Webster Financial (WBS) 10-Q 7 May 18 2017 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 Period End Date	Mar. 31, 2018
Document Type	10-Q
Amendment Flag	false
Entity Registrant Name	WEBSTER FINANCIAL CORPORATION
Entity Common Stock, Shares Outstanding		92,098,422
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Trading Symbol	WBS
Entity Central Index Key	801,337
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Cash and due from banks	$ 164,927	$ 231,158
Interest-bearing deposits	45,899	25,628
Investment securities available-for-sale, at fair value	2,773,506	2,638,037
Investment securities held-to-maturity (fair value of $4,297,039 and $4,456,350)	4,408,321	4,487,392
Federal Home Loan Bank and Federal Reserve Bank stock	125,328	151,566
Loans held for sale, fair value option	19,727	20,888
Loans and leases	17,805,575	17,523,858
Allowance for loan and lease losses	(205,349)	(199,994)
Loans and leases, net	17,600,226	17,323,864
Deferred tax assets, net	99,199	92,630
Premises and equipment, net	127,196	130,001
Goodwill	538,373	538,373
Other intangible assets, net	28,650	29,611
Cash surrender value of life insurance policies	535,391	531,820
Accrued interest receivable and other assets	285,404	286,677
Total assets	26,752,147	26,487,645
Liabilities and shareholders' equity:
Noninterest-bearing Deposit Liabilities	4,074,992	4,191,496
Interest-bearing Deposit Liabilities	17,310,050	16,802,233
Total deposits	21,385,042	20,993,729
Securities sold under agreements to repurchase and other borrowings	931,299	643,269
Federal Home Loan Bank advances	1,202,030	1,677,105
Long-term debt	225,830	225,767
Accrued expenses and other liabilities	291,804	245,817
Total liabilities	24,036,005	23,785,687
Shareholders’ equity:
Common stock, $.01 par value: Authorized - 200,000,000 shares: Issued (93,651,601 shares)	937	937
Paid-in capital	1,120,522	1,122,164
Retained earnings	1,649,524	1,595,762
Treasury stock, at cost (1,799,401 and 1,658,526 shares)	(84,399)	(70,430)
Accumulated other comprehensive loss, net of tax	(115,479)	(91,531)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,716,142	2,701,958
Total liabilities and shareholders' equity	26,752,147	26,487,645
Series F Preferred Stock [Member]
Shareholders’ equity:
Preferred stock, $.01 par value; Authorized - 3,000,000 shares: Series E issued and outstanding (5,060 shares)	$ 145,037	$ 145,056

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Securities held-to-maturity ,fair value	$ 4,297,039	$ 4,456,350
Originated loans held for sale	$ 19,727	$ 20,888
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	3,000,000	3,000,000
Preferred stock, shares issued (in shares)	6,000	5,060
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)		93,680,291
Treasury stock ,shares (in shares)	1,799,401	1,658,526
Common Stock [Member]
Shares, Issued	93,680,291

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest Income:
Interest and fees on loans and leases	$ 193,220	$ 167,808
Taxable interest and dividends on investments	47,288	45,940
Non-taxable interest on investment securities	5,271	5,616
Loans held for sale	142	316
Total interest income	245,921	219,680
Interest Expense:
Deposits	18,156	13,435
Securities sold under agreements to repurchase and other borrowings	3,640	3,540
Federal Home Loan Bank advances	7,281	7,493
Long-term debt	2,676	2,548
Total interest expense	31,753	27,016
Net interest income	214,168	192,664
Provision for loan and lease losses	11,000	10,500
Net interest income after provision for loan and lease losses	203,168	182,164
Non-interest Income:
Deposit service fees	40,451	37,006
Loan and lease related fees	6,996	7,208
Wealth and investment services	7,870	7,273
Mortgage banking activities	1,144	2,266
Increase in cash surrender value of life insurance policies	3,572	3,575
Other income	8,714	5,714
Total non-interest income	68,747	63,042
Non-interest Expense:
Compensation and benefits	94,765	87,499
Occupancy	15,145	16,179
Technology and equipment	23,862	21,608
Intangible assets amortization	962	1,055
Marketing	3,552	5,441
Professional and outside services	4,788	4,276
Deposit insurance	6,717	6,732
Other expense	21,824	20,994
Total non-interest expense	171,615	163,784
Income (loss) before income tax expense	100,300	81,422
Income tax expense	20,075	21,951
Net income	80,225	59,471
Preferred stock dividends and other	(2,142)	(2,129)
Earnings applicable to common shareholders	$ 78,083	$ 57,342
Earnings per common share:
Basic (in dollars per share)	$ 0.85	$ 0.62
Diluted (in dollars per share)	$ 0.85	$ 0.62

Condensed Consolidated Stateme5

Condensed 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	$ 80,225	$ 59,471
Other comprehensive (loss) income, net of tax:
Total securities available-for-sale	(27,424)	(2,225)
Total derivative instruments	2,522	1,159
Total defined benefit pension and other postretirement benefit plans	954	1,032
Other comprehensive loss, net of tax	(23,948)	(34)
Comprehensive income	$ 56,277	$ 59,437

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series E Preferred Stock [Member]	Series F Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member]Series F Preferred Stock [Member]	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]Series E Preferred Stock [Member]	Retained Earnings [Member]Series F Preferred Stock [Member]	Treasury Stock, at cost [Member]	AOCI Attributable to Parent [Member]
Beginning Balance at Dec. 31, 2016	$ 2,527,012			$ 122,710		$ 937	$ 1,125,937	$ 1,425,320			$ (70,899)	$ (76,993)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	59,471							59,471
Other comprehensive loss, net of tax	(34)											(34)
Dividends and dividend equivalents declared on common stock $0.25 and $0.23 per share during the 3 months ended March 31, 2017 and 2016, respectively	(23,094)						39	(23,133)
Dividends on Series E preferred stock $400.00 per share for the 3 months ended March 31, 2017 and 2016		$ (2,024)							$ (2,024)
Stock-based compensation	5,226						0	392			4,834
Exercise of stock options	2,793						(1,076)				3,869
Common shares acquired related to stock compensation plan activity	(8,992)										(8,992)
Ending Balance at Mar. 31, 2017	2,560,358			122,710		937	1,124,900	1,460,026			(71,188)	(77,027)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Fair Value	4,456,350
Beginning Balance at Dec. 31, 2017	2,701,958			145,056		937	1,122,164	1,595,762			(70,430)	(91,531)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	80,225							80,225
Other comprehensive loss, net of tax	(23,948)											(23,948)
Dividends and dividend equivalents declared on common stock $0.25 and $0.23 per share during the 3 months ended March 31, 2017 and 2016, respectively	(24,068)						43	(24,111)
Dividends on Series E preferred stock $400.00 per share for the 3 months ended March 31, 2017 and 2016		$ (1,969)	$ (22)						$ (1,969)	$ (22)
Stock-based compensation	3,335						(1,541)	957			3,919
Exercise of stock options	290						(144)				434
Common shares acquired related to stock compensation plan activity	(6,164)										(6,164)
Common stock repurchase program	(12,158)										(12,158)
Ending Balance at Mar. 31, 2018	2,716,142			$ 145,037		$ 937	$ 1,120,522	1,649,524			$ (84,399)	$ (115,479)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Other			$ (19)		$ (19)
Cumulative Effect of New Accounting Principle in Period of Adoption	(1,362)							$ (1,362)
Fair Value	$ 4,297,039

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Dividends on common stock and dividend equivalents declared (in dollars per share)	$ 0.26	$ 0.25
Series E Preferred Stock [Member]
Dividends on preferred stock (in dollars per share)	$ 328.13	$ 400

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities:
Net income	$ 80,225	$ 59,471
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	11,000	10,500
Deferred tax expense	1,286	7,548
Depreciation and amortization	9,489	9,637
Amortization of earning assets and funding, premiums/discounts, net	13,390	13,619
Stock-based compensation	3,335	3,318
Gain on sale, net of write-down, on foreclosed and repossessed assets	(89)	(74)
Write-down, net on premises and equipment	57	530
Increase in cash surrender value of life insurance policies	(3,572)	(3,575)
Mortgage banking activities	(1,144)	(2,266)
Proceeds from sale of loans held for sale	44,806	106,620
Origination of loans held for sale	(43,131)	(72,984)
Net decrease in derivative contract assets net of liabilities	11,744	15,832
Net increase in accrued interest receivable and other assets	(10,484)	(6,673)
Net increase in accrued expenses and other liabilities	15,355	2,590
Net cash provided by operating activities	132,267	144,093
Investing Activities:
Net increase in interest-bearing deposits	(20,271)	(8,689)
Purchases of available for sale investment securities	(251,920)	(52,031)
Proceeds from maturities and principal payments of available for sale investment securities	111,231	160,350
Purchases of held-to-maturity investment securities	(64,281)	(234,477)
Proceeds from maturities and principal payments of held-to-maturity investment securities	133,692	175,881
Net proceeds of Federal Home Loan Bank stock	26,238	31,089
Alternative investments return of capital (capital call), net	(364)	563
Net increase in loans	(289,165)	(76,329)
Proceeds from loans not originated for sale	34	7,445
Proceeds from the sale of foreclosed and repossessed assets	1,948	1,285
Additions to premises and equipment	(5,780)	(7,232)
Proceeds from Sale of Other Assets	0	7,581
Net cash (used for) provided by investing activities	(358,638)	5,436
Financing Activities:
Net increase in deposits	391,087	937,040
Proceeds from Federal Home Loan Bank advances	1,525,000	3,875,000
Repayments of Federal Home Loan Bank advances	(2,000,075)	(4,795,073)
Net decrease in securities sold under agreements to repurchase and other borrowings	288,030	(141,953)
Dividends paid to common shareholders	(23,901)	(22,939)
Dividends paid to preferred shareholders	(1,969)	(2,024)
Exercise of stock options	290	2,793
Common stock repurchase program	(12,158)	0
Common shares purchased related to stock compensation plan activity	(6,164)	(8,992)
Net cash (used for) provided by financing activities	160,140	(156,148)
Net decrease in cash and due from banks	(66,231)	(6,619)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	164,927	184,044
Cash and due from banks at beginning of period	231,158
Cash and due from banks at end of period	164,927
Supplemental disclosure of cash flow information:
Interest paid	33,986	26,797
Income taxes paid	3,313	5,386
Noncash investing and financing activities:
Real Estate Owned, Transfer to Real Estate Owned	1,626	1,410
Transfer of loans from portfolio to loans-held-for-sale	$ 35	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies Nature of Operations Webster Financial Corporation is a bank holding company and financial holding company under the Bank Holding Company Act, incorporated under the laws of Delaware in 1986 and headquartered in Waterbury, Connecticut. At March 31, 2018 , Webster Financial Corporation's principal asset is all of the outstanding capital stock of Webster Bank, National Association (Webster Bank). Webster delivers financial services to individuals, families, and businesses primarily within its regional footprint from New York to Massachusetts. Webster provides business and consumer banking, mortgage lending, financial planning, trust, and investment services through banking offices, ATMs, mobile banking, and its internet website ( www.websterbank.com or www.wbst.com ). Webster also offers equipment financing, commercial real estate lending, and asset-based lending primarily across the Northeast. On a nationwide basis, through its HSA Bank division, Webster Bank offers and administers health savings accounts, flexible spending accounts, health reimbursement accounts, and commuter benefits. Basis of Presentation The accounting and reporting policies of the Company that materially affect its financial statements conform with U.S. Generally Accepted Accounting Principles (GAAP). The accompanying unaudited Condensed Consolidated Financial Statements of the Company have been prepared in conformity with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements and should be read in conjunction with the Company's Consolidated Financial Statements, and Notes thereto, for the year ended December 31, 2017 , included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (SEC) on March 1, 2018. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts of assets and liabilities as of the date of the financial statements as well as income and expense during the period. Actual results could differ from those estimates. Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for the full year or any future period. Accounting Standards Adopted During 2018 Effective January1, 2018 , the following new Accounting Standards Updates (ASUs) were adopted by the Company: ASU No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities. The Update shortens the amortization period for certain investments in callable debt securities purchased at a premium by requiring that the premium be amortized to the earliest call date. Prior to adoption, the Company amortized the premium as a yield adjustment over the contractual life of such debt securities. The Update accelerates the Company's recognition of premium amortization on certain debt securities held within the portfolio. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company elected to early adopt the Update during the first quarter of 2018 on a modified retrospective basis. As a result, the Company recorded a $2.8 million cumulative-effect adjustment directly to retained earnings as of January 1, 2018. ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715) - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The Update requires the Company to retrospectively report service cost as a part of compensation expense and the other components of net periodic benefit cost separately from service cost in the Company's consolidated financial statements. The Company previously included all components of net periodic benefit cost as a component of compensation and benefits expense. Upon adoption, only service cost remains in compensation and benefits expense, while the interest cost on benefit obligations, expected return on plan assets, amortization of prior service cost, and recognized net loss components of the net periodic benefit cost are included in other expense, in the accompanying Condensed Consolidated Statements of Income. The Company adopted the Update during the first quarter of 2018 on a retrospective basis. As a result, the Company reclassified, for prior periods, the components of it's net periodic benefit costs other than the service cost component from compensation and benefits to other expense in the accompanying Condensed Consolidated Statements of Income. The adoption of this guidance did not have a material impact on the Company's consolidated financial statements. ASU No. 2016-15, Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments. The Update addresses the following eight specific cash flow issues, with the objective of reducing the existing diversity in practice: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company adopted the Update during the first quarter of 2018 on a retrospective basis. The adoption of this guidance did not have a material impact on the Company's consolidated financial statements. ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities, and ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10) The Updates included targeted amendments in connection with the recognition, measurement, presentation, and disclosure of financial instruments. The main provisions require investments in equity securities to be measured at fair value through net income, unless they qualify for a practical expedient, and require fair value changes arising from changes in instrument-specific credit risk for financial liabilities that are measured under the fair value option to be recognized in other comprehensive income. The provisions also emphasized the existing requirement to use exit prices to measure fair value for disclosure purposes. The Company adopted the Updates during the first quarter of 2018 primarily on a modified retrospective basis. As a result, the Company recorded a benefit of $1.4 million for a cumulative-effect adjustment directly to retained earnings, as of January 1, 2018, due to a change in valuation method, from cost less impairment, to net asset value using the practical expedient. Also, the measurement alternative has been elected for equity securities, existing as of January 1, 2018, without readily determinable fair values on a prospective basis. ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). Also, subsequent ASUs issued to clarify this Topic. The Update, and subsequent related updates, establish a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most previous revenue recognition guidance, including industry-specific guidance. The Updates are intended to increase comparability across industries. The core principle of the revenue model is that a company will recognize revenue when it transfers control of goods or services to customers, at an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. The Company adopted the Updates during the first quarter of 2018 on a modified retrospective transition approach. The Company did not identify any material changes to the timing of revenue recognition. The Company is changing how it presents certain recurring revenue streams associated with wealth and investment services as other income, versus a contra expense; however, these changes did not have a significant impact on the Company's consolidated financial statements. The adoption of this guidance did not have a material impact on the Company's financial condition or results of operations, and there was no cumulative effect adjustment to opening retained earnings as no material changes were identified in the timing of revenue recognition, however, additional disclosure has been incorporated in Note 17: Revenue from Contracts with Customers . Accounting Standards Issued But Not Yet Adopted The following list identifies ASUs applicable to the Company that have been issued by the FASB but are not yet effective: ASU No. 2017-12, Derivatives and Hedging (Topic 815) - Targeted Improvements to Accounting for Hedging Activities. The purpose of the Update is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. The update requires a modified retrospective transition method in which a Company will recognize a cumulative effect of the change on the opening balance for each affected component of equity in the financial statements as of the date of adoption. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company is in the process of assessing all potential impacts of the standard. ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350) - Simplifying the Test for Goodwill Impairment. The Update simplifies quantitative goodwill impairment testing by requiring entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit's fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. This changes current guidance by eliminating the second step of the goodwill impairment analysis which involves calculating the implied fair value of goodwill determined in the same manner as the amount of goodwill recognized in a business combination upon acquisition. Entities will still have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The Update must be applied prospectively and is effective for the Company on January 1, 2020. Early adoption is permitted. The Company does not expect the new guidance to have a material impact on its financial statements. ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments. Current GAAP requires an "incurred loss" methodology for recognizing credit losses. This approach delays recognition until it is probable a loss has been incurred. Both financial institutions and users of their financial statements expressed concern that current GAAP restricts the ability to record credit losses that are expected, but do not yet meet the "probable" threshold. The main objective of this Update is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in this Update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The Change from an "incurred loss" method to an "expected loss" method represents a fundamental shift from existing GAAP, and is likely to result in a material increase to the Company's accounting for credit losses on financial instruments. To prepare for implementation of the new standard the Company has established a project lead and has finalized a cross functional steering committee comprised of members from different disciplines including Credit, Finance and Treasury as well as specific working groups to focus on key components of the development process. In addition, through one of the working groups, the Company has begun to evaluate the effect that this Update will have on its financial statements and related disclosures. An implementation project plan has been created and is made up of targeted work streams focused on credit models, data management, accounting, and governance. These work streams are collectively assessing resources that may be required, use of existing and new models, data availability, and system solutions to facilitate implementation. The Update will be effective for the Company on January 1, 2020. While we are currently unable to reasonably estimate the impact of adopting the Update, we expect the impact of adoption will be significantly influenced by the composition, characteristics, and quality of our loan and securities portfolios as well as the economic conditions as of the adoption date. ASU No. 2016-02, Leases (Topic 842). The Update introduces a lessee model that requires substantially all leases to be recorded as assets and liabilities on the balance sheet and will require both quantitative and qualitative disclosures regarding key information about leasing arrangements. The Company is in the process of reviewing its existing leases, including certain service contracts for embedded leases, to evaluate the impact of the standard on the consolidated financial statements, as well as the impact to regulatory reporting, such as capital and risk-weighted assets. The Company has engaged a third party consultant to assist with the implementation efforts.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities A summary of the amortized cost and fair value of investment securities is presented below: At March 31, 2018 At December 31, 2017 (In thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Amortized Cost Unrealized Gains Unrealized Losses Fair Value Available-for-sale: U.S. Treasury Bills $ 449 $ — $ — $ 449 $ 1,247 $ — $ — $ 1,247 Agency CMO 290,105 526 (6,052 ) 284,579 308,989 1,158 (3,814 ) 306,333 Agency MBS 1,304,856 1,522 (41,110 ) 1,265,268 1,124,960 2,151 (19,270 ) 1,107,841 Agency CMBS 622,400 — (31,098 ) 591,302 608,276 — (20,250 ) 588,026 CMBS 365,006 2,045 (157 ) 366,894 358,984 2,157 (74 ) 361,067 CLO 201,254 691 (108 ) 201,837 209,075 910 (134 ) 209,851 Single issuer-trust preferred 7,111 — (70 ) 7,041 7,096 — (46 ) 7,050 Corporate debt 56,350 496 (710 ) 56,136 56,504 797 (679 ) 56,622 Available-for-sale $ 2,847,531 $ 5,280 $ (79,305 ) $ 2,773,506 $ 2,675,131 $ 7,173 $ (44,267 ) $ 2,638,037 Held-to-maturity: Agency CMO $ 245,663 $ 417 $ (7,139 ) $ 238,941 $ 260,114 $ 664 $ (4,824 ) $ 255,954 Agency MBS 2,544,104 12,571 (80,678 ) 2,475,997 2,569,735 16,989 (37,442 ) 2,549,282 Agency CMBS 689,602 — (20,744 ) 668,858 696,566 — (10,011 ) 686,555 Municipal bonds and notes 692,582 2,400 (16,091 ) 678,891 711,381 8,584 (6,558 ) 713,407 CMBS 236,172 891 (2,909 ) 234,154 249,273 2,175 (620 ) 250,828 Private Label MBS 198 — 198 323 1 — 324 Held-to-maturity $ 4,408,321 $ 16,279 $ (127,561 ) $ 4,297,039 $ 4,487,392 $ 28,413 $ (59,455 ) $ 4,456,350 Other-Than-Temporary Impairment The amount in the amortized cost columns in the table above includes other-than-temporary impairment (OTTI) related to certain CLO positions that were previously considered Covered Funds as defined by Section 619 of the Dodd-Frank Act, commonly known as the Volcker Rule. The Company has taken measures to bring its CLO positions into conformance with the Volcker Rule. The following table presents activity for OTTI: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 1,364 $ 3,243 Reduction for investment securities sold or called — (12 ) Ending balance $ 1,364 $ 3,231 To the extent that changes occur in interest rates, credit movements, or other factors that impact fair value and expected recovery of amortized cost of its investment securities, the Company may, in future periods, be required to recognize OTTI in earnings. Fair Value and Unrealized Losses The following tables provide information on fair value and unrealized losses for the individual investment securities with an unrealized loss, aggregated by classification and length of time that the individual investment securities have been in a continuous unrealized loss position: At March 31, 2018 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 113,804 $ (1,601 ) $ 110,998 $ (4,451 ) 34 $ 224,802 $ (6,052 ) Agency MBS 597,062 (13,730 ) 577,081 (27,380 ) 159 1,174,143 (41,110 ) Agency CMBS 72,147 (2,248 ) 519,155 (28,850 ) 37 591,302 (31,098 ) CMBS 53,552 (157 ) — — 9 53,552 (157 ) CLO 99,288 (12 ) 15,068 (96 ) 6 114,356 (108 ) Single issuer-trust preferred 7,041 (70 ) — — 1 7,041 (70 ) Corporate debt 11,077 (406 ) 6,248 (304 ) 4 17,325 (710 ) Available-for-sale in an unrealized loss position $ 953,971 $ (18,224 ) $ 1,228,550 $ (61,081 ) 250 $ 2,182,521 $ (79,305 ) Held-to-maturity: Agency CMO $ 104,568 $ (2,199 ) $ 101,482 $ (4,940 ) 22 $ 206,050 $ (7,139 ) Agency MBS 1,066,786 (24,771 ) 1,143,544 (55,907 ) 253 2,210,330 (80,678 ) Agency CMBS 542,868 (15,740 ) 125,991 (5,004 ) 56 668,859 (20,744 ) Municipal bonds and notes 233,121 (4,137 ) 218,963 (11,954 ) 200 452,084 (16,091 ) CMBS 148,267 (2,595 ) 13,276 (314 ) 20 161,543 (2,909 ) Held-to-maturity in an unrealized loss position $ 2,095,610 $ (49,442 ) $ 1,603,256 $ (78,119 ) 551 $ 3,698,866 $ (127,561 ) At December 31, 2017 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 81,001 $ (449 ) $ 119,104 $ (3,365 ) 27 $ 200,105 $ (3,814 ) Agency MBS 416,995 (2,920 ) 606,021 (16,350 ) 135 1,023,016 (19,270 ) Agency CMBS 54,182 (851 ) 533,844 (19,399 ) 36 588,026 (20,250 ) CMBS 23,869 (74 ) — — 6 23,869 (74 ) CLO 56,335 (134 ) — — 3 56,335 (134 ) Single issuer-trust preferred 7,050 (46 ) — — 1 7,050 (46 ) Corporate debt 11,082 (395 ) 6,265 (284 ) 4 17,347 (679 ) Available-for-sale in an unrealized loss position $ 650,514 $ (4,869 ) $ 1,265,234 $ (39,398 ) 212 $ 1,915,748 $ (44,267 ) Held-to-maturity: Agency CMO $ 98,090 $ (1,082 ) $ 106,775 $ (3,742 ) 22 $ 204,865 $ (4,824 ) Agency MBS 762,107 (4,555 ) 1,197,839 (32,887 ) 205 1,959,946 (37,442 ) Agency CMBS 576,770 (7,599 ) 109,785 (2,412 ) 56 686,555 (10,011 ) Municipal bonds and notes 6,432 (38 ) 226,861 (6,520 ) 92 233,293 (6,558 ) CMBS 92,670 (413 ) 14,115 (207 ) 13 106,785 (620 ) Held-to-maturity in an unrealized loss position $ 1,536,069 $ (13,687 ) $ 1,655,375 $ (45,768 ) 388 $ 3,191,444 $ (59,455 ) Impairment Analysis The following impairment analysis summarizes the basis for evaluating if investment securities within the Company’s available-for-sale and held-to-maturity portfolios have been impacted by OTTI since December 31, 2017 . Unless otherwise noted for an investment security type, management does not intend to sell these investment securities and has determined, based upon available evidence, that it is more likely than not that the Company will not be required to sell these investment securities before the recovery of their amortized cost. As such, based on the following impairment analysis, the Company does not consider any of these investment securities, in unrealized loss positions, to be other-than-temporarily impaired at March 31, 2018 . Available-for-Sale Securities Agency CMO. There were unrealized losses of $6.1 million on the Company’s investment in Agency CMO at March 31, 2018 , compared to $3.8 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances decreased for this asset class since December 31, 2017 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Agency MBS. There were unrealized losses of $41.1 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at March 31, 2018 , compared to $19.3 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances increased for this asset class since December 31, 2017 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Agency CMBS. There were unrealized losses of $31.1 million on the Company's investment in commercial mortgage-backed securities issued by government agencies at March 31, 2018 , compared to $20.3 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances increased for this asset class since December 31, 2017 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. CMBS. There were unrealized losses of $157 thousand on the Company’s investment in CMBS at March 31, 2018 , compared to $74 thousand at December 31, 2017 . Unrealized losses and balances were essentially unchanged for the portfolio of mainly floating rate CMBS at March 31, 2018 compared to December 31, 2017 . Internal stress tests are performed on individual bonds to monitor potential losses under stress scenarios. Contractual cash flows for the bonds continue to perform as expected. CLO. There were unrealized losses of $108 thousand on the Company’s investments in CLO at March 31, 2018 compared to $134 thousand unrealized losses at December 31, 2017 . Unrealized losses were essentially unchanged while principal balances decreased from December 31, 2017 . Internal stress tests are performed on individual bonds to monitor potential losses under stress scenarios. Contractual cash flows for the bonds continue to perform as expected. Single issuer-trust preferred. There were unrealized losses of $70 thousand on the Company's investment in single issuer-trust preferred at March 31, 2018 , compared to $46 thousand at December 31, 2017 . Unrealized losses and balances were essentially unchanged for this asset class. Single issuer-trust preferred is one investment issued by a large capitalization money center financial institution, which continues to service its debt. The Company performs periodic credit reviews of the issuer to assess the likelihood for ultimate recovery of amortized cost. Corporate debt. There were unrealized losses of $710 thousand on the Company's corporate debt portfolio at March 31, 2018 , compared to $679 thousand at December 31, 2017 . Unrealized losses and balances were essentially unchanged since December 31, 2017 . The Company performs periodic credit reviews of the issuer to assess the likelihood for ultimate recovery of amortized cost. Held-to-Maturity Securities Agency CMO. There were unrealized losses of $7.1 million on the Company’s investment in Agency CMO at March 31, 2018 , compared to $4.8 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances decreased since December 31, 2017 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Agency MBS. There were unrealized losses of $80.7 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at March 31, 2018 , compared to $37.4 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances were essentially unchanged for this asset class since December 31, 2017 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Agency CMBS. There were unrealized losses of $20.7 million on the Company’s investment in commercial mortgage-backed securities issued by government agencies at March 31, 2018 , compared to $10.0 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances decreased since December 31, 2017 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Municipal bonds and notes. There were unrealized losses of $16.1 million on the Company’s investment in municipal bonds and notes at March 31, 2018 , compared to $6.6 million at December 31, 2017 . Unrealized losses increased due to higher market rates while principal balances decreased since December 31, 2017 . The Company performs periodic credit reviews of the issuers and the securities are currently performing as expected. CMBS. There were unrealized losses of $2.9 million on the Company’s investment in CMBS at March 31, 2018 , compared to $0.6 million unrealized losses at December 31, 2017 . Unrealized losses increased due to higher market rates on mainly seasoned fixed rate conduit transactions while principal balances decreased since December 31, 2017 . Internal stress tests are performed on individual bonds to monitor potential losses under stress scenarios. Sales of Available-for Sale Investment Securities There were no sales during the three months ended March 31, 2018 or the three months ended March 31, 2017 . Contractual Maturities The amortized cost and fair value of debt securities by contractual maturity are set forth below: At March 31, 2018 Available-for-Sale Held-to-Maturity (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 449 $ 449 $ 24,222 $ 24,489 Due after one year through five years 54,883 55,020 3,532 3,545 Due after five through ten years 343,072 343,803 42,410 42,687 Due after ten years 2,449,127 2,374,234 4,338,157 4,226,318 Total debt securities $ 2,847,531 $ 2,773,506 $ 4,408,321 $ 4,297,039 For the maturity schedule above, mortgage-backed securities and CLO, which are not due at a single maturity date, have been categorized based on the maturity date of the underlying collateral. Actual principal cash flows may differ from this maturity date presentation as borrowers have the right to prepay obligations with or without prepayment penalties. At March 31, 2018 , the Company had a carrying value of $1.2 billion in callable investment securities in its CMBS, CLO, and municipal bond portfolios. The Company considers prepayment risk in the evaluation of its interest rate risk profile. These maturities may not reflect actual durations, which may be impacted by prepayments. Investment securities with a carrying value totaling $2.6 billion at March 31, 2018 and $2.4 billion at December 31, 2017

