
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	1	11	76
Commercial real estate | Mixed use and other
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,036	5,472	1,567
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,281	5,561	1,586
Impaired Financing Receivable, Related Allowance	388	902	379
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,054	5,486	1,599
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	30	67	77
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	5,284	6,153	5,275
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	5,981	6,961	6,731
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	5,340	6,234	5,559
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	80	91	351
Home equity
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,697	3,863	1,606
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,889	3,891	1,869
Impaired Financing Receivable, Related Allowance	749	1,979	784
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,699	3,866	1,626
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	19	35	81
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	8,405	8,015	7,648
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	12,535	10,420	11,648
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	8,255	8,176	9,114
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	151	123	603
Residential real estate
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,253	5,116	3,798
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,956	5,652	3,910
Impaired Financing Receivable, Related Allowance	148	666	586
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,258	5,166	3,790
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	33	57	146
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	18,305	11,478	17,455
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	20,983	12,673	20,327
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	18,630	11,522	17,926
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	222	151	860
Consumer and other
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	25	92	26
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	27	94	28
Impaired Financing Receivable, Related Allowance	25	92	26
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	25	95	27
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0	1	2
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	723	313	733
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	870	401	890
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	726	315	773
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	$ 12	$ 5	$ 48

Allowance for Loan Losses, Al60

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Narrative) (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)contracts	Mar. 31, 2017USD ($)contracts	Mar. 31, 2018USD ($)Loan	Mar. 31, 2017USD ($)Loan	Dec. 31, 2017USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
TDRs, number	7	4	24	14
Allowance for loan losses related to impaired loans	$ 6,863,000	$ 8,165,000	$ 6,863,000	$ 8,165,000	$ 8,023,000
TDRs, Additions	$ 990,000	$ 1,513,000	23,802,000	5,687,000
Weighted average extension term	74 months	10 months
Weighted average stated interest rate, basis points	2.87%	0.48%
Loan forgiveness	$ 0	$ 0
Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
TDRs	$ 47,676,000	39,669,000	47,676,000	39,669,000	$ 49,786,000
TDRs, number | contracts	85
Allowance for loan losses related to impaired loans	$ 1,100,000		1,100,000
Interest income, passage of time	21,000	55,000
Residential Real Estate | Financing Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Foreclosed residential properties	8,600,000		8,600,000
In process other real estate owned	$ 11,400,000	$ 13,500,000	$ 11,400,000	$ 13,500,000

Allowance for Loan Losses, Al61

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of the Post-Modification Balance of TDRs) (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)contracts	Mar. 31, 2017USD ($)contracts	Mar. 31, 2018USD ($)Loan	Mar. 31, 2017USD ($)Loan
Financing Receivable, Modifications [Line Items]
TDRs, number	7	4	24	14
TDRs, Additions	$ 990	$ 1,513	$ 23,802	$ 5,687
Extension at Below Market Terms
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	7	4
TDRs, Additions	$ 990	$ 1,513
Reduction of Interest Rate
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	2	2
TDRs, Additions	$ 111	$ 173
Modification to Interest Only Payments
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Forgiveness of Debt
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Residential real estate and other
Financing Receivable, Modifications [Line Items]
TDRs, number	5	2	15	8
TDRs, Additions	$ 835	$ 173	$ 3,711	$ 1,095
Residential real estate and other | Extension at Below Market Terms
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	5	2
TDRs, Additions	$ 835	$ 173
Residential real estate and other | Reduction of Interest Rate
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	2	2
TDRs, Additions	$ 111	$ 173
Residential real estate and other | Modification to Interest Only Payments
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Residential real estate and other | Forgiveness of Debt
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Commercial, industrial and other | Commercial
Financing Receivable, Modifications [Line Items]
TDRs, number	1	1	5	3
TDRs, Additions	$ 96	$ 95	$ 3,776	$ 398
Commercial, industrial and other | Commercial | Extension at Below Market Terms
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	1	1
TDRs, Additions	$ 96	$ 95
Commercial, industrial and other | Commercial | Reduction of Interest Rate
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Commercial, industrial and other | Commercial | Modification to Interest Only Payments
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Commercial, industrial and other | Commercial | Forgiveness of Debt
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Office | Commercial real estate
Financing Receivable, Modifications [Line Items]
TDRs, number	1	0	1	0
TDRs, Additions	$ 59	$ 0	$ 59	$ 0
Office | Commercial real estate | Extension at Below Market Terms
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	1	0
TDRs, Additions	$ 59	$ 0
Office | Commercial real estate | Reduction of Interest Rate
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Office | Commercial real estate | Modification to Interest Only Payments
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Office | Commercial real estate | Forgiveness of Debt
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Industrial | Commercial real estate
Financing Receivable, Modifications [Line Items]
TDRs, number	0	0	0	0
TDRs, Additions	$ 0	$ 0	$ 0	$ 0
Industrial | Commercial real estate | Extension at Below Market Terms
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Industrial | Commercial real estate | Reduction of Interest Rate
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Industrial | Commercial real estate | Modification to Interest Only Payments
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Industrial | Commercial real estate | Forgiveness of Debt
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Mixed use and other | Commercial real estate
Financing Receivable, Modifications [Line Items]
TDRs, number	0	1	0	1
TDRs, Additions	$ 0	$ 1,245	$ 0	$ 1,245
Mixed use and other | Commercial real estate | Extension at Below Market Terms
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	1
TDRs, Additions	$ 0	$ 1,245
Mixed use and other | Commercial real estate | Reduction of Interest Rate
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Mixed use and other | Commercial real estate | Modification to Interest Only Payments
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0
Mixed use and other | Commercial real estate | Forgiveness of Debt
Financing Receivable, Modifications [Line Items]
TDRs, number | contracts	0	0
TDRs, Additions	$ 0	$ 0

Allowance for Loan Losses, Al62

Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of TDRs Subsequent Default Under the Restructured Terms) (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)Loancontracts	Mar. 31, 2017USD ($)Loancontracts	Mar. 31, 2018USD ($)Loan	Mar. 31, 2017USD ($)Loan
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	7	4	24	14
Total, Balance	$ 990	$ 1,513	$ 23,802	$ 5,687
Subsequent Default, Count | Loan	10	2
Subsequent Default, Balance	$ 6,327	$ 260
Commercial | Commercial, industrial and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	1	1	5	3
Total, Balance	$ 96	$ 95	$ 3,776	$ 398
Subsequent Default, Count | Loan	5	1
Subsequent Default, Balance	$ 3,776	$ 28
Commercial | Leases
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count | Loan			3	2
Total, Balance			$ 16,256	$ 2,949
Subsequent Default, Count | Loan	0	0
Subsequent Default, Balance	$ 0	$ 0
Commercial real estate | Office
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	1	0	1	0
Total, Balance	$ 59	$ 0	$ 59	$ 0
Subsequent Default, Count | Loan	0	0
Subsequent Default, Balance	$ 0	$ 0
Commercial real estate | Industrial
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	0	0	0
Total, Balance	$ 0	$ 0	$ 0	$ 0
Subsequent Default, Count | Loan	0	0
Subsequent Default, Balance	$ 0	$ 0
Commercial real estate | Mixed use and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	1	0	1
Total, Balance	$ 0	$ 1,245	$ 0	$ 1,245
Subsequent Default, Count | Loan	0	0
Subsequent Default, Balance	$ 0	$ 0
Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	5	2	15	8
Total, Balance	$ 835	$ 173	$ 3,711	$ 1,095
Subsequent Default, Count | Loan	5	1
Subsequent Default, Balance	$ 2,551	$ 232

