Webster Financial (WBS) 10-Q 5 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document and Entity Information [Abstract]
Document Period End Date	Sep. 30, 2018
Document Type	10-Q
Amendment Flag	false
Entity Registrant Name	WEBSTER FINANCIAL CORPORATION
Entity Common Stock, Shares Outstanding		92,236,627
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	WBS
Entity Central Index Key	801,337
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets:
Cash and due from banks	$ 222,234	$ 231,158
Interest-bearing deposits	99,746	25,628
Investment securities available-for-sale, at fair value	2,823,953	2,638,037
Investment securities held-to-maturity (fair value of $4,164,359 and $4,456,350)	4,332,458	4,487,392
Federal Home Loan Bank and Federal Reserve Bank stock	133,740	151,566
Loans held for sale, fair value option	17,137	20,888
Loans and leases	18,321,019	17,523,858
Allowance for loan and lease losses	(211,832)	(199,994)
Loans and leases, net	18,109,187	17,323,864
Deferred tax assets, net	92,910	92,630
Premises and equipment, net	128,507	130,001
Goodwill	538,373	538,373
Other intangible assets, net	26,726	29,611
Cash surrender value of life insurance policies	539,923	531,820
Accrued interest receivable and other assets	281,423	286,677
Total assets	27,346,317	26,487,645
Liabilities and shareholders' equity:
Noninterest-bearing Deposit Liabilities	4,231,505	4,191,496
Interest-bearing Deposit Liabilities	17,766,118	16,802,233
Total deposits	21,997,623	20,993,729
Securities sold under agreements to repurchase and other borrowings	564,488	643,269
Federal Home Loan Bank advances	1,441,884	1,677,105
Long-term debt	225,957	225,767
Accrued expenses and other liabilities	300,167	245,817
Total liabilities	24,530,119	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	1,114,848	1,122,164
Retained earnings	1,761,036	1,595,762
Treasury stock, at cost (1,536,554 and 1,658,526 shares)	(74,096)	(70,430)
Accumulated other comprehensive loss, net of tax	(131,564)	(91,531)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,816,198	2,701,958
Total liabilities and shareholders' equity	27,346,317	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 Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Securities held-to-maturity ,fair value	$ 4,164,359	$ 4,456,350
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)	1,536,554	1,658,526
Common Stock [Member]
Common stock, shares issued (in shares)	93,680,724

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Income:
Interest and fees on loans and leases	$ 215,448	$ 181,130	$ 616,488	$ 523,394
Taxable interest and dividends on investments	47,646	43,819	142,361	136,167
Non-taxable interest on investment securities	5,061	5,765	15,428	17,103
Loans held for sale	208	307	498	826
Total interest income	268,363	231,021	774,775	677,490
Interest Expense:
Deposits	24,397	16,760	62,778	44,874
Securities sold under agreements to repurchase and other borrowings	3,084	3,847	10,722	10,970
Federal Home Loan Bank advances	7,685	6,894	23,437	22,543
Long-term debt	2,825	2,616	8,288	7,748
Total interest expense	37,991	30,117	105,225	86,135
Net interest income	230,372	200,904	669,550	591,355
Provision for loan and lease losses	10,500	10,150	32,000	27,900
Net interest income after provision for loan and lease losses	219,872	190,754	637,550	563,455
Non-interest Income:
Deposit service fees	40,601	38,321	121,911	113,519
Loan and lease related fees	10,782	6,346	24,111	19,898
Wealth and investment services	8,412	7,750	24,738	22,900
Mortgage banking activities	1,305	2,421	3,684	8,038
Increase in cash surrender value of life insurance policies	3,706	3,720	10,921	10,943
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0	0	0	(126)
Other income	7,478	7,288	24,040	18,267
Total non-interest income	72,284	65,846	209,405	193,439
Non-interest Expense:
Compensation and benefits	96,640	88,395	284,457	262,288
Occupancy	14,502	14,744	45,489	46,957
Technology and equipment	24,553	22,580	73,019	66,646
Intangible assets amortization	961	1,002	2,885	3,085
Marketing	4,052	4,045	12,493	14,101
Professional and outside services	4,930	4,030	14,099	11,813
Deposit insurance	9,694	6,344	30,098	19,701
Other expense	23,451	20,683	68,317	65,435
Total non-interest expense	178,783	161,823	530,857	490,026
Income (loss) before income tax expense	113,373	94,777	316,098	266,868
Income tax expense	13,700	30,281	54,518	81,322
Net income	99,673	64,496	261,580	185,546
Preferred stock dividends and other	(2,213)	(2,070)	(6,540)	(6,284)
Earnings applicable to common shareholders	$ 97,460	$ 62,426	$ 255,040	$ 179,262
Earnings per common share:
Basic (in dollars per share)	$ 1.06	$ 0.68	$ 2.77	$ 1.95
Diluted (in dollars per share)	$ 1.06	$ 0.67	$ 2.77	$ 1.94

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 99,673	$ 64,496	$ 261,580	$ 185,546
Other comprehensive (loss) income (OCL) OCI, net of tax:
Total securities available-for-sale	(13,811)	872	(50,481)	1,847
Total derivative instruments	1,635	1,111	5,837	2,921
Total defined benefit pension and other postretirement benefit plans	2,548	1,001	4,611	3,127
Other comprehensive (loss) income, net of tax	(9,628)	2,984	(40,033)	7,895
Comprehensive income	$ 90,045	$ 67,480	$ 221,547	$ 193,441