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities The Company has an investment interest in the following entities that meet the definition of a variable interest entity (VIE). Consolidated Rabbi Trust. The Company established a Rabbi Trust to meet the obligations due under its Deferred Compensation Plan for Directors and Officers and to mitigate the expense volatility of the aforementioned plan. The funding of the Rabbi Trust and the discontinuation of the Deferred Compensation Plan for Directors and Officers occurred during 2012. Investments held in the Rabbi Trust primarily consist of mutual funds that invest in equity and fixed income securities. The Company is considered the primary beneficiary of the Rabbi Trust as it has the power to direct the activities of the Rabbi Trust that significantly affect the VIE's economic performance and it has the obligation to absorb losses of the VIE that could potentially be significant to the VIE. The Company consolidates the invested assets of the trust along with the total deferred compensation obligations and includes them in accrued interest receivable and other assets and accrued expenses and other liabilities, respectively, in the accompanying Condensed Consolidated Balance Sheets. Earnings in the Rabbi Trust, including appreciation or depreciation, are reflected as other non-interest income, and changes in the corresponding liability are reflected as compensation and benefits, in the accompanying Condensed Consolidated Statements of Income. See Note 13: Fair Value Measurements for additional information. Non-Consolidated Securitized Investments. The Company, through normal investment activities, makes passive investments in securities issued by VIEs for which Webster is not the manager. The investment securities consist of Agency CMO, Agency MBS, Agency CMBS, CLO and single issuer-trust preferred. The Company has not provided financial or other support with respect to these investment securities other than its original investment. For these investment securities, the Company determined it is not the primary beneficiary due to the relative size of its investment in comparison to the principal amount of the structured securities issued by the VIEs, the level of credit subordination which reduces the Company’s obligation to absorb losses or right to receive benefits and its inability to direct the activities that most significantly impact the economic performance of the VIEs. The Company’s maximum exposure to loss is limited to the amount of its investment in the VIEs. See Note 3: Investment Securities for additional information. Tax Credit - Finance Investments. The Company makes equity investments in entities that finance affordable housing and other community development projects and provide a return primarily through the realization of tax benefits. In most instances the investments require the funding of capital commitments in the future. While the Company's investment in an entity may exceed 50% of its outstanding equity interests, the entity is not consolidated as Webster is not involved in its management. For these investments, the Company determined it is not the primary beneficiary due to its inability to direct the activities that most significantly impact the economic performance of the VIEs. The Company applies the proportional amortization method to account for its investments in qualified affordable housing projects. At March 31, 2018 and December 31, 2017 , the aggregate carrying value of the Company's tax credit-finance investments were $32.5 million and $33.5 million , respectively. At March 31, 2018 and December 31, 2017 , unfunded commitments have been recognized, totaling $16.2 million and $17.3 million , respectively, and are included in accrued expenses and other liabilities in the accompanying Condensed Consolidated Balance Sheets. Webster Statutory Trust. The Company owns all the outstanding common stock of Webster Statutory Trust, a financial vehicle that has issued, and in the future may issue, trust preferred securities. The trust is a VIE in which the Company is not the primary beneficiary. The trust's only assets are junior subordinated debentures issued by the Company, which were acquired by the trust using the proceeds from the issuance of the trust preferred securities and common stock. The junior subordinated debentures are included in long-term debt in the accompanying Condensed Consolidated Balance Sheets, and the related interest expense is reported as interest expense on long-term debt in the accompanying Condensed Consolidated Statements of Income. Other Investments. The Company invests in various alternative investments in which it holds a variable interest. Alternative investments are non-public entities which cannot be redeemed since the Company’s investment is distributed as the underlying equity is liquidated. For these investments, the Company has determined it is not the primary beneficiary due to its inability to direct the activities that most significantly impact the economic performance of the VIEs. At March 31, 2018 and December 31, 2017 , the aggregate carrying value of the Company's other investments in VIEs were $16.3 million and $13.8 million , respectively, and the total exposure of the Company's other investments in VIEs, including unfunded commitments, were $25.3 million and $22.9 million , respectively. The Company's equity interests in Tax Credit-Finance Investments, Webster Statutory Trust, and Other Investments are included in accrued interest receivable and other assets in the accompanying Condensed Consolidated Balance Sheets. For a description of the Company's accounting policy regarding the consolidation of VIEs, refer to Note 1 to the Consolidated Financial Statements included in its Form 10-K, for the year ended December 31, 2017

Loans and Leases

Loans and Leases	3 Months Ended
	Mar. 31, 2018
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	Loans and Leases The following table summarizes loans and leases: (In thousands) At March 31, At December 31, 2017 Residential $ 4,459,862 $ 4,490,878 Consumer 2,522,380 2,590,225 Commercial 5,759,124 5,368,694 Commercial Real Estate 4,544,831 4,523,828 Equipment Financing 519,378 550,233 Loans and leases (1) (2) $ 17,805,575 $ 17,523,858 (1) Loans and leases include net deferred fees and net premiums/discounts of $17.9 million and $20.6 million at March 31, 2018 and December 31, 2017 , respectively. (2) At March 31, 2018 the Company had pledged $6.6 billion of eligible residential, consumer, and commercial loans as collateral to support borrowing capacity at the Federal Home Loan Bank (FHLB) Boston and the Federal Reserve Bank (FRB) of Boston. Loans and Leases Aging The following tables summarize the aging of loans and leases: At March 31, 2018 (In thousands) 30-59 Days Past Due and Accruing 60-89 Days 90 or More Days Past Due and Accruing Non-accrual Total Past Due and Non-accrual Current Total Loans Residential $ 13,829 $ 3,571 $ — $ 44,574 $ 61,974 $ 4,397,888 $ 4,459,862 Consumer: Home equity 8,951 5,627 — 35,894 50,472 2,239,473 2,289,945 Other consumer 2,008 1,061 — 1,614 4,683 227,752 232,435 Commercial: Commercial non-mortgage 1,526 236 604 42,990 45,356 4,839,497 4,884,853 Asset-based — — — 1,534 1,534 872,737 874,271 Commercial real estate: Commercial real estate 508 603 245 3,889 5,245 4,343,274 4,348,519 Commercial construction — — — — — 196,312 196,312 Equipment financing 2,840 156 — 3,668 6,664 512,714 519,378 Total $ 29,662 $ 11,254 $ 849 $ 134,163 $ 175,928 $ 17,629,647 $ 17,805,575 At December 31, 2017 (In thousands) 30-59 Days 60-89 Days Past Due and Accruing 90 or More Days Past Due Non-accrual Total Past Due and Non-accrual Current Total Loans Residential $ 8,643 $ 5,146 $ — $ 44,481 $ 58,270 $ 4,432,608 $ 4,490,878 Consumer: Home equity 12,668 5,770 — 35,645 54,083 2,298,185 2,352,268 Other consumer 2,556 1,444 — 1,707 5,707 232,250 237,957 Commercial: Commercial non-mortgage 5,212 603 644 39,214 45,673 4,488,242 4,533,915 Asset-based — — — 589 589 834,190 834,779 Commercial real estate: Commercial real estate 478 77 248 4,484 5,287 4,238,987 4,244,274 Commercial construction — — — — — 279,554 279,554 Equipment financing 1,732 626 — 393 2,751 547,482 550,233 Total $ 31,289 $ 13,666 $ 892 $ 126,513 $ 172,360 $ 17,351,498 $ 17,523,858 Interest on non-accrual loans and leases that would have been recorded as additional interest income had the loans and leases been current in accordance with the original terms totaled $2.1 million and $3.1 million for the three months ended March 31, 2018 and 2017 , respectively. Allowance for Loan and Lease Losses The following tables summarize the activity in, as well as the loan and lease balances that were evaluated for, the allowance for loan and lease losses (ALLL): At or for the three months ended March 31, 2018 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 19,058 $ 36,190 $ 89,533 $ 49,407 $ 5,806 $ 199,994 Provision (benefit) charged to expense 251 1,680 7,420 2,104 (455 ) 11,000 Charge-offs (917 ) (5,074 ) (1,497 ) (77 ) (45 ) (7,610 ) Recoveries 385 1,443 117 2 18 1,965 Balance, end of period $ 18,777 $ 34,239 $ 95,573 $ 51,436 $ 5,324 $ 205,349 Individually evaluated for impairment $ 4,574 $ 1,579 $ 11,166 $ 257 $ 21 $ 17,597 Collectively evaluated for impairment $ 14,203 $ 32,660 $ 84,407 $ 51,179 $ 5,303 $ 187,752 Loan and lease balances: Individually evaluated for impairment $ 111,937 $ 42,587 $ 76,573 $ 10,928 $ 6,455 $ 248,480 Collectively evaluated for impairment 4,347,925 2,479,793 5,682,551 4,533,903 512,923 17,557,095 Loans and leases $ 4,459,862 $ 2,522,380 $ 5,759,124 $ 4,544,831 $ 519,378 $ 17,805,575 At or for the three months ended March 31, 2017 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 23,226 $ 45,233 $ 71,905 $ 47,477 $ 6,479 $ 194,320 (Benefit) provision charged to expense (2,467 ) 5,326 4,250 3,345 46 10,500 Charge-offs (732 ) (6,474 ) (123 ) (102 ) (185 ) (7,616 ) Recoveries 237 1,323 322 7 14 1,903 Balance, end of period $ 20,264 $ 45,408 $ 76,354 $ 50,727 $ 6,354 $ 199,107 Individually evaluated for impairment $ 6,981 $ 2,605 $ 11,564 $ 256 $ 5 $ 21,411 Collectively evaluated for impairment $ 13,283 $ 42,803 $ 64,790 $ 50,471 $ 6,349 $ 177,696 Loan and lease balances: Individually evaluated for impairment $ 120,976 $ 47,281 $ 86,805 $ 23,954 $ 6,148 $ 285,164 Collectively evaluated for impairment 4,169,709 2,586,782 4,932,578 4,506,553 613,713 16,809,335 Loans and leases $ 4,290,685 $ 2,634,063 $ 5,019,383 $ 4,530,507 $ 619,861 $ 17,094,499 Impaired Loans and Leases The following tables summarize impaired loans and leases: At March 31, 2018 (In thousands) Unpaid Principal Balance Total Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential $ 122,063 $ 111,937 $ 70,143 $ 41,794 $ 4,574 Consumer - home equity 47,452 42,587 32,408 10,179 1,579 Commercial : Commercial non-mortgage 83,660 75,039 30,078 44,961 11,166 Asset-based 4,282 1,534 1,534 — — Commercial real estate: Commercial real estate 11,690 10,928 6,305 4,623 257 Commercial construction 212 — — — — Equipment financing 6,465 6,455 5,999 456 21 Total $ 275,824 $ 248,480 $ 146,467 $ 102,013 $ 17,597 At December 31, 2017 (In thousands) Unpaid Principal Balance Total Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential $ 125,352 $ 114,295 $ 69,759 $ 44,536 $ 4,805 Consumer - home equity 50,809 45,436 34,418 11,018 1,668 Commercial : Commercial non-mortgage 79,900 71,882 27,313 44,569 9,786 Asset-based 3,272 589 589 — — Commercial real estate: Commercial real estate 11,994 11,226 6,387 4,839 272 Commercial construction — — — — — Equipment financing 3,409 3,325 2,932 393 23 Total $ 274,736 $ 246,753 $ 141,398 $ 105,355 $ 16,554 The following table summarizes the average recorded investment and interest income recognized for impaired loans and leases: Three months ended March 31, 2018 2017 (In thousands) Average Recorded Investment Accrued Cash Basis Interest Income Average Recorded Investment Accrued Cash Basis Interest Income Residential $ 113,116 $ 981 $ 253 $ 120,200 $ 1,070 $ 415 Consumer - home equity 44,011 294 250 46,500 322 313 Commercial Commercial Non-Mortgage 73,461 539 — 69,921 222 — Asset based 1,061 — — — — — Commercial real estate: Commercial real estate 11,077 96 — 23,170 135 — Commercial construction — — — 1,184 12 — Equipment financing 4,890 36 — 6,284 71 — Total $ 247,616 $ 1,946 $ 503 $ 267,259 $ 1,832 $ 728 Credit Quality Indicators. To measure credit risk for the commercial, commercial real estate, and equipment financing portfolios, the Company employs a dual grade credit risk grading system for estimating the probability of default (PD) and the loss given default (LGD). The credit risk grade system assigns a rating to each borrower and to the facility, which together form a Composite Credit Risk Profile. The credit risk grade system categorizes borrowers by common financial characteristics that measure the credit strength of borrowers and facilities by common structural characteristics. The Composite Credit Risk Profile has ten grades, with each grade corresponding to a progressively greater risk of default. Grades (1) - (6) are considered pass ratings, and (7) - (10) are considered criticized, as defined by the regulatory agencies. Risk ratings, assigned to differentiate risk within the portfolio, are reviewed on an ongoing basis and revised to reflect changes in a borrower's current financial position and outlook, risk profile, and the related collateral and structural position. Loan officers review updated financial information on at least an annual basis for all pass rated loans to assess the accuracy of the risk grade. Criticized loans undergo more frequent reviews and enhanced monitoring. A (7) "Special Mention" credit has the potential weakness that, if left uncorrected, may result in deterioration of the repayment prospects for the asset. An (8) "Substandard" asset has a well defined weakness that jeopardizes the full repayment of the debt. An asset rated (9) "Doubtful" has all of the same weaknesses as a substandard credit with the added characteristic that the weakness makes collection or liquidation in full, given current facts, conditions, and values, improbable. Assets classified as (10) "Loss" in accordance with regulatory guidelines are considered uncollectible and charged off. The following table summarizes commercial, commercial real estate and equipment financing loans and leases segregated by risk rating exposure: Commercial Commercial Real Estate Equipment Financing (In thousands) At March 31, At December 31, At March 31, At December 31, At March 31, At December 31, (1) - (6) Pass $ 5,337,985 $ 5,048,162 $ 4,384,598 $ 4,355,916 $ 493,311 $ 525,105 (7) Special Mention 210,164 104,594 44,742 62,065 7,119 8,022 (8) Substandard 201,959 206,883 115,491 105,847 18,948 17,106 (9) Doubtful 9,016 9,055 — — — — Total $ 5,759,124 $ 5,368,694 $ 4,544,831 $ 4,523,828 $ 519,378 $ 550,233 For residential and consumer loans, the primary credit quality indicator that the Company considers is past due status. Other factors, such as, updated Fair Isaac Corporation (FICO) scores, employment status, collateral, geography, loans discharged in bankruptcy, and the status of first lien position loans on second lien position loans as credit quality indicators may also be evaluated. On an ongoing basis for portfolio monitoring purposes, the Company estimates the current value of property secured as collateral for home equity and residential first mortgage lending products. The estimate is based on home price indices compiled by the S&P/Case-Shiller Home Price Indices. The real estate price data is applied to the loan portfolios taking into account the age of the most recent valuation and geographic area. Troubled Debt Restructurings The following table summarizes information for troubled debt restructurings (TDRs): (Dollars in thousands) At March 31, At December 31, 2017 Accrual status $ 141,608 $ 147,113 Non-accrual status 77,930 74,291 Total recorded investment of TDRs $ 219,538 $ 221,404 Specific reserves for TDRs included in the balance of ALLL $ 13,874 $ 12,384 Additional funds committed to borrowers in TDR status 3,347 2,736 For the portion of TDRs deemed to be uncollectible, Webster charged off $0.7 million , and $2.0 million for the three months ended March 31, 2018 and 2017 , respectively. The following table provides information on the type of concession for loans and leases modified as TDRs: Three months ended March 31, 2018 2017 Number of Post- (1) Number of Post- (1) (Dollars in thousands) Residential: Extended Maturity — $ — 5 $ 970 Maturity/Rate Combined — — 3 492 Other (2) 5 757 19 2,938 Consumer - home equity Extended Maturity 2 193 2 39 Maturity/Rate Combined 2 113 7 1,983 Other (2) 11 778 33 2,193 Commercial non - mortgage Extended Maturity 3 85 2 35 Other (2) 2 4,684 1 4 Commercial real estate: Extended Maturity 1 45 — — Total TDRs 26 $ 6,655 72 $ 8,654 (1) Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant. (2) Other includes covenant modifications, forbearance, loans discharged under Chapter 7 bankruptcy, or other concessions. There were no significant amounts of loans and leases modified as TDRs within the previous 12 months and for which there was a payment default for the three months ended March 31, 2018 or 2017 . The recorded investment of TDRs in commercial, commercial real estate, and equipment financing segregated by risk rating exposure is as follows: (In thousands) At March 31, 2018 At December 31, 2017 (1) - (6) Pass $ 8,591 $ 8,268 (7) Special Mention 349 355 (8) Substandard 56,074 53,050 (9) Doubtful — — Total $ 65,014 $ 61,673

Transfers of Financial Assets

Transfers of Financial Assets	3 Months Ended
	Mar. 31, 2018
Transfers and Servicing [Abstract]
Transfers of Financial Assets	Transfers of Financial Assets The Company sells financial assets in the normal course of business, primarily residential mortgage loans sold to government-sponsored enterprises through established programs and securitizations. The gain or loss on residential mortgage loans sold and the related origination fee income, and the fair value adjustment to loans held-for-sale are included as mortgage banking activities in the accompanying Condensed Consolidated Statements of Income. The Company may be required to repurchase a loan in the event of certain breaches of the representations and warranties, or in the event of default of the borrower within 90 days of sale, as provided for in the sale agreements. A reserve for loan repurchases provides for estimated losses pertaining to the potential repurchase of loans associated with the Company’s mortgage banking activities. The reserve reflects management’s evaluation of the identity of the counterparty, the vintage of the loans sold, the amount of open repurchase requests, specific loss estimates for each open request, the current level of loan losses in similar vintages held in the residential loan portfolio, and estimated recoveries on the underlying collateral. The reserve also reflects management’s expectation of losses from repurchase requests for which the Company has not yet been notified, as the performance of loans sold and the quality of the servicing provided by the acquirer also may impact the reserve. The provision recorded at the time of the loan sale is netted from the gain or loss recorded in mortgage banking activities, while any incremental provision, post loan sale, is recorded in other non-interest expense in the accompanying Condensed Consolidated Statements of Income. The following table provides a summary of activity in the reserve for loan repurchases: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 872 $ 790 (Benefit) provision charged to expense (203 ) 34 Repurchased loans and settlements charged off (5 ) — Ending balance $ 664 $ 824 The following table provides information for mortgage banking activities: Three months ended March 31, (In thousands) 2018 2017 Residential mortgage loans held for sale: Proceeds from sale $ 44,806 $ 106,620 Loans sold with servicing rights retained 39,904 99,500 Net gain on sale 1,083 251 Ancillary fees 410 768 Fair value option adjustment (349 ) 1,247 The Company has retained servicing rights on residential mortgage loans totaling $2.6 billion at both March 31, 2018 and December 31, 2017 . The following table presents the changes in carrying value for mortgage servicing assets: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 25,139 $ 24,466 Additions 1,412 2,009 Amortization (2,148 ) (2,139 ) Ending balance $ 24,403 $ 24,336 Loan servicing fees, net of mortgage servicing rights amortization, were $0.3 million and $0.2 million for the three months ended March 31, 2018 and 2017 , respectively, and are included as a component of loan related fees in the accompanying Condensed Consolidated Statements of Income. See Note 13: Fair Value Measurements for additional fair value information on loans held for sale and mortgage servicing assets. Additionally, loans not originated for sale were sold approximately at carrying value, for cash proceeds of $34 thousand for certain commercial loans and $7.4 million for certain residential loans for the three months ended March 31, 2018 and 2017

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 Goodwill and other intangible assets by reportable segment consisted of the following: At March 31, 2018 At December 31, 2017 (In thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Goodwill: Community Banking $ 516,560 $ 516,560 HSA Bank 21,813 21,813 Total goodwill $ 538,373 $ 538,373 Other intangible assets: HSA Bank - Core deposits $ 22,000 $ (9,167 ) $ 12,833 $ 22,000 $ (8,610 ) $ 13,390 HSA Bank - Customer relationships 21,000 (5,183 ) 15,817 21,000 (4,779 ) 16,221 Total other intangible assets $ 43,000 $ (14,350 ) $ 28,650 $ 43,000 $ (13,389 ) $ 29,611 As of March 31, 2018 , the remaining estimated aggregate future amortization expense for intangible assets is as follows: (In thousands) Remainder of 2018 $ 2,886 2019 3,847 2020 3,847 2021 3,847 2022 3,847 Thereafter 10,376

Deposits

Deposits	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Deposits	Deposits A summary of deposits by type follows: (In thousands) At March 31, At December 31, Non-interest-bearing: Demand $ 4,074,992 $ 4,191,496 Interest-bearing: Checking 2,624,885 2,736,952 Health savings accounts 5,487,627 5,038,681 Money market 2,344,526 2,209,492 Savings 4,299,759 4,348,700 Time deposits 2,553,253 2,468,408 Total interest-bearing 17,310,050 16,802,233 Total deposits $ 21,385,042 $ 20,993,729 Time deposits and interest-bearing checking, included in above balances, obtained through brokers $ 864,362 $ 898,157 Time deposits, included in above balance, that meet or exceed the Federal Deposit Insurance Corporation (FDIC) limit 741,349 561,512 Deposit overdrafts reclassified as loan balances 1,984 2,210 The scheduled maturities of time deposits are as follows: (In thousands) At March 31, Remainder of 2018 $ 1,301,903 2019 822,693 2020 246,205 2021 117,426 2022 49,543 Thereafter 15,483 Total time deposits $ 2,553,253