Goodwill And Other Intangible63

Goodwill And Other Intangible Assets (Goodwill Assets by Business Segment) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 501,884
Goodwill Acquired	10,229
Impairment Loss	0
Goodwill Adjustments	(616)
Ending balance	511,497
Community banking
Goodwill [Roll Forward]
Beginning balance	429,520
Goodwill Acquired	10,229
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	439,749
Specialty finance
Goodwill [Roll Forward]
Beginning balance	40,250
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	(616)
Ending balance	39,634
Wealth management
Goodwill [Roll Forward]
Beginning balance	32,114
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	$ 32,114

Goodwill And Other Intangible64

Goodwill And Other Intangible Assets (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Indefinite-lived Intangible Assets [Line Items]
Goodwill increase (decrease) due to foreign currency translation adjustments	$ (616)
Amortization of other intangible assets	1,004	$ 1,164
Community banking
Indefinite-lived Intangible Assets [Line Items]
Goodwill increase	10,200
Goodwill increase (decrease) due to foreign currency translation adjustments	$ 0
Community banking | Core deposit intangibles
Indefinite-lived Intangible Assets [Line Items]
Amortization period in years, other intangible assets	10 years
Specialty finance
Indefinite-lived Intangible Assets [Line Items]
Goodwill increase (decrease) due to foreign currency translation adjustments	$ (616)
Specialty finance | Customer list intangibles
Indefinite-lived Intangible Assets [Line Items]
Amortization period in years, other intangible assets	18 years
Wealth management
Indefinite-lived Intangible Assets [Line Items]
Goodwill increase (decrease) due to foreign currency translation adjustments	$ 0
Wealth management | Customer list intangibles
Indefinite-lived Intangible Assets [Line Items]
Amortization period in years, other intangible assets	10 years

Goodwill And Other Intangible65

Goodwill And Other Intangible Assets (Summary of Intangible Assets) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets, net	$ 22,413	$ 17,621	$ 20,687
Community banking
Finite-Lived Intangible Assets [Line Items]
Total net carrying amount	16,792	11,845	14,638
Trademark | Community banking
Finite-Lived Intangible Assets [Line Items]
Carrying amount	5,800	0	0
Core deposit intangibles | Community banking
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	37,272	37,272	37,272
Accumulated amortization	(26,280)	(25,427)	(22,634)
Net carrying amount	10,992	11,845	14,638
Customer list intangibles | Specialty finance
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,967	1,972	1,800
Accumulated amortization	(1,335)	(1,298)	(1,191)
Net carrying amount	632	674	609
Customer list and other intangibles | Wealth management
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	7,940	7,940	7,940
Accumulated amortization	(2,951)	(2,838)	(2,500)
Net carrying amount	$ 4,989	$ 5,102	$ 5,440

Goodwill And Other Intangible66

Goodwill And Other Intangible Assets (Estimated Amortization) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Actual in three months ended March 31, 2018	$ 1,004	$ 1,164
Estimated remaining in 2018	2,792
Estimated—2019	3,223
Estimated—2020	2,597
Estimated—2021	2,056
Estimated—2022	$ 1,556

Mortgage Servicing Rights ("M67

Mortgage Servicing Rights ("MSRs") (Schedule Of Changes In Carrying Value Of MSR) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of the period	$ 33,676	$ 19,103
Additions from loans sold with servicing retained	4,159	2,766
Additions from acquisitions	13,806	0
Estimate of changes in fair value due to:
Payoffs and paydowns	(1,202)	(429)
Changes in valuation inputs or assumptions	4,133	156
Fair value at end of the period	54,572	21,596
Unpaid principal balance of mortgage loans serviced for others	$ 4,795,335	$ 1,972,592

Deposits (Summary of Deposits)

Deposits (Summary of Deposits) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Balance:
Non-interest bearing	$ 6,612,319	$ 6,792,497	$ 5,790,579
NOW and interest bearing demand deposits	2,315,122	2,315,055	2,484,676
Wealth management deposits	2,495,134	2,323,699	2,390,464
Money market	4,617,122	4,515,353	4,555,752
Savings	2,901,504	2,829,373	2,287,958
Time certificates of deposit	4,338,126	4,407,370	4,221,012
Total deposits	$ 23,279,327	$ 23,183,347	$ 21,730,441
Mix:
Non-interest bearing	28.00%	29.00%	27.00%
NOW and interest bearing demand deposits	10.00%	10.00%	11.00%
Wealth management deposits	11.00%	10.00%	11.00%
Money market	20.00%	20.00%	21.00%
Savings	12.00%	12.00%	11.00%
Time certificates of deposit	19.00%	19.00%	19.00%
Total deposits	100.00%	100.00%	100.00%

FHLB Advances, Other Borrowin69

FHLB Advances, Other Borrowings and Subordinated Notes (Summary of Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Debt Disclosure [Abstract]
FHLB advances	$ 915,000	$ 559,663	$ 227,585
Other borrowings:
Notes payable	33,727	41,222	48,702
Short-term borrowings	17,977	17,209	39,246
Other	48,742	49,131	17,949
Secured borrowings	146,646	158,561	132,890
Total other borrowings	247,092	266,123	238,787
Subordinated notes	139,111	139,088	138,993
Total FHLB advances, other borrowings and subordinated notes	$ 1,301,203	$ 964,874	$ 605,365

FHLB Advances, Other Borrowin70

FHLB Advances, Other Borrowings and Subordinated Notes (Narrative) (Details) $ in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2017CAD ($)	Dec. 31, 2015CAD ($)	Mar. 31, 2018USD ($)Rate	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2014CAD ($)	Dec. 15, 2014USD ($)
Debt Instrument [Line Items]
Notes payable			$ 33,727,000	$ 41,222,000		$ 48,702,000
Loan agreement with unaffiliated banks			150,000,000
Short-term borrowings			17,977,000	17,209,000		39,246,000
Other			48,742,000	49,131,000		17,949,000
Secured borrowings			146,646,000	158,561,000		132,890,000
Subordinated notes			$ 139,111,000	139,088,000		138,993,000
Base Rate Loan | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Base Rate Loan | Eurodollar Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Term Facility
Debt Instrument [Line Items]
Notes payable			$ 33,700,000	41,200,000		48,700,000		$ 75,000,000
Term Facility | Base Rate Loan | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.75%
Term Facility | Eurodollar Rate Loan | Eurodollar Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.75%
Revolving Credit Facility
Debt Instrument [Line Items]
Notes payable			$ 0	0		0
Maximum borrowing capacity								$ 75,000,000
Commitment fee (as a percent) | Rate			0.20%
Revolving Credit Facility | Base Rate Loan | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Revolving Credit Facility | Eurodollar Rate Loan | Eurodollar Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.50%
Securities sold under repurchase agreements
Debt Instrument [Line Items]
Securities sold under agreements to repurchase			$ 18,000,000	17,200,000		39,200,000
Pledged financial instruments			43,400,000
Fixed Rate Promissory Note
Debt Instrument [Line Items]
Other			$ 48,700,000	49,000,000		17,600,000
Fixed rate (as a percent)			3.36%
Non Recourse Debt
Debt Instrument [Line Items]
Other			$ 75,000	151,000		374,000
Secured Debt
Debt Instrument [Line Items]
Secured borrowings			$ 15,000,000
Secured Debt | Receivables Purchase Agreement
Debt Instrument [Line Items]
Fixed rate (as a percent)			2.4253%
Secured borrowings		$ 160	$ 131,700,000	$ 135,100,000	$ 170	$ 120,100,000	$ 150
Additional amount paid by third party	$ 10	$ 10
Subordinated Debt
Debt Instrument [Line Items]
Fixed rate (as a percent)			5.00%