Condensed Consolidated Statem_3

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	185,546							185,546
Other comprehensive loss, net of tax	7,895											7,895
Dividends and dividend equivalents declared on common stock	(70,972)						124	(71,096)
Dividends on preferred stock		$ (6,072)							$ (6,072)
Stock-based compensation	10,957						0	1,887			9,070
Exercise of stock options	5,301						(2,376)				7,677
Common shares acquired from stock compensation plan activity	(9,295)										(9,295)
Common stock repurchase program	(11,585)										(11,585)
Ending Balance at Sep. 30, 2017	2,638,787			122,710		937	1,123,685	1,535,585			(75,032)	(69,098)
Beginning Balance at Jun. 30, 2017												(72,082)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	64,496
Other comprehensive loss, net of tax	2,984											2,984
Ending Balance at Sep. 30, 2017	2,638,787			122,710		937	1,123,685	1,535,585			(75,032)	(69,098)
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	261,580							261,580
Other comprehensive loss, net of tax	(40,033)											(40,033)
Dividends and dividend equivalents declared on common stock	(84,903)						99	(85,002)
Dividends on preferred stock		$ 22	$ (5,906)						$ 22	$ (5,906)
Stock-based compensation	8,598						(1,541)	2,426			7,713
Exercise of stock options	2,110						(5,308)				7,418
Stock Issued During Period, Value, Conversion of Units	0						(566)	(6,484)			7,050
Common shares acquired from stock compensation plan activity	(13,689)										(13,689)
Common stock repurchase program	(12,158)										(12,158)
Ending Balance at Sep. 30, 2018	2,816,198			145,037		937	1,114,848	1,761,036			(74,096)	(131,564)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Other			$ (19)		$ (19)
Beginning Balance at Jun. 30, 2018												(121,936)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	99,673
Other comprehensive loss, net of tax	(9,628)											(9,628)
Ending Balance at Sep. 30, 2018	2,816,198			$ 145,037		$ 937	$ 1,114,848	1,761,036			$ (74,096)	$ (131,564)
Cumulative Effect of New Accounting Principle in Period of Adoption	$ (1,362)							$ (1,362)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Dividends on common stock and dividend equivalents declared (in dollars per share)	$ 0.92	$ 0.77
Series E Preferred Stock [Member]
Dividends on preferred stock (in dollars per share)		$ 1,200
Series F Preferred Stock [Member]
Dividends on preferred stock (in dollars per share)	$ 995.3125

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Activities:
Net income	$ 261,580	$ 185,546
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	32,000	27,900
Deferred tax expense (benefit)	13,138	(3,241)
Depreciation and amortization	28,991	28,060
Amortization of premium/discount on earning assets and funding, net	38,905	33,338
Stock-based compensation	8,598	9,050
Gain on sale, net of write-down, on foreclosed and repossessed assets	(745)	(551)
Write-down, net on premises and equipment	295	218
Impairment loss on investment securities recognized in earnings	0	126
Increase in cash surrender value of life insurance policies	(10,921)	(10,943)
Gain from life insurance policies	(1,453)	0
Mortgage banking activities	(3,684)	(8,038)
Proceeds from sale of loans held for sale	147,105	262,029
Origination of loans held for sale	(141,699)	(227,435)
Net decrease in derivative contract assets net of liabilities	130,250	11,235
Net increase in accrued interest receivable and other assets	(9,506)	(19,405)
Net increase in accrued expenses and other liabilities	3,529	12,386
Net cash provided by operating activities	496,383	300,275
Investing Activities:
Net (increase) decrease in interest-bearing deposits	(74,118)	2,469
Purchases of available for sale investment securities	(760,575)	(305,309)
Proceeds from maturities and principal payments of available for sale investment securities	445,704	695,595
Purchases of held-to-maturity investment securities	(283,770)	(887,240)
Proceeds from maturities and principal payments of held-to-maturity investment securities	414,487	525,499
Net proceeds of Federal Home Loan Bank stock	17,826	58,306
Alternative investments return of capital, net	231	107
Net increase in loans	(826,400)	(446,454)
Proceeds from loans not originated for sale	674	7,445
Proceeds from life insurance policies	4,271	746
Proceeds from the sale of foreclosed and repossessed assets	7,046	5,651
Proceeds from the sale of premises and equipment	0	2,182
Additions to premises and equipment	(25,481)	(20,034)
Proceeds from redemption of other assets	0	7,581
Net cash used for investing activities	(1,080,105)	(353,456)
Financing Activities:
Net increase in deposits	1,003,445	1,551,987
Proceeds from Federal Home Loan Bank advances	5,225,000	9,245,000
Repayments of Federal Home Loan Bank advances	(5,460,221)	(10,580,218)
Net decrease in securities sold under agreements to repurchase and other borrowings	(78,781)	(46,624)
Dividends paid to common shareholders	(85,002)	(70,732)
Dividends paid to preferred shareholders	(5,906)	(6,072)
Exercise of stock options	2,110	5,301
Common stock repurchase program	(12,158)	(11,585)
Common shares purchased related to stock compensation plan activity	(13,689)	(9,295)
Net cash (used for) provided by financing activities	574,798	77,762
Net decrease in cash and due from banks	(8,924)	24,581
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Beginning of Period	231,158	190,663
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents End of Period	222,234	215,244
Supplemental disclosure of cash flow information:
Interest paid	104,861	85,242
Income taxes paid	51,237	78,832
Noncash investing and financing activities:
Real Estate Owned, Transfer to Real Estate Owned	5,548	6,503
Transfer of loans from portfolio to loans-held-for-sale	$ 482	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 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 September 30, 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. Use of Estimates 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. Federal Deposit Insurance Corporation (FDIC) Assessment. Reclassification of certain loans under existing and modified FDIC loan category classifications resulted in an obligation for additional FDIC premiums for the period June 30, 2015 through December 31, 2017. An initial accrual of approximately $7.2 million was made in the second quarter to establish an expected liability at June 30, 2018. During the third quarter, the Company made a $10.0 million payment to the FDIC to resolve its obligation. Accounting Standards Adopted During 2018 Effective January 1, 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 held within the portfolio. The Update accelerates the Company's recognition of premium amortization on those debt securities. The Company adopted 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. 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) - Recognition and Measurement of Financial Assets and Financial Liabilities. 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) and 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. 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. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract The Update aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The updated guidance also requires an entity to amortize the capitalized implementation costs as an expense over the term of the hosting arrangement and to present in the same income statement line item as the fees associated with the hosting arrangement. This Update is effective for the Company on January 1, 2020, with early adoption permitted. The Company does not intend to early adopt this Update. The Company will apply the amendments in this update prospectively to all implementation costs incurred after the date of adoption. The Company does not expect this Update to have a material impact on its consolidated financial statements. ASU No. 2018-14, Compensation-Retirement Benefits - Defined Benefit Plan - General (Subtopic 715-20) - Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans The Update modifies the disclosure requirements for defined benefit pension plans and other postretirement plans. This updated guidance will be effective for the Company on January 1, 2021. The Company does not expect this Update to have a material impact on its consolidated financial statements. ASU No. 2018-13, Fair Value Measurement (Topic 820) - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement The Update modifies the disclosure requirements on fair value measurements. The updated guidance will no longer require entities to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. However, it will require public companies to disclose changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 measurements. This Update is effective for the Company on January 1, 2020, and earlier adoption is permitted. The Company does not expect this Update to have a material impact on its consolidated financial statements. 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. The Company does not expect the new guidance to have a material impact on its consolidated financial statements. 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 is effective for the Company on January 1, 2020 and early adoption is permitted. The Update must be applied prospectively. The Company does not expect the new guidance to have a material impact on its consolidated 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 may 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 empowered 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. Through these 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, treasury, and accounting. These work streams are collectively assessing required resources, use of existing and new models, and data availability. The Company expects that the new credit models will include additional assumptions used to calculate credit losses over the estimated life of the financial assets and will include expected future changes in macroeconomic conditions. The Company contracted with system solution providers and is in the process of implementing the selected solutions that will be used to run its credit loss models. The Update is effective for the Company on January 1, 2020. The impact of adopting the Update is expected to be influenced by assessment of the composition, characteristics, and credit quality of our loan and securities portfolios as well as the economic conditions in effect at the adoption date. Therefore, we are unable to reasonably estimate the impact of adopting the Update at this time. ASU No. 2016-02, Leases (Topic 842) and subsequent ASUs issued to amend this Topic. 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. During Q3 2018, the FASB issued a subsequent Update which, among other issues, incorporates a new transition method option that would allow the Company to use the effective date, January 1, 2019 for the Company, as the date of initial application of the new leases standard and recognize cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company currently expects to elect this transition method. The Company is in the process of reviewing its existing leases, and certain service contracts for embedded leases, to evaluate the impact of these Updates on the consolidated financial statements. The Company has engaged a third party consultant to assist with the implementation efforts and has selected a third party software solution to assist with the accounting under these Updates. The Updates are effective beginning January 1, 2019 and early adoption is permitted. The Company does not plan to early adopt, and the effect of the adoption will depend on the lease portfolio at the time of transition. SEC’s Final Rule on Disclosure Update and Simplification