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Borrowings	Borrowings Total borrowings of $2.4 billion at March 31, 2018 and $2.5 billion at December 31, 2017 are described in detail below. The following table summarizes securities sold under agreements to repurchase and other borrowings: At March 31, At December 31, (In thousands) Amount Rate Amount Rate Securities sold under agreements to repurchase (1) : Original maturity of one year or less $ 215,299 0.18 % $ 288,269 0.17 % Original maturity of greater than one year, non-callable 300,000 3.10 300,000 3.10 Total securities sold under agreements to repurchase 515,299 1.88 588,269 1.66 Fed funds purchased 416,000 1.72 55,000 1.37 Securities sold under agreements to repurchase and other borrowings $ 931,299 1.81 $ 643,269 1.64 (1) The Company has right of offset with respect to all repurchase agreement assets and liabilities. However, securities sold under agreements to repurchase represents the gross amount for these transactions, as only liabilities are outstanding for the periods presented. Repurchase agreements are used as a source of borrowed funds and are collateralized by U.S. Government agency mortgage-backed securities. Repurchase agreement counterparties are limited to primary dealers in government securities and commercial or municipal customers through Webster’s Treasury Unit. The following table provides information for FHLB advances: At March 31, At December 31, (Dollars in thousands) Amount Weighted- Average Contractual Coupon Rate Amount Weighted- Average Contractual Coupon Rate Maturing within 1 year $ 700,000 1.81 % $ 1,150,000 1.48 % After 1 but within 2 years 128,026 1.82 103,026 1.81 After 2 but within 3 years 165,000 1.77 215,000 1.73 After 3 but within 4 years (1) 200,000 2.33 200,000 2.06 After 4 but within 5 years 165 — 170 — After 5 years (1) 8,839 2.65 8,909 2.65 FHLB advances and overall rate (1) $ 1,202,030 1.90 $ 1,677,105 1.61 Aggregate carrying value of assets pledged as collateral $ 6,327,590 $ 6,402,066 Remaining borrowing capacity 3,035,521 2,600,624 (1) Weighted-average contractual coupon rates for December 31, 2017 are presented as revised for these classifications to correct an immaterial error in presentation. The percentages included in the Company's Annual Report on Form 10-K as reported were: After 3 but within 4 years - 4.13% ; After 5 years - 1.96% ; and overall rate - 1.85% . Webster Bank is in compliance with FHLB collateral requirements for the periods presented. Eligible collateral, primarily certain residential and commercial real estate loans, has been pledged to secure FHLB advances. The following table summarizes long-term debt: (Dollars in thousands) At March 31, At December 31, 4.375% Senior fixed-rate notes due February 15, 2024 $ 150,000 $ 150,000 Junior subordinated debt Webster Statutory Trust I floating-rate notes due September 17, 2033 (1) 77,320 77,320 Total notes and subordinated debt 227,320 227,320 Discount on senior fixed-rate notes (697 ) (727 ) Debt issuance cost on senior fixed-rate notes (793 ) (826 ) Long-term debt $ 225,830 $ 225,767 (1) The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month London Interbank Offered Rate (LIBOR) plus 2.95% , was 5.13% at March 31, 2018 and 4.55% at December 31, 2017

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss, Net of Tax	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Accumulated Other Comprehensive Loss, Net of Tax	Accumulated Other Comprehensive Loss, Net of Tax The following tables summarize the changes in accumulated other comprehensive loss, net of tax (AOCL) by component: Three months ended March 31, 2018 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (27,947 ) $ (15,016 ) $ (48,568 ) $ (91,531 ) Other comprehensive income (loss) (OCI/OCL) before reclassifications (27,424 ) 1,129 — (26,295 ) Amounts reclassified from AOCL — 1,393 954 2,347 Net current-period OCI/OCL (27,424 ) 2,522 954 (23,948 ) Ending balance $ (55,371 ) $ (12,494 ) $ (47,614 ) $ (115,479 ) Three months ended March 31, 2017 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (15,476 ) $ (17,068 ) $ (44,449 ) $ (76,993 ) OCI/OCL before reclassifications (2,225 ) 61 — (2,164 ) Amounts reclassified from AOCL — 1,098 1,032 2,130 Net current-period OCI/OCL (2,225 ) 1,159 1,032 (34 ) Ending balance $ (17,701 ) $ (15,909 ) $ (43,417 ) $ (77,027 ) The following tables provide information for the items reclassified from AOCL: (In thousands) Three months ended March 31, Associated Line Item in the Condensed Consolidated Statements of Income AOCL Components 2018 2017 Derivative instruments: Cash flow hedges $ (1,871 ) $ (1,735 ) Total interest expense Tax benefit 478 637 Income tax expense Net of tax $ (1,393 ) $ (1,098 ) Defined benefit pension and other postretirement benefit plans: Amortization of net loss $ (1,285 ) $ (1,638 ) (1) Tax benefit 331 606 Income tax expense Net of tax $ (954 ) $ (1,032 )

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2018
Regulatory Capital Requirements [Abstract]
Regulatory Matters	Regulatory Matters Capital Requirements Webster Financial Corporation is subject to regulatory capital requirements administered by the Federal Reserve System, while Webster Bank is subject to regulatory capital requirements administered by the Office of the Comptroller of the Currency (OCC). Regulatory authorities can initiate certain mandatory actions if Webster Financial Corporation or Webster Bank fail to meet minimum capital requirements, which could have a direct material effect on the Company’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, both Webster Financial Corporation and Webster Bank must meet specific capital guidelines that involve quantitative measures of assets, liabilities, and certain off-balance sheet items calculated under regulatory accounting practices. These quantitative measures require minimum amounts and ratios to ensure capital adequacy. Basel III total risk-based capital is comprised of three categories: CET1 capital, additional Tier 1 capital, and Tier 2 capital. CET1 capital includes common shareholders' equity, less deductions for goodwill, other intangibles, and certain deferred tax adjustments. Common shareholders' equity, for purposes of CET1 capital, excludes AOCL components as permitted by the opt-out election taken by Webster upon adoption of Basel III. Tier 1 capital is comprised of CET1 capital plus perpetual preferred stock, while Tier 2 capital includes qualifying subordinated debt and qualifying allowance for credit losses, that together equal total capital. The following table provides information on the capital ratios for Webster Financial Corporation and Webster Bank: At March 31, 2018 Actual Minimum Requirement Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio Webster Financial Corporation CET1 risk-based capital $ 2,094,607 10.99 % $ 857,874 4.5 % $ 1,239,151 6.5 % Total risk-based capital 2,524,608 13.24 1,525,109 8.0 1,906,386 10.0 Tier 1 risk-based capital 2,239,644 11.75 1,143,832 6.0 1,525,109 8.0 Tier 1 leverage capital 2,239,644 8.54 1,049,009 4.0 1,311,261 5.0 Webster Bank CET1 risk-based capital $ 2,062,650 10.83 % $ 857,184 4.5 % $ 1,238,155 6.5 % Total risk-based capital 2,270,294 11.92 1,523,883 8.0 1,904,853 10.0 Tier 1 risk-based capital 2,062,650 10.83 1,142,912 6.0 1,523,883 8.0 Tier 1 leverage capital 2,062,650 7.87 1,048,468 4.0 1,310,585 5.0 At December 31, 2017 Actual Minimum Requirement Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio Webster Financial Corporation CET1 risk-based capital $ 2,093,116 11.14 % $ 845,389 4.5 % $ 1,221,118 6.5 % Total risk-based capital 2,517,848 13.40 1,502,914 8.0 1,878,643 10.0 Tier 1 risk-based capital 2,238,172 11.91 1,127,186 6.0 1,502,914 8.0 Tier 1 leverage capital 2,238,172 8.63 1,036,817 4.0 1,296,021 5.0 Webster Bank CET1 risk-based capital $ 2,114,224 11.26 % $ 844,693 4.5 % $ 1,220,113 6.5 % Total risk-based capital 2,316,580 12.34 1,501,677 8.0 1,877,097 10.0 Tier 1 risk-based capital 2,114,224 11.26 1,126,258 6.0 1,501,677 8.0 Tier 1 leverage capital 2,114,224 8.14 1,038,442 4.0 1,298,052 5.0 Dividend Restrictions Webster Financial Corporation is dependent upon dividends from Webster Bank to provide funds for its cash requirements, including payments of dividends to shareholders. Banking regulations may limit the amount of dividends that may be paid. Approval by regulatory authorities is required if the effect of dividends declared would cause the regulatory capital of Webster Bank to fall below specified minimum levels, or if dividends declared exceed the net income for that year combined with the undistributed net income for the preceding two years. In addition, the OCC has discretion to prohibit any otherwise permitted capital distribution on general safety and soundness grounds. Dividends paid by Webster Bank to Webster Financial Corporation totaled $100 million during the three months ended March 31, 2018 compared to $10 million during the three months ended March 31, 2017 . Cash Restrictions Webster Bank is required by Federal Reserve System regulations to hold cash reserve balances on hand or with the Federal Reserve Bank. Pursuant to this requirement, Webster Bank held $79.8 million and $82.3 million at March 31, 2018 and December 31, 2017

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share Reconciliation of the calculation of basic and diluted earnings per common share follows: Three months ended March 31, (In thousands, except per share data) 2018 2017 Earnings for basic and diluted earnings per common share: Net income $ 80,225 $ 59,471 Less: Preferred stock dividends 1,947 2,024 Net income available to common shareholders 78,278 57,447 Less: Earnings applicable to participating securities 195 105 Earnings applicable to common shareholders $ 78,083 $ 57,342 Shares: Weighted-average common shares outstanding - basic 91,921 91,886 Effect of dilutive securities: Stock options and restricted stock 327 450 Warrants 6 6 Weighted-average common shares outstanding - diluted 92,254 92,342 Earnings per common share: Basic $ 0.85 $ 0.62 Diluted 0.85 0.62 Potential common shares from non-participating restricted stock, of $72 thousand and $40 thousand for the three months ended March 31, 2018 and 2017 , respectively, are excluded from the effect of dilutive securities because, due to performance conditions, they would have been anti-dilutive.

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 Risk Management Objective of Using Derivatives Webster manages economic risks, such as interest rate, liquidity, and credit risks by managing the amount, sources, and duration of its debt funding in conjunction with the use of interest rate derivative financial instruments. Webster enters into interest rate derivatives to mitigate the exposure related to business activities that result in the future receipt or payment of, both known and uncertain, cash amounts that are impacted by interest rates. The primary objective for using interest rate derivatives is to add stability to interest expense by managing exposure to interest rate movements. To accomplish this objective, Webster uses interest rate swaps and interest rate caps as part of its interest rate risk management strategy. Interest rate swaps and interest rate caps designated as cash flow hedges are designed to manage the risk associated with a forecasted event or an uncertain variable-rate cash flow. Forward-settle interest rate swaps protect the Company against adverse fluctuations in interest rates by reducing its exposure to variability in cash flows relating to interest payments on forecasted debt issuances. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of variable amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for payment of an up-front premium. Cash flow hedges are used to regulate the variable cash flows associated with existing variable-rate debt and forecasted issuances of debt. Derivative instruments designated as cash flow hedges are recorded on the balance sheet at fair value. The effective portion of the change in fair value of the derivatives which are designated as cash flow hedges, and that qualify for hedge accounting, is recorded to AOCL and is reclassified into earnings in the subsequent periods that the hedged forecasted transaction affects earnings. The ineffective portion of the change in fair value of these derivatives, attributable to the difference in the effective date of the hedge and the effective date of the debt issuance, is recognized directly in earnings. During the periods presented, there was no ineffectiveness to be recognized in earnings. Certain fixed-rate obligations can be exposed to a change in fair value attributable to changes in benchmark interest rates. On occasion, interest rate swaps will be used to manage this exposure. An interest rate swap which involves the receipt of fixed-rate amounts from a counterparty in exchange for Webster making variable-rate payments over the life of the agreement, without the exchange of the underlying notional amount, is designated as a fair value hedge. For a qualifying derivative designated as a fair value hedge, the gain or loss on the derivative, as well as the gain or loss on the hedged item, is recognized in interest expense. During the periods presented, Webster did not have any interest rate derivative financial instruments designated as fair value hedges and as a result, there was no impact to interest expense. Additionally, in order to address certain other risk management matters, the Company also utilizes derivative instruments that do not qualify for hedge accounting. These derivative instruments, which are recorded on the balance sheet at fair value, with changes in fair value recognized each period as other non-interest income in the accompanying Condensed Consolidated Statements of Income, are described in the following paragraphs. Interest rate swap and cap contracts are sold to commercial and other customers who wish to modify loan interest rate sensitivity. These contracts are offset with dealer counterparty transactions structured with matching terms. As a result, there is minimal impact on earnings, except for fee income earned in such transactions. Risk participation agreements (RPAs) are entered into as financial guarantees of performance on interest rate swap derivatives. The purchased (asset) or sold (liability) guarantee allows the Company to participate-in (fee received) or participate-out (fee paid) the risk associated with certain derivative positions executed with the borrower by the lead bank in a loan syndication. Other derivatives include foreign currency forward contracts related to lending arrangements, a VISA equity swap transaction, and mortgage banking derivatives such as mortgage-backed securities related to residential loan commitments and loans held for sale. Mortgage banking derivatives are utilized by Webster in its efforts to manage risk of loss associated with its mortgage loan commitments and mortgage loans held for sale. Prior to closing and funding certain single-family residential mortgage loans interest rate lock commitments are generally extended to the borrowers. During the period from commitment date to closing date, Webster is subject to the risk that market rates of interest may change. If market rates rise, investors generally will pay less to purchase such loans causing a reduction in the anticipated gain on sale of the loans, or possibly resulting in a loss. In an effort to mitigate such risk, forward delivery sales commitments are established under which Webster agrees to deliver whole mortgage loans to various investors or issue mortgage-backed securities. Mandatory forward commitments establish the price to be received upon the sale of the related mortgage loan, thereby mitigating certain interest rate risk. There is, however, still certain execution risk specifically related to Webster’s ability to close and deliver to its investors the mortgage loans it has committed to sell. Balance Sheet Impact of Derivative Instruments The following table presents the notional amounts and fair value of derivative positions: At March 31, 2018 At December 31, 2017 Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives (In thousands) Notional Fair Notional Fair Notional Fair Notional Fair Designated as hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) $ 325,000 $ 4,289 $ — $ — $ 325,000 $ 2,770 $ — $ — Not designated as hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) 3,258,511 10,659 437,308 848 2,791,760 5,977 721,048 1,968 Mortgage banking derivatives (3) 34,744 545 31,162 168 28,497 421 39,230 110 Other 17,763 144 17,788 61 7,914 258 30,328 419 Positions not subject to a master netting agreement (4) Interest rate derivatives 636,754 9,863 3,059,075 57,952 1,366,299 23,009 2,146,518 25,631 RPAs 93,275 48 84,999 69 93,713 80 116,882 111 Other 530 3 861 17 — — 2,073 184 Total not designated as hedging instruments 4,041,577 21,262 3,631,193 59,115 4,288,183 29,745 3,056,079 28,423 Gross derivative instruments, before netting $ 4,366,577 25,551 $ 3,631,193 59,115 $ 4,613,183 32,515 $ 3,056,079 28,423 Less: Legally enforceable master netting agreements 818 818 2,245 2,245 Less: Cash collateral posted 13,994 — 6,704 — Total derivative instruments, after netting $ 10,739 $ 58,297 $ 23,566 $ 26,178 (1) The Company has elected to report derivative positions subject to a legally enforceable master netting agreement on a net basis, net of cash collateral. Refer to the Offsetting Derivatives section of this footnote for additional information. (2) In accordance with the Chicago Mercantile Exchange (CME) rulebook, balances related to CME are presented as a single unit of account. (3) Notional amounts include mandatory forward commitments of $37.0 million , while notional amounts do not include approved floating rate commitments of $15.1 million , at March 31, 2018 . (4) Fair value of assets are included in accrued interest receivable and other assets, while, fair value of liabilities are included in accrued expenses and other liabilities, in the accompanying Condensed Consolidated Balance Sheets. Income Statement Impact of Derivative Instruments The following table presents the effect on the income statement from derivative positions: Three months ended March 31, (In thousands) 2018 2017 Designated as hedging instruments: Interest rate derivatives (1) $ 1,823 $ 2,039 Not designated as hedging instruments: Interest rate derivatives $ 3,791 $ 1,534 RPAs 10 53 Mortgage banking derivatives 65 (2,041 ) Other (600 ) (447 ) Total not designated as hedging instruments (2) $ 3,266 $ (901 ) (1) The impact from interest rate derivatives designated as hedging instruments is included in interest expense on borrowings in the accompanying Condensed Consolidated Statements of Income. (2) The impact from the total not designated as hedging instruments is included in other non-interest income in the accompanying Condensed Consolidated Statements of Income. Amounts for the effective portion of changes in the fair value of derivatives qualifying for hedge accounting treatment are reclassified to interest expense as interest payments are made on Webster's variable-rate debt. Over the next twelve months, the Company estimates that $0.2 million will be reclassified from AOCL as an increase to interest expense. Webster records gains and losses related to hedge terminations to AOCL. These balances are subsequently amortized into interest expense over the respective terms of the hedged debt instruments. At March 31, 2018 , the remaining unamortized loss on the termination of cash flow hedges is $13.3 million . Over the next twelve months, the Company estimates that $5.6 million will be reclassified from AOCL as an increase to interest expense. Additional information about cash flow hedge activity impacting AOCL, and the related amounts reclassified to interest expense is provided in Note 9: Accumulated Other Comprehensive Loss, Net of Tax . Information about the valuation methods used to measure the fair value of derivatives is provided in Note 13: Fair Value Measurements . Offsetting Derivatives Derivatives subject to a legally enforceable master netting agreement are reported on a net basis, net of cash collateral. Net gain positions are recorded as assets and are included in accrued interest receivable and other assets, while, net loss positions are recorded as liabilities and are included in accrued expenses and other liabilities, in the accompanying Condensed Consolidated Balance Sheets. The following table presents the transition from a gross basis to net basis, due to the application of counterparty netting agreements: At March 31, 2018 At December 31, 2017 (In thousands) Gross Amount Relationship Offset Cash Collateral Offset Net Amount Gross Amount Relationship Offset Cash Collateral Offset Net Amount Derivative instrument gains: Hedge accounting $ 4,289 $ — $ 4,289 $ — $ 2,770 $ 91 $ 2,679 $ — Non-hedge accounting 10,523 818 9,705 — 6,222 2,154 4,025 43 Total assets $ 14,812 $ 818 $ 13,994 $ — $ 8,992 $ 2,245 $ 6,704 $ 43 Derivative instrument losses: Hedge accounting $ — $ — $ — $ — $ — $ — $ — $ — Non-hedge accounting 909 818 — 91 2,387 2,245 — 142 Total liabilities $ 909 $ 818 $ — $ 91 $ 2,387 $ 2,245 $ — $ 142 Counterparty Credit Risk Use of derivative contracts may expose the bank to counterparty credit risk. The Company has International Swaps Derivative Association (ISDA) master agreements, including a Credit Support Annex, with all derivative counterparties. The ISDA master agreements provide that on each payment date, all amounts otherwise owing the same currency under the same transaction are netted so that only a single amount is owed in that currency. The ISDA provides, if the parties so elect, for such netting of amounts in the same currency among all transactions identified as being subject to such election that have common payment dates and booking offices. Under the Credit Support Annex, daily net exposure in excess of a negotiated threshold is secured by posted cash collateral. The Company has negotiated a zero threshold with the majority of its approved financial institution counterparties. In accordance with Webster policies, institutional counterparties must be analyzed and approved through the Company’s credit approval process. The Company’s credit exposure on interest rate derivatives with non-dealer counterparties is limited to the net favorable value, including accrued interest, of all such instruments, reduced by the amount of collateral pledged by the counterparties. The Company's credit exposure related to derivatives with dealer counterparties is significantly mitigated with cash collateral equal to, or in excess of, the market value of the instrument updated daily. In accordance with counterparty credit agreements and derivative clearing rules, the Company had approximately $50.1 million in net margin collateral received from financial counterparties at March 31, 2018 , comprised of $33.5 million in initial margin and $83.6 million in variation margin collateral received from financial counterparties or the derivative clearing organization. Collateral levels for approved financial institution counterparties are monitored daily and adjusted as necessary. In the event of default, should the collateral not be returned, the exposure would be offset by terminating the transaction. The Company regularly evaluates the credit risk of its counterparties, taking into account the likelihood of default, net exposures, and remaining contractual life, among other related factors. The Company's net current credit exposure relating to interest rate derivatives with Webster Bank customers was $9.9 million at March 31, 2018 . In addition, the Company monitors potential future exposure, representing its best estimate of exposure to remaining contractual maturity. The potential future exposure relating to interest rate derivatives with Webster Bank customers totaled $29.6 million at March 31, 2018