FHLB Advances, Other Borrowin71

FHLB Advances, Other Borrowings and Subordinated Notes (Summary of Pledged Securities Related to Securities Sold Under Repurchase Agreements) (Details) - Securities sold under repurchase agreements - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged financial instruments	$ 43,400
Securities sold under agreements to repurchase	18,000	$ 17,200	$ 39,200
Overnight Sweep Collateral
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged financial instruments	43,385
Excess collateral	25,408
Securities sold under agreements to repurchase	17,977
Overnight Sweep Collateral | Available-for-sale securities pledged | Mortgage-backed securities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged financial instruments	21,499
Overnight Sweep Collateral | Held-to-maturity securities pledged | U.S. Government agencies
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged financial instruments	$ 21,886

Junior Subordinated Debenture72

Junior Subordinated Debentures (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)trustRate	Dec. 31, 2017USD ($)	Mar. 31, 2017USD ($)
Subordinated Borrowing [Line Items]
Percentage ownership interest in subsidiary trusts	100.00%
Number of unconsolidated subsidiary trusts | trust	11
Common securities, approximate percentage of junior subordinated debentures	3.00%
Trust preferred securities, approximate percentage of junior subordinated debentures	97.00%
Junior subordinated debentures	$ 253,566,000	$ 253,566,000	$ 253,566,000
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 253,566,000
Debt, weighted average interest rate (as a percent) | Rate	4.33%
Period of deferred payment, not to exceed	60 months
Tier one risk based capital	$ 0
Tier two risk based capital	$ 245,500,000

Junior Subordinated Debenture73

Junior Subordinated Debentures (Summary of Junior Subordinated Debentures) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures	$ 253,566,000	$ 253,566,000	$ 253,566,000
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures	$ 253,566,000
Debt, weighted average interest rate (as a percent)	4.33%
Junior Subordinated Debt | Wintrust Capital Trust III
Subordinated Borrowing [Line Items]
Common Securities	$ 774,000
Trust Preferred Securities	25,000,000
Junior Subordinated Debentures	$ 25,774,000
Contractual rate (as a percent)	4.97%
Junior Subordinated Debt | Wintrust Capital Trust III | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	3.25%
Junior Subordinated Debt | Wintrust Statutory Trust IV
Subordinated Borrowing [Line Items]
Common Securities	$ 619,000
Trust Preferred Securities	20,000,000
Junior Subordinated Debentures	$ 20,619,000
Contractual rate (as a percent)	5.11%
Junior Subordinated Debt | Wintrust Statutory Trust IV | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	2.80%
Junior Subordinated Debt | Wintrust Statutory Trust V
Subordinated Borrowing [Line Items]
Common Securities	$ 1,238,000
Trust Preferred Securities	40,000,000
Junior Subordinated Debentures	$ 41,238,000
Contractual rate (as a percent)	4.91%
Junior Subordinated Debt | Wintrust Statutory Trust V | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	2.60%
Junior Subordinated Debt | Wintrust Capital Trust VII
Subordinated Borrowing [Line Items]
Common Securities	$ 1,550,000
Trust Preferred Securities	50,000,000
Junior Subordinated Debentures	$ 51,550,000
Contractual rate (as a percent)	4.07%
Junior Subordinated Debt | Wintrust Capital Trust VII | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	1.95%
Junior Subordinated Debt | Wintrust Capital Trust VIII
Subordinated Borrowing [Line Items]
Common Securities	$ 1,238,000
Trust Preferred Securities	25,000,000
Junior Subordinated Debentures	$ 26,238,000
Contractual rate (as a percent)	3.76%
Junior Subordinated Debt | Wintrust Capital Trust VIII | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	1.45%
Junior Subordinated Debt | Wintrust Capital Trust IX
Subordinated Borrowing [Line Items]
Common Securities	$ 1,547,000
Trust Preferred Securities	50,000,000
Junior Subordinated Debentures	$ 51,547,000
Contractual rate (as a percent)	3.75%
Junior Subordinated Debt | Wintrust Capital Trust IX | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	1.63%
Junior Subordinated Debt | Northview Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186,000
Trust Preferred Securities	6,000,000
Junior Subordinated Debentures	$ 6,186,000
Contractual rate (as a percent)	4.77%
Junior Subordinated Debt | Northview Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	3.00%
Junior Subordinated Debt | Town Bankshares Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186,000
Trust Preferred Securities	6,000,000
Junior Subordinated Debentures	$ 6,186,000
Contractual rate (as a percent)	4.77%
Junior Subordinated Debt | Town Bankshares Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	3.00%
Junior Subordinated Debt | First Northwest Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 155,000
Trust Preferred Securities	5,000,000
Junior Subordinated Debentures	$ 5,155,000
Contractual rate (as a percent)	5.31%
Junior Subordinated Debt | First Northwest Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	3.00%
Junior Subordinated Debt | Suburban Illinois Capital Trust II
Subordinated Borrowing [Line Items]
Common Securities	$ 464,000
Trust Preferred Securities	15,000,000
Junior Subordinated Debentures	$ 15,464,000
Contractual rate (as a percent)	3.87%
Junior Subordinated Debt | Suburban Illinois Capital Trust II | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	1.75%
Junior Subordinated Debt | Community Financial Shares Statutory Trust II
Subordinated Borrowing [Line Items]
Common Securities	$ 109,000
Trust Preferred Securities	3,500,000
Junior Subordinated Debentures	$ 3,609,000
Contractual rate (as a percent)	3.74%
Junior Subordinated Debt | Community Financial Shares Statutory Trust II | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure, incremental interest rate over base rate (as a percent)	1.62%

Revenue from Contracts with C74

Revenue from Contracts with Customers - Disaggregation of Revenue by Source (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 38,180	$ 33,526
Mortgage broker fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	279	316
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,857	8,265
Administrative services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,061	1,024
Card related fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,139	1,415
Other deposit related fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,858	2,358
Wealth management
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	22,986	20,148
Wealth management | Brokerage and insurance product commissions
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6,031	6,220
Wealth management | Trust
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,417	3,308
Wealth management | Asset management
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 13,538	$ 10,620

Revenue from Contracts with C75

Revenue from Contracts with Customers - Contract Assets, Contract Liabilities and Receivables from Contracts with Customers (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract assets	$ 0	$ 0	$ 0
Contract liabilities	1,614	1,706	1,983
Mortgage broker fees receivable	20	69	9
Wealth management receivable	8,111	8,102	7,484
Card related fees receivable	320	202	304
Total receivables from contracts with customer	$ 8,451	$ 8,373	$ 7,797

Revenue from Contracts with C76

Revenue from Contracts with Customers - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from Contract with Customer [Abstract]
Revenue recognized from contract liability balance	$ 92	$ 82

Revenue from Contracts with C77

Revenue from Contracts with Customers - Performance Obligations Unsatisfied at End of Period (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation unsatisfied or partially unsatisfied	$ 277
Performance obligation satisfaction period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation unsatisfied or partially unsatisfied	$ 369
Performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation unsatisfied or partially unsatisfied	$ 369
Performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation unsatisfied or partially unsatisfied	$ 303
Performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation unsatisfied or partially unsatisfied	$ 153
Performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation unsatisfied or partially unsatisfied	$ 1,614
Performance obligation satisfaction period	1 year

Segment Information (Narrative)

Segment Information (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2018subsidiarysegment
Segment Reporting Information [Line Items]
Number of reportable segments	3
Number of subsidiaries | subsidiary	15
Community banking
Segment Reporting Information [Line Items]
Number of reportable segments	1