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 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, CMBS, and CLO. 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 September 30, 2018 and December 31, 2017 , the aggregate carrying value of the Company's tax credit-finance investments were $30.0 million and $33.5 million , respectively. At September 30, 2018 and December 31, 2017 , unfunded commitments have been recognized, totaling $10.7 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. These 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 September 30, 2018 and December 31, 2017 , the aggregate carrying value of the Company's other investments in VIEs were $16.4 million and $13.8 million , respectively, and the total exposure of the Company's other investments in VIEs, including unfunded commitments, were $28.7 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

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 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 September 30, 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 $ 9,215 $ — $ (1 ) $ 9,214 $ 1,247 $ — $ — $ 1,247 Agency CMO 254,549 79 (8,162 ) 246,466 308,989 1,158 (3,814 ) 306,333 Agency MBS 1,466,973 641 (57,883 ) 1,409,731 1,124,960 2,151 (19,270 ) 1,107,841 Agency CMBS 610,411 — (39,862 ) 570,549 608,276 — (20,250 ) 588,026 CMBS 404,104 850 (52 ) 404,902 358,984 2,157 (74 ) 361,067 CLO 127,743 202 (284 ) 127,661 209,075 910 (134 ) 209,851 Single issuer-trust preferred — — — — 7,096 — (46 ) 7,050 Corporate debt 56,032 361 (963 ) 55,430 56,504 797 (679 ) 56,622 Available-for-sale $ 2,929,027 $ 2,133 $ (107,207 ) $ 2,823,953 $ 2,675,131 $ 7,173 $ (44,267 ) $ 2,638,037 Held-to-maturity: Agency CMO $ 218,351 $ 143 $ (9,192 ) $ 209,302 $ 260,114 $ 664 $ (4,824 ) $ 255,954 Agency MBS 2,535,043 8,256 (110,035 ) 2,433,264 2,569,735 16,989 (37,442 ) 2,549,282 Agency CMBS 672,505 — (28,222 ) 644,283 696,566 — (10,011 ) 686,555 Municipal bonds and notes 684,587 804 (26,487 ) 658,904 711,381 8,584 (6,558 ) 713,407 CMBS 221,969 380 (3,746 ) 218,603 249,273 2,175 (620 ) 250,828 Private Label MBS 3 — — 3 323 1 — 324 Held-to-maturity $ 4,332,458 $ 9,583 $ (177,682 ) $ 4,164,359 $ 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 Wall Street Reform and Consumer Protection Act of 2010 (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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 1,103 $ 3,231 $ 1,364 $ 3,243 Reduction for investment securities called (281 ) (1,028 ) (542 ) (1,166 ) Additions for OTTI not previously recognized in earnings — — — 126 Ending balance $ 822 $ 2,203 $ 822 $ 2,203 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 September 30, 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: U.S. Treasury Bills $ 9,214 $ (1 ) $ — $ — 2 $ 9,214 $ (1 ) Agency CMO 108,055 (2,046 ) 123,570 (6,116 ) 43 231,625 (8,162 ) Agency MBS 632,866 (13,665 ) 751,739 (44,218 ) 185 1,384,605 (57,883 ) Agency CMBS 28,075 (1,074 ) 542,474 (38,788 ) 37 570,549 (39,862 ) CMBS 68,695 (52 ) — — 14 68,695 (52 ) CLO 41,156 (143 ) 15,009 (141 ) 3 56,165 (284 ) Single issuer-trust preferred — — — — — — — Corporate debt 8,862 (72 ) 17,157 (891 ) 5 26,019 (963 ) Available-for-sale in an unrealized loss position $ 896,923 $ (17,053 ) $ 1,449,949 $ (90,154 ) 289 $ 2,346,872 $ (107,207 ) Held-to-maturity: Agency CMO $ 31,749 $ (959 ) $ 155,428 $ (8,233 ) 26 $ 187,177 $ (9,192 ) Agency MBS 757,451 (20,783 ) 1,467,605 (89,252 ) 274 2,225,056 (110,035 ) Agency CMBS 43,474 (697 ) 600,808 (27,525 ) 57 644,282 (28,222 ) Municipal bonds and notes 343,560 (11,463 ) 216,401 (15,024 ) 272 559,961 (26,487 ) CMBS 160,047 (3,256 ) 17,152 (490 ) 21 177,199 (3,746 ) Held-to-maturity in an unrealized loss position $ 1,336,281 $ (37,158 ) $ 2,457,394 $ (140,524 ) 650 $ 3,793,675 $ (177,682 ) 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: U.S. Treasury Bills $ — $ — $ — $ — — $ — $ — 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 are impaired as of September 30, 2018 . 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 September 30, 2018 . Available-for-Sale Securities Agency CMO. There were unrealized losses of $8.2 million on the Company’s investment in Agency CMO at September 30, 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 $57.9 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at September 30, 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 $39.9 million on the Company's investment in commercial mortgage-backed securities issued by government agencies at September 30, 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 $52 thousand on the Company’s investment in CMBS at September 30, 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 September 30, 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 $284 thousand on the Company’s investments in CLO at September 30, 2018 compared to $134 thousand unrealized losses at December 31, 2017 . Unrealized losses remained insignificant while principal balances decreased from December 31, 2017 . Contractual cash flows for the bonds continue to perform as expected. Corporate debt. There were unrealized losses of $963 thousand on the Company's corporate debt portfolio at September 30, 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. Contractual cash flows for the bonds continue to perform as expected. Held-to-Maturity Securities Agency CMO. There were unrealized losses of $9.2 million on the Company’s investment in Agency CMO at September 30, 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 $110.0 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at September 30, 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 $28.2 million on the Company’s investment in commercial mortgage-backed securities issued by government agencies at September 30, 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 $26.5 million on the Company’s investment in municipal bonds and notes at September 30, 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 $3.7 million on the Company’s investment in CMBS at September 30, 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. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Sales of Available-for Sale Investment Securities There were no sales during the three and nine months ended September 30, 2018 and 2017 . Contractual Maturities The amortized cost and fair value of debt securities by contractual maturity are set forth below: At September 30, 2018 Available-for-Sale Held-to-Maturity (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 29,730 $ 29,750 $ 6,352 $ 6,378 Due after one year through five years 31,012 31,092 4,244 4,272 Due after five through ten years 276,583 276,143 40,016 39,933 Due after ten years 2,591,702 2,486,968 4,281,846 4,113,776 Total debt securities $ 2,929,027 $ 2,823,953 $ 4,332,458 $ 4,164,359 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 September 30, 2018 , the Company had a carrying value of $1.1 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 $2.5 billion at September 30, 2018 and $2.4 billion December 31, 2017