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is best determined using quoted market prices. However, in many instances, quoted market prices are not available. In such instances, fair values are determined using appropriate valuation techniques. Various assumptions and observable inputs must be relied upon in applying these techniques. Accordingly, categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. As such, the fair value estimates may not be realized in an immediate transfer of the respective asset or liability. Fair value estimates are made at a specific point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the entire holdings or any part of a particular financial instrument. Fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments, and other factors. These factors are subjective in nature and involve uncertainties and matters of significant judgment and, therefore, cannot be determined with precision. Changes in assumptions could significantly affect the estimates. Fair Value Hierarchy The three levels within the fair value hierarchy are as follows: • Level 1: Valuation is based upon unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. • Level 2: Fair value is calculated using significant inputs other than quoted market prices that are directly or indirectly observable for the asset or liability. The valuation may rely on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit ratings, etc.), or inputs that are derived principally or corroborated by market data, by correlation, or other means. • Level 3: Inputs for determining the fair value of the respective assets or liabilities are not observable. Level 3 valuations are reliant upon pricing models and techniques that require significant management judgment or estimation. Assets and Liabilities Measured at Fair Value on a Recurring Basis Available-for-Sale Investment Securities. When quoted prices are available in an active market, the Company classifies investment securities within Level 1 of the valuation hierarchy. U.S. Treasury Bills are classified within Level 1 of the fair value hierarchy. When quoted market prices are not available, the Company employs an independent pricing service that utilizes matrix pricing to calculate fair value. Such fair value measurements consider observable data such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayments speeds, credit information, and respective terms and conditions for debt instruments. Management maintains procedures to monitor the pricing service's results and establishes processes to challenge their valuations, or methodology, that appear unusual or unexpected. Available-for-Sale investment securities which include Agency CMO, Agency MBS, Agency CMBS, CMBS, CLO, single issuer-trust preferred, and corporate debt, are classified within Level 2 of the fair value hierarchy. Derivative Instruments. Foreign exchange contracts are valued based on unadjusted quoted prices in active markets and classified within Level 1 of the fair value hierarchy. All other derivative instruments are valued using third-party valuation software, which considers the present value of cash flows discounted using observable forward rate assumptions. The resulting fair values are validated against valuations performed by independent third parties and are classified within Level 2 of the fair value hierarchy. In determining if any fair value adjustment related to credit risk is required, Webster evaluates the credit risk of its counterparties by considering factors such as the likelihood of default by the counterparties, its net exposures, the remaining contractual life, as well as the amount of collateral securing the position. Webster reviews its counterparty exposure on a regular basis, and, when necessary, appropriate business actions are taken to mitigate the exposure. When determining fair value, Webster applies the portfolio exception with respect to measuring counterparty credit risk for all of its derivative transactions subject to a master netting arrangement. The Chicago Mercantile Exchange rulebooks legally characterize variation margin payments for over-the-counter derivatives to clear as settlements rather than collateral, which impacts one of Webster's counterparty relationships, resulting in the fair value of the instrument including cash collateral to be represented as a single unit of account. The change in value of derivative assets and liabilities attributable to credit risk was not significant during the reported periods. Mortgage Banking Derivatives. Forward sales of mortgage loans and mortgage-backed securities are utilized by the Company in its efforts to manage risk of loss associated with its mortgage loan commitments and mortgage loans held for sale. Prior to closing and funding certain single-family residential mortgage loans, an interest rate lock commitment is generally extended to the borrower. During the period from commitment date to closing date, the Company is subject to the risk that market rates of interest may change. If market rates rise, investors generally will pay less to purchase such loans resulting in a reduction in the gain on sale of the loans or, possibly, a loss. In an effort to mitigate such risk, forward delivery sales commitments are established, under which the Company agrees to deliver whole mortgage loans to various investors or issue mortgage-backed securities. The fair value of mortgage banking derivatives is determined based on current market prices for similar assets in the secondary market and, therefore, classified within Level 2 of the fair value hierarchy. Originated Loans Held For Sale. Residential mortgage loans typically are classified as held for sale upon origination based on management's intent to sell such loans. The Company has elected to measure originated loans held for sale under the fair value option of Accounting Standards Codification ( ASC) Topic 825 "Financial Instruments," on a loan-by-loan basis. The fair value of residential mortgage loans held for sale is based on quoted market prices of similar loans sold in conjunction with securitization transactions. Accordingly, these loans are classified within Level 2 of the fair value hierarchy. The following table presents the fair value, unpaid principal balance, and accrual status of assets accounted for under the fair value option: March 31, 2018 December 31, 2017 (In thousands) Fair Value Unpaid Principal Balance Difference Fair Value Unpaid Principal Balance Difference Originated loans held for sale $ 19,727 $ 19,663 $ 64 $ 20,888 $ 20,346 $ 542 Electing to measure originated loans held for sale at fair value reduces certain timing differences and better matches changes in the value of these assets with changes in the value of the derivatives used as an economic hedge on these assets. Assets accounted for under the fair value option are initially measured at fair value. Gains and losses from initial measurement and subsequent changes in fair value are recognized in earnings. For the three months ended March 31, 2018 net loss from fair value changes was $0.3 million and for the three months ended March 31, 2017 net gains from fair value changes was $1.2 million . The Company does not account for liabilities under the fair value option. Investments Held in Rabbi Trust. Investments held in the Rabbi Trust primarily include mutual funds that invest in equity and fixed income securities. Shares of mutual funds are valued based on net asset value, which represents quoted market prices for the underlying shares held in the mutual funds. Therefore, investments held in the Rabbi Trust are classified within Level 1 of the fair value hierarchy. Webster has elected to measure the investments held in the Rabbi Trust at fair value. The cost basis of the investments held in the Rabbi Trust is $2.1 million at March 31, 2018 . Alternative Investments Net Asset Value (NAV). Alternative investments that are fair valued on a recurring basis are based upon the NAV of the respective fund. Therefore, alternative investments (NAV) are not classified within the fair value hierarchy. At March 31, 2018 , alternative investments (NAV) had a remaining unfunded commitment of $0.3 million . The Company's alternative investments (NAV) consists of investments in non-public entities that generally cannot be redeemed since the Company’s investments are distributed as the underlying equity is liquidated. Summaries of the fair values of assets and liabilities measured at fair value on a recurring basis are as follows: At March 31, 2018 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 449 $ — $ — $ 449 Agency CMO — 284,579 — 284,579 Agency MBS — 1,265,268 — 1,265,268 Agency CMBS — 591,302 — 591,302 CMBS — 366,894 — 366,894 CLO — 201,837 — 201,837 Single issuer-trust preferred — 7,041 — 7,041 Corporate debt — 56,136 — 56,136 Total available-for-sale investment securities 449 2,773,057 — 2,773,506 Gross derivative instruments, before netting (1) 147 25,404 — 25,551 Originated loans held for sale — 19,727 — 19,727 Investments held in Rabbi Trust 4,694 — — 4,694 Alternative investments (NAV) (2) — — — 3,495 Total financial assets held at fair value $ 5,290 $ 2,818,188 $ — $ 2,826,973 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 62 $ 59,053 $ — $ 59,115 At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 1,247 $ — $ — $ 1,247 Agency CMO — 306,333 — 306,333 Agency MBS — 1,107,841 — 1,107,841 Agency CMBS — 588,026 — 588,026 CMBS — 361,067 — 361,067 CLO — 209,851 — 209,851 Single issuer-trust preferred — 7,050 — 7,050 Corporate debt — 56,622 — 56,622 Total available-for-sale investment securities 1,247 2,636,790 — 2,638,037 Gross derivative instruments, before netting (1) 258 32,257 — 32,515 Originated loans held for sale — 20,888 — 20,888 Investments held in Rabbi Trust 4,801 — — 4,801 Alternative investments (NAV) (2) — — — 3,495 Total financial assets held at fair value $ 6,306 $ 2,689,935 $ — $ 2,699,736 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 587 $ 27,836 $ — $ 28,423 (1) For information relating to the impact of netting derivative assets and derivative liabilities as well as the impact from offsetting cash collateral paid to the same derivative counterparties see Note 12: Derivative Financial Instruments . (2) Fair value for this investment is measured using the net asset value practical expedient and therefore is not classified within the fair value hierarchy. Assets Measured at Fair Value on a Non-Recurring Basis Certain assets are measured at fair value on a non-recurring basis; that is, the assets are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances, for example, when there is evidence of impairment. The following is a description of valuation methodologies used for assets measured on a non-recurring basis. Alternative Investments. Alternative investments are investments in non-public entities that generally cannot be redeemed since the investment is distributed as the underlying equity is liquidated. The measurement alternative has been elected for alternative investments without readily determinable fair values that do not qualify for the NAV practical expedient. The measurement alternative requires investments to be accounted for 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. Accordingly, these alternative investments are classified within Level 3 of the fair value hierarchy. The carrying amount of these alternative investments was $7.9 million at March 31, 2018 . No reduction for impairments, or increase or decrease due to observable price changes, was identified during the three months ended March 31, 2018 . Transferred Loans Held For Sale. Certain loans are transferred to loans held for sale once a decision has been made to sell such loans. These loans are accounted for at the lower of cost or market and are considered to be recognized at fair value when they are recorded at below cost. This activity is primarily commercial loans with observable inputs and is classified within Level 2. On the occasion should these loans include adjustments for changes in loan characteristics using unobservable inputs, the loans would be classified within Level 3. Collateral Dependent Impaired Loans and Leases. Impaired loans and leases for which repayment is expected to be provided solely by the value of the underlying collateral are considered collateral dependent and are valued based on the estimated fair value of such collateral using customized discounting criteria. As such, collateral dependent impaired loans and leases are classified as Level 3 of the fair value hierarchy. Other Real Estate Owned and Repossessed Assets. The total book value of other real estate owned (OREO) and repossessed assets was $5.8 million at March 31, 2018 . OREO and repossessed assets are accounted for at the lower of cost or market and are considered to be recognized at fair value when they are recorded at below cost. The fair value of OREO is based on independent appraisals or internal valuation methods, less estimated selling costs. The valuation may consider available pricing guides, auction results, and price opinions. Certain assets require assumptions about factors that are not observable in an active market in the determination of fair value; as such, OREO and repossessed assets are classified within Level 3 of the fair value hierarchy. The table below presents the valuation methodology and unobservable inputs for Level 3 assets measured at fair value on a non-recurring basis as of March 31, 2018 : (Dollars in thousands) Asset Fair Value Valuation Methodology Unobservable Inputs Range of Inputs Collateral dependent impaired loans and leases $ 13,424 Real Estate Appraisals Discount for appraisal type 0% - 15% Discount for costs to sell 0% - 8% OREO $ 858 Real Estate Appraisals Discount for costs to sell 8% Fair Value of Financial Instruments and Servicing Assets The Company is required to disclose the estimated fair value of financial instruments, both assets and liabilities, for which it is practicable to estimate fair value. The following is a description of valuation methodologies used for those assets and liabilities. Cash, Due from Banks, and Interest-bearing Deposits. The carrying amount of cash, due from banks, and interest-bearing deposits is used to approximate fair value, given the short time frame to maturity and, as such, these assets do not present unanticipated credit concerns. Cash, due from banks, and interest-bearing deposits are classified within Level 1 of the fair value hierarchy. Held-to-Maturity Investment Securities. When quoted market prices are not available, the Company employs an independent pricing service that utilizes matrix pricing to calculate fair value. Such fair value measurements consider observable data such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayments speeds, credit information, and respective terms and conditions for debt instruments. Management maintains procedures to monitor the pricing service's results and establishes processes to challenge their valuations, or methodology, that appear unusual or unexpected. Held-to-Maturity investment securities, which include Agency CMO, Agency MBS, Agency CMBS, CMBS, municipal bonds and notes, and private label MBS securities, are classified within Level 2 of the fair value hierarchy. Loans and Leases, net. The estimated fair value of loans and leases held for investment is calculated using a discounted cash flow method, using future prepayments and market interest rates inclusive of an illiquidity premium for comparable loans and leases. The associated cash flows are adjusted for credit and other potential losses. Fair value for impaired loans and leases is estimated using the net present value of the expected cash flows. Loans and leases are classified within Level 3 of the fair value hierarchy. Deposit Liabilities. The fair value of demand deposits, savings accounts, and certain money market deposits is the amount payable on demand at the reporting date. Deposit liabilities are classified within Level 2 of the fair value hierarchy. Time Deposits. The fair value of a fixed-maturity certificate of deposit is estimated using the rates currently offered for deposits of similar remaining maturities. Time deposits are classified within Level 2 of the fair value hierarchy. Securities Sold Under Agreements to Repurchase and Other Borrowings. The carrying value is an estimate of fair value for those securities sold under agreements to repurchase and other borrowings that mature within 90 days. Fair value of all other borrowings is estimated using discounted cash flow analysis based on current market rates adjusted, as appropriate, for associated credit risks. Securities sold under agreements to repurchase and other borrowings are classified within Level 2 of the fair value hierarchy. Federal Home Loan Bank Advances and Long-Term Debt. The fair value of FHLB advances and long-term debt is estimated using a discounted cash flow technique. Discount rates are matched with the time period of the expected cash flow and are adjusted, as appropriate, to reflect credit risk. FHLB advances and long-term debt are classified within Level 2 of the fair value hierarchy. Mortgage Servicing Assets. Mortgage servicing assets are accounted for at cost, subject to impairment testing. Mortgage servicing assets are considered to be recognized at fair value when they are recorded at below cost. Changes in fair value are included as a component of other non-interest income in the accompanying Condensed Consolidated Statements of Income. Fair value is calculated as the present value of estimated future net servicing income and relies on market based assumptions for loan prepayment speeds, servicing costs, discount rates, and other economic factors; as such, the primary risk inherent in valuing mortgage servicing assets is the impact of fluctuating interest rates on the servicing revenue stream. Mortgage servicing assets are classified within Level 3 of the fair value hierarchy. The estimated fair values of selected financial instruments and servicing assets are as follows: At March 31, 2018 At December 31, 2017 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Level 2 Held-to-maturity investment securities $ 4,408,321 $ 4,297,039 $ 4,487,392 $ 4,456,350 Level 3 Loans and leases, net 17,600,226 17,391,087 17,323,864 17,211,619 Mortgage servicing assets 24,403 51,668 25,139 45,309 Liabilities: Level 2 Deposit liabilities $ 18,831,789 $ 18,831,789 $ 18,525,321 $ 18,525,321 Time deposits 2,553,253 2,527,441 2,468,408 2,455,245 Securities sold under agreements to repurchase and other borrowings 931,299 930,683 643,269 644,084 FHLB advances 1,202,030 1,204,045 1,677,105 1,678,070 Long-term debt (1) 225,830 232,586 225,767 234,359 (1) Adjustments to the carrying amount of long-term debt for unamortized discount and debt issuance cost on senior fixed-rate notes are not included for determination of fair value, see Note 8: Borrowings

Retirement Benefit Plans

Retirement Benefit Plans	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Retirement Benefit Plans	Retirement Benefit Plans Defined benefit pension and other postretirement benefits The following table summarizes the components of net periodic benefit cost: Three months ended March 31, 2018 2017 (In thousands) Pension Plan SERP Other Benefits Pension Plan SERP Other Benefits Service cost $ — $ — $ — $ 12 $ — $ — Interest cost on benefit obligations 1,785 187 20 1,813 92 25 Expected return on plan assets (3,180 ) — — (3,073 ) — — Amortization of prior service cost — — — — — — Recognized net loss 1,160 125 — 1,417 213 8 Net periodic benefit cost $ (235 ) $ 312 $ 20 $ 169 $ 305 $ 33

Share-Based Plans

Share-Based Plans	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Plans	Share-Based Plans Stock compensation plans Webster maintains stock compensation plans under which non-qualified stock options, incentive stock options, restricted stock, restricted stock units, or stock appreciation rights may be granted to employees and directors. The Company believes these share awards better align the interests of its employees with those of its shareholders. Stock compensation cost is recognized over the required service vesting period for the awards, based on the grant-date fair value, net of estimated forfeitures, and is included as a component of compensation and benefits reflected in non-interest expense. Stock compensation expense of $3.3 million for both the three months ended March 31, 2018 and 2017 , related to restricted stock awards, was recognized in the accompanying Condensed Consolidated Statements of Income. At March 31, 2018 there was $21.0 million of unrecognized stock compensation expense for restricted stock expected to be recognized over a weighted-average period of 2.3 years . The following table provides a summary of the stock compensation plans activity for the three months ended March 31, 2018 : Restricted Stock Awards Outstanding Stock Options Outstanding Time-Based Performance-Based Number of Shares Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Exercise Price Outstanding, at January1, 2018 207,800 $ 43.16 78,916 $ 45.35 673,039 $ 18.75 Granted 113,264 56.58 75,707 55.82 — — Exercised options — — — — 11,516 25.15 Vested restricted stock awards (1) 46,137 41.46 19,398 43.01 — — Forfeited 1,144 35.61 — — — — Outstanding and exercisable, at March 31, 2018 273,783 $ 48.96 135,225 $ 51.54 661,523 $ 18.64 (1) Vested for purposes of recording compensation expense. Time-based restricted stock. Time-based restricted stock awards vest over the applicable service period ranging from 1 to 5 years. The number of time-based awards that may be granted to an eligible individual in a calendar year is limited to 100,000 shares. Compensation expense is recorded over the vesting period based on a fair value, which is measured using the Company's common stock closing price at the date of grant. Performance-based restricted stock. Performance-based restricted stock awards vest after a 3 year performance period. The awards vest with a share quantity dependent on that performance, in a range from 0 to 150% . The performance criteria for 50% of the shares granted in 2018 is based upon Webster's ranking for total shareholder return versus Webster's compensation peer group companies and the remaining 50% is based upon Webster's average of return on equity during the 3 year vesting period. The compensation peer group companies are utilized because they represent the financial institutions that best compare with Webster. The Company records compensation expense over the vesting period, based on a fair value calculated using the Monte-Carlo simulation model, which allows for the incorporation of the performance condition for the 50% of the performance-based shares tied to total shareholder return versus the compensation peer group, and based on a fair value of the market price on the date of grant for the remaining 50% of the performance-based shares tied to Webster's return on equity. Compensation expense is subject to adjustment based on management's assessment of Webster's return on equity performance relative to the target number of shares condition. Stock options. Stock option awards have an exercise price equal to the market price of Webster Financial Corporation's stock on the date of grant. Each option grants the holder the right to acquire a share of Webster Financial Corporation common stock over a contractual life of up to 10 years. All awarded options have vested. There were 627,635 non-qualified stock options and 33,888 incentive stock options outstanding at March 31, 2018

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting Webster’s operations are organized into three reportable segments that represent its primary businesses - Commercial Banking, HSA Bank, and Community Banking. These three segments reflect how executive management responsibilities are assigned, the primary businesses, the products and services provided, the type of customer served, and how discrete financial information is currently evaluated. The Corporate Treasury unit of the Company, along with the amounts required to reconcile profitability metrics to amounts reported in accordance with GAAP, are included in the Corporate and Reconciling category. Description of Segment Reporting Methodology Webster’s reportable segment results are intended to reflect each segment as if it were a stand-alone business. Webster uses an internal profitability reporting system to generate information by operating segment, which is based on a series of management estimates and allocations regarding funds transfer pricing, provision for loan and lease losses, non-interest expense, income taxes, and equity capital. These estimates and allocations, certain of which are subjective in nature, are periodically reviewed and refined. Changes in estimates and allocations that affect the reported results of any operating segment do not affect the consolidated financial position or results of operations of Webster as a whole. The full profitability measurement reports, which are prepared for each operating segment, reflect non-GAAP reporting methodologies. The differences between full profitability and GAAP results are reconciled in the Corporate and Reconciling category. Webster allocates interest income and interest expense to each business, while also transferring the primary interest rate risk exposures to the Corporate and Reconciling category, using a matched maturity funding concept called Funds Transfer Pricing (FTP). The allocation process considers the specific interest rate risk and liquidity risk of financial instruments and other assets and liabilities in each line of business. The matched maturity funding concept considers the origination date and the earlier of the maturity date or the repricing date of a financial instrument to assign an FTP rate for loans and deposits originated each day. Loans are assigned an FTP rate for funds used and deposits are assigned an FTP rate for funds provided. This process is executed by the Company’s Financial Planning and Analysis division and is overseen by the Company's Asset/Liability Committee (ALCO). Webster allocates the provision for loan and lease losses to each segment based on management’s estimate of the inherent loss content in each of the specific loan and lease portfolios. Provision expense for certain elements of risk that are not deemed specifically attributable to a reportable segment, such as the provision for the consumer liquidating portfolio, is shown as part of the Corporate and Reconciling category. Webster allocates a majority of non-interest expense to each reportable segment using a full-absorption costing process. Costs, including corporate overhead, are analyzed, pooled by process, and assigned to the appropriate reportable segment. Beginning in 2018, income tax expense is estimated for each reportable segment individually. The 2017 income tax expense was estimated for all segments using the consolidated effective tax rate. This change in the estimate of income tax expense reflects an estimate of full profitability for each of the individual business segments based on the nature of their operations. The following table presents total assets for Webster's reportable segments and the Corporate and Reconciling category: Total Assets (In thousands) Commercial Banking Community Banking HSA Bank Corporate and Reconciling Consolidated Total At March 31, 2018 $ 9,718,543 $ 8,828,329 $ 77,883 $ 8,127,392 $ 26,752,147 At December 31, 2017 9,350,028 8,909,671 76,308 8,151,638 26,487,645 The following tables present the operating results, including all appropriate allocations, for Webster’s reportable segments and the Corporate and Reconciling category: Three months ended March 31, 2018 (In thousands) Commercial Banking Community Banking HSA Bank Corporate and Reconciling Consolidated Total Net interest income (expense) $ 84,651 $ 98,928 $ 32,924 $ (2,335 ) $ 214,168 Provision for loan and lease losses 7,178 3,822 — — 11,000 Net interest income (expense) after provision for loan and lease losses 77,473 95,106 32,924 (2,335 ) 203,168 Non-interest income 15,316 25,195 22,669 5,567 68,747 Non-interest expense 41,245 96,829 31,515 2,026 171,615 Income before income tax expense 51,544 23,472 24,078 1,206 100,300 Income tax expense (benefit) 12,680 4,671 6,260 (3,536 ) 20,075 Net income $ 38,864 $ 18,801 $ 17,818 $ 4,742 $ 80,225 Three months ended March 31, 2017 (In thousands) Commercial Banking Community Banking HSA Bank Corporate and Reconciling Consolidated Total Net interest income (expense) $ 78,247 $ 93,590 $ 24,052 $ (3,225 ) $ 192,664 Provision for loan and lease losses 6,797 3,703 — — 10,500 Net interest income (expense) after provision for loan and lease losses 71,450 89,887 24,052 (3,225 ) 182,164 Non-interest income 13,424 25,379 19,271 4,968 63,042 Non-interest expense 38,124 95,179 28,239 2,242 163,784 Income (loss) before income tax expense 46,750 20,087 15,084 (499 ) 81,422 Income tax expense (benefit) 12,604 5,416 4,066 (135 ) 21,951 Net income (loss) $ 34,146 $ 14,671 $ 11,018 $ (364 ) $ 59,471

Revenue from Contracts with Cus

Revenue from Contracts with Customers Revenue from Contracts with customers	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenue from Contracts with Customers The Company adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606) and subsequent clarifying ASUs effective January 1, 2018. The Updates are applicable to the Company's deposit service fees, wealth and investment services, and an insignificant component of other income included within non-interest income in the accompanying Condensed Consolidated Statements of Income. The Company's revenue associated with net interest income, and certain non-interest income line items (loan and lease related fees, mortgage banking activities, increase in cash surrender value of life insurance policies, gain on sale of investment securities, net, impairment loss on securities recognized in earnings, and a majority of other income), are not within the scope of Topic 606. As a result, a substantial amount of the Company's revenue was not affected. Under the updated guidance, for in-scope revenue streams, the Company identifies the performance obligations included in the contracts with customers, determines the transaction price, allocates the transaction price to the performance, as applicable, and recognizes revenue when performance obligations are satisfied. The Company's existing recognition practices are largely consistent with the updated guidance. The following tables present the disaggregation by operating segment and major revenue stream, with disaggregated revenue reconciled to segment revenue as presented in Note 16: Segment Reporting : Three months ended March 31, 2018 (In thousands) Commercial Community HSA Corporate and Consolidated Major Revenue Streams Deposit service fees $ 3,222 $ 15,309 $ 21,812 $ 108 $ 40,451 Wealth and investment services 2,539 5,339 — (8 ) 7,870 Other income — 493 857 — 1,350 Revenue from contracts with customers 5,761 21,141 22,669 100 49,671 Non-interest income within the scope of other GAAP topics 9,555 4,054 — 5,467 19,076 Total non-interest income $ 15,316 $ 25,195 $ 22,669 $ 5,567 $ 68,747 Three months ended March 31, 2017 (In thousands) Commercial Community HSA Corporate and Consolidated Major Revenue Streams Deposit service fees $ 2,878 $ 15,530 $ 18,484 $ 114 $ 37,006 Wealth and investment services 2,372 4,909 — (8 ) 7,273 Other income — 224 787 — 1,011 Revenue from contracts with customers 5,250 20,663 19,271 106 45,290 Non-interest income within the scope of other GAAP topics 8,174 4,716 — 4,862 17,752 Total non-interest income $ 13,424 $ 25,379 $ 19,271 $ 4,968 $ 63,042 Deposit service fees Deposit service fees predominately consist of fees earned from deposit accounts and interchange revenue. Fees earned from deposit accounts relate to event-driven services and periodic account maintenance activities. Webster's obligations for event-driven services are satisfied at the time the service is delivered, while the obligations for maintenance services is satisfied monthly. Interchange fees are assessed as the performance obligation is satisfied, which is at the point in time the card transaction is authorized. Wealth and investment services

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Credit-Related Financial Instruments The Company offers credit-related financial instruments in the normal course of business to meet certain financing needs of its customers, that involve off-balance sheet risk. These transactions may include an unused commitment to extend credit, standby letter of credit, or commercial letter of credit. Such transactions involve, to varying degrees, elements of credit risk. The following table summarizes the outstanding amounts of credit-related financial instruments with off-balance sheet risk: (In thousands) At March 31, 2018 At December 31, 2017 Commitments to extend credit $ 5,648,126 $ 5,567,687 Standby letter of credit 167,899 195,902 Commercial letter of credit 44,535 43,200 Total credit-related financial instruments with off-balance sheet risk $ 5,860,560 $ 5,806,789 Commitments to Extend Credit . The Company makes commitments under various terms to lend funds to customers at a future point in time. These commitments include revolving credit arrangements, term loan commitments, and short-term borrowing agreements. Most of these loans have fixed expiration dates or other termination clauses where a fee may be required. Since commitments routinely expire without being funded, or after required availability of collateral occurs, the total commitment amount does not necessarily represent future liquidity requirements. Standby Letter of Credit . A standby letter of credit commits the Company to make payments on behalf of customers if certain specified future events occur. The Company has recourse against the customer for any amount required to be paid to a third party under a standby letter of credit, which is often part of a larger credit agreement under which security is provided. Historically, a large percentage of standby letters of credit expire without being funded. The contractual amount of a standby letter of credit represents the maximum amount of potential future payments the Company could be required to make, and is the Company's maximum credit risk. Commercial Letter of Credit . A commercial letter of credit is issued to facilitate either domestic or foreign trade arrangements for customers. As a general rule, drafts are committed to be drawn when the goods underlying the transaction are in transit. Similar to a standby letter of credit, a commercial letter of credit is often secured by an underlying security agreement including the assets or inventory to which they relate. These commitments subject the Company to potential exposure in excess of the amounts recorded in the financial statements, and therefore, management maintains a specific reserve for unfunded credit commitments. This reserve is reported as a component of accrued expenses and other liabilities in the accompanying Condensed Consolidated Balance Sheets. The following table provides a summary of activity in the reserve for unfunded credit commitments: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 2,362 $ 2,287 (Benefit) provision charged to expense (68 ) 368 Ending balance $ 2,294 $ 2,655 Litigation Webster is involved in routine legal proceedings occurring in the ordinary course of business and is subject to loss contingencies related to such litigation and claims arising therefrom. Webster evaluates these contingencies based on information currently available, including advice of counsel and assessment of available insurance coverage. Webster establishes an accrual for litigation and claims when a loss contingency is considered probable and the related amount is reasonably estimable. This accrual is periodically reviewed and may be adjusted as circumstances change. Webster also estimates certain loss contingencies for possible litigation and claims, whether or not there is an accrued probable loss. Webster believes it has defenses to all the claims asserted against it in existing litigation matters and intends to defend itself in all matters. Based upon its current knowledge, after consultation with counsel and after taking into consideration its current litigation accrual, Webster believes that at March 31, 2018

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accounting and reporting policies of the Company that materially affect its financial statements conform with U.S. Generally Accepted Accounting Principles (GAAP). The accompanying unaudited Condensed Consolidated Financial Statements of the Company have been prepared in conformity with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements and should be read in conjunction with the Company's Consolidated Financial Statements, and Notes thereto, for the year ended December 31, 2017 , included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (SEC) on March 1, 2018.
Reclassification	.
New Accounting Pronouncements, Policy [Policy Text Block]	Accounting Standards Adopted During 2018 Effective January1, 2018 , the following new Accounting Standards Updates (ASUs) were adopted by the Company: ASU No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities. The Update shortens the amortization period for certain investments in callable debt securities purchased at a premium by requiring that the premium be amortized to the earliest call date. Prior to adoption, the Company amortized the premium as a yield adjustment over the contractual life of such debt securities. The Update accelerates the Company's recognition of premium amortization on certain debt securities held within the portfolio. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company elected to early adopt the Update during the first quarter of 2018 on a modified retrospective basis. As a result, the Company recorded a $2.8 million cumulative-effect adjustment directly to retained earnings as of January 1, 2018. ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715) - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The Update requires the Company to retrospectively report service cost as a part of compensation expense and the other components of net periodic benefit cost separately from service cost in the Company's consolidated financial statements. The Company previously included all components of net periodic benefit cost as a component of compensation and benefits expense. Upon adoption, only service cost remains in compensation and benefits expense, while the interest cost on benefit obligations, expected return on plan assets, amortization of prior service cost, and recognized net loss components of the net periodic benefit cost are included in other expense, in the accompanying Condensed Consolidated Statements of Income. The Company adopted the Update during the first quarter of 2018 on a retrospective basis. As a result, the Company reclassified, for prior periods, the components of it's net periodic benefit costs other than the service cost component from compensation and benefits to other expense in the accompanying Condensed Consolidated Statements of Income. The adoption of this guidance did not have a material impact on the Company's consolidated financial statements. ASU No. 2016-15, Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments. The Update addresses the following eight specific cash flow issues, with the objective of reducing the existing diversity in practice: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company adopted the Update during the first quarter of 2018 on a retrospective basis. The adoption of this guidance did not have a material impact on the Company's consolidated financial statements. ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities, and ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10) The Updates included targeted amendments in connection with the recognition, measurement, presentation, and disclosure of financial instruments. The main provisions require investments in equity securities to be measured at fair value through net income, unless they qualify for a practical expedient, and require fair value changes arising from changes in instrument-specific credit risk for financial liabilities that are measured under the fair value option to be recognized in other comprehensive income. The provisions also emphasized the existing requirement to use exit prices to measure fair value for disclosure purposes. The Company adopted the Updates during the first quarter of 2018 primarily on a modified retrospective basis. As a result, the Company recorded a benefit of $1.4 million for a cumulative-effect adjustment directly to retained earnings, as of January 1, 2018, due to a change in valuation method, from cost less impairment, to net asset value using the practical expedient. Also, the measurement alternative has been elected for equity securities, existing as of January 1, 2018, without readily determinable fair values on a prospective basis. ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). Also, subsequent ASUs issued to clarify this Topic. The Update, and subsequent related updates, establish a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most previous revenue recognition guidance, including industry-specific guidance. The Updates are intended to increase comparability across industries. The core principle of the revenue model is that a company will recognize revenue when it transfers control of goods or services to customers, at an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. The Company adopted the Updates during the first quarter of 2018 on a modified retrospective transition approach. The Company did not identify any material changes to the timing of revenue recognition. The Company is changing how it presents certain recurring revenue streams associated with wealth and investment services as other income, versus a contra expense; however, these changes did not have a significant impact on the Company's consolidated financial statements. The adoption of this guidance did not have a material impact on the Company's financial condition or results of operations, and there was no cumulative effect adjustment to opening retained earnings as no material changes were identified in the timing of revenue recognition, however, additional disclosure has been incorporated in Note 17: Revenue from Contracts with Customers . Accounting Standards Issued But Not Yet Adopted The following list identifies ASUs applicable to the Company that have been issued by the FASB but are not yet effective: ASU No. 2017-12, Derivatives and Hedging (Topic 815) - Targeted Improvements to Accounting for Hedging Activities. The purpose of the Update is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. The update requires a modified retrospective transition method in which a Company will recognize a cumulative effect of the change on the opening balance for each affected component of equity in the financial statements as of the date of adoption. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company is in the process of assessing all potential impacts of the standard. ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350) - Simplifying the Test for Goodwill Impairment. The Update simplifies quantitative goodwill impairment testing by requiring entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit's fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. This changes current guidance by eliminating the second step of the goodwill impairment analysis which involves calculating the implied fair value of goodwill determined in the same manner as the amount of goodwill recognized in a business combination upon acquisition. Entities will still have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The Update must be applied prospectively and is effective for the Company on January 1, 2020. Early adoption is permitted. The Company does not expect the new guidance to have a material impact on its financial statements. ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments. Current GAAP requires an "incurred loss" methodology for recognizing credit losses. This approach delays recognition until it is probable a loss has been incurred. Both financial institutions and users of their financial statements expressed concern that current GAAP restricts the ability to record credit losses that are expected, but do not yet meet the "probable" threshold. The main objective of this Update is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in this Update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The Change from an "incurred loss" method to an "expected loss" method represents a fundamental shift from existing GAAP, and is likely to result in a material increase to the Company's accounting for credit losses on financial instruments. To prepare for implementation of the new standard the Company has established a project lead and has finalized a cross functional steering committee comprised of members from different disciplines including Credit, Finance and Treasury as well as specific working groups to focus on key components of the development process. In addition, through one of the working groups, the Company has begun to evaluate the effect that this Update will have on its financial statements and related disclosures. An implementation project plan has been created and is made up of targeted work streams focused on credit models, data management, accounting, and governance. These work streams are collectively assessing resources that may be required, use of existing and new models, data availability, and system solutions to facilitate implementation. The Update will be effective for the Company on January 1, 2020. While we are currently unable to reasonably estimate the impact of adopting the Update, we expect the impact of adoption will be significantly influenced by the composition, characteristics, and quality of our loan and securities portfolios as well as the economic conditions as of the adoption date. ASU No. 2016-02, Leases (Topic 842). The Update introduces a lessee model that requires substantially all leases to be recorded as assets and liabilities on the balance sheet and will require both quantitative and qualitative disclosures regarding key information about leasing arrangements. The Company is in the process of reviewing its existing leases, including certain service contracts for embedded leases, to evaluate the impact of the standard on the consolidated financial statements, as well as the impact to regulatory reporting, such as capital and risk-weighted assets. The Company has engaged a third party consultant to assist with the implementation efforts.