Segment Information (Summary of

Segment Information (Summary of Segment Information) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Net interest income:
Net interest income	$ 225,082	$ 192,580
Net interest income, Change in Contribution	$ 32,502
Net interest income, Change in Contribution (as a percent)	17.00%
Non-interest income:
Non-interest income	$ 85,679	68,765
Non-interest income, Change in Contribution	$ 16,914
Non-interest income, Change in Contribution (as a percent)	25.00%
Net revenue:
Net revenue	$ 310,761	261,345
Net revenue, Change in Contribution	$ 49,416
Net revenue, Change in Contribution (as a percent)	19.00%
Segment profit:
Segment profit	$ 81,981	58,378
Segment profit, Change in Contribution	$ 23,603
Segment profit, Change in Contribution (as a percent)	40.00%
Segment assets:
Segment assets	$ 28,456,772	25,778,893	$ 27,915,970
Segment assets, Change in Contribution	$ 2,677,879
Segment assets, Change in Contribution (as a percent)	10.00%
Community banking
Segment profit:
Segment profit	$ 57,280	37,677
Segment profit, Change in Contribution	$ 19,603
Segment profit, Change in Contribution (as a percent)	52.00%
Segment assets:
Segment assets	$ 23,213,499	21,164,041
Segment assets, Change in Contribution	$ 2,049,458
Segment assets, Change in Contribution (as a percent)	10.00%
Specialty finance
Segment profit:
Segment profit	$ 20,000	16,098
Segment profit, Change in Contribution	$ 3,902
Segment profit, Change in Contribution (as a percent)	24.00%
Segment assets:
Segment assets	$ 4,568,906	3,966,542
Segment assets, Change in Contribution	$ 602,364
Segment assets, Change in Contribution (as a percent)	15.00%
Wealth management
Segment profit:
Segment profit	$ 4,701	4,603
Segment profit, Change in Contribution	$ 98
Segment profit, Change in Contribution (as a percent)	2.00%
Segment assets:
Segment assets	$ 674,367	648,310
Segment assets, Change in Contribution	$ 26,057
Segment assets, Change in Contribution (as a percent)	4.00%
Operating Segments
Net interest income:
Net interest income	$ 220,607	188,148
Net interest income, Change in Contribution	$ 32,459
Net interest income, Change in Contribution (as a percent)	17.00%
Non-interest income:
Non-interest income	$ 95,230	77,674
Non-interest income, Change in Contribution	$ 17,556
Non-interest income, Change in Contribution (as a percent)	23.00%
Net revenue:
Net revenue	$ 315,837	265,822
Net revenue, Change in Contribution	$ 50,015
Net revenue, Change in Contribution (as a percent)	19.00%
Operating Segments | Community banking
Net interest income:
Net interest income	$ 183,254	156,280
Net interest income, Change in Contribution	$ 26,974
Net interest income, Change in Contribution (as a percent)	17.00%
Non-interest income:
Non-interest income	$ 56,547	42,716
Non-interest income, Change in Contribution	$ 13,831
Non-interest income, Change in Contribution (as a percent)	32.00%
Net revenue:
Net revenue	$ 239,801	198,996
Net revenue, Change in Contribution	$ 40,805
Net revenue, Change in Contribution (as a percent)	21.00%
Operating Segments | Specialty finance
Net interest income:
Net interest income	$ 32,912	26,812
Net interest income, Change in Contribution	$ 6,100
Net interest income, Change in Contribution (as a percent)	23.00%
Non-interest income:
Non-interest income	$ 15,725	14,156
Non-interest income, Change in Contribution	$ 1,569
Non-interest income, Change in Contribution (as a percent)	11.00%
Net revenue:
Net revenue	$ 48,637	40,968
Net revenue, Change in Contribution	$ 7,669
Net revenue, Change in Contribution (as a percent)	19.00%
Operating Segments | Wealth management
Net interest income:
Net interest income	$ 4,441	5,056
Net interest income, Change in Contribution	$ (615)
Net interest income, Change in Contribution (as a percent)	(12.00%)
Non-interest income:
Non-interest income	$ 22,958	20,802
Non-interest income, Change in Contribution	$ 2,156
Non-interest income, Change in Contribution (as a percent)	10.00%
Net revenue:
Net revenue	$ 27,399	25,858
Net revenue, Change in Contribution	$ 1,541
Net revenue, Change in Contribution (as a percent)	6.00%
Intersegment Eliminations
Net interest income:
Net interest income	$ 4,475	4,432
Net interest income, Change in Contribution	$ 43
Net interest income, Change in Contribution (as a percent)	1.00%
Non-interest income:
Non-interest income	$ (9,551)	(8,909)
Non-interest income, Change in Contribution	$ (642)
Non-interest income, Change in Contribution (as a percent)	(7.00%)
Net revenue:
Net revenue	$ (5,076)	$ (4,477)
Net revenue, Change in Contribution	$ (599)
Net revenue, Change in Contribution (as a percent)	(13.00%)

Derivative Financial Instrume80

Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Derivative [Line Items]
Derivative assets	$ 78,960	$ 52,069	$ 54,273
Derivative liabilities	55,699	35,671	41,531
Interest Rate Contract
Derivative [Line Items]
Derivative assets	72,970	48,985	48,168
Derivative liabilities	52,443	33,716	35,459
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	19,974	14,846	11,692
Derivative liabilities	35	12	0
Designated as Hedging Instrument | Interest Rate Contract | Cash Flow Hedging
Derivative [Line Items]
Derivative assets	15,012	11,914	9,311
Derivative liabilities	35	12	0
Designated as Hedging Instrument | Interest Rate Contract | Fair Value Hedging
Derivative [Line Items]
Derivative assets	4,962	2,932	2,381
Derivative liabilities	0	0	0
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	58,986	37,223	42,581
Derivative liabilities	55,664	35,659	41,531
Not Designated as Hedging Instrument | Interest Rate Contract
Derivative [Line Items]
Derivative assets	52,996	34,139	36,476
Derivative liabilities	52,408	33,704	35,459
Not Designated as Hedging Instrument | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative assets	5,449	2,843	5,600
Derivative liabilities	1,207	269	2,981
Not Designated as Hedging Instrument | Forward Commitments to Sell Mortgage Loans
Derivative [Line Items]
Derivative assets	3	14	69
Derivative liabilities	1,464	1,457	2,656
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative assets	538	227	436
Derivative liabilities	$ 585	$ 229	$ 435

Derivative Financial Instrume81

Derivative Financial Instruments (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)derivative_instruments	Dec. 31, 2017derivative_instruments	Mar. 31, 2017derivative_instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income to interest expense in the next twelve months	$ 8,800,000
Net derivative liability position, aggregate fair value	456,000
Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	5,000,000,000
Forward Commitments to Sell Mortgage Loans | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	813,400,000
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	376,300,000
Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 38,100,000
Covered Call Options | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	0	0	0
Cash Flow Hedging | Cash flow hedge of variable rate deposits | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instruments	8
Fair Value Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instruments	11
Notional amount	$ 125,300,000

Derivative Financial Instrume82

Derivative Financial Instruments (Schedule Of Cash Flow Hedging Instruments) (Detail) - Cash Flow Hedging - Designated as Hedging Instrument	Mar. 31, 2018USD ($)
June 2,019
Derivative [Line Items]
Notional Amount	$ 200,000,000
Fair Value Asset (Liability)	1,496,000
July 2,019
Derivative [Line Items]
Notional Amount	250,000,000
Fair Value Asset (Liability)	4,209,000
August 2,019
Derivative [Line Items]
Notional Amount	275,000,000
Fair Value Asset (Liability)	5,347,000
January 2,020
Derivative [Line Items]
Notional Amount	175,000,000
Fair Value Asset (Liability)	891,000
January 2,020
Derivative [Line Items]
Notional Amount	25,000,000
Fair Value Asset (Liability)	127,000
April 2,020
Derivative [Line Items]
Notional Amount	50,000,000
Fair Value Asset (Liability)	(7,000)
April 2,020
Derivative [Line Items]
Notional Amount	200,000,000
Fair Value Asset (Liability)	(28,000)
June 2,020
Derivative [Line Items]
Notional Amount	200,000,000
Fair Value Asset (Liability)	2,942,000
Total Cash Flow Hedges
Derivative [Line Items]
Notional Amount	1,375,000,000
Fair Value Asset (Liability)	$ 14,977,000