Loans and Leases

Loans and Leases	9 Months Ended
	Sep. 30, 2018
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	Loans and Leases The following table summarizes loans and leases: (In thousands) At September 30, At December 31, 2017 Residential $ 4,415,063 $ 4,490,878 Consumer 2,441,181 2,590,225 Commercial 6,174,396 5,368,694 Commercial Real Estate 4,771,325 4,523,828 Equipment Financing 519,054 550,233 Loans and leases (1) (2) $ 18,321,019 $ 17,523,858 (1) Loans and leases include net deferred fees and net premiums/discounts of $13.6 million and $20.6 million at September 30, 2018 and December 31, 2017 , respectively. (2) At September 30, 2018 the Company had pledged $7.1 billion of eligible residential, consumer, and commercial loans as collateral to support borrowing capacity at the Federal Home Loan Bank (FHLB) of Boston and the Federal Reserve Bank (FRB) of Boston. Loans and Leases Aging The following tables summarize the aging of loans and leases: At September 30, 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 $ 9,023 $ 5,510 $ — $ 49,469 $ 64,002 $ 4,351,061 $ 4,415,063 Consumer: Home equity 9,519 3,442 — 35,174 48,135 2,165,340 2,213,475 Other consumer 1,819 898 — 1,490 4,207 223,499 227,706 Commercial: Commercial non-mortgage 659 543 147 55,040 56,389 5,148,962 5,205,351 Asset-based — — — 1,029 1,029 968,016 969,045 Commercial real estate: Commercial real estate 2,715 35 — 7,254 10,004 4,564,320 4,574,324 Commercial construction — — — — — 197,001 197,001 Equipment financing 1,371 3,617 — 3,339 8,327 510,727 519,054 Total $ 25,106 $ 14,045 $ 147 $ 152,795 $ 192,093 $ 18,128,926 $ 18,321,019 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 $4.3 million and $2.8 million for the three months ended September 30, 2018 and 2017 , respectively, and $7.9 million and $6.4 million for the nine months ended September 30, 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 September 30, 2018 Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 19,007 $ 31,759 $ 95,340 $ 55,833 $ 5,383 $ 207,322 Provision (benefit) charged to expense 407 474 5,686 4,146 (213 ) 10,500 Charge-offs (874 ) (4,863 ) (740 ) (1,922 ) (136 ) (8,535 ) Recoveries 133 1,827 431 143 11 2,545 Balance, end of period $ 18,673 $ 29,197 $ 100,717 $ 58,200 $ 5,045 $ 211,832 At or for the three months ended September 30, 2017 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 18,427 $ 42,488 $ 79,964 $ 52,402 $ 6,297 $ 199,578 (Benefit) provision charged to expense (348 ) (41 ) 12,166 (2,129 ) 502 10,150 Charge-offs (585 ) (6,197 ) (3,002 ) (749 ) (121 ) (10,654 ) Recoveries 280 1,894 466 10 79 2,729 Balance, end of period $ 17,774 $ 38,144 $ 89,594 $ 49,534 $ 6,757 $ 201,803 At or for the nine months ended September 30, 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 1,316 2,967 17,596 10,678 (557 ) 32,000 Charge-offs (2,545 ) (14,844 ) (7,869 ) (2,039 ) (246 ) (27,543 ) Recoveries 844 4,884 1,457 154 42 7,381 Balance, end of period $ 18,673 $ 29,197 $ 100,717 $ 58,200 $ 5,045 $ 211,832 Individually evaluated for impairment $ 4,319 $ 1,428 $ 10,491 $ 1,544 $ 15 $ 17,797 Collectively evaluated for impairment $ 14,354 $ 27,769 $ 90,226 $ 56,656 $ 5,030 $ 194,035 Loan and lease balances: Individually evaluated for impairment $ 105,600 $ 39,808 $ 104,353 $ 9,767 $ 6,489 $ 266,017 Collectively evaluated for impairment 4,309,463 2,401,373 6,070,043 4,761,558 512,565 18,055,002 Loans and leases $ 4,415,063 $ 2,441,181 $ 6,174,396 $ 4,771,325 $ 519,054 $ 18,321,019 At or for the nine months ended September 30, 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 (4,436 ) 6,847 21,905 2,987 597 27,900 Charge-offs (1,940 ) (18,273 ) (5,321 ) (951 ) (425 ) (26,910 ) Recoveries 924 4,337 1,105 21 106 6,493 Balance, end of period $ 17,774 $ 38,144 $ 89,594 $ 49,534 $ 6,757 $ 201,803 Individually evaluated for impairment $ 4,925 $ 1,689 $ 10,844 $ 290 $ 38 $ 17,786 Collectively evaluated for impairment $ 12,849 $ 36,455 $ 78,750 $ 49,244 $ 6,719 $ 184,017 Loan and lease balances: Individually evaluated for impairment $ 116,706 $ 46,224 $ 85,385 $ 18,199 $ 3,642 $ 270,156 Collectively evaluated for impairment 4,382,735 2,520,759 5,262,918 4,446,718 563,135 17,176,265 Loans and leases $ 4,499,441 $ 2,566,983 $ 5,348,303 $ 4,464,917 $ 566,777 $ 17,446,421 Impaired Loans and Leases The following tables summarize impaired loans and leases: At September 30, 2018 (In thousands) Unpaid Principal Balance Total Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential $ 115,959 $ 105,600 $ 66,484 $ 39,116 $ 4,319 Consumer - home equity 45,299 39,808 30,924 8,884 1,428 Commercial : Commercial non-mortgage 117,223 103,324 65,968 37,356 10,491 Asset-based 1,074 1,029 1,029 — — Commercial real estate 12,239 9,767 2,561 7,206 1,544 Equipment financing 6,536 6,489 6,164 325 15 Total $ 298,330 $ 266,017 $ 173,130 $ 92,887 $ 17,797 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 11,994 11,226 6,387 4,839 272 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 September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Average Recorded Investment Accrued Interest Income Cash Basis Interest Income Average Accrued Cash Basis Interest Income Average Recorded Investment Accrued Cash Basis Interest Income Average Recorded Investment Accrued Cash Basis Interest Income Residential $ 107,618 $ 923 $ 301 $ 118,841 $ 1,027 $ 285 $ 109,948 $ 2,852 $ 819 $ 118,065 $ 3,133 $ 986 Consumer - home equity 40,722 292 238 46,753 341 246 42,622 876 738 45,972 998 808 Commercial: Commercial non-mortgage 