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Investment Securities	A summary of the amortized cost and fair value of investment securities is presented below: At March 31, 2018 At December 31, 2017 (In thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Amortized Cost Unrealized Gains Unrealized Losses Fair Value Available-for-sale: U.S. Treasury Bills $ 449 $ — $ — $ 449 $ 1,247 $ — $ — $ 1,247 Agency CMO 290,105 526 (6,052 ) 284,579 308,989 1,158 (3,814 ) 306,333 Agency MBS 1,304,856 1,522 (41,110 ) 1,265,268 1,124,960 2,151 (19,270 ) 1,107,841 Agency CMBS 622,400 — (31,098 ) 591,302 608,276 — (20,250 ) 588,026 CMBS 365,006 2,045 (157 ) 366,894 358,984 2,157 (74 ) 361,067 CLO 201,254 691 (108 ) 201,837 209,075 910 (134 ) 209,851 Single issuer-trust preferred 7,111 — (70 ) 7,041 7,096 — (46 ) 7,050 Corporate debt 56,350 496 (710 ) 56,136 56,504 797 (679 ) 56,622 Available-for-sale $ 2,847,531 $ 5,280 $ (79,305 ) $ 2,773,506 $ 2,675,131 $ 7,173 $ (44,267 ) $ 2,638,037 Held-to-maturity: Agency CMO $ 245,663 $ 417 $ (7,139 ) $ 238,941 $ 260,114 $ 664 $ (4,824 ) $ 255,954 Agency MBS 2,544,104 12,571 (80,678 ) 2,475,997 2,569,735 16,989 (37,442 ) 2,549,282 Agency CMBS 689,602 — (20,744 ) 668,858 696,566 — (10,011 ) 686,555 Municipal bonds and notes 692,582 2,400 (16,091 ) 678,891 711,381 8,584 (6,558 ) 713,407 CMBS 236,172 891 (2,909 ) 234,154 249,273 2,175 (620 ) 250,828 Private Label MBS 198 — 198 323 1 — 324 Held-to-maturity $ 4,408,321 $ 16,279 $ (127,561 ) $ 4,297,039 $ 4,487,392 $ 28,413 $ (59,455 ) $ 4,456,350
Summary of Changes in OTTI	The following table presents activity for OTTI: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 1,364 $ 3,243 Reduction for investment securities sold or called — (12 ) Ending balance $ 1,364 $ 3,231
Summary of Gross Unrealized Losses not Considered OTTI	The following tables provide information on fair value and unrealized losses for the individual investment securities with an unrealized loss, aggregated by classification and length of time that the individual investment securities have been in a continuous unrealized loss position: At March 31, 2018 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 113,804 $ (1,601 ) $ 110,998 $ (4,451 ) 34 $ 224,802 $ (6,052 ) Agency MBS 597,062 (13,730 ) 577,081 (27,380 ) 159 1,174,143 (41,110 ) Agency CMBS 72,147 (2,248 ) 519,155 (28,850 ) 37 591,302 (31,098 ) CMBS 53,552 (157 ) — — 9 53,552 (157 ) CLO 99,288 (12 ) 15,068 (96 ) 6 114,356 (108 ) Single issuer-trust preferred 7,041 (70 ) — — 1 7,041 (70 ) Corporate debt 11,077 (406 ) 6,248 (304 ) 4 17,325 (710 ) Available-for-sale in an unrealized loss position $ 953,971 $ (18,224 ) $ 1,228,550 $ (61,081 ) 250 $ 2,182,521 $ (79,305 ) Held-to-maturity: Agency CMO $ 104,568 $ (2,199 ) $ 101,482 $ (4,940 ) 22 $ 206,050 $ (7,139 ) Agency MBS 1,066,786 (24,771 ) 1,143,544 (55,907 ) 253 2,210,330 (80,678 ) Agency CMBS 542,868 (15,740 ) 125,991 (5,004 ) 56 668,859 (20,744 ) Municipal bonds and notes 233,121 (4,137 ) 218,963 (11,954 ) 200 452,084 (16,091 ) CMBS 148,267 (2,595 ) 13,276 (314 ) 20 161,543 (2,909 ) Held-to-maturity in an unrealized loss position $ 2,095,610 $ (49,442 ) $ 1,603,256 $ (78,119 ) 551 $ 3,698,866 $ (127,561 ) At December 31, 2017 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 81,001 $ (449 ) $ 119,104 $ (3,365 ) 27 $ 200,105 $ (3,814 ) Agency MBS 416,995 (2,920 ) 606,021 (16,350 ) 135 1,023,016 (19,270 ) Agency CMBS 54,182 (851 ) 533,844 (19,399 ) 36 588,026 (20,250 ) CMBS 23,869 (74 ) — — 6 23,869 (74 ) CLO 56,335 (134 ) — — 3 56,335 (134 ) Single issuer-trust preferred 7,050 (46 ) — — 1 7,050 (46 ) Corporate debt 11,082 (395 ) 6,265 (284 ) 4 17,347 (679 ) Available-for-sale in an unrealized loss position $ 650,514 $ (4,869 ) $ 1,265,234 $ (39,398 ) 212 $ 1,915,748 $ (44,267 ) Held-to-maturity: Agency CMO $ 98,090 $ (1,082 ) $ 106,775 $ (3,742 ) 22 $ 204,865 $ (4,824 ) Agency MBS 762,107 (4,555 ) 1,197,839 (32,887 ) 205 1,959,946 (37,442 ) Agency CMBS 576,770 (7,599 ) 109,785 (2,412 ) 56 686,555 (10,011 ) Municipal bonds and notes 6,432 (38 ) 226,861 (6,520 ) 92 233,293 (6,558 ) CMBS 92,670 (413 ) 14,115 (207 ) 13 106,785 (620 ) Held-to-maturity in an unrealized loss position $ 1,536,069 $ (13,687 ) $ 1,655,375 $ (45,768 ) 388 $ 3,191,444 $ (59,455 )
Summary of Debt Securities by Contractual Maturity	The amortized cost and fair value of debt securities by contractual maturity are set forth below: At March 31, 2018 Available-for-Sale Held-to-Maturity (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 449 $ 449 $ 24,222 $ 24,489 Due after one year through five years 54,883 55,020 3,532 3,545 Due after five through ten years 343,072 343,803 42,410 42,687 Due after ten years 2,449,127 2,374,234 4,338,157 4,226,318 Total debt securities $ 2,847,531 $ 2,773,506 $ 4,408,321 $ 4,297,039

Loans and Leases (Tables)

Loans and Leases (Tables)	3 Months Ended
	Mar. 31, 2018
Loans and Leases Receivable Disclosure [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	The following table summarizes loans and leases: (In thousands) At March 31, At December 31, 2017 Residential $ 4,459,862 $ 4,490,878 Consumer 2,522,380 2,590,225 Commercial 5,759,124 5,368,694 Commercial Real Estate 4,544,831 4,523,828 Equipment Financing 519,378 550,233 Loans and leases (1) (2) $ 17,805,575 $ 17,523,858 (1) Loans and leases include net deferred fees and net premiums/discounts of $17.9 million and $20.6 million at March 31, 2018 and December 31, 2017 , respectively. (2) At March 31, 2018 the Company had pledged $6.6 billion
Past Due Financing Receivables	The following tables summarize the aging of loans and leases: At March 31, 2018 (In thousands) 30-59 Days Past Due and Accruing 60-89 Days 90 or More Days Past Due and Accruing Non-accrual Total Past Due and Non-accrual Current Total Loans Residential $ 13,829 $ 3,571 $ — $ 44,574 $ 61,974 $ 4,397,888 $ 4,459,862 Consumer: Home equity 8,951 5,627 — 35,894 50,472 2,239,473 2,289,945 Other consumer 2,008 1,061 — 1,614 4,683 227,752 232,435 Commercial: Commercial non-mortgage 1,526 236 604 42,990 45,356 4,839,497 4,884,853 Asset-based — — — 1,534 1,534 872,737 874,271 Commercial real estate: Commercial real estate 508 603 245 3,889 5,245 4,343,274 4,348,519 Commercial construction — — — — — 196,312 196,312 Equipment financing 2,840 156 — 3,668 6,664 512,714 519,378 Total $ 29,662 $ 11,254 $ 849 $ 134,163 $ 175,928 $ 17,629,647 $ 17,805,575 At December 31, 2017 (In thousands) 30-59 Days 60-89 Days Past Due and Accruing 90 or More Days Past Due Non-accrual Total Past Due and Non-accrual Current Total Loans Residential $ 8,643 $ 5,146 $ — $ 44,481 $ 58,270 $ 4,432,608 $ 4,490,878 Consumer: Home equity 12,668 5,770 — 35,645 54,083 2,298,185 2,352,268 Other consumer 2,556 1,444 — 1,707 5,707 232,250 237,957 Commercial: Commercial non-mortgage 5,212 603 644 39,214 45,673 4,488,242 4,533,915 Asset-based — — — 589 589 834,190 834,779 Commercial real estate: Commercial real estate 478 77 248 4,484 5,287 4,238,987 4,244,274 Commercial construction — — — — — 279,554 279,554 Equipment financing 1,732 626 — 393 2,751 547,482 550,233 Total $ 31,289 $ 13,666 $ 892 $ 126,513 $ 172,360 $ 17,351,498 $ 17,523,858
Activity In Allowance For Losses	The following tables summarize the activity in, as well as the loan and lease balances that were evaluated for, the allowance for loan and lease losses (ALLL): At or for the three months ended March 31, 2018 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 19,058 $ 36,190 $ 89,533 $ 49,407 $ 5,806 $ 199,994 Provision (benefit) charged to expense 251 1,680 7,420 2,104 (455 ) 11,000 Charge-offs (917 ) (5,074 ) (1,497 ) (77 ) (45 ) (7,610 ) Recoveries 385 1,443 117 2 18 1,965 Balance, end of period $ 18,777 $ 34,239 $ 95,573 $ 51,436 $ 5,324 $ 205,349 Individually evaluated for impairment $ 4,574 $ 1,579 $ 11,166 $ 257 $ 21 $ 17,597 Collectively evaluated for impairment $ 14,203 $ 32,660 $ 84,407 $ 51,179 $ 5,303 $ 187,752 Loan and lease balances: Individually evaluated for impairment $ 111,937 $ 42,587 $ 76,573 $ 10,928 $ 6,455 $ 248,480 Collectively evaluated for impairment 4,347,925 2,479,793 5,682,551 4,533,903 512,923 17,557,095 Loans and leases $ 4,459,862 $ 2,522,380 $ 5,759,124 $ 4,544,831 $ 519,378 $ 17,805,575 At or for the three months ended March 31, 2017 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 23,226 $ 45,233 $ 71,905 $ 47,477 $ 6,479 $ 194,320 (Benefit) provision charged to expense (2,467 ) 5,326 4,250 3,345 46 10,500 Charge-offs (732 ) (6,474 ) (123 ) (102 ) (185 ) (7,616 ) Recoveries 237 1,323 322 7 14 1,903 Balance, end of period $ 20,264 $ 45,408 $ 76,354 $ 50,727 $ 6,354 $ 199,107 Individually evaluated for impairment $ 6,981 $ 2,605 $ 11,564 $ 256 $ 5 $ 21,411 Collectively evaluated for impairment $ 13,283 $ 42,803 $ 64,790 $ 50,471 $ 6,349 $ 177,696 Loan and lease balances: Individually evaluated for impairment $ 120,976 $ 47,281 $ 86,805 $ 23,954 $ 6,148 $ 285,164 Collectively evaluated for impairment 4,169,709 2,586,782 4,932,578 4,506,553 613,713 16,809,335 Loans and leases $ 4,290,685 $ 2,634,063 $ 5,019,383 $ 4,530,507 $ 619,861 $ 17,094,499
Impaired Loans	The following tables summarize impaired loans and leases: At March 31, 2018 (In thousands) Unpaid Principal Balance Total Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential $ 122,063 $ 111,937 $ 70,143 $ 41,794 $ 4,574 Consumer - home equity 47,452 42,587 32,408 10,179 1,579 Commercial : Commercial non-mortgage 83,660 75,039 30,078 44,961 11,166 Asset-based 4,282 1,534 1,534 — — Commercial real estate: Commercial real estate 11,690 10,928 6,305 4,623 257 Commercial construction 212 — — — — Equipment financing 6,465 6,455 5,999 456 21 Total $ 275,824 $ 248,480 $ 146,467 $ 102,013 $ 17,597 At December 31, 2017 (In thousands) Unpaid Principal Balance Total Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential $ 125,352 $ 114,295 $ 69,759 $ 44,536 $ 4,805 Consumer - home equity 50,809 45,436 34,418 11,018 1,668 Commercial : Commercial non-mortgage 79,900 71,882 27,313 44,569 9,786 Asset-based 3,272 589 589 — — Commercial real estate: Commercial real estate 11,994 11,226 6,387 4,839 272 Commercial construction — — — — — Equipment financing 3,409 3,325 2,932 393 23 Total $ 274,736 $ 246,753 $ 141,398 $ 105,355 $ 16,554 The following table summarizes the average recorded investment and interest income recognized for impaired loans and leases: Three months ended March 31, 2018 2017 (In thousands) Average Recorded Investment Accrued Cash Basis Interest Income Average Recorded Investment Accrued Cash Basis Interest Income Residential $ 113,116 $ 981 $ 253 $ 120,200 $ 1,070 $ 415 Consumer - home equity 44,011 294 250 46,500 322 313 Commercial Commercial Non-Mortgage 73,461 539 — 69,921 222 — Asset based 1,061 — — — — — Commercial real estate: Commercial real estate 11,077 96 — 23,170 135 — Commercial construction — — — 1,184 12 — Equipment financing 4,890 36 — 6,284 71 — Total $ 247,616 $ 1,946 $ 503 $ 267,259 $ 1,832 $ 728
Financing Receivable Credit Quality Indicators	The following table summarizes commercial, commercial real estate and equipment financing loans and leases segregated by risk rating exposure: Commercial Commercial Real Estate Equipment Financing (In thousands) At March 31, At December 31, At March 31, At December 31, At March 31, At December 31, (1) - (6) Pass $ 5,337,985 $ 5,048,162 $ 4,384,598 $ 4,355,916 $ 493,311 $ 525,105 (7) Special Mention 210,164 104,594 44,742 62,065 7,119 8,022 (8) Substandard 201,959 206,883 115,491 105,847 18,948 17,106 (9) Doubtful 9,016 9,055 — — — — Total $ 5,759,124 $ 5,368,694 $ 4,544,831 $ 4,523,828 $ 519,378 $ 550,233
Troubled Debt Restructurings on Financing Receivables	Troubled Debt Restructurings The following table summarizes information for troubled debt restructurings (TDRs): (Dollars in thousands) At March 31, At December 31, 2017 Accrual status $ 141,608 $ 147,113 Non-accrual status 77,930 74,291 Total recorded investment of TDRs $ 219,538 $ 221,404 Specific reserves for TDRs included in the balance of ALLL $ 13,874 $ 12,384 Additional funds committed to borrowers in TDR status 3,347 2,736 For the portion of TDRs deemed to be uncollectible, Webster charged off $0.7 million , and $2.0 million for the three months ended March 31, 2018 and 2017 , respectively. The following table provides information on the type of concession for loans and leases modified as TDRs: Three months ended March 31, 2018 2017 Number of Post- (1) Number of Post- (1) (Dollars in thousands) Residential: Extended Maturity — $ — 5 $ 970 Maturity/Rate Combined — — 3 492 Other (2) 5 757 19 2,938 Consumer - home equity Extended Maturity 2 193 2 39 Maturity/Rate Combined 2 113 7 1,983 Other (2) 11 778 33 2,193 Commercial non - mortgage Extended Maturity 3 85 2 35 Other (2) 2 4,684 1 4 Commercial real estate: Extended Maturity 1 45 — — Total TDRs 26 $ 6,655 72 $ 8,654 (1) Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant. (2) Other includes covenant modifications, forbearance, loans discharged under Chapter 7 bankruptcy, or other concessions. There were no significant amounts of loans and leases modified as TDRs within the previous 12 months and for which there was a payment default for the three months ended March 31, 2018 or 2017 . The recorded investment of TDRs in commercial, commercial real estate, and equipment financing segregated by risk rating exposure is as follows: (In thousands) At March 31, 2018 At December 31, 2017 (1) - (6) Pass $ 8,591 $ 8,268 (7) Special Mention 349 355 (8) Substandard 56,074 53,050 (9) Doubtful — — Total $ 65,014 $ 61,673

Transfers of Financial Assets (

Transfers of Financial Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Transfers and Servicing [Abstract]
Schedule Of Reserve For Loan Repurchases Table	The following table provides a summary of activity in the reserve for loan repurchases: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 872 $ 790 (Benefit) provision charged to expense (203 ) 34 Repurchased loans and settlements charged off (5 ) — Ending balance $ 664 $ 824 Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 2,362 $ 2,287 (Benefit) provision charged to expense (68 ) 368 Ending balance $ 2,294 $ 2,655
Transfer of Financial Assets Accounted for as Sales [Table Text Block]	Three months ended March 31, (In thousands) 2018 2017 Residential mortgage loans held for sale: Proceeds from sale $ 44,806 $ 106,620 Loans sold with servicing rights retained 39,904 99,500 Net gain on sale 1,083 251 Ancillary fees 410 768 Fair value option adjustment (349 ) 1,247
Servicing Asset at Amortized Cost [Table Text Block]	The following table presents the changes in carrying value for mortgage servicing assets: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 25,139 $ 24,466 Additions 1,412 2,009 Amortization (2,148 ) (2,139 ) Ending balance $ 24,403 $ 24,336

Goodwill and Other Intangible31

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	Goodwill and other intangible assets by reportable segment consisted of the following: At March 31, 2018 At December 31, 2017 (In thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Goodwill: Community Banking $ 516,560 $ 516,560 HSA Bank 21,813 21,813 Total goodwill $ 538,373 $ 538,373 Other intangible assets: HSA Bank - Core deposits $ 22,000 $ (9,167 ) $ 12,833 $ 22,000 $ (8,610 ) $ 13,390 HSA Bank - Customer relationships 21,000 (5,183 ) 15,817 21,000 (4,779 ) 16,221 Total other intangible assets $ 43,000 $ (14,350 ) $ 28,650 $ 43,000 $ (13,389 ) $ 29,611
Schedule Of Expected Amortization Expense, Next Four Years	As of March 31, 2018 , the remaining estimated aggregate future amortization expense for intangible assets is as follows: (In thousands) Remainder of 2018 $ 2,886 2019 3,847 2020 3,847 2021 3,847 2022 3,847 Thereafter 10,376

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Deposit Liabilities, Type [Table Text Block]	A summary of deposits by type follows: (In thousands) At March 31, At December 31, Non-interest-bearing: Demand $ 4,074,992 $ 4,191,496 Interest-bearing: Checking 2,624,885 2,736,952 Health savings accounts 5,487,627 5,038,681 Money market 2,344,526 2,209,492 Savings 4,299,759 4,348,700 Time deposits 2,553,253 2,468,408 Total interest-bearing 17,310,050 16,802,233 Total deposits $ 21,385,042 $ 20,993,729 Time deposits and interest-bearing checking, included in above balances, obtained through brokers $ 864,362 $ 898,157 Time deposits, included in above balance, that meet or exceed the Federal Deposit Insurance Corporation (FDIC) limit 741,349 561,512 Deposit overdrafts reclassified as loan balances 1,984 2,210
Time Deposit Maturities [Table Text Block]	The scheduled maturities of time deposits are as follows: (In thousands) At March 31, Remainder of 2018 $ 1,301,903 2019 822,693 2020 246,205 2021 117,426 2022 49,543 Thereafter 15,483 Total time deposits $ 2,553,253

Borrowings (Tables)

Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Repurchase Agreements	The following table summarizes securities sold under agreements to repurchase and other borrowings: At March 31, At December 31, (In thousands) Amount Rate Amount Rate Securities sold under agreements to repurchase (1) : Original maturity of one year or less $ 215,299 0.18 % $ 288,269 0.17 % Original maturity of greater than one year, non-callable 300,000 3.10 300,000 3.10 Total securities sold under agreements to repurchase 515,299 1.88 588,269 1.66 Fed funds purchased 416,000 1.72 55,000 1.37 Securities sold under agreements to repurchase and other borrowings $ 931,299 1.81 $ 643,269 1.64
Federal Home Loan Bank, Advances	The following table provides information for FHLB advances: At March 31, At December 31, (Dollars in thousands) Amount Weighted- Average Contractual Coupon Rate Amount Weighted- Average Contractual Coupon Rate Maturing within 1 year $ 700,000 1.81 % $ 1,150,000 1.48 % After 1 but within 2 years 128,026 1.82 103,026 1.81 After 2 but within 3 years 165,000 1.77 215,000 1.73 After 3 but within 4 years (1) 200,000 2.33 200,000 2.06 After 4 but within 5 years 165 — 170 — After 5 years (1) 8,839 2.65 8,909 2.65 FHLB advances and overall rate (1) $ 1,202,030 1.90 $ 1,677,105 1.61 Aggregate carrying value of assets pledged as collateral $ 6,327,590 $ 6,402,066 Remaining borrowing capacity 3,035,521 2,600,624 (1) Weighted-average contractual coupon rates for December 31, 2017 are presented as revised for these classifications to correct an immaterial error in presentation. The percentages included in the Company's Annual Report on Form 10-K as reported were: After 3 but within 4 years - 4.13% ; After 5 years - 1.96% ; and overall rate - 1.85%
Schedule of Long-term Debt Instruments	The following table summarizes long-term debt: (Dollars in thousands) At March 31, At December 31, 4.375% Senior fixed-rate notes due February 15, 2024 $ 150,000 $ 150,000 Junior subordinated debt Webster Statutory Trust I floating-rate notes due September 17, 2033 (1) 77,320 77,320 Total notes and subordinated debt 227,320 227,320 Discount on senior fixed-rate notes (697 ) (727 ) Debt issuance cost on senior fixed-rate notes (793 ) (826 ) Long-term debt $ 225,830 $ 225,767 (1) The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month London Interbank Offered Rate (LIBOR) plus 2.95% , was 5.13% at March 31, 2018 and 4.55% at December 31, 2017