Derivative Financial Instrume83

Derivative Financial Instruments (Rollforward Of Amounts In Accumulated Other Comprehensive Income Related To Interest Rate Swaps Designated As Cash Flow Hedges) (Detail) - Interest Rate Contract - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Unrealized gain at beginning of period	$ 11,902	$ 6,944
Amount reclassified from accumulated other comprehensive loss to interest expense on deposits and junior subordinated debentures	(680)	356
Amount of gain recognized in other comprehensive income	3,755	1,259
Unrealized gain at end of period	$ 14,977	$ 8,559

Derivative Financial Instrume84

Derivative Financial Instruments (Schedule of Carrying Amount of Hedged Assets/(Liabilities)) (Detail) - Fair Value Hedging - Designated as Hedging Instrument - Interest Rate Swap $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Derivative [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	$ 115,092
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	(5,106)
Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued	0
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (45)

Derivative Financial Instrume85

Derivative Financial Instruments (Summary Amounts Included In Consolidated Statement Of Income Related To Derivatives) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest rate swaps and caps | Trading gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ 153	$ (303)
Mortgage banking derivatives | Mortgage banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	1,418	738
Covered call options | Fees from covered call options
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	1,597	759
Foreign exchange contracts | Trading gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ (43)	$ (28)

Derivative Financial Instrume86

Derivative Financial Instruments (Derivative Asset and Liability Balance Sheet Offsetting) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Offsetting Assets [Line Items]
Net amount presented in the Statements of Financial Condition	$ 78,960	$ 52,069	$ 54,273
Derivative Liabilities
Net amount presented in the Statements of Financial Condition	55,699	35,671	41,531
Interest Rate Contract
Offsetting Assets [Line Items]
Gross Amounts Recognized	72,970	48,985	48,168
Less: Amounts offset in the Statements of Financial Condition	0	0	0
Net amount presented in the Statements of Financial Condition	72,970	48,985	48,168
Offsetting Derivative Positions	(9,627)	(14,878)	(16,529)
Collateral Posted	(54,490)	(18,060)	(6,990)
Net Credit Exposure	8,853	16,047	24,649
Derivative Liabilities
Gross Amounts Recognized	52,443	33,716	35,459
Less: Amounts offset in the Statements of Financial Condition	0	0	0
Net amount presented in the Statements of Financial Condition	52,443	33,716	35,459
Offsetting Derivative Positions	(9,627)	(14,878)	(16,529)
Collateral Posted	(340)	(2,220)	(12,300)
Net Credit Exposure	$ 42,476	$ 16,618	$ 6,630

Fair Values of Assets and Lia87

Fair Values of Assets and Liabilities (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)$ / Loan	Dec. 31, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 1,895,688,000	$ 1,803,666,000	$ 1,803,733,000
Loans held-for-investment	67,962,000		28,548,000
MSRs	54,572,000	33,676,000	21,596,000	$ 19,103,000
Derivative assets	78,960,000	52,069,000	54,273,000
Mortgage loans held-for-sale, at fair value	411,505,000	313,592,000	288,964,000
Impaired loans—collateral based	$ 103,131,000	105,088,000	87,522,000
Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Appraisal adjustment - cost of sale (as a percent)	10.00%
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 1,895,688,000	1,803,666,000	1,803,733,000
MSRs	54,572,000	33,676,000	21,596,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	396,900,000	299,500,000	277,300,000
Mortgage loans held-for-sale, at fair value	411,505,000	313,592,000	288,964,000
Portion at Other than Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	34,400,000
Non-performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale, at fair value	0	0	0
Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	67,962,000	33,717,000	28,548,000
MSRs	54,572,000	33,676,000	21,596,000
Derivative assets	78,960,000	52,069,000	54,273,000
Mortgage loans held-for-sale, at fair value	411,505,000	313,592,000	288,964,000
Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	68,684,000
Other real estate owned	36,598,000
Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	26,620,000	33,717,000	28,548,000
MSRs	54,572,000	33,676,000	21,596,000
Derivative assets	4,605,000	2,157,000	3,582,000
Mortgage loans held-for-sale, at fair value	$ 0	0	0
Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Constant prepayment rate (CPR)	8.76%
Level 3 | Measured at fair value on a recurring basis: | Minimum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input (as a percent)	3.00%
Credit discount	0.00%
Level 3 | Measured at fair value on a recurring basis: | Minimum | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input (as a percent)	7.00%
Constant prepayment rate (CPR)	0.00%
Level 3 | Measured at fair value on a recurring basis: | Minimum | Derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull-through rate (as a percent)	32.00%
Level 3 | Measured at fair value on a recurring basis: | Maximum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input (as a percent)	4.00%
Credit discount	11.00%
Level 3 | Measured at fair value on a recurring basis: | Maximum | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input (as a percent)	17.00%
Constant prepayment rate (CPR)	87.00%
Level 3 | Measured at fair value on a recurring basis: | Maximum | Derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull-through rate (as a percent)	100.00%
Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input (as a percent)	4.14%
Credit discount	1.88%
Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate input (as a percent)	10.02%
Constant prepayment rate (CPR)	9.40%
Cost of servicing loan (in dollars per loan) | $ / Loan	78
Cost of servicing loan - delinquent (in dollars per loan) | $ / Loan	368
Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs | Derivatives | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pull-through rate (as a percent)	85.34%
Level 3 | Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	$ 68,684,000
Other real estate owned	36,598,000
Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	121,758,000	115,352,000	127,563,000
Municipal Securities | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	121,758,000	115,352,000	127,563,000
Municipal Securities | Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	84,592,000	77,181,000	79,745,000
U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	149,336,000	156,915,000	177,829,000
U.S. Government agencies | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	149,336,000	156,915,000	177,829,000
U.S. Government agencies | Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 3,616,000	$ 3,779,000	$ 4,283,000