94,618 847 — 81,816 249 — 87,603 2,257 — 64,932 704 — Asset based 1,095 — — 4,279 — — 809 — — 4,279 — — Commercial real estate: Commercial real estate 11,222 30 — 20,249 96 — 10,497 164 — 20,647 329 — Commercial construction — — — 828 — — — — — 831 12 — Equipment financing 6,337 41 — 4,895 30 — 4,907 112 — 5,031 168 — Total $ 261,612 $ 2,133 $ 539 $ 277,661 $ 1,743 $ 531 $ 256,386 $ 6,261 $ 1,557 $ 259,757 $ 5,344 $ 1,794 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 September 30, At December 31, At September 30, At December 31, At September 30, At December 31, (1) - (6) Pass $ 5,742,170 $ 5,048,162 $ 4,561,901 $ 4,355,916 $ 499,167 $ 525,105 (7) Special Mention 188,905 104,594 105,778 62,065 1,574 8,022 (8) Substandard 236,246 206,883 103,646 105,847 18,313 17,106 (9) Doubtful 7,075 9,055 — — — — Total $ 6,174,396 $ 5,368,694 $ 4,771,325 $ 4,523,828 $ 519,054 $ 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, may also be evaluated as credit quality indicators. 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 September 30, At December 31, 2017 Accrual status $ 145,219 $ 147,113 Non-accrual status 95,154 74,291 Total recorded investment of TDRs $ 240,373 $ 221,404 Specific reserves for TDRs included in the balance of ALLL $ 16,338 $ 12,384 Additional funds committed to borrowers in TDR status 2,926 2,736 For the portion of TDRs deemed to be uncollectible, Webster charged off $1.1 million and $0.4 million for the three months ended September 30, 2018 and 2017 , respectively, and $6.3 million , and $3.0 million for the nine months ended September 30, 2018 and 2017 , respectively. The following table provides information on the type of concession for loans and leases modified as TDRs: Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Number of Post- (1) Number of Post- (1) Number of Post- (1) Number of Post- (1) (Dollars in thousands) Residential Extended Maturity 1 $ 20 — $ — 1 $ 20 9 $ 1,390 Adjusted Interest Rate — — — — — — 2 335 Maturity/Rate Combined 4 440 4 570 7 716 9 1,416 Other (2) 3 356 6 1,357 16 2,798 32 5,471 Consumer - home equity Extended Maturity 1 148 2 158 3 341 8 822 Adjusted Interest Rate — — 1 247 — — 1 247 Maturity/Rate Combined 3 170 2 399 6 618 13 3,212 Other (2) 5 258 12 839 30 1,951 55 3,733 Commercial non - mortgage Extended Maturity 4 537 — — 7 622 8 813 Maturity/Rate Combined 8 8,185 8 299 10 8,236 13 9,153 Other (2) 8 10,585 — — 17 39,328 1 4 Commercial real estate Extended Maturity — — — — 2 97 — — Maturity/Rate Combined — — — — 1 245 — — Other (2) — — — — 1 5,111 — — Total TDRs 37 $ 20,699 35 $ 3,869 101 $ 60,083 151 $ 26,596 (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. Loans and leases modified as TDRs within the previous 12 months and for which there was a payment default, consisted of 1 residential loan with an recorded investment of $241 thousand and 1 residential loan with an recorded investment $248 thousand for the three months ended September 30, 2018 and 2017 , respectively, and 2 residential loans with an recorded investment of $261 thousand and 1 residential loan with an recorded investment $248 thousand for the nine months ended September 30, 2018 and 2017 , respectively. The recorded investment of TDRs in commercial, commercial real estate, and equipment financing segregated by risk rating exposure is as follows: (In thousands) At September 30, 2018 At December 31, 2017 (1) - (6) Pass $ 12,733 $ 8,268 (7) Special Mention 334 355 (8) Substandard 74,822 53,050 (9) Doubtful 7,075 — Total $ 94,964 $ 61,673

Transfers of Financial Assets

Transfers of Financial Assets	9 Months Ended
	Sep. 30, 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. Gains and losses from initial measurement and subsequent changes in fair value are recognized in earnings. The gain or loss on residential mortgage loans sold and the related origination fee income, as well as fair value adjustments 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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 674 $ 843 $ 872 $ 790 Provision (benefit) charged to expense 18 25 (172 ) 78 Repurchased loans and settlements charged off (10 ) (18 ) (18 ) (18 ) Ending balance $ 682 $ 850 $ 682 $ 850 The following table provides information for mortgage banking activities: Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Residential mortgage loans held for sale: Proceeds from sale $ 57,042 $ 88,691 $ 147,105 $ 262,029 Loans sold with servicing rights retained 51,014 79,690 130,740 239,357 Net gain on sale 1,051 1,979 2,732 4,356 Ancillary fees 463 682 1,275 2,091 Fair value option adjustment (209 ) (240 ) (323 ) 1,591 The Company has retained servicing rights on residential mortgage loans totaling $2.5 billion at September 30, 2018 and $2.6 billion at December 31, 2017 . The following table presents the changes in carrying value for mortgage servicing assets: Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 23,341 $ 24,708 $ 25,139 $ 24,466 Additions 1,428 2,576 3,878 7,063 Amortization (2,125 ) (2,144 ) (6,373 ) (6,389 ) Ending balance $ 22,644 $ 25,140 $ 22,644 $ 25,140 Loan servicing fees, net of mortgage servicing rights amortization, were $0.3 million and $0.2 million for the three months ended September 30, 2018 and 2017 , respectively, and $0.9 million and $0.6 million for the nine months ended September 30, 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 $674 thousand for certain commercial loans and $7.4 million for certain residential loans for the nine months ended September 30, 2018 and 2017