Accumulated Other Comprehensi34

Accumulated Other Comprehensive Loss, Net of Tax (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Loss by Component	The following tables summarize the changes in accumulated other comprehensive loss, net of tax (AOCL) by component: Three months ended March 31, 2018 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (27,947 ) $ (15,016 ) $ (48,568 ) $ (91,531 ) Other comprehensive income (loss) (OCI/OCL) before reclassifications (27,424 ) 1,129 — (26,295 ) Amounts reclassified from AOCL — 1,393 954 2,347 Net current-period OCI/OCL (27,424 ) 2,522 954 (23,948 ) Ending balance $ (55,371 ) $ (12,494 ) $ (47,614 ) $ (115,479 ) Three months ended March 31, 2017 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (15,476 ) $ (17,068 ) $ (44,449 ) $ (76,993 ) OCI/OCL before reclassifications (2,225 ) 61 — (2,164 ) Amounts reclassified from AOCL — 1,098 1,032 2,130 Net current-period OCI/OCL (2,225 ) 1,159 1,032 (34 ) Ending balance $ (17,701 ) $ (15,909 ) $ (43,417 ) $ (77,027 )
Schedule of Accumulated Other Comprehensive Loss	The following tables provide information for the items reclassified from AOCL: (In thousands) Three months ended March 31, Associated Line Item in the Condensed Consolidated Statements of Income AOCL Components 2018 2017 Derivative instruments: Cash flow hedges $ (1,871 ) $ (1,735 ) Total interest expense Tax benefit 478 637 Income tax expense Net of tax $ (1,393 ) $ (1,098 ) Defined benefit pension and other postretirement benefit plans: Amortization of net loss $ (1,285 ) $ (1,638 ) (1) Tax benefit 331 606 Income tax expense Net of tax $ (954 ) $ (1,032 )

Regulatory Matters (Tables)

Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2018
Regulatory Capital Requirements [Abstract]
Information On The Capital Ratios	The following table provides information on the capital ratios for Webster Financial Corporation and Webster Bank: At March 31, 2018 Actual Minimum Requirement Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio Webster Financial Corporation CET1 risk-based capital $ 2,094,607 10.99 % $ 857,874 4.5 % $ 1,239,151 6.5 % Total risk-based capital 2,524,608 13.24 1,525,109 8.0 1,906,386 10.0 Tier 1 risk-based capital 2,239,644 11.75 1,143,832 6.0 1,525,109 8.0 Tier 1 leverage capital 2,239,644 8.54 1,049,009 4.0 1,311,261 5.0 Webster Bank CET1 risk-based capital $ 2,062,650 10.83 % $ 857,184 4.5 % $ 1,238,155 6.5 % Total risk-based capital 2,270,294 11.92 1,523,883 8.0 1,904,853 10.0 Tier 1 risk-based capital 2,062,650 10.83 1,142,912 6.0 1,523,883 8.0 Tier 1 leverage capital 2,062,650 7.87 1,048,468 4.0 1,310,585 5.0 At December 31, 2017 Actual Minimum Requirement Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio Webster Financial Corporation CET1 risk-based capital $ 2,093,116 11.14 % $ 845,389 4.5 % $ 1,221,118 6.5 % Total risk-based capital 2,517,848 13.40 1,502,914 8.0 1,878,643 10.0 Tier 1 risk-based capital 2,238,172 11.91 1,127,186 6.0 1,502,914 8.0 Tier 1 leverage capital 2,238,172 8.63 1,036,817 4.0 1,296,021 5.0 Webster Bank CET1 risk-based capital $ 2,114,224 11.26 % $ 844,693 4.5 % $ 1,220,113 6.5 % Total risk-based capital 2,316,580 12.34 1,501,677 8.0 1,877,097 10.0 Tier 1 risk-based capital 2,114,224 11.26 1,126,258 6.0 1,501,677 8.0 Tier 1 leverage capital 2,114,224 8.14 1,038,442 4.0 1,298,052 5.0

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share Basic And Diluted	Reconciliation of the calculation of basic and diluted earnings per common share follows: Three months ended March 31, (In thousands, except per share data) 2018 2017 Earnings for basic and diluted earnings per common share: Net income $ 80,225 $ 59,471 Less: Preferred stock dividends 1,947 2,024 Net income available to common shareholders 78,278 57,447 Less: Earnings applicable to participating securities 195 105 Earnings applicable to common shareholders $ 78,083 $ 57,342 Shares: Weighted-average common shares outstanding - basic 91,921 91,886 Effect of dilutive securities: Stock options and restricted stock 327 450 Warrants 6 6 Weighted-average common shares outstanding - diluted 92,254 92,342 Earnings per common share: Basic $ 0.85 $ 0.62 Diluted 0.85 0.62
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Potential common shares from non-participating restricted stock, of $72 thousand and $40 thousand for the three months ended March 31, 2018 and 2017 , respectively, are excluded from the effect of dilutive securities because, due to performance conditions, they would have been anti-dilutive.

Derivative Financial Instrume37

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value Of Derivative Financial Instruments Designated As Cash Flow Hedges	The following table presents the notional amounts and fair value of derivative positions: At March 31, 2018 At December 31, 2017 Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives (In thousands) Notional Fair Notional Fair Notional Fair Notional Fair Designated as hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) $ 325,000 $ 4,289 $ — $ — $ 325,000 $ 2,770 $ — $ — Not designated as hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) 3,258,511 10,659 437,308 848 2,791,760 5,977 721,048 1,968 Mortgage banking derivatives (3) 34,744 545 31,162 168 28,497 421 39,230 110 Other 17,763 144 17,788 61 7,914 258 30,328 419 Positions not subject to a master netting agreement (4) Interest rate derivatives 636,754 9,863 3,059,075 57,952 1,366,299 23,009 2,146,518 25,631 RPAs 93,275 48 84,999 69 93,713 80 116,882 111 Other 530 3 861 17 — — 2,073 184 Total not designated as hedging instruments 4,041,577 21,262 3,631,193 59,115 4,288,183 29,745 3,056,079 28,423 Gross derivative instruments, before netting $ 4,366,577 25,551 $ 3,631,193 59,115 $ 4,613,183 32,515 $ 3,056,079 28,423 Less: Legally enforceable master netting agreements 818 818 2,245 2,245 Less: Cash collateral posted 13,994 — 6,704 — Total derivative instruments, after netting $ 10,739 $ 58,297 $ 23,566 $ 26,178 (1) The Company has elected to report derivative positions subject to a legally enforceable master netting agreement on a net basis, net of cash collateral. Refer to the Offsetting Derivatives section of this footnote for additional information. (2) In accordance with the Chicago Mercantile Exchange (CME) rulebook, balances related to CME are presented as a single unit of account. (3) Notional amounts include mandatory forward commitments of $37.0 million , while notional amounts do not include approved floating rate commitments of $15.1 million , at March 31, 2018
Other Derivatives Not Designated For Hedge Accounting	Three months ended March 31, (In thousands) 2018 2017 Designated as hedging instruments: Interest rate derivatives (1) $ 1,823 $ 2,039 Not designated as hedging instruments: Interest rate derivatives $ 3,791 $ 1,534 RPAs 10 53 Mortgage banking derivatives 65 (2,041 ) Other (600 ) (447 ) Total not designated as hedging instruments (2) $ 3,266 $ (901 )
Offsetting Liabilities	The following table presents the transition from a gross basis to net basis, due to the application of counterparty netting agreements: At March 31, 2018 At December 31, 2017 (In thousands) Gross Amount Relationship Offset Cash Collateral Offset Net Amount Gross Amount Relationship Offset Cash Collateral Offset Net Amount Derivative instrument gains: Hedge accounting $ 4,289 $ — $ 4,289 $ — $ 2,770 $ 91 $ 2,679 $ — Non-hedge accounting 10,523 818 9,705 — 6,222 2,154 4,025 43 Total assets $ 14,812 $ 818 $ 13,994 $ — $ 8,992 $ 2,245 $ 6,704 $ 43 Derivative instrument losses: Hedge accounting $ — $ — $ — $ — $ — $ — $ — $ — Non-hedge accounting 909 818 — 91 2,387 2,245 — 142 Total liabilities $ 909 $ 818 $ — $ 91 $ 2,387 $ 2,245 $ — $ 142

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Of Assets And Liabilities Measured On Recurring Basis	Summaries of the fair values of assets and liabilities measured at fair value on a recurring basis are as follows: At March 31, 2018 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 449 $ — $ — $ 449 Agency CMO — 284,579 — 284,579 Agency MBS — 1,265,268 — 1,265,268 Agency CMBS — 591,302 — 591,302 CMBS — 366,894 — 366,894 CLO — 201,837 — 201,837 Single issuer-trust preferred — 7,041 — 7,041 Corporate debt — 56,136 — 56,136 Total available-for-sale investment securities 449 2,773,057 — 2,773,506 Gross derivative instruments, before netting (1) 147 25,404 — 25,551 Originated loans held for sale — 19,727 — 19,727 Investments held in Rabbi Trust 4,694 — — 4,694 Alternative investments (NAV) (2) — — — 3,495 Total financial assets held at fair value $ 5,290 $ 2,818,188 $ — $ 2,826,973 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 62 $ 59,053 $ — $ 59,115 At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 1,247 $ — $ — $ 1,247 Agency CMO — 306,333 — 306,333 Agency MBS — 1,107,841 — 1,107,841 Agency CMBS — 588,026 — 588,026 CMBS — 361,067 — 361,067 CLO — 209,851 — 209,851 Single issuer-trust preferred — 7,050 — 7,050 Corporate debt — 56,622 — 56,622 Total available-for-sale investment securities 1,247 2,636,790 — 2,638,037 Gross derivative instruments, before netting (1) 258 32,257 — 32,515 Originated loans held for sale — 20,888 — 20,888 Investments held in Rabbi Trust 4,801 — — 4,801 Alternative investments (NAV) (2) — — — 3,495 Total financial assets held at fair value $ 6,306 $ 2,689,935 $ — $ 2,699,736 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 587 $ 27,836 $ — $ 28,423 (1) For information relating to the impact of netting derivative assets and derivative liabilities as well as the impact from offsetting cash collateral paid to the same derivative counterparties see Note 12: Derivative Financial Instruments
Schedule Of Quantitative Inputs And Assumptions For Items Categorized In Level 3 Of The Fair Value Hierarchy
Fair Value, Option, Quantitative Disclosures [Table Text Block]	The following table presents the fair value, unpaid principal balance, and accrual status of assets accounted for under the fair value option: March 31, 2018 December 31, 2017 (In thousands) Fair Value Unpaid Principal Balance Difference Fair Value Unpaid Principal Balance Difference Originated loans held for sale $ 19,727 $ 19,663 $ 64 $ 20,888 $ 20,346 $ 542 Electing to measure originated loans held for sale at fair value reduces certain timing differences and better matches changes in the value of these assets with changes in the value of the derivatives used as an economic hedge on these assets. Assets accounted for under the fair value option are initially measured at fair value. Gains and losses from initial measurement and subsequent changes in fair value are recognized in earnings. For the three months ended March 31, 2018 net loss from fair value changes was $0.3 million and for the three months ended March 31, 2017 net gains from fair value changes was $1.2 million
Schedule Of Valuation Methodology And Unobservable Inputs	The table below presents the valuation methodology and unobservable inputs for Level 3 assets measured at fair value on a non-recurring basis as of March 31, 2018 : (Dollars in thousands) Asset Fair Value Valuation Methodology Unobservable Inputs Range of Inputs Collateral dependent impaired loans and leases $ 13,424 Real Estate Appraisals Discount for appraisal type 0% - 15% Discount for costs to sell 0% - 8% OREO $ 858 Real Estate Appraisals Discount for costs to sell 8%
Summary Of Estimated Fair Values Of Significant Financial Instruments	The estimated fair values of selected financial instruments and servicing assets are as follows: At March 31, 2018 At December 31, 2017 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Level 2 Held-to-maturity investment securities $ 4,408,321 $ 4,297,039 $ 4,487,392 $ 4,456,350 Level 3 Loans and leases, net 17,600,226 17,391,087 17,323,864 17,211,619 Mortgage servicing assets 24,403 51,668 25,139 45,309 Liabilities: Level 2 Deposit liabilities $ 18,831,789 $ 18,831,789 $ 18,525,321 $ 18,525,321 Time deposits 2,553,253 2,527,441 2,468,408 2,455,245 Securities sold under agreements to repurchase and other borrowings 931,299 930,683 643,269 644,084 FHLB advances 1,202,030 1,204,045 1,677,105 1,678,070 Long-term debt (1) 225,830 232,586 225,767 234,359 (1) Adjustments to the carrying amount of long-term debt for unamortized discount and debt issuance cost on senior fixed-rate notes are not included for determination of fair value, see Note 8: Borrowings

Retirement Benefit Plans (Table

Retirement Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Summary of Net Periodic Benefit Cost	The following table summarizes the components of net periodic benefit cost: Three months ended March 31, 2018 2017 (In thousands) Pension Plan SERP Other Benefits Pension Plan SERP Other Benefits Service cost $ — $ — $ — $ 12 $ — $ — Interest cost on benefit obligations 1,785 187 20 1,813 92 25 Expected return on plan assets (3,180 ) — — (3,073 ) — — Amortization of prior service cost — — — — — — Recognized net loss 1,160 125 — 1,417 213 8 Net periodic benefit cost $ (235 ) $ 312 $ 20 $ 169 $ 305 $ 33

Share-Based Plans (Tables)

Share-Based Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Activity	The following table provides a summary of the stock compensation plans activity for the three months ended March 31, 2018 : Restricted Stock Awards Outstanding Stock Options Outstanding Time-Based Performance-Based Number of Shares Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Exercise Price Outstanding, at January1, 2018 207,800 $ 43.16 78,916 $ 45.35 673,039 $ 18.75 Granted 113,264 56.58 75,707 55.82 — — Exercised options — — — — 11,516 25.15 Vested restricted stock awards (1) 46,137 41.46 19,398 43.01 — — Forfeited 1,144 35.61 — — — — Outstanding and exercisable, at March 31, 2018 273,783 $ 48.96 135,225 $ 51.54 661,523 $ 18.64 (1)

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Operating Results And Total Assets Reportable Segments	The following table presents total assets for Webster's reportable segments and the Corporate and Reconciling category: Total Assets (In thousands) Commercial Banking Community Banking HSA Bank Corporate and Reconciling Consolidated Total At March 31, 2018 $ 9,718,543 $ 8,828,329 $ 77,883 $ 8,127,392 $ 26,752,147 At December 31, 2017 9,350,028 8,909,671 76,308 8,151,638 26,487,645 The following tables present the operating results, including all appropriate allocations, for Webster’s reportable segments and the Corporate and Reconciling category: Three months ended March 31, 2018 (In thousands) Commercial Banking Community Banking HSA Bank Corporate and Reconciling Consolidated Total Net interest income (expense) $ 84,651 $ 98,928 $ 32,924 $ (2,335 ) $ 214,168 Provision for loan and lease losses 7,178 3,822 — — 11,000 Net interest income (expense) after provision for loan and lease losses 77,473 95,106 32,924 (2,335 ) 203,168 Non-interest income 15,316 25,195 22,669 5,567 68,747 Non-interest expense 41,245 96,829 31,515 2,026 171,615 Income before income tax expense 51,544 23,472 24,078 1,206 100,300 Income tax expense (benefit) 12,680 4,671 6,260 (3,536 ) 20,075 Net income $ 38,864 $ 18,801 $ 17,818 $ 4,742 $ 80,225 Three months ended March 31, 2017 (In thousands) Commercial Banking Community Banking HSA Bank Corporate and Reconciling Consolidated Total Net interest income (expense) $ 78,247 $ 93,590 $ 24,052 $ (3,225 ) $ 192,664 Provision for loan and lease losses 6,797 3,703 — — 10,500 Net interest income (expense) after provision for loan and lease losses 71,450 89,887 24,052 (3,225 ) 182,164 Non-interest income 13,424 25,379 19,271 4,968 63,042 Non-interest expense 38,124 95,179 28,239 2,242 163,784 Income (loss) before income tax expense 46,750 20,087 15,084 (499 ) 81,422 Income tax expense (benefit) 12,604 5,416 4,066 (135 ) 21,951 Net income (loss) $ 34,146 $ 14,671 $ 11,018 $ (364 ) $ 59,471

Revenue from Contracts with C42

Revenue from Contracts with Customers Disaggregation of Revenue (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables present the disaggregation by operating segment and major revenue stream, with disaggregated revenue reconciled to segment revenue as presented in Note 16: Segment Reporting : Three months ended March 31, 2018 (In thousands) Commercial Community HSA Corporate and Consolidated Major Revenue Streams Deposit service fees $ 3,222 $ 15,309 $ 21,812 $ 108 $ 40,451 Wealth and investment services 2,539 5,339 — (8 ) 7,870 Other income — 493 857 — 1,350 Revenue from contracts with customers 5,761 21,141 22,669 100 49,671 Non-interest income within the scope of other GAAP topics 9,555 4,054 — 5,467 19,076 Total non-interest income $ 15,316 $ 25,195 $ 22,669 $ 5,567 $ 68,747 Three months ended March 31, 2017 (In thousands) Commercial Community HSA Corporate and Consolidated Major Revenue Streams Deposit service fees $ 2,878 $ 15,530 $ 18,484 $ 114 $ 37,006 Wealth and investment services 2,372 4,909 — (8 ) 7,273 Other income — 224 787 — 1,011 Revenue from contracts with customers 5,250 20,663 19,271 106 45,290 Non-interest income within the scope of other GAAP topics 8,174 4,716 — 4,862 17,752 Total non-interest income $ 13,424 $ 25,379 $ 19,271 $ 4,968 $ 63,042

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Outstanding Financial Instruments Contract Amounts Represent Credit Risk	The following table summarizes the outstanding amounts of credit-related financial instruments with off-balance sheet risk: (In thousands) At March 31, 2018 At December 31, 2017 Commitments to extend credit $ 5,648,126 $ 5,567,687 Standby letter of credit 167,899 195,902 Commercial letter of credit 44,535 43,200 Total credit-related financial instruments with off-balance sheet risk $ 5,860,560 $ 5,806,789
Reserve For Unfunded Credit Commitments	The following table provides a summary of activity in the reserve for loan repurchases: Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 872 $ 790 (Benefit) provision charged to expense (203 ) 34 Repurchased loans and settlements charged off (5 ) — Ending balance $ 664 $ 824 Three months ended March 31, (In thousands) 2018 2017 Beginning balance $ 2,362 $ 2,287 (Benefit) provision charged to expense (68 ) 368 Ending balance $ 2,294 $ 2,655

Summary of Significant Accoun44

Summary of Significant Accounting Policies New Accounting Pronouncements or Change in Accounting Principle (Details) $ in Millions	Mar. 31, 2018USD ($)
ASU No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 2.8
ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10) [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 1.4

Investment Securities (Summary

Investment Securities (Summary Of Investment Securities) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities [Abstract]
Amortized Cost	$ 2,847,531	$ 2,675,131
Unrealized Gains	5,280	7,173
Unrealized Losses	(79,305)	(44,267)
Fair Value	2,773,506	2,638,037
Held-to-maturity Securities [Abstract]
Amortized Cost	4,408,321	4,487,392
Unrealized Gains	16,279	28,413
Unrealized Losses	(127,561)	(59,455)
Fair Value	4,297,039	4,456,350
US Treasury Bill Securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	449	1,247
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	449	1,247
Agency CMO [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	290,105	308,989
Unrealized Gains	526	1,158
Unrealized Losses	(6,052)	(3,814)
Fair Value	284,579	306,333
Held-to-maturity Securities [Abstract]
Amortized Cost	245,663	260,114
Unrealized Gains	417	664
Unrealized Losses	(7,139)	(4,824)
Fair Value	238,941	255,954
Agency MBS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	1,304,856	1,124,960
Unrealized Gains	1,522	2,151
Unrealized Losses	(41,110)	(19,270)
Fair Value	1,265,268	1,107,841
Held-to-maturity Securities [Abstract]
Amortized Cost	2,544,104	2,569,735
Unrealized Gains	12,571	16,989
Unrealized Losses	(80,678)	(37,442)
Fair Value	2,475,997	2,549,282
Agency CMBS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	622,400	608,276
Unrealized Gains	0	0
Unrealized Losses	(31,098)	(20,250)
Fair Value	591,302	588,026
Held-to-maturity Securities [Abstract]
Amortized Cost	689,602	696,566
Unrealized Gains	0	0
Unrealized Losses	(20,744)	(10,011)
Fair Value	668,858	686,555
Non-agency CMBS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	365,006	358,984
Unrealized Gains	2,045	2,157
Unrealized Losses	(157)	(74)
Fair Value	366,894	361,067
Held-to-maturity Securities [Abstract]
Amortized Cost	236,172	249,273
Unrealized Gains	891	2,175
Unrealized Losses	(2,909)	(620)
Fair Value	234,154	250,828
CLO [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	201,254	209,075
Unrealized Gains	691	910
Unrealized Losses	(108)	(134)
Fair Value	201,837	209,851
Single issuer trust preferred securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	7,111	7,096
Unrealized Gains	0	0
Unrealized Losses	(70)	(46)
Fair Value	7,041	7,050
Corporate debt securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	56,350	56,504
Unrealized Gains	496	797
Unrealized Losses	(710)	(679)
Fair Value	56,136	56,622
Municipal bonds and notes [Member]
Held-to-maturity Securities [Abstract]
Amortized Cost	692,582	711,381
Unrealized Gains	2,400	8,584
Unrealized Losses	(16,091)	(6,558)
Fair Value	678,891	713,407
Private Label MBS [Member]
Held-to-maturity Securities [Abstract]
Amortized Cost	198	323
Unrealized Gains		1
Unrealized Losses	0	0
Fair Value	$ 198	$ 324

Investment Securities (Other Th

Investment Securities (Other Than Temporary Impairment Credit Losses Recognized In Earnings) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of OTTI, beginning of period	$ 1,364	$ 3,243
Reduction for securities sold, called	0	(12)
Balance of OTTI, end of period	$ 1,364	$ 3,231

Investment Securities (Summar47

Investment Securities (Summary Of Gross Unrealized Losses Not Considered OTTI) (Detail) $ in Thousands	Mar. 31, 2018USD ($)holding	Dec. 31, 2017USD ($)holding
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 953,971	$ 650,514
Available for sale, Unrealized Losses - Less Than Twelve Months	(18,224)	(4,869)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,228,550	1,265,234
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (61,081)	$ (39,398)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	250	212
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 2,182,521	$ 1,915,748
Available for sale, Unrealized Losses - Total	(79,305)	(44,267)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,095,610	1,536,069
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(49,442)	(13,687)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,603,256	1,655,375
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (78,119)	$ (45,768)
Held-to-maturity, Number of Holdings - Total | holding	551	388
Held-to-maturity, Fair Value - Total	$ 3,698,866	$ 3,191,444
Held-to-maturity, Unrealized Losses - Total	(127,561)	(59,455)
Agency CMO [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	113,804	81,001
Available for sale, Unrealized Losses - Less Than Twelve Months	(1,601)	(449)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	110,998	119,104
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (4,451)	$ (3,365)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	34	27
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 224,802	$ 200,105
Available for sale, Unrealized Losses - Total	(6,052)	(3,814)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	104,568	98,090
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(2,199)	(1,082)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	101,482	106,775
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (4,940)	$ (3,742)
Held-to-maturity, Number of Holdings - Total | holding	22	22
Held-to-maturity, Fair Value - Total	$ 206,050	$ 204,865
Held-to-maturity, Unrealized Losses - Total	(7,139)	(4,824)
Agency MBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	597,062	416,995
Available for sale, Unrealized Losses - Less Than Twelve Months	(13,730)	(2,920)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	577,081	606,021
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (27,380)	$ (16,350)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	159	135
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 1,174,143	$ 1,023,016
Available for sale, Unrealized Losses - Total	(41,110)	(19,270)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,066,786	762,107
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(24,771)	(4,555)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,143,544	1,197,839
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (55,907)	$ (32,887)
Held-to-maturity, Number of Holdings - Total | holding	253	205
Held-to-maturity, Fair Value - Total	$ 2,210,330	$ 1,959,946
Held-to-maturity, Unrealized Losses - Total	(80,678)	(37,442)
Agency CMBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	72,147	54,182
Available for sale, Unrealized Losses - Less Than Twelve Months	(2,248)	(851)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	519,155	533,844
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (28,850)	$ (19,399)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	37	36
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 591,302	$ 588,026
Available for sale, Unrealized Losses - Total	(31,098)	(20,250)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	542,868	576,770
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(15,740)	(7,599)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	125,991	109,785
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (5,004)	$ (2,412)
Held-to-maturity, Number of Holdings - Total | holding	56	56
Held-to-maturity, Fair Value - Total	$ 668,859	$ 686,555
Held-to-maturity, Unrealized Losses - Total	(20,744)	(10,011)
Non-agency CMBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	53,552	23,869
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (157)	$ (74)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	9	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 53,552	$ 23,869
Available for sale, Unrealized Losses - Total	(157)	(74)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	148,267	92,670
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(2,595)	(413)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	13,276	14,115
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (314)	$ (207)
Held-to-maturity, Number of Holdings - Total | holding	20	13
Held-to-maturity, Fair Value - Total	$ 161,543	$ 106,785
Held-to-maturity, Unrealized Losses - Total	(2,909)	(620)
CLO [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	99,288	56,335
Available for sale, Unrealized Losses - Less Than Twelve Months	(12)	$ (134)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	15,068
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (96)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	6	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 114,356	$ 56,335
Available for sale, Unrealized Losses - Total	(108)	(134)
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	7,041	7,050
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (70)	$ (46)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 7,041	$ 7,050
Available for sale, Unrealized Losses - Total	(70)	(46)
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	11,077	11,082
Available for sale, Unrealized Losses - Less Than Twelve Months	(406)	(395)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	6,248	6,265
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (304)	$ (284)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	4	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 17,325	$ 17,347
Available for sale, Unrealized Losses - Total	(710)	(679)
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	233,121	6,432
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(4,137)	(38)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	218,963	226,861
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (11,954)	$ (6,520)
Held-to-maturity, Number of Holdings - Total | holding	200	92
Held-to-maturity, Fair Value - Total	$ 452,084	$ 233,293
Held-to-maturity, Unrealized Losses - Total	$ (16,091)	$ (6,558)