Fair Values of Assets and Lia88

Fair Values of Assets and Liabilities (Summary of Balances of Assets and Liabilities Measured at Fair Value On A Recurring Basis) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 1,895,688	$ 1,803,666	$ 1,803,733
Trading account securities	1,682	995	714
Fair Value	37,832	0	0
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
Loans held-for-investment	67,962		28,548
MSRs	54,572	33,676	21,596	$ 19,103
Derivative assets	78,960	52,069	54,273
Derivative liabilities	55,699	35,671	41,531
U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	24,727	143,822	142,156
U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	149,336	156,915	177,829
Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	121,758	115,352	127,563
Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,500,153	1,319,725	1,256,044
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	36,802	34,717
Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	1,682	995	714
Fair Value	37,832
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
Loans held-for-investment	67,962	33,717	28,548
MSRs	54,572	33,676	21,596
Nonqualified deferred compensation assets	11,724	11,065	10,347
Derivative assets	78,960	52,069	54,273
Total	2,559,925	2,248,780	2,208,175
Derivative liabilities	55,699	35,671	41,531
Measured at fair value on a recurring basis: | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	24,727	143,822	142,156
Measured at fair value on a recurring basis: | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	149,336	156,915	177,829
Measured at fair value on a recurring basis: | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	121,758	115,352	127,563
Measured at fair value on a recurring basis: | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	99,714	31,050	65,424
Measured at fair value on a recurring basis: | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,500,153	1,319,725	1,256,044
Measured at fair value on a recurring basis: | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		36,802	34,717
Measured at fair value on a recurring basis: | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment		0
Measured at fair value on a recurring basis: | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	1,682	995	714
Fair Value	37,832
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
Loans held-for-investment	41,342	0	0
MSRs	0	0	0
Nonqualified deferred compensation assets	11,724	11,065	10,347
Derivative assets	74,355	49,912	50,691
Total	2,385,920	2,098,270	2,070,421
Derivative liabilities	55,699	35,671	41,531
Measured at fair value on a recurring basis: | Level 2 | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	24,727	143,822	142,156
Measured at fair value on a recurring basis: | Level 2 | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	145,720	153,136	173,546
Measured at fair value on a recurring basis: | Level 2 | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	37,166	38,171	47,818
Measured at fair value on a recurring basis: | Level 2 | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	99,714	31,050	65,424
Measured at fair value on a recurring basis: | Level 2 | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,500,153	1,319,725	1,256,044
Measured at fair value on a recurring basis: | Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		36,802	34,717
Measured at fair value on a recurring basis: | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	0	0	0
Fair Value	0
Mortgage loans held-for-sale, at fair value	0	0	0
Loans held-for-investment	26,620	33,717	28,548
MSRs	54,572	33,676	21,596
Nonqualified deferred compensation assets	0	0	0
Derivative assets	4,605	2,157	3,582
Total	174,005	150,510	137,754
Derivative liabilities	0	0	0
Measured at fair value on a recurring basis: | Level 3 | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 3 | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	3,616	3,779	4,283
Measured at fair value on a recurring basis: | Level 3 | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	84,592	77,181	79,745
Measured at fair value on a recurring basis: | Level 3 | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 3 | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	0	0
Measured at fair value on a recurring basis: | Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		$ 0	$ 0

Fair Values of Assets and Lia89

Fair Values of Assets and Liabilities (Summary of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Loans held-for- investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 33,717	$ 22,137
Net Income	(1,128)	(112)
Other comprehensive loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(6,255)	(3,332)
Net transfers into/(out of) Level 3	286	9,855
Ending Balance	26,620	28,548
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	33,676	19,103
Net Income	7,090	2,493
Other comprehensive loss		0
Purchases	13,806	0
Issuances	0	0
Settlements		0
Net transfers into/(out of) Level 3	0	0
Ending Balance	54,572	21,596
Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	2,157	2,291
Net Income	2,448	1,291
Other comprehensive loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into/(out of) Level 3	0	0
Ending Balance	4,605	3,582
Municipal Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	77,181	79,626
Net Income		0
Other comprehensive loss	(2,190)	457
Purchases	12,270	7,586
Issuances	0	0
Sales	0	0
Settlements	(2,669)	(7,924)
Net transfers into/(out of) Level 3		0
Ending Balance	84,592	79,745
U.S. Government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	3,779	0
Net Income	0	0
Other comprehensive loss	(163)	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into/(out of) Level 3	0	4,283
Ending Balance	$ 3,616	$ 4,283

Fair Values of Assets and Lia90

Fair Values of Assets and Liabilities (Summary of Assets Measured at Fair Value on a Nonrecurring Basis) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	$ 103,131	$ 105,088	$ 87,522
Fair Value Losses Recognized, Impaired loans—collateral based	3,886
Fair Value Losses Recognized, Other real estate owned	2,158
Fair Value Losses Recognized, Total	6,044
Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	68,684
Other real estate owned	36,598
Total	105,282
Measured at fair value on a non-recurring basis: | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	0
Other real estate owned	0
Total	0
Measured at fair value on a non-recurring basis: | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	0
Other real estate owned	0
Total	0
Measured at fair value on a non-recurring basis: | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	68,684
Other real estate owned	36,598
Total	$ 105,282

Fair Values of Assets and Lia91

Fair Values of Assets and Liabilities (Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Measure Both Recurring and Non-Recurring) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)$ / Loan	Dec. 31, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	$ 1,895,688	$ 1,803,666	$ 1,803,733
Loans held-for-investment	67,962		28,548
MSRs	54,572	33,676	21,596	$ 19,103
Derivative assets	78,960	52,069	54,273
Impaired loans—collateral based	$ 103,131	105,088	87,522
Other real estate owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Appraisal adjustment - cost of sale	10.00%
Municipal Securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	$ 121,758	115,352	127,563
U.S. Government agencies
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	149,336	156,915	177,829
Measured at fair value on a recurring basis:
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Loans held-for-investment	67,962	33,717	28,548
MSRs	54,572	33,676	21,596
Derivative assets	78,960	52,069	54,273
Measured at fair value on a recurring basis: | Municipal Securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	121,758	115,352	127,563
Measured at fair value on a recurring basis: | U.S. Government agencies
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	149,336	156,915	177,829
Measured at fair value on a non-recurring basis:
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans—collateral based	68,684
Other real estate owned	36,598
Level 3 | Measured at fair value on a recurring basis:
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Loans held-for-investment	26,620	33,717	28,548
MSRs	54,572	33,676	21,596
Derivative assets	$ 4,605	2,157	3,582
Level 3 | Measured at fair value on a recurring basis: | Loans held-for- investment
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Constant prepayment rate (CPR)	8.76%
Level 3 | Measured at fair value on a recurring basis: | Loans held-for- investment | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	3.00%
Credit discount	0.00%
Level 3 | Measured at fair value on a recurring basis: | Loans held-for- investment | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	4.00%
Credit discount	11.00%
Level 3 | Measured at fair value on a recurring basis: | Loans held-for- investment | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	4.14%
Credit discount	1.88%
Level 3 | Measured at fair value on a recurring basis: | Mortgage servicing rights | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	7.00%
Constant prepayment rate (CPR)	0.00%
Level 3 | Measured at fair value on a recurring basis: | Mortgage servicing rights | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	17.00%
Constant prepayment rate (CPR)	87.00%
Level 3 | Measured at fair value on a recurring basis: | Mortgage servicing rights | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	10.02%
Constant prepayment rate (CPR)	9.40%
Cost of servicing (in dollars per loan) | $ / Loan	78
Cost of servicing - delinquent (in dollars per loan) | $ / Loan	368
Level 3 | Measured at fair value on a recurring basis: | Municipal Securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	$ 84,592	77,181	79,745
Level 3 | Measured at fair value on a recurring basis: | U.S. Government agencies
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	3,616	$ 3,779	$ 4,283
Level 3 | Measured at fair value on a non-recurring basis:
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans—collateral based	68,684
Other real estate owned	$ 36,598
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Discount Rate | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	3.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Discount Rate | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	4.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Discount Rate | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	4.14%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Credit Spread | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Credit discount	0.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Credit Spread | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Credit discount	11.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Credit Spread | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Credit discount	1.88%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Constant Prepayment Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Constant prepayment rate (CPR)	8.76%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Loans held-for-investment Constant Prepayment Rate | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Constant prepayment rate (CPR)	8.76%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Discount Rate | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	7.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Discount Rate | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	17.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Discount Rate | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate	10.02%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Prepayment Rate | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Constant prepayment rate (CPR)	0.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Prepayment Rate | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Constant prepayment rate (CPR)	87.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Prepayment Rate | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Constant prepayment rate (CPR)	9.40%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Cost of servicing | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cost of servicing (in dollars per loan) | $ / Loan	70
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Cost of servicing | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cost of servicing (in dollars per loan) | $ / Loan	200
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Cost of servicing | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cost of servicing (in dollars per loan) | $ / Loan	78
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Cost of servicing - delinquent | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cost of servicing - delinquent (in dollars per loan) | $ / Loan	200
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Cost of servicing - delinquent | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cost of servicing - delinquent (in dollars per loan) | $ / Loan	1,000
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Mortgage Servicing Rights Cost of servicing - delinquent | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cost of servicing - delinquent (in dollars per loan) | $ / Loan	368
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Derivatives | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Pull-through rate	32.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Derivatives | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Pull-through rate	100.00%
Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Derivatives | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Pull-through rate	85.34%
Appraisal value | Level 3 | Measured at fair value on a non-recurring basis: | Impaired loans—collateral based
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Appraisal adjustment - cost of sale	10.00%
Appraisal value | Level 3 | Measured at fair value on a non-recurring basis: | Impaired loans—collateral based | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Appraisal adjustment - cost of sale	10.00%
Appraisal value | Level 3 | Measured at fair value on a non-recurring basis: | Other real estate owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Appraisal adjustment - cost of sale	10.00%
Appraisal value | Level 3 | Measured at fair value on a non-recurring basis: | Other real estate owned | Weighted Average of Inputs
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Appraisal adjustment - cost of sale	10.00%