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 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 September 30, 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 $ (10,283 ) $ 11,717 $ 22,000 $ (8,610 ) $ 13,390 HSA Bank - Customer relationships 21,000 (5,991 ) 15,009 21,000 (4,779 ) 16,221 Total other intangible assets $ 43,000 $ (16,274 ) $ 26,726 $ 43,000 $ (13,389 ) $ 29,611 As of September 30, 2018 , the remaining estimated aggregate future amortization expense for intangible assets is as follows: (In thousands) Remainder of 2018 $ 962 2019 3,847 2020 3,847 2021 3,847 2022 3,847 Thereafter 10,376

Deposits

Deposits	9 Months Ended
	Sep. 30, 2018
Banking and Thrift [Abstract]
Deposits	A summary of deposits by type follows: (In thousands) At September 30, At December 31, Non-interest-bearing: Demand $ 4,231,505 $ 4,191,496 Interest-bearing: Health savings accounts 5,599,596 5,038,681 Checking 2,587,679 2,736,952 Money market 2,376,649 2,209,492 Savings 4,106,942 4,348,700 Time deposits 3,095,252 2,468,408 Total interest-bearing 17,766,118 16,802,233 Total deposits $ 21,997,623 $ 20,993,729 Time deposits and interest-bearing checking, included in above balances, obtained through brokers $ 938,092 $ 898,157 Time deposits, included in above balance, that exceed the FDIC limit 506,955 561,512 Deposit overdrafts reclassified as loan balances 1,761 2,210 The scheduled maturities of time deposits are as follows: (In thousands) At September 30, Remainder of 2018 $ 683,421 2019 1,771,721 2020 437,240 2021 125,265 2022 49,295 Thereafter 28,310 Total time deposits $ 3,095,252

Borrowings

Borrowings	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Borrowings	Borrowings Total borrowings of $2.2 billion at September 30, 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 September 30, At December 31, (In thousands) Amount Rate Amount Rate Securities sold under agreements to repurchase (1) : Original maturity of one year or less $ 264,488 0.29 % $ 288,269 0.17 % Original maturity of greater than one year, non-callable 100,000 2.50 300,000 3.10 Total securities sold under agreements to repurchase 364,488 0.89 588,269 1.66 Fed funds purchased 200,000 2.25 55,000 1.37 Securities sold under agreements to repurchase and other borrowings $ 564,488 1.37 $ 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 September 30, At December 31, (Dollars in thousands) Amount Weighted- Average Contractual Coupon Rate Amount Weighted- Average Contractual Coupon Rate Maturing within 1 year $ 948,731 2.18 % $ 1,150,000 1.48 % After 1 but within 2 years 259,295 1.79 103,026 1.81 After 2 but within 3 years 75,000 1.51 215,000 1.73 After 3 but within 4 years 150,049 3.27 200,000 2.06 (1) After 4 but within 5 years 193 1.69 170 — After 5 years 8,616 2.64 8,909 2.65 (1) FHLB advances and overall rate $ 1,441,884 2.19 $ 1,677,105 1.61 (1) Aggregate carrying value of assets pledged as collateral $ 6,773,182 $ 6,402,066 Remaining borrowing capacity 3,018,052 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 reported in the Company's 2017 Annual Report on Form 10-K 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 September 30, 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 (638 ) (727 ) Debt issuance cost on senior fixed-rate notes (725 ) (826 ) Long-term debt $ 225,957 $ 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 plus 2.95% , was 5.28% at September 30, 2018 and 4.55% at December 31, 2017

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss, Net of Tax	9 Months Ended
	Sep. 30, 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 September 30, 2018 Nine months ended September 30, 2018 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (64,617 ) $ (10,814 ) $ (46,505 ) $ (121,936 ) $ (27,947 ) $ (15,016 ) $ (48,568 ) $ (91,531 ) (OCL) OCI before reclassifications (13,811 ) 197 — (13,614 ) (50,481 ) 1,620 — (48,861 ) Amounts reclassified from AOCL — 1,438 2,548 3,986 — 4,217 4,611 8,828 Net current-period OCI/(OCL) (13,811 ) 1,635 2,548 (9,628 ) (50,481 ) 5,837 4,611 (40,033 ) Ending balance $ (78,428 ) $ (9,179 ) $ (43,957 ) $ (131,564 ) $ (78,428 ) $ (9,179 ) $ (43,957 ) $ (131,564 ) Three months ended September 30, 2017 Nine months ended September 30, 2017 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (14,501 ) $ (15,258 ) $ (42,323 ) $ (72,082 ) $ (15,476 ) $ (17,068 ) $ (44,449 ) $ (76,993 ) OCI/(OCL) before reclassifications 872 (34 ) — 838 1,847 (445 ) — 1,402 Amounts reclassified from AOCL — 1,145 1,001 2,146 — 3,366 3,127 6,493 Net current-period OCI 872 1,111 1,001 2,984 1,847 2,921 3,127 7,895 Ending balance $ (13,629 ) $ (14,147 ) $ (41,322 ) $ (69,098 ) $ (13,629 ) $ (14,147 ) $ (41,322 ) $ (69,098 ) The following tables provide information for the items reclassified from AOCL: (In thousands) Three months ended September 30, Nine months ended September 30, Associated Line Item in the Condensed Consolidated Statements of Income AOCL Components 2018 2017 2018 2017 Derivative instruments: Cash flow hedges $ (1,932 ) $ (1,810 ) $ (5,664 ) $ (5,316 ) Total interest expense Tax benefit 494 665 1,447 1,950 Income tax expense Net of tax $ (1,438 ) $ (1,145 ) $ (4,217 ) $ (3,366 ) Defined benefit pension and other postretirement benefit plans: Amortization of net loss $ (3,431 ) $ (1,587 ) $ (6,209 ) $ (4,959 ) (1) Tax benefit 883 586 1,598 1,832 Income tax expense Net of tax $ (2,548 ) $ (1,001 ) $ (4,611 ) $ (3,127 )