Investment Securities (Summar48

Investment Securities (Summary Of Debt Securities By Contractual Maturity) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available-for-sale, Amortized Cost - Due in one year or less	$ 449
Available-for-sale, Amortized Cost - Due after one year through five years	54,883
Available-for-sale, Amortized Cost - Due after five through ten years	343,072
Available-for-sale, Amortized Cost - Due after ten years	2,449,127
Available-for-sale, Amortized Cost - Total debt securities	2,847,531
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale, Fair Value - Due in one year or less	449
Available-for-sale, Fair Value - Due after one year through five years	55,020
Available-for-sale, Fair Value - Due after five through ten years	343,803
Available-for-sale, Fair Value - Due after ten years	2,374,234
Available-for-sale, Fair Value - Total debt securities	2,773,506
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Held-to-maturity, Amortized Cost - Due in one year or less	24,222
Held-to-maturity, Amortized Cost - Due after one year through five years	3,532
Held-to-maturity, Amortized Cost - Due after five through ten years	42,410
Held-to-maturity, Amortized Cost - Due after ten years	4,338,157
Amortized Cost	4,408,321	$ 4,487,392
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Held to maturity, Fair Value - Due in one year or less	24,489
Held-to-maturity, Fair Value - Due after one year through five years	3,545
Held to maturity, Fair Value - Due after five through ten years	42,687
Held to maturity, Fair Value - Due after ten years	4,226,318
Fair Value	$ 4,297,039	$ 4,456,350

Investment Securities Investmen

Investment Securities Investment Securities (Narrative) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities [Abstract]
Unrealized Losses	$ (79,305)	$ (44,267)
Held-to-maturity Securities [Abstract]
Unrealized Losses	(127,561)	(59,455)
Investment securities available-for-sale, at fair value	2,773,506	2,638,037
Pledged Financial Instruments, Not Separately Reported, Securities	2,600,000	2,400,000
Agency CMO [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(6,052)	(3,814)
Held-to-maturity Securities [Abstract]
Unrealized Losses	(7,139)	(4,824)
Investment securities available-for-sale, at fair value	284,579	306,333
Agency MBS [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(41,110)	(19,270)
Held-to-maturity Securities [Abstract]
Unrealized Losses	(80,678)	(37,442)
Investment securities available-for-sale, at fair value	1,265,268	1,107,841
Agency CMBS [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(31,098)	(20,250)
Held-to-maturity Securities [Abstract]
Unrealized Losses	(20,744)	(10,011)
Investment securities available-for-sale, at fair value	591,302	588,026
Non-agency CMBS [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(157)	(74)
Held-to-maturity Securities [Abstract]
Unrealized Losses	(2,909)	(620)
Investment securities available-for-sale, at fair value	366,894	361,067
CLO [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(108)	(134)
Held-to-maturity Securities [Abstract]
Investment securities available-for-sale, at fair value	201,837	209,851
Single issuer trust preferred securities [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(70)	(46)
Held-to-maturity Securities [Abstract]
Investment securities available-for-sale, at fair value	7,041	7,050
Corporate Debt Securities [Member]
Available-for-sale Securities [Abstract]
Unrealized Losses	(710)	(679)
Held-to-maturity Securities [Abstract]
Investment securities available-for-sale, at fair value	56,136	56,622
Municipal Bonds [Member]
Held-to-maturity Securities [Abstract]
Unrealized Losses	(16,091)	$ (6,558)
Callable at the option of the counterparty [Member]
Held-to-maturity Securities [Abstract]
Investment securities available-for-sale, at fair value	$ 1,200,000

Investment Securities (Narrativ

Investment Securities (Narrative) (Summary Of Realized Gain (Loss) on Investments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Gain (Loss) on Investments [Line Items]
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	$ 0	$ 0

Variable Interest Entities (Var

Variable Interest Entities (Variable Interest Entity, Consolidated, Carrying Amount, Assets) (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 32.5	$ 33.5
Accounts Payable and Accrued Liabilities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	16.2	17.3
Other Investments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	16.3	13.8
Unfunded Loan Commitment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 25.3	$ 22.9

Loans and Leases (Detail)

Loans and Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 17,805,575	$ 17,523,858	$ 17,094,499
Unamortized premiums	17,900	20,600
Pledged Financial Instruments, Not Separately Reported, Loans Receivable Pledged as Collateral	6,600,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,459,862	4,490,878	4,290,685
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,522,380	2,590,225	2,634,063
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	5,759,124	5,368,694	5,019,383
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,544,831	4,523,828	4,530,507
Finance Leases Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 519,378	$ 550,233	$ 619,861

Loans and Leases (Summary Of Lo

Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 175,928	$ 172,360
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	849	892
Financing Receivable, Recorded Investment, Nonaccrual Status	134,163	126,513
Financing Receivable, Recorded Investment, Current	17,629,647	17,351,498
Loans and leases	17,805,575	17,523,858	$ 17,094,499
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	29,662	31,289
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	11,254	13,666
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	61,974	58,270
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	44,574	44,481
Financing Receivable, Recorded Investment, Current	4,397,888	4,432,608
Loans and leases	4,459,862	4,490,878	4,290,685
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	13,829	8,643
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	3,571	5,146
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	2,522,380	2,590,225	2,634,063
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	50,472	54,083
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	35,894	35,645
Financing Receivable, Recorded Investment, Current	2,239,473	2,298,185
Loans and leases	2,289,945	2,352,268
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	8,951	12,668
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	5,627	5,770
Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	4,683	5,707
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	1,614	1,707
Financing Receivable, Recorded Investment, Current	227,752	232,250
Loans and leases	232,435	237,957
Consumer Portfolio Segment [Member] | Consumer Borrower [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,008	2,556
Consumer Portfolio Segment [Member] | Consumer Borrower [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,061	1,444
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	5,759,124	5,368,694	5,019,383
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	45,356	45,673
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	604	644
Financing Receivable, Recorded Investment, Nonaccrual Status	42,990	39,214
Financing Receivable, Recorded Investment, Current	4,839,497	4,488,242
Loans and leases	4,884,853	4,533,915
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,526	5,212
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	236	603
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,534	589
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	1,534	589
Financing Receivable, Recorded Investment, Current	872,737	834,190
Loans and leases	874,271	834,779
Commercial Portfolio Segment [Member] | Asset Based Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Portfolio Segment [Member] | Asset Based Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	4,544,831	4,523,828	4,530,507
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	0
Financing Receivable, Recorded Investment, Current	196,312	279,554
Loans and leases	196,312	279,554
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	5,245	5,287
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	245	248
Financing Receivable, Recorded Investment, Nonaccrual Status	3,889	4,484
Financing Receivable, Recorded Investment, Current	4,343,274	4,238,987
Loans and leases	4,348,519	4,244,274
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	508	478
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	603	77
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	6,664	2,751
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	3,668	393
Financing Receivable, Recorded Investment, Current	512,714	547,482
Loans and leases	519,378	550,233	$ 619,861
Finance Leases Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,840	1,732
Finance Leases Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 156	$ 626

Loans and Leases (Narrative) (D

Loans and Leases (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	$ 2.1	$ 3.1
Write-down of TDR's	$ (0.7)	$ (2)

Loans and Leases (Allowance For

Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 199,994	$ 194,320
Provision (benefit) charged to expense	11,000	10,500
Charge-offs	(7,610)	(7,616)
Recoveries	1,965	1,903
Balance, end of period	199,994	194,320	$ 205,349	$ 199,994	$ 199,107
ALLL, Individually evaluated for impairment			17,597		21,411
ALLL, Collectively evaluated for impairment			187,752		177,696
Loan and lease balances, Individually evaluated for impairment			248,480		285,164
Loan and lease balances, Collectively evaluated for impairment			17,557,095		16,809,335
Loans and leases			17,805,575	17,523,858	17,094,499
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	19,058	23,226
Provision (benefit) charged to expense	251	(2,467)
Charge-offs	(917)	(732)
Recoveries	385	237
Balance, end of period	19,058	23,226	18,777	19,058	20,264
ALLL, Individually evaluated for impairment			4,574		6,981
ALLL, Collectively evaluated for impairment			14,203		13,283
Loan and lease balances, Individually evaluated for impairment			111,937		120,976
Loan and lease balances, Collectively evaluated for impairment			4,347,925		4,169,709
Loans and leases			4,459,862	4,490,878	4,290,685
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	36,190	45,233
Provision (benefit) charged to expense	1,680	5,326
Charge-offs	(5,074)	(6,474)
Recoveries	1,443	1,323
Balance, end of period	36,190	45,233	34,239	36,190	45,408
ALLL, Individually evaluated for impairment			1,579		2,605
ALLL, Collectively evaluated for impairment			32,660		42,803
Loan and lease balances, Individually evaluated for impairment			42,587		47,281
Loan and lease balances, Collectively evaluated for impairment			2,479,793		2,586,782
Loans and leases			2,522,380	2,590,225	2,634,063
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	89,533	71,905
Provision (benefit) charged to expense	7,420	4,250
Charge-offs	(1,497)	(123)
Recoveries	117	322
Balance, end of period	89,533	71,905	95,573	89,533	76,354
ALLL, Individually evaluated for impairment			11,166		11,564
ALLL, Collectively evaluated for impairment			84,407		64,790
Loan and lease balances, Individually evaluated for impairment			76,573		86,805
Loan and lease balances, Collectively evaluated for impairment			5,682,551		4,932,578
Loans and leases			5,759,124	5,368,694	5,019,383
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	49,407	47,477
Provision (benefit) charged to expense	2,104	3,345
Charge-offs	(77)	(102)
Recoveries	2	7
Balance, end of period	49,407	47,477	51,436	49,407	50,727
ALLL, Individually evaluated for impairment			257		256
ALLL, Collectively evaluated for impairment			51,179		50,471
Loan and lease balances, Individually evaluated for impairment			10,928		23,954
Loan and lease balances, Collectively evaluated for impairment			4,533,903		4,506,553
Loans and leases			4,544,831	4,523,828	4,530,507
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	5,806	6,479
Provision (benefit) charged to expense	(455)	46
Charge-offs	(45)	(185)
Recoveries	18	14
Balance, end of period	$ 5,806	$ 6,479	5,324	5,806	6,354
ALLL, Individually evaluated for impairment			21		5
ALLL, Collectively evaluated for impairment			5,303		6,349
Loan and lease balances, Individually evaluated for impairment			6,455		6,148
Loan and lease balances, Collectively evaluated for impairment			512,923		613,713
Loans and leases			$ 519,378	$ 550,233	$ 619,861

Loans and Leases (Impaired Loan

Loans and Leases (Impaired Loans And Leases By Class) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 275,824	$ 274,736
Total Recorded Investment	248,480	246,753
Recorded Investment No Allowance	146,467	141,398
Recorded Investment With Allowance	102,013	105,355
Related Valuation Allowance	17,597	16,554
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	122,063	125,352
Total Recorded Investment	111,937	114,295
Recorded Investment No Allowance	70,143	69,759
Recorded Investment With Allowance	41,794	44,536
Related Valuation Allowance	4,574	4,805
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance		50,809
Total Recorded Investment		45,436
Recorded Investment No Allowance		34,418
Recorded Investment With Allowance		11,018
Related Valuation Allowance		1,668
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	47,452
Total Recorded Investment	42,587
Recorded Investment No Allowance	32,408
Recorded Investment With Allowance	10,179
Related Valuation Allowance	1,579
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	83,660	79,900
Total Recorded Investment	75,039	71,882
Recorded Investment No Allowance	30,078	27,313
Recorded Investment With Allowance	44,961	44,569
Related Valuation Allowance	11,166	9,786
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	4,282	3,272
Total Recorded Investment	1,534	589
Recorded Investment No Allowance	1,534	589
Recorded Investment With Allowance	0	0
Related Valuation Allowance	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	11,690	11,994
Total Recorded Investment	10,928	11,226
Recorded Investment No Allowance	6,305	6,387
Recorded Investment With Allowance	4,623	4,839
Related Valuation Allowance	257	272
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	212	0
Total Recorded Investment	0	0
Recorded Investment No Allowance	0	0
Recorded Investment With Allowance	0	0
Related Valuation Allowance	0	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	6,465	3,409
Total Recorded Investment	6,455	3,325
Recorded Investment No Allowance	5,999	2,932
Recorded Investment With Allowance	456	393
Related Valuation Allowance	$ 21	$ 23

Loans and Leases (Interest Inco

Loans and Leases (Interest Income From Impaired Loans And Leases, By Class) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 247,616	$ 267,259
Accrued Interest Income	1,946	1,832
Cash Basis Interest Income	503	728
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	113,116	120,200
Accrued Interest Income	981	1,070
Cash Basis Interest Income	253	415
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	44,011	46,500
Accrued Interest Income	294	322
Cash Basis Interest Income	250	313
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	73,461	69,921
Accrued Interest Income	539	222
Cash Basis Interest Income	0	0
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,061	0
Accrued Interest Income	0	0
Cash Basis Interest Income	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	11,077	23,170
Accrued Interest Income	96	135
Cash Basis Interest Income	0	0
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	1,184
Accrued Interest Income	0	12
Cash Basis Interest Income	0	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	4,890	6,284
Accrued Interest Income	36	71
Cash Basis Interest Income	$ 0	$ 0

Loans and Leases (Commercial, C

Loans and Leases (Commercial, Commercial Real Estate Loans And Equipment Financing Loans Segregated By Risk Rating Exposure) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 17,805,575	$ 17,523,858	$ 17,094,499
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	5,759,124	5,368,694	5,019,383
Commercial Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	5,337,985	5,048,162
Commercial Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	210,164	104,594
Commercial Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	201,959	206,883
Commercial Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	9,016	9,055
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	4,544,831	4,523,828	4,530,507
Commercial Real Estate Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	4,384,598	4,355,916
Commercial Real Estate Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	44,742	62,065
Commercial Real Estate Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	115,491	105,847
Commercial Real Estate Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	0	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	519,378	550,233	$ 619,861
Finance Leases Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	493,311	525,105
Finance Leases Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	7,119	8,022
Finance Leases Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	18,948	17,106
Finance Leases Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 0	$ 0

Loans and Leases (Summary Of Th

Loans and Leases (Summary Of The Recorded Investment Of Company's TDRs) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 219,538	$ 221,404
Specific reserves for TDRs included in the balance of ALLL	205,349	199,994	$ 199,107	$ 194,320
Additional funds committed to borrowers in TDR status	3,347	2,736
Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	141,608	147,113
Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	77,930	74,291
Nonperforming Financial Instruments [Member] | Troubled Debt Restructures [Member]
Financing Receivable, Modifications [Line Items]
Specific reserves for TDRs included in the balance of ALLL	$ 13,874	$ 12,384

Loans and Leases (Information o

Loans and Leases (Information on How Loans and Leases were Modified as a TDR) (Detail) $ in Thousands		3 Months Ended
		Mar. 31, 2018USD ($)loan	Mar. 31, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		26	72
Post-Modification Recorded Investment | $	[1]	$ 6,655	$ 8,654
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	5
Post-Modification Recorded Investment | $	[1]	$ 0	$ 970
Residential Portfolio Segment [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	3
Post-Modification Recorded Investment | $	[1]	$ 0	$ 492
Residential Portfolio Segment [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	5	19
Post-Modification Recorded Investment | $	[1],[2]	$ 757	$ 2,938
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		2	2
Post-Modification Recorded Investment | $	[1]	$ 193	$ 39
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		2	7
Post-Modification Recorded Investment | $	[1]	$ 113	$ 1,983
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	11	33
Post-Modification Recorded Investment | $	[1],[2]	$ 778	$ 2,193
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		3	2
Post-Modification Recorded Investment | $	[1]	$ 85	$ 35
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	2	1
Post-Modification Recorded Investment | $	[1],[2]	$ 4,684	$ 4
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		1	0
Post-Modification Recorded Investment | $	[1]	$ 45	$ 0
[1]	ost-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant.
[2]	ther includes covenant modifications, forbearance, loans discharged under Chapter 7 bankruptcy, or other concessions.

Loans and Leases (Information61

Loans and Leases (Information on Loans and Leases Modified as TDR within the Previous 12 Months with payment default) (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0

Loans and Leases (Investments i

Loans and Leases (Investments in TDRs, Segregated by Risk Rating Exposure) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 219,538	$ 221,404
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	65,014	61,673
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (1) - (6) Pass [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	8,591	8,268
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (7) Special Mention [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	349	355
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (8) Substandard [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	56,074	53,050
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (9) Doubtful [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 0	$ 0

Transfers of Financial Assets63

Transfers of Financial Assets (Reserve for loan repurchases) (Detail) - Reserve for Off-balance Sheet Activities [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 872	$ 790
(Benefit) provision charged to expense	(203)	34
Repurchased loans and settlements charged off	(5)	0
Ending balance	$ 664	$ 824

Transfers of Financial Assets64

Transfers of Financial Assets (Loans sold) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gain on sale	$ 1,144	$ 2,266
Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale	44,806	106,620
Loans sold with servicing rights retained	39,904	99,500
Net gain on sale	1,083	251
Ancillary Fee Income Generated by Servicing Financial Assets, Amount	410	768
Fair value option adjustment	$ (349)	$ 1,247

Transfers of Financial Assets65

Transfers of Financial Assets (Mortgage Servicing Assets) (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Proceeds from loans not originated for sale	$ 34	$ 7,445
Residential Mortgage [Member]
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Retained servicing rights	2,600,000		$ 2,600,000
Bank servicing fees	300	200
Proceeds from loans not originated for sale		$ 7,400
Commercial Loan [Member]
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Proceeds from loans not originated for sale	$ 34

Transfers of Financial Assets S

Transfers of Financial Assets Servicing Assets at Amortized Cost Roll Forward (Details) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Beginning Balance	$ 25,139	$ 24,466
Additions	1,412	2,009
Amortization	(2,148)	(2,139)
Ending Balance	$ 24,403	$ 24,336

Goodwill and Other Intangible67

Goodwill and Other Intangible Assets (Gross Carrying Value And Accumulated Amortization Of Other Intangible Assets) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 43,000	$ 43,000
Accumulated Amortization	(14,350)	(13,389)
Net Carrying Amount	28,650	29,611
Goodwill	538,373	538,373
HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	21,813	21,813
Community Banking [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	516,560	516,560
Core Deposits [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22,000	22,000
Accumulated Amortization	(9,167)	(8,610)
Net Carrying Amount	12,833	13,390
Customer Relationships [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,000	21,000
Accumulated Amortization	(5,183)	(4,779)
Net Carrying Amount	$ 15,817	$ 16,221

Goodwill and Other Intangible68

Goodwill and Other Intangible Assets (Schedule Of Expected Future Amortization Expense) (Detail) $ in Thousands	Mar. 31, 2018USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2017	$ 2,886
2,018	3,847
2,019	3,847
2,020	3,847
2,021	3,847
Thereafter	$ 10,376

Deposits (Summary Of Deposits)

Deposits (Summary Of Deposits) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Non-interest-bearing:
Demand	$ 4,074,992	$ 4,191,496
Interest-bearing:
Checking	2,624,885	2,736,952
Health savings accounts	5,487,627	5,038,681
Money market	2,344,526	2,209,492
Savings	4,299,759	4,348,700
Time deposits	2,553,253	2,468,408
Total interest-bearing	17,310,050	16,802,233
Total deposits	21,385,042	20,993,729
Time deposits and interest-bearing checking, included in above balances, obtained through brokers	864,362	898,157
Time deposits, included in above balance, that meet or exceed the Federal Deposit Insurance Corporation (FDIC) limit	741,349	561,512
Deposit overdrafts reclassified as loan balances	$ 1,984	$ 2,210

Deposits (Scheduled Maturities

Deposits (Scheduled Maturities Of Time Deposits) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Remainder of 2017	$ 1,301,903
2,018	822,693
2,019	246,205
2,020	117,426
2,021	49,543
Thereafter	15,483
Total time deposits	$ 2,553,253	$ 2,468,408

Borrowings Borrowings - (Narrat

Borrowings Borrowings - (Narrative) (Details) - USD ($) $ in Billions	Mar. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Total borrowings	$ 2.4	$ 2.5

Borrowings (Summary Of Securiti

Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 515,299	$ 588,269
Fed funds purchased	416,000	55,000
Securities sold under agreements to repurchase and other borrowings	$ 931,299	$ 643,269
Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time	1.88%	1.66%
Federal Funds Purchased [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time	1.72%	1.37%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time	1.81%	1.64%
Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 215,299	$ 288,269
Original maturity of one year or less [Member] | Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.18%	0.17%
Original maturity of greater than one year, non-callable [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 300,000	$ 300,000
Original maturity of greater than one year, non-callable [Member] | Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time	3.10%	3.10%

Borrowings (Federal Home Loan A

Borrowings (Federal Home Loan Advances) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank, Advances, Weighted Average Interest Rate [Abstract]
FHLB advances maturing within 1 year, Weighted Average Contractual Coupon Rate (as a percent)	1.81%	1.48%
FHLB advances maturing after 1 but within 2 years, Weighted Average Contractual Coupon Rate (as a percent)	1.82%	1.81%
FHLB advances maturing after 2 but within 3 years, Weighted Average Contractual Coupon Rate (as a percent)	1.77%	1.73%
FHLB advances maturing after 3 but within 4 years, Weighted Average Contractual Coupon Rate (as a percent)	2.33%	2.06%
FHLB advances maturing after 4 but within 5 years, Weighted Average Contractual Coupon Rate (as a percent)	0.00%	0.00%
FHLB advances maturing after 5 years, Weighted Average Contractual Coupon Rate (as a percent)	2.65%	2.65%
Federal Home Loan Bank, Advances, Weighted Average Contractual Coupon Rate (as a percent)	1.90%	1.61%
Federal Home Loan Bank, Advances, Maturity, Rolling Year [Abstract]
FHLB advances maturing within 1 year, Total Outstanding	$ 700,000	$ 1,150,000
FHLB advances maturing after 1 but within 2 years, Total Outstanding	128,026	103,026
FHLB advances maturing after 2 but within 3 years, Total Outstanding	165,000	215,000
FHLB advances maturing after 3 but within 4 years, Total Outstanding	200,000	200,000
FHLB advances maturing after 4 but within 5 years, Total Outstanding	165	170
FHLB advances maturing after 5 years, Total Outstanding	8,839	8,909
Federal Home Loan Bank, Advances	1,202,030	1,677,105
Pledged Financial Instruments, Not Separately Reported, Loans Receivable, for Federal Home Loan Bank Debt	6,327,590	6,402,066
Remaining borrowing capacity	$ 3,035,521	$ 2,600,624
Scenario, Previously Reported [Member]
Federal Home Loan Bank, Advances, Weighted Average Interest Rate [Abstract]
FHLB advances maturing after 3 but within 4 years, Weighted Average Contractual Coupon Rate (as a percent)		4.13%
FHLB advances maturing after 5 years, Weighted Average Contractual Coupon Rate (as a percent)		1.96%
Federal Home Loan Bank, Advances, Weighted Average Contractual Coupon Rate (as a percent)		1.85%

Borrowings (Long Term Debt) (De

Borrowings (Long Term Debt) (Details) - USD ($)		Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Notes and subordinated debt		$ 227,320,000	$ 227,320,000
Debt issuance cost on senior fixed-rates		(793,000)	(826,000)
Long-term debt		$ 225,830,000	$ 225,767,000
Variable interest rate		5.13%	4.55%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		2.95%
Long-term Debt [Member]
Debt Instrument [Line Items]
Discount on senior fixed-rate notes		$ (697,000)	$ (727,000)
4.375% Senior fixed-rate notes due February 15, 2024 [Member]
Debt Instrument [Line Items]
Senior notes, interest rate (as a percent)		4.375%
Notes and subordinated debt		$ 150,000,000	150,000,000
Junior subordinated debt Webster Statutory Trust I floating-rate notes due September 17, 2033 [Member]
Debt Instrument [Line Items]
Notes and subordinated debt	[1]	$ 77,320,000	$ 77,320,000
[1]	The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month London Interbank Offered Rate (LIBOR) plus 2.95% , was 5.13% at March 31, 2018 and 4.55% at December 31, 2017

Accumulated Other Comprehensi75

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Other Comprehensive Income (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 2,701,958	$ 2,527,012
Other comprehensive income (loss), net of tax	(23,948)	(34)
Ending Balance	2,716,142	2,560,358
Available For Sale and Transferred Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(27,947)	(15,476)
Other comprehensive income (loss) (OCI/OCL) before reclassifications	(27,424)	(2,225)
Amounts reclassified from AOCL	0	0
Other comprehensive income (loss), net of tax	(27,424)	(2,225)
Ending Balance	(55,371)	(17,701)
Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(15,016)	(17,068)
Other comprehensive income (loss) (OCI/OCL) before reclassifications	1,129	61
Amounts reclassified from AOCL	1,393	1,098
Other comprehensive income (loss), net of tax	2,522	1,159
Ending Balance	(12,494)	(15,909)
Defined Benefit Pension and Other Postretirement Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(48,568)	(44,449)
Other comprehensive income (loss) (OCI/OCL) before reclassifications	0	0
Amounts reclassified from AOCL	954	1,032
Other comprehensive income (loss), net of tax	954	1,032
Ending Balance	(47,614)	(43,417)
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(91,531)	(76,993)
Other comprehensive income (loss) (OCI/OCL) before reclassifications	(26,295)	(2,164)
Amounts reclassified from AOCL	2,347	2,130
Other comprehensive income (loss), net of tax	(23,948)	(34)
Ending Balance	$ (115,479)	$ (77,027)