Fair Values of Assets and Lia92

Fair Values of Assets and Liabilities (Summary Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 231,464	$ 277,591	$ 217,148	$ 270,045
Interest bearing deposits with banks	980,380	1,063,242	1,007,468
Available-for-sale securities	1,895,688	1,803,666	1,803,733
Held-to-maturity securities	862,527	812,516	647,895
Trading account securities	1,682	995	714
Equity securities with readily determinable fair value	37,832	0	0
FHLB and FRB stock, at cost	104,956	89,989	78,904
Brokerage customer receivables	24,531	26,431	23,171
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
MSRs	54,572	33,676	21,596	19,103
Accrued interest receivable and other	601,794	567,374	560,741
FHLB advances	915,000	559,663	227,585
Other borrowings	247,092	266,123	238,787
Subordinated notes	139,111	139,088	138,993
Junior subordinated debentures	253,566	253,566	253,566
Derivative liabilities	55,699	35,671	41,531
FDIC indemnification liability			18,263	$ 16,701
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	231,464	277,591	217,148
Interest bearing deposits with banks	980,380	1,063,242	1,007,468
Available-for-sale securities	1,895,688	1,803,666	1,803,733
Held-to-maturity securities	892,937	826,449	667,764
Trading account securities	1,682	995	714
Equity securities with readily determinable fair value	37,832	0	0
FHLB and FRB stock, at cost	104,956	89,989	78,904
Brokerage customer receivables	24,531	26,431	23,171
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
Loans held-for-investment, at fair value	67,962	33,717	28,548
Loans held-for-investment, at amortized cost	21,994,172	21,607,080	19,954,869
MSRs	54,572	33,676	21,596
Nonqualified deferred compensation assets	11,724	11,065	10,347
Derivative assets	78,960	52,069	54,273
Accrued interest receivable and other	236,131	227,649	209,623
Total financial assets	27,024,496	26,367,211	24,367,122
Non-maturity deposits	18,941,201	18,775,977	17,509,429
Deposits with stated maturities	4,338,126	4,407,370	4,221,012
FHLB advances	915,000	559,663	227,585
Other borrowings	247,092	266,123	238,787
Subordinated notes	139,111	139,088	138,993
Junior subordinated debentures	253,566	253,566	253,566
Derivative liabilities	55,699	35,671	41,531
FDIC indemnification liability	0	0	18,264
Accrued interest payable	11,442	8,030	7,944
Total financial liabilities	24,901,237	24,445,488	22,657,111
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	231,464	277,591	217,148
Interest bearing deposits with banks	980,380	1,063,242	1,007,468
Available-for-sale securities	1,895,688	1,803,666	1,803,733
Held-to-maturity securities	862,527	812,516	647,895
Trading account securities	1,682	995	714
Equity securities with readily determinable fair value	37,832	0	0
FHLB and FRB stock, at cost	104,956	89,989	78,904
Brokerage customer receivables	24,531	26,431	23,171
Mortgage loans held-for-sale, at fair value	411,505	313,592	288,964
Loans held-for-investment, at fair value	67,962	33,717	28,548
Loans held-for-investment, at amortized cost	22,234,795	21,768,978	21,048,751
MSRs	54,572	33,676	21,596
Nonqualified deferred compensation assets	11,724	11,065	10,347
Derivative assets	78,960	52,069	54,273
Accrued interest receivable and other	236,131	227,649	209,623
Total financial assets	27,234,709	26,515,176	25,441,135
Non-maturity deposits	18,941,201	18,775,977	17,509,429
Deposits with stated maturities	4,344,584	4,350,004	4,210,294
FHLB advances	916,513	544,750	229,338
Other borrowings	247,092	266,123	238,787
Subordinated notes	140,889	144,266	141,180
Junior subordinated debentures	268,873	264,696	254,417
Derivative liabilities	55,699	35,671	41,531
FDIC indemnification liability	0	0	18,264
Accrued interest payable	11,442	8,030	7,944
Total financial liabilities	$ 24,926,293	$ 24,389,517	$ 22,651,184

Stock-Based Compensation Plan93

Stock-Based Compensation Plans (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	May 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants (in shares)	3,400,000
Number of stock options granted	0	0
Stock-based compensation expense	$ 3.7	$ 2.9
Aggregate intrinsic value of options exercised	7.5	10.2
Cash received from option exercises	$ 7.2	$ 12.8
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved for issuance (in shares)			5,485,000
2007 Plan and 2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based payment award options term	7 years
2007 Plan and 2015 Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
2007 Plan and 2015 Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	5 years
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	5 years
LTIP Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
LTIP Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance based award payouts	0.00%
Granted after 2014 | LTIP Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance based award payouts	150.00%
Granted prior to 2015 | LTIP Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance based award payouts	200.00%

Stock-Based Compensation Plan94

Stock-Based Compensation Plans (Summary Of Stock Option Activity) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Common Shares
Common Shares, Outstanding at beginning of the period (in shares)	1,084,756	1,698,912
Common Shares, Granted (in shares)	0	0
Common Shares, Exercised (in shares)	(169,387)	(319,802)
Common Shares, Forfeited or canceled (in shares)	(1,703)	(6,496)
Common Shares, Outstanding at end of the period (in shares)	913,666	1,372,614
Stock Options, Exercisable (in shares)	712,535	819,955
Weighted Average Strike Price
Weighted Average Strike Price, Outstanding at beginning of period (usd per share)	$ 41.98	$ 41.50
Weighted Average Strike Price, Granted (usd per share)	0	0
Weighted Average Strike Price, Exercised (usd per share)	42.47	39.97
Weighted Average Strike Price, Forfeited or canceled (usd per share)	40.87	42.65
Weighted Average Strike Price, Outstanding at end of period (usd per share)	41.89	41.85
Stock Options, Weighted Average Strike Price, Exercisable (usd per share)	$ 42	$ 41.60
Stock Options, Remaining Contractual Term, Outstanding, Years	3 years 8 months 12 days	4 years 7 months 6 days
Stock Options, Remaining Contractual Term, Exercisable, Years	3 years 4 months 24 days	4 years
Stock Options, Intrinsic Value, Outstanding	$ 40,351	$ 37,436
Stock Options, Intrinsic Value, Exercisable	$ 31,391	$ 22,568