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 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 September 30, 2018 Actual Minimum Requirement Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio Webster Financial Corporation CET1 risk-based capital $ 2,215,456 11.23 % $ 887,910 4.5 % $ 1,282,537 6.5 % Total risk-based capital 2,652,270 13.44 1,578,507 8.0 1,973,133 10.0 Tier 1 risk-based capital 2,360,493 11.96 1,183,880 6.0 1,578,507 8.0 Tier 1 leverage capital 2,360,493 8.89 1,061,977 4.0 1,327,471 5.0 Webster Bank CET1 risk-based capital $ 2,137,249 10.84 % $ 887,232 4.5 % $ 1,281,558 6.5 % Total risk-based capital 2,351,706 11.93 1,577,302 8.0 1,971,628 10.0 Tier 1 risk-based capital 2,137,249 10.84 1,182,977 6.0 1,577,302 8.0 Tier 1 leverage capital 2,137,249 8.05 1,061,427 4.0 1,326,784 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 Office of the Comptroller of the Currency (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 $220 million during the nine months ended September 30, 2018 compared to $80 million during the nine months ended September 30, 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 $98.6 million and $82.3 million at September 30, 2018 and December 31, 2017

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 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 September 30, Nine Months Ended September 30, (In thousands, except per share data) 2018 2017 2018 2017 Earnings for basic and diluted earnings per common share: Net income $ 99,673 $ 64,496 $ 261,580 $ 185,546 Less: Preferred stock dividends 1,968 2,024 5,884 6,072 Net income available to common shareholders 97,705 62,472 255,696 179,474 Less: Earnings applicable to participating securities 245 46 656 212 Earnings applicable to common shareholders $ 97,460 $ 62,426 $ 255,040 $ 179,262 Shares: Weighted-average common shares outstanding - basic 91,959 92,125 91,912 92,003 Effect of dilutive securities: Stock options and restricted stock 243 372 303 403 Warrants 6 6 6 6 Weighted-average common shares outstanding - diluted 92,208 92,503 92,221 92,412 Earnings per common share: Basic $ 1.06 $ 0.68 $ 2.77 $ 1.95 Diluted 1.06 0.67 2.77 1.94 Potential common shares from non-participating restricted stock, of 97 thousand and 80 thousand for the three months ended September 30, 2018 and 2017 , respectively, and 54 thousand and 61 thousand for the nine months ended September 30, 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	9 Months Ended
	Sep. 30, 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, which results in minimal impact on earnings, except for fee income earned in such transactions. All contracts eligible for clearing are cleared through Chicago Mercantile Exchange (CME). In accordance with its amended rulebook, CME legally characterizes variation margin payments made to and received from CME as settlement of derivatives rather than as collateral against derivatives. 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 and customer hedging activity, 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 September 30, 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 cash flow hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) $ 325,000 $ 4,951 $ — $ — $ 325,000 $ 2,770 $ — $ — Not designated as hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) 3,852,438 13,226 76,789 215 2,791,760 5,977 721,048 1,968 Mortgage banking derivatives (3) 52,067 223 3,063 7 28,497 421 39,230 110 Other 24,879 199 23,927 435 7,914 258 30,328 419 Positions not subject to a master netting agreement (4) Interest rate derivatives 677,679 3,090 3,242,821 83,142 1,366,299 23,009 2,146,518 25,631 RPAs 84,702 19 100,294 43 93,713 80 116,882 111 Other 6,918 300 2,517 47 — — 2,073 184 Total not designated as hedging instruments 4,698,683 17,057 3,449,411 83,889 4,288,183 29,745 3,056,079 28,423 Gross derivative instruments, before netting $ 5,023,683 22,008 $ 3,449,411 83,889 $ 4,613,183 32,515 $ 3,056,079 28,423 Less: Legally enforceable master netting agreements 586 586 2,245 2,245 Less: Cash collateral posted 17,709 — 6,704 — Total derivative instruments, after netting $ 3,713 $ 83,303 $ 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) Balances related to CME are presented as a single unit of account. Notional amounts of interest rate swaps cleared through CME include; $2.7 billion and $1.9 billion for asset derivatives and $47 million and $595 million for liability derivatives at September 30, 2018 and December 31, 2017, respectively, with related fair values of approximately zero . (3) Notional amounts include mandatory forward commitments of $33.0 million , while notional amounts do not include approved floating rate commitments of $9.1 million , at September 30, 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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Designated as cash flow hedging instruments: Interest rate derivatives (1) $ 1,667 $ 1,928 $ 5,158 $ 5,953 Not designated as hedging instruments: Interest rate derivatives (2) $ 1,623 $ 2,955 $ 7,372 $ 5,850 RPAs 22 51 117 157 Mortgage banking derivatives (26 ) (219 ) (95 ) (1,886 ) Other (2) (226 ) (756 ) 1,113 (1,748 ) Total not designated as hedging instruments (2) (3) $ 1,393 $ 2,031 $ 8,507 $ 2,373 (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) Amounts for 2017 are presented as revised to include impact of accrued interest for net customer swap arrangements. (3) 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 $264 thousand will be reclassified from AOCL as an increase to interest income. 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 September 30, 2018 , the remaining unamortized loss on the termination of cash flow hedges is $10.1 million . Over the next twelve months, the Company estimates that $4.3 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 Non-cleared 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 September 30, 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 $ 4,951 $ — $ 4,951 $ — $ 2,770 $ 91 $ 2,679 $ — Non-hedge accounting 13,425 586 12,758 81 6,222 2,154 4,025 43 Total assets $ 18,376 $ 586 $ 17,709 $ 81 $ 8,992 $ 2,245 $ 6,704 $ 43 Derivative instrument losses: Hedge accounting $ — $ — $ — $ — $ — $ — $ — $ — Non-hedge accounting 651 586 — 65 2,387 2,245 — 142 Total liabilities $ 651 $ 586 $ — $ 65 $ 2,387 $ 2,245 $ — $ 142 Counterparty Credit Risk Use of derivative contracts may expose Webster Bank to counterparty credit risk. The Company has International Swaps and Derivatives Association Master Agreements, including a Credit Support Annex, with all derivative counterparties. In accordance with counterparty credit agreements and derivative clearing rules, the Company had approximately $80.0 million in net margin collateral received from financial counterparties or the derivative clearing organization at September 30, 2018 , comprised of $36.3 million in initial margin posted, $98.2 million in settlement-to-market received, and $18.1 million in collateral-to-market received. 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. Credit risk exposure is mitigated as transactions with customers are generally secured by the same collateral of the underlying transactions being hedged. The Company's net current credit exposure relating to interest rate derivatives with Webster Bank customers was $3.1 million at September 30, 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 $31.7 million at September 30, 2018