Accumulated Other Comprehensi76

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Accumulated Other Comprehensive Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ (20,075)	$ (21,951)
Earnings applicable to common shareholders	78,083	57,342
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	0	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	(1,393)	(1,098)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	478	637
Earnings applicable to common shareholders	(1,393)	(1,098)
Total interest expense	(1,871)	(1,735)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(1,285)	(1,638)
Defined benefit pension and postretirement benefit plans [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	331	606
Net of tax	$ (954)	$ (1,032)

Regulatory Matters (Information

Regulatory Matters (Information On The Capital Ratios) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,094,607		$ 2,093,116
Common Equity Tier One Capital Ratio	10.99%		11.14%
Common Equity Tier One Capital Required for Capital Adequacy	$ 857,874		$ 845,389
Common Equity Tier One Capital Required to be Well-Capitalized	1,239,151		1,221,118
Total risk-based capital, Actual Amount	$ 2,524,608		$ 2,517,848
Total risk-based capital, Actual Ratio	13.24%		13.40%
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,525,109		$ 1,502,914
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%		8.00%
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,906,386		$ 1,878,643
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%		10.00%
Tier 1 capital, Actual Amount	$ 2,239,644		$ 2,238,172
Tier 1 capital, Actual Ratio	11.75%		11.91%
Tier 1 capital, Capital Requirements, Minimum Amount	$ 1,143,832		$ 1,127,186
Tier 1 capital, Capital Requirements, Minimum Ratio	6.00%		6.00%
Tier 1 capital, Capital Requirements, Well Capitalized Amount	$ 1,525,109		$ 1,502,914
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	8.00%		8.00%
Tier 1 leverage capital ratio, Actual Amount	$ 2,239,644		$ 2,238,172
Tier 1 leverage capital ratio, Actual Ratio	8.54%		8.63%
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	$ 1,049,009		$ 1,036,817
Tier 1 leverage capital ratio, Capital Requirements, Minimum Ratio	4.00%		4.00%
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Amount	$ 1,311,261		$ 1,296,021
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	5.00%		5.00%
Dividends paid	$ 100,000	$ 10,000
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,062,650		$ 2,114,224
Common Equity Tier One Capital Ratio	10.83%		11.26%
Common Equity Tier One Capital Required for Capital Adequacy	$ 857,184		$ 844,693
Common Equity Tier One Capital Required to be Well-Capitalized	1,238,155		1,220,113
Total risk-based capital, Actual Amount	$ 2,270,294		$ 2,316,580
Total risk-based capital, Actual Ratio	11.92%		12.34%
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,523,883		$ 1,501,677
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%		8.00%
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,904,853		$ 1,877,097
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%		10.00%
Tier 1 capital, Actual Amount	$ 2,062,650		$ 2,114,224
Tier 1 capital, Actual Ratio	10.83%		11.26%
Tier 1 capital, Capital Requirements, Minimum Amount	$ 1,142,912		$ 1,126,258
Tier 1 capital, Capital Requirements, Minimum Ratio	6.00%		6.00%
Tier 1 capital, Capital Requirements, Well Capitalized Amount	$ 1,523,883		$ 1,501,677
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	8.00%		8.00%
Tier 1 leverage capital ratio, Actual Amount	$ 2,062,650		$ 2,114,224
Tier 1 leverage capital ratio, Actual Ratio	7.87%		8.14%
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	$ 1,048,468		$ 1,038,442
Tier 1 leverage capital ratio, Capital Requirements, Minimum Ratio	4.00%		4.00%
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Amount	$ 1,310,585		$ 1,298,052
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	5.00%		5.00%
Cash Pass-through Reserve, Federal Home Loan Bank	$ 79,800		$ 82,300
Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	4.50%		4.50%
Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets [Member] | Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	4.50%		4.50%
Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	6.50%		6.50%
Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets [Member] | Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Ratio	6.50%		6.50%

Earnings Per Common Share (Earn

Earnings Per Common Share (Earnings Per Share Basic And Diluted) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings for basic and diluted earnings per common share:
Net income	$ 80,225	$ 59,471
Less: Preferred stock dividends	1,947	2,024
Undistributed Earnings, Basic	78,278	57,447
Net income available to common shareholders	78,278	57,447
Less: Earnings applicable to participating securities	195	105
Less: Earnings applicable to participating securities	195	105
Earnings applicable to common shareholders	78,083	57,342
Earnings applicable to common shareholders	$ 78,083	$ 57,342
Shares:
Weighted average common shares outstanding - basic (in shares)	91,921	91,886
Effect of dilutive securities:
Stock options and restricted stock (in shares)	327	450
Warrants (in shares)	6	6
Weighted-average common shares outstanding - diluted (in shares)	92,254	92,342
Earnings per common share:
Basic (in dollars per share)	$ 0.85	$ 0.62
Diluted (in dollars per share)	$ 0.85	$ 0.62

Earnings Per Common Share Sched

Earnings Per Common Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restricted stock (due to performance conditions on non-participating shares) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	72	40

Derivative Financial Instrume80

Derivative Financial Instruments (Schedule fair value of derivative instruments) (Detail) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative instrument assets, Gross Amount		$ 14,812	$ 8,992
Asset Derivatives, Fair Value, Less: Cash collateral posted		33,500
Derivative Asset		0	43
Liability Derivatives, Fair Value, Gross Liability		909	2,387
Liability Derivatives, Fair Value, Less: Cash collateral posted		83,600
Derivative liability		91	142
Subject to and not subject to Master Netting Agreements [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		4,366,577	4,613,183
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		25,551	32,515
Asset Derivatives, Fair Value, Less: Legally enforceable master netting agreements		818	2,245
Asset Derivatives, Fair Value, Less: Cash collateral posted		13,994	6,704
Derivative Asset		10,739	23,566
Liability Derivatives, Notional Amount		3,631,193	3,056,079
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		59,115	28,423
Liability Derivatives, Fair Value, Less: Legally enforceable master netting agreements		818	2,245
Liability Derivatives, Fair Value, Less: Cash collateral posted		0	0
Derivative liability		58,297	26,178
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instrument assets, Gross Amount		4,289	2,770
Asset Derivatives, Fair Value, Less: Legally enforceable master netting agreements		0	91
Asset Derivatives, Fair Value, Less: Cash collateral posted		4,289	2,679
Derivative Asset		0	0
Liability Derivatives, Fair Value, Gross Liability		0	0
Liability Derivatives, Fair Value, Less: Legally enforceable master netting agreements		0	0
Liability Derivatives, Fair Value, Less: Cash collateral posted		0	0
Derivative liability		0	0
Designated as Hedging Instrument [Member] | Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Interest rate derivatives [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	[1]	325,000	325,000
Derivative instrument assets, Gross Amount	[1]	4,289	2,770
Liability Derivatives, Notional Amount	[1]	0	0
Liability Derivatives, Fair Value, Gross Liability	[1]	0	0
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instrument assets, Gross Amount		10,523	6,222
Asset Derivatives, Fair Value, Less: Legally enforceable master netting agreements		818	2,154
Asset Derivatives, Fair Value, Less: Cash collateral posted		9,705	4,025
Derivative Asset		0	43
Liability Derivatives, Fair Value, Gross Liability		909	2,387
Liability Derivatives, Fair Value, Less: Legally enforceable master netting agreements		818	2,245
Liability Derivatives, Fair Value, Less: Cash collateral posted		0	0
Derivative liability		91	142
Not Designated as Hedging Instrument [Member] | Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Interest rate derivatives [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	[1]	3,258,511	2,791,760
Derivative instrument assets, Gross Amount	[1]	10,659	5,977
Liability Derivatives, Notional Amount	[1]	437,308	721,048
Liability Derivatives, Fair Value, Gross Liability	[1]	848	1,968
Not Designated as Hedging Instrument [Member] | Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Mortgage Banking Derivatives [Member] | RPA-Out [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		34,744	28,497
Derivative instrument assets, Gross Amount		545	421
Not Designated as Hedging Instrument [Member] | Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Mortgage Banking Derivatives [Member] | RPA-In [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount		31,162	39,230
Liability Derivatives, Fair Value, Gross Liability		168	110
Not Designated as Hedging Instrument [Member] | Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Other [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	[1]	17,763	7,914
Derivative instrument assets, Gross Amount	[1]	144	258
Liability Derivatives, Notional Amount	[1]	17,788	30,328
Liability Derivatives, Fair Value, Gross Liability	[1]	61	419
Not Designated as Hedging Instrument [Member] | Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		4,041,577	4,288,183
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		21,262	29,745
Liability Derivatives, Notional Amount		3,631,193	3,056,079
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		59,115	28,423
Not Designated as Hedging Instrument [Member] | Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Interest rate derivatives [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		636,754	1,366,299
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		9,863	23,009
Liability Derivatives, Notional Amount		3,059,075	2,146,518
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		57,952	25,631
Not Designated as Hedging Instrument [Member] | Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | RPAs [Member] | RPA-Out [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		93,275	93,713
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		48	80
Not Designated as Hedging Instrument [Member] | Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | RPAs [Member] | RPA-In [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount		84,999	116,882
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		69	111
Not Designated as Hedging Instrument [Member] | Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Other [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		530	0
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		3	0
Liability Derivatives, Notional Amount		861	2,073
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		17	$ 184
Loan Origination Commitments [Member]
Derivatives, Fair Value [Line Items]
Other Commitment		37,000
Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Other Commitment		$ 15,100
[1]	o report derivative positions subject to a legally enforceable master netting agreement on a net basis, net of cash collateral. Refer to the Offsetting Derivatives section of this footnote for additional information.

Derivative Financial Instrume81

Derivative Financial Instruments (Schedule of the changes in the fair value of non-hedge accounting derivatives) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 3,266	$ (901)
Interest Rate Derivatives [Member] | Operating Expense [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	1,823	2,039
Interest Rate Derivatives [Member] | Operating Expense [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	3,791	1,534
RPA [Member] | Operating Expense [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	10	53
Mortgage Banking Derivatives [Member] | Operating Expense [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	65	(2,041)
Other [Member] | Operating Expense [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ (600)	$ (447)

Derivative Financial Instrume82

Derivative Financial Instruments (AOCI Related to Cash Flow Hedges) (Narrative) (Detail) - Cash Flow Hedging [Member] $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Estimate of amount to be reclassified from AOCL	$ (5.6)
Remaining unamortized gain (loss) on termination of cash flow hedges	(13.3)
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Estimate of amount to be reclassified from AOCL	$ 0.2

Derivative Financial Instrume83

Derivative Financial Instruments (Offsetting Derivatives) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative instrument assets, Gross Amount	$ 14,812	$ 8,992
Derivative instrument asset, Amount Offset	33,500
Derivative Asset	0	43
Liability Derivatives, Fair Value, Gross Liability	909	2,387
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	(83,600)
Derivative liability	91	142
Hedge Accounting Positions [Member]
Derivative [Line Items]
Derivative instrument assets, Gross Amount	4,289	2,770
Derivative instrument asset, Amount Offset, Total	0	(91)
Derivative instrument asset, Amount Offset	4,289	2,679
Derivative Asset	0	0
Liability Derivatives, Fair Value, Gross Liability	0	0
Derivative instrument liability, Amount Offset, Total	0	0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative liability	0	0
Non-Hedged Accounting Positions [Member]
Derivative [Line Items]
Derivative instrument assets, Gross Amount	10,523	6,222
Derivative instrument asset, Amount Offset, Total	(818)	(2,154)
Derivative instrument asset, Amount Offset	9,705	4,025
Derivative Asset	0	43
Liability Derivatives, Fair Value, Gross Liability	909	2,387
Derivative instrument liability, Amount Offset, Total	(818)	(2,245)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative liability	91	142
Subject to and not subject to Master Netting Agreements [Member]
Derivative [Line Items]
Derivative instrument asset, Amount Offset, Total	(818)	(2,245)
Derivative instrument asset, Amount Offset	13,994	6,704
Derivative Asset	10,739	23,566
Derivative instrument liability, Amount Offset, Total	(818)	(2,245)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative liability	$ 58,297	$ 26,178

Derivative Financial Instrume84

Derivative Financial Instruments (Counterparty Credit Risk Narrative) (Detail) $ in Millions	Mar. 31, 2018USD ($)
Derivative [Line Items]
Derivative, Collateral, Right to Reclaim Cash	$ (50.1)
Derivative instrument asset, Amount Offset	33.5
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	(83.6)
Credit Derivative, Maximum Exposure, Undiscounted	9.9
Market Approach Valuation Technique [Member]
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 29.6

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,860,560		$ 5,806,789
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book value of other real estate owned (OREO) and repossessed assets	5,800
Rabbi Trust [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	2,100
Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total credit-related financial instruments with off-balance sheet risk	300
Alternative investments [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	7,900
Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value option adjustment	$ (349)	$ 1,247

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring Basis) (Detail) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		$ 2,773,506	$ 2,638,037
Derivative Asset		0	43
Originated loans held for sale		19,727	20,888
Financial liabilities held at fair value:
Derivative liability		91	142
Fair Value, Measurements, Recurring [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		2,773,506	2,638,037
Alternative Investment, Fair Value Disclosure		3,495	3,495
Total financial assets held at fair value		2,826,973	2,699,736
Financial liabilities held at fair value:
Derivative liability	[1]	59,115	28,423
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		449	1,247
Alternative Investment, Fair Value Disclosure		0	0
Total financial assets held at fair value		5,290	6,306
Financial liabilities held at fair value:
Derivative liability	[1]	62	587
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		2,773,057	2,636,790
Alternative Investment, Fair Value Disclosure		0	0
Total financial assets held at fair value		2,818,188	2,689,935
Financial liabilities held at fair value:
Derivative liability	[1]	59,053	27,836
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]	25,551	32,515
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Derivative Asset	[1]	147	258
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Derivative Asset	[1]	25,404	32,257
Fair Value, Measurements, Recurring [Member] | Investments Held In Rabbi Trust [Member]
Financial assets held at fair value:
Other assets		4,694	4,801
Fair Value, Measurements, Recurring [Member] | Investments Held In Rabbi Trust [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Other assets		4,694	4,801
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member]
Financial assets held at fair value:
Originated loans held for sale		19,727	20,888
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Originated loans held for sale		0	0
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Originated loans held for sale		19,727	20,888
Fair Value, Measurements, Recurring [Member] | US Treasury Bill Securities [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		449	1,247
Fair Value, Measurements, Recurring [Member] | US Treasury Bill Securities [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		449	1,247
Fair Value, Measurements, Recurring [Member] | Agency CMO [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		284,579	306,333
Fair Value, Measurements, Recurring [Member] | Agency CMO [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		284,579	306,333
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		1,265,268	1,107,841
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		1,265,268	1,107,841
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		591,302	588,026
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		0	0
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		591,302	588,026
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		0	0
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		366,894	361,067
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		0	0
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		366,894	361,067
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		0	0
Fair Value, Measurements, Recurring [Member] | CLO [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		201,837	209,851
Fair Value, Measurements, Recurring [Member] | CLO [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		201,837	209,851
Fair Value, Measurements, Recurring [Member] | Single issuer trust preferred securities [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		7,041	7,050
Fair Value, Measurements, Recurring [Member] | Single issuer trust preferred securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		7,041	7,050
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		56,136	56,622
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value		$ 56,136	$ 56,622
[1]	or information relating to the impact of netting derivative assets and derivative liabilities as well as the impact from offsetting cash collateral paid to the same derivative counterparties see Note 12: Derivative Financial Instruments

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Option, Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Originated loans held for sale	$ 19,727		$ 20,888
Fair Value, Option, Loans Held as Assets, Aggregate Difference	64		542
Residential Mortgage [Member] | Other Income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(300)	$ 1,200
loans held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans and Leases Receivable, Gross, Consumer, Real Estate	$ 19,663		$ 20,346

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Valuation Methodology And Unobservable Inputs) (Detail) - Significant Unobservable Inputs (Level 3) [Member] - Fair Value, Measurements, Nonrecurring [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Impaired Loans and Leases [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Collateral dependent impaired loans and leases	$ 13,424
Impaired Loans and Leases [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	0.00%
Impaired Loans and Leases [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	15.00%
Impaired Loans and Leases [Member] | Cost Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	0.00%
Impaired Loans and Leases [Member] | Cost Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	8.00%
Other Real Estate Owned [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
OREO	$ 858
Other Real Estate Owned [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	8.00%

Fair Value Measurements (Summar

Fair Value Measurements (Summary Of Estimated Fair Values Of Significant 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]
Loans held for sale		$ 19,727	$ 20,888
Mortgage servicing assets, Carrying Amount		24,403	25,139	$ 24,336	$ 24,466
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases, net		17,600,226	17,323,864
Securities sold under agreements to repurchase and other borrowings		931,299	643,269
FHLB advances	[1]	1,202,030	1,677,105
Long-term debt	[1]	225,830	225,767
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Deposits Liabilities, other than time deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits		18,831,789	18,525,321
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Time Deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits		2,553,253	2,468,408
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Held-to-maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		4,408,321	4,487,392
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage servicing assets, Carrying Amount		24,403	25,139
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities sold under agreements to repurchase and other borrowings		930,683	644,084
FHLB advances	[1]	1,204,045	1,678,070
Long-term debt	[1]	232,586	234,359
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases, net		17,391,087	17,211,619
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Deposits Liabilities, other than time deposits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits		18,831,789	18,525,321
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Time Deposits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits		2,527,441	2,455,245
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Held-to-maturity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		4,297,039	4,456,350
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Residential Mortgage [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage servicing assets, Fair value		$ 51,668	$ 45,309
[1]	djustments to the carrying amount of long-term debt for unamortized discount and debt issuance cost on senior fixed-rate notes are not included for determination of fair value, see Note 8: Borrowings

Retirement Benefit Plans (Detai

Retirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 12
Interest cost on benefit obligations	1,785	1,813
Expected return on plan assets	(3,180)	(3,073)
Amortization of prior service cost	0	0
Recognized net loss	1,160	1,417
Net periodic benefit cost	(235)	169
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost on benefit obligations	187	92
Expected return on plan assets	0	0
Amortization of prior service cost	0	0
Recognized net loss	125	213
Net periodic benefit cost	312	305
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost on benefit obligations	20	25
Expected return on plan assets	0	0
Amortization of prior service cost	0	0
Recognized net loss	0	8
Net periodic benefit cost	$ 20	$ 33

Share-Based Plans (Narrative) (

Share-Based Plans (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 3.3
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock compensation expense	$ 21
Weighted average recognition period	2 years 3 months 18 days
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	100,000
Time Based Restricted Stock Awards [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Time Based Restricted Stock Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years
Performance-Based Restricted Stock Awards Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Vesting range (as a percent)	50.00%
Performance-Based Restricted Stock Awards Shares [Member] | Minimum [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting range (as a percent)	0.00%
Performance-Based Restricted Stock Awards Shares [Member] | Maximum [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting range (as a percent)	150.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	661,523	673,039
Employee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award (in years)	P10Y
Non-Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	627,635
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	33,888

Share-Based Plans (Summary of R

Share-Based Plans (Summary of Restricted Stock and Stock Option Activity) (Detail) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense | $	$ 3.3
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock, Outstanding at beginning of period (in shares) | shares	207,800
Restricted stock, Granted (in shares) | shares	113,264
Restricted stock, Vested restricted stock awards (in shares) | shares	46,137	[1]
Restricted stock, Forfeited (in shares) | shares	1,144
Restricted stock, Outstanding at end of period (in shares) | shares	273,783
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 43.16
Restricted stock, Granted (in dollars per share) | $ / shares	56.58
Restricted stock, Vested restricted stock awards (in dollars per share) | $ / shares	41.46	[1]
Restricted stock, Forfeited (in dollars per share) | $ / shares	35.61
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 48.96
Performance-Based Restricted Stock Awards Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock, Outstanding at beginning of period (in shares) | shares	78,916
Restricted stock, Granted (in shares) | shares	75,707
Restricted stock, Vested restricted stock awards (in shares) | shares	19,398	[1]
Restricted stock, Forfeited (in shares) | shares	0
Restricted stock, Outstanding at end of period (in shares) | shares	135,225
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 45.35
Restricted stock, Granted (in dollars per share) | $ / shares	55.82
Restricted stock, Vested restricted stock awards (in dollars per share) | $ / shares	43.01	[1]
Restricted stock, Forfeited (in dollars per share) | $ / shares	0
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 51.54
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, at beginning of period, Number of Shares | shares	673,039
Options granted, Number of Shares | shares	0
Exercised options, Number of Shares | shares	11,516
Options forfeited, Number of Shares | shares	0
Options outstanding, at end of period, Number of Shares | shares	661,523
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Options, at beginning of period, Weighted-average Exercise Price (in dollars per share) | $ / shares	$ 18.75
Options granted, Weighted-Average Exercise Price (in dollars per share) | $ / shares	0
Exercised options, Weighted-Average Exercise Price (in dollars per share) | $ / shares	25.15
Options forfeited, Weighted-Average Exercise Price (in dollars per share) | $ / shares	0
Options, at end of period, Weighted-average Exercise Price (in dollars per share) | $ / shares	$ 18.64
[1]	ested for purposes of recording compensation expense.

Segment Reporting (Operating Re

Segment Reporting (Operating Results and Total Assets Reportable Segments) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Assets	$ 26,752,147		$ 26,487,645
Net interest income (expense)	214,168	$ 192,664
Provision for Loan and Lease Losses	11,000	10,500
Net interest income after provision for loan and lease losses	203,168	182,164
Noninterest Income	68,747	63,042
Total non-interest expense	171,615	163,784
Income (loss) before income tax expense	100,300	81,422
Income tax expense	20,075	21,951
Net income	80,225	59,471
Operating Segments [Member] | Commercial Banking [Member]
Segment Reporting Information [Line Items]
Total Assets	9,718,543		9,350,028
Net interest income (expense)	84,651	78,247
Provision for Loan and Lease Losses	7,178	6,797
Net interest income after provision for loan and lease losses	77,473	71,450
Noninterest Income	15,316	13,424
Total non-interest expense	41,245	38,124
Income (loss) before income tax expense	51,544	46,750
Income tax expense	12,680	12,604
Net income	38,864	34,146
Operating Segments [Member] | Community Banking [Member]
Segment Reporting Information [Line Items]
Total Assets	8,828,329		8,909,671
Net interest income (expense)	98,928	93,590
Provision for Loan and Lease Losses	3,822	3,703
Net interest income after provision for loan and lease losses	95,106	89,887
Noninterest Income	25,195	25,379
Total non-interest expense	96,829	95,179
Income (loss) before income tax expense	23,472	20,087
Income tax expense	4,671	5,416
Net income	18,801	14,671
Operating Segments [Member] | HSA Bank [Member]
Segment Reporting Information [Line Items]
Total Assets	77,883		76,308
Net interest income (expense)	32,924	24,052
Provision for Loan and Lease Losses	0	0
Net interest income after provision for loan and lease losses	32,924	24,052
Noninterest Income	22,669	19,271
Total non-interest expense	31,515	28,239
Income (loss) before income tax expense	24,078	15,084
Income tax expense	6,260	4,066
Net income	17,818	11,018
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total Assets	8,127,392		$ 8,151,638
Net interest income (expense)	(2,335)	(3,225)
Provision for Loan and Lease Losses	0	0
Net interest income after provision for loan and lease losses	(2,335)	(3,225)
Noninterest Income	5,567	4,968
Total non-interest expense	2,026	2,242
Income (loss) before income tax expense	1,206	(499)
Income tax expense	(3,536)	(135)
Net income	$ 4,742	$ (364)

Segment Reporting Segment Repor

Segment Reporting Segment Reporting Narrative (Details)	3 Months Ended
	Mar. 31, 2018Segment
Segment Reporting Information [Line Items]
Number of Reportable Segments	3

Revenue from Contracts with C95

Revenue from Contracts with Customers Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 49,671	$ 45,290
Noninterest Income	68,747	63,042
Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	40,451	37,006
Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	7,870	7,273
Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,350	1,011
Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	19,076	17,752
Operating Segments [Member] | Commercial Banking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,761	5,250
Noninterest Income	15,316	13,424
Operating Segments [Member] | Commercial Banking [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,222	2,878
Operating Segments [Member] | Commercial Banking [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,539	2,372
Operating Segments [Member] | Commercial Banking [Member] | Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Operating Segments [Member] | Commercial Banking [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9,555	8,174
Operating Segments [Member] | Community Banking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	21,141	20,663
Noninterest Income	25,195	25,379
Operating Segments [Member] | Community Banking [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	15,309	15,530
Operating Segments [Member] | Community Banking [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,339	4,909
Operating Segments [Member] | Community Banking [Member] | Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	493	224
Operating Segments [Member] | Community Banking [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,054	4,716
Operating Segments [Member] | HSA Bank [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	22,669	19,271
Noninterest Income	22,669	19,271
Operating Segments [Member] | HSA Bank [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	21,812	18,484
Operating Segments [Member] | HSA Bank [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Operating Segments [Member] | HSA Bank [Member] | Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	857	787
Operating Segments [Member] | HSA Bank [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Corporate, Non-Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	100	106
Noninterest Income	5,567	4,968
Corporate, Non-Segment [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	108	114
Corporate, Non-Segment [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(8)	(8)
Corporate, Non-Segment [Member] | Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Corporate, Non-Segment [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 5,467	$ 4,862

Commitments and Contingencies96

Commitments and Contingencies (Outstanding Financial Instruments Contract Amounts Represent Credit Risk) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,860,560	$ 5,806,789
Standby letter of credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	167,899	195,902
Commercial letter of credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	44,535	43,200
Commitments to extend credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,648,126	$ 5,567,687

(Reserve for Unfunded Commitmen

(Reserve for Unfunded Commitments) (Detail) - Allowance for Credit Loss [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 2,362	$ 2,287
(Benefit) provision charged to expense	(68)	368
Ending balance	$ 2,294	$ 2,655

Uncategorized Items - wbs-03x31

Label	Element	Value
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	$ 190,663,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	$ 231,158,000