Stock-Based Compensation Plan95

Stock-Based Compensation Plans (Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity) (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restricted Stock
Common Shares
Outstanding Beginning of the Period (in shares)	127,787	133,425
Granted (in shares)	20,700	8,425
Vested and issued (in shares)	(7,258)	(5,063)
Forfeited (in shares)	(982)	0
Outstanding End of the Period (in shares)	140,247	136,787
Vested, but not issuable (in shares)	89,924	89,215
Weighted Average Grant-Date Fair Value
Beginning Weighted Average Grant-Date Fair Value (usd per share)	$ 53.33	$ 49.94
Weighted Average Grant-Date Fair Value, Granted (usd per share)	86.42	72.52
Weighted Average Grant-Date Fair Value, Vested and issued (usd per share)	53.47	42.71
Weighted Average Grant-Date Fair Value, Forfeited (usd per share)	55.39	0
Ending Weighted Average Grant-Date Fair Value (usd per share)	58.20	51.60
Weighted Average Grant-Date Fair Value, Vested, but not issuable (usd per share)	$ 51.71	$ 51.51
Performance Shares
Common Shares
Outstanding Beginning of the Period (in shares)	359,196	298,180
Granted (in shares)	127,419	141,399
Vested and issued (in shares)	(82,307)	(68,712)
Forfeited (in shares)	(6,580)	(7,731)
Outstanding End of the Period (in shares)	397,728	363,136
Vested, but not issuable (in shares)	21,388	13,564
Weighted Average Grant-Date Fair Value
Beginning Weighted Average Grant-Date Fair Value (usd per share)	$ 54.37	$ 43.64
Weighted Average Grant-Date Fair Value, Granted (usd per share)	88.20	72.55
Weighted Average Grant-Date Fair Value, Vested and issued (usd per share)	44.39	46.85
Weighted Average Grant-Date Fair Value, Forfeited (usd per share)	49.42	50.11
Ending Weighted Average Grant-Date Fair Value (usd per share)	67.35	54.15
Weighted Average Grant-Date Fair Value, Vested, but not issuable (usd per share)	$ 43.32	$ 42.55

Shareholders' Equity And Earn96

Shareholders' Equity And Earnings Per Share (Components Of Other Comprehensive Income (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	$ 2,976,939	$ 2,695,617
Total other comprehensive (loss) income	(26,406)	5,504
Balance at the end	3,031,250	2,764,983
Accumulated Unrealized Gains (Losses) on Securities
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	(15,813)	(29,309)
Other comprehensive (loss) income during the period, net of tax, before reclassifications	(26,474)	4,479
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	713	34
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	3	(867)
Total other comprehensive (loss) income	(25,758)	3,646
Balance at the end	(47,968)	(25,663)
Accumulated Unrealized Losses on Derivative Instruments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	7,164	4,165
Other comprehensive (loss) income during the period, net of tax, before reclassifications	2,746	765
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	(497)	216
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	0	0
Total other comprehensive (loss) income	2,249	981
Balance at the end	10,956	5,146
Accumulated Foreign Currency Translation Adjustments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	(33,186)	(40,184)
Other comprehensive (loss) income during the period, net of tax, before reclassifications	(2,897)	877
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	0	0
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	0	0
Total other comprehensive (loss) income	(2,897)	877
Balance at the end	(36,083)	(39,307)
Accumulated other comprehensive loss
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	(41,835)	(65,328)
Other comprehensive (loss) income during the period, net of tax, before reclassifications	(26,625)	6,121
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	216	250
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	3	(867)
Total other comprehensive (loss) income	(26,406)	5,504
Balance at the end	$ (73,095)	$ (59,824)
ASU 2016-01
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			$ 0
ASU 2016-01 | Accumulated Unrealized Gains (Losses) on Securities
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			(1,880)
ASU 2016-01 | Accumulated Unrealized Losses on Derivative Instruments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			0
ASU 2016-01 | Accumulated Foreign Currency Translation Adjustments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			0
ASU 2016-01 | Accumulated other comprehensive loss
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			(1,880)
ASU 2018-02
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			0
ASU 2018-02 | Accumulated Unrealized Gains (Losses) on Securities
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			(4,517)
ASU 2018-02 | Accumulated Unrealized Losses on Derivative Instruments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			1,543
ASU 2018-02 | Accumulated Foreign Currency Translation Adjustments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			0
ASU 2018-02 | Accumulated other comprehensive loss
Activity Accumulated Other Comprehensive Income [Roll Forward]
Cumulative effect adjustment			$ (2,974)

Shareholders' Equity And Earn97

Shareholders' Equity And Earnings Per Share (Other Comprehensive Income Reclassified from AOCI) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Losses on investment securities, net	$ (351)	$ (55)
Income before taxes	108,066	88,018
Income tax expense	(26,085)	(29,640)
Interest on deposits	26,549	16,270
Interest on junior subordinated debentures	2,463	2,408
Net income	81,981	58,378
Reclassification Out of Accumulated Other Comprehensive Income | Accumulated Unrealized Gains (Losses) on Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Losses on investment securities, net	(975)	(55)
Income before taxes	(975)	(55)
Income tax expense	262	21
Net income	(713)	(34)
Reclassification Out of Accumulated Other Comprehensive Income | Accumulated Unrealized Losses on Derivative Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income before taxes	680	(356)
Income tax expense	(183)	140
Interest on deposits	(680)	42
Interest on junior subordinated debentures	0	314
Net income	$ 497	$ (216)

Shareholders' Equity And Earn98

Shareholders' Equity And Earnings Per Share (Computation Of Basic And Diluted Earnings Per Common Share) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income	$ 81,981	$ 58,378
Less: Preferred stock dividends	2,050	3,628
Net income applicable to common shares	79,931	54,750
Add: Dividends on convertible preferred stock, if dilutive	0	1,578
Net income applicable to common shares—Diluted	$ 79,931	$ 56,328
Weighted average common shares outstanding (in shares)	56,137	52,267
Effect of dilutive potential common shares
Common stock equivalents (in shares)	888	1,060
Convertible preferred stock, if dilutive (in shares)	0	3,100
Total dilutive potential common shares (in shares)	888	4,160
Weighted average common shares and effect of dilutive potential common shares (in shares)	57,025	56,427
Net income per common share:
Basic (usd per share)	$ 1.42	$ 1.05
Diluted (usd per share)	$ 1.40	$ 1

Shareholders' Equity And Earn99

Shareholders' Equity And Earnings Per Share (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Thousands	Apr. 27, 2017	Apr. 25, 2017	Dec. 19, 2008	Jan. 31, 2018	Jun. 30, 2015	Mar. 31, 2012	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Temporary Equity [Line Items]
Cash dividends declared per common share (usd per share)				$ 0.19			$ 0.19	$ 0.14
Common stock dividends per share declared annualized (usd per share)				$ 0.76
US Treasury
Temporary Equity [Line Items]
Warrants outstanding, shares			1,643,295				10,160
Warrant termination period			10 years
Investment warrants, exercise price (usd per share)							$ 22.62
Warrants exercised, shares							13,201
Common stock shares issued from exercise of warrants							9,677
Common stock
Temporary Equity [Line Items]
Common stock issued, conversion of preferred stock, shares	3,069,828	51,244
Series D Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)					5,000,000		5,000,000	5,000,000	5,000,000
Preferred stock, liquidation value per share (usd per share)					$ 25		$ 25	$ 25	$ 25
Preferred stock, value					$ 125,000		$ 125,000	$ 125,000	$ 125,000
Preferred stock, dividend rate, percentage					6.50%
Series C Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)						126,500	0	126,257	0
Preferred stock, liquidation value per share (usd per share)						$ 1,000	$ 1,000	$ 1,000	$ 1,000
Preferred stock, value						$ 126,500	$ 0	$ 126,257	$ 0
Preferred stock, dividend rate, percentage						5.00%
Convertible preferred stock, rate of conversion, shares	24.72
Number of shares converted	124,184	2,073
London Interbank Offered Rate (LIBOR) | Series D Preferred Stock
Temporary Equity [Line Items]
Preferred stock, dividend rate, percentage, variable spread					4.06%