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 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,) 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, 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. The change in value of derivative assets and liabilities attributable to credit risk was not significant during the reported periods. 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 CME rulebook legally characterizes variation margin payments for over-the-counter derivatives as settlements rather than collateral, which impacts Webster's counterparty relationship with CME, resulting in the fair value of the instrument including cash collateral to be represented as a single unit of account. 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 into issuances of 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: At September 30, 2018 At December 31, 2017 (In thousands) Fair Value Unpaid Principal Balance Difference Fair Value Unpaid Principal Balance Difference Originated loans held for sale $ 17,137 $ 17,288 $ (151 ) $ 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. 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 unadjusted market prices in active markets 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 $2.0 million at September 30, 2018 . Alternative Investments. Equity investments have a readily determinable fair value when quoted prices are available in an active market. The Company classifies alternative investments with a readily determinable fair value within Level 1 of the fair value hierarchy. Equity investments that do not have a readily available fair value may qualify for net asset value (NAV) measurement based on specific requirements. The Company's alternative investments accounted for at NAV consist of investments in non-public entities that generally cannot be redeemed since the Company’s investments are distributed as the underlying equity is liquidated. Alternative investments recorded at NAV are not classified within the fair value hierarchy. At September 30, 2018 , these alternative investments had a remaining unfunded commitment of $1.1 million . Summaries of the fair values of assets and liabilities measured at fair value on a recurring basis are as follows: At September 30, 2018 (In thousands) Level 1 Level 2 Level 3 NAV Total Financial assets held at fair value: U.S. Treasury Bills $ 9,214 $ — $ — $ — $ 9,214 Agency CMO — 246,466 — — 246,466 Agency MBS — 1,409,731 — — 1,409,731 Agency CMBS — 570,549 — — 570,549 CMBS — 404,902 — — 404,902 CLO — 127,661 — — 127,661 Single issuer-trust preferred — — — — — Corporate debt — 55,430 — — 55,430 Total available-for-sale investment securities 9,214 2,814,739 — — 2,823,953 Gross derivative instruments, before netting (1) 498 21,510 — — 22,008 Originated loans held for sale — 17,137 — — 17,137 Investments held in Rabbi Trust 4,930 — — — 4,930 Alternative investments — — — 2,073 2,073 Total financial assets held at fair value $ 14,642 $ 2,853,386 $ — $ 2,073 $ 2,870,101 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 462 $ 83,427 $ — $ — $ 83,889 At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 NAV 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 — — — 3,495 3,495 Total financial assets held at fair value $ 6,306 $ 2,689,935 $ — $ 3,495 $ 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 . 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. 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. These alternative investments are investments in non-public entities that generally cannot be redeemed since the investment is distributed as the underlying equity is liquidated. Accordingly, these alternative investments are classified within Level 2 of the fair value hierarchy. The carrying amount of these alternative investments was $3.6 million at September 30, 2018 . No reduction for impairments, or adjustments due to observable price changes, was identified during the three or nine months ended September 30, 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 primarily consists of commercial loans with observable inputs and is classified within Level 2. On the occasion that these loans should 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 $5.3 million at September 30, 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. At September 30, 2018 , there were no significant assets measured at fair value on a non-recurring basis. 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, as well as servicing assets. 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 and subsequently measured under the amortization method. Mortgage servicing assets are subject to impairment testing and considered to be recognized at fair value when they are recorded at below cost. Amortization, and impairment charges, if any, 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 September 30, 2018 At December 31, 2017 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Level 2 Held-to-maturity investment securities $ 4,332,458 $ 4,164,359 $ 4,487,392 $ 4,456,350 Level 3 Loans and leases, net 18,109,187 17,913,452 17,323,864 17,211,619 Mortgage servicing assets 22,644 48,661 25,139 45,309 Liabilities: Level 2 Deposit liabilities $ 18,902,371 $ 18,902,371 $ 18,525,321 $ 18,525,321 Time deposits 3,095,252 3,067,487 2,468,408 2,455,245 Securities sold under agreements to repurchase and other borrowings 564,488 564,396 643,269 644,084 FHLB advances 1,441,884 1,439,155 1,677,105 1,678,070 Long-term debt (1) 225,957 229,336 225,767 234,359 (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	9 Months Ended
	Sep. 30, 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 September 30, 2018 2017 (In thousands) Pension Plan SERP Other Benefits Pension Plan SERP Other Benefits Service cost $ — $ — $ — $ 12 $ — $ — Interest cost on benefit obligations 1,857 35 20 1,829 96 19 Expected return on plan assets (3,178 ) — — (3,074 ) — — Amortization of prior service cost — — — — — — Recognized net loss 1,160 2,271 — 1,466 136 (15 ) Net periodic benefit cost $ (161 ) $ 2,306 $ 20 $ 233 $ 232 $ 4 Nine months ended September 30, 2018 2017 (In thousands) Pension Plan SERP Other Benefits Pension Plan SERP Other Benefits Service cost $ — $ — $ — $ 37 $ — $ — Interest cost on benefit obligations 5,577 201 59 5,486 281 69 Expected return on plan assets (9,538 ) — — (9,222 ) — — Amortization of prior service cost — — — — — — Recognized net loss 3,480 2,729 — 4,398 561 — Net periodic benefit cost $ (481 ) $ 2,930 $ 59 $ 699 $ 842 $ 69

Share-Based Plans

Share-Based Plans	9 Months Ended
	Sep. 30, 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 restricted stock, restricted stock units, non-qualified stock options, incentive stock options, 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 $2.7 million and $3.0 million for the three months ended September 30, 2018 and 2017 , respectively, and $8.6 million and $9.1 million for the nine months ended September 30, 2018 and 2017 , respectively, related to restricted stock awards, was recognized in the accompanying Condensed Consolidated Statements of Income. At September 30, 2018 there was $16.4 million of unrecognized stock compensation expense for restricted stock expected to be recognized over a weighted-average period of 2.0 years . The following table provides a summary of the stock compensation plans activity for the nine months ended September 30, 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 January 1, 2018 207,800 $ 43.16 78,916 $ 45.35 673,039 $ 18.75 Granted 145,382 58.36 75,707 55.82 — — Vested restricted stock awards (1) 129,445 44.80 55,112 46.08 — — Forfeited 8,041 52.53 13,847 51.19 — — Exercised options — — — — 180,247 11.71 Outstanding and exercisable, at September 30, 2018 215,696 51.91 85,664 53.19 492,792 21.33 (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 3 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 458,904 non-qualified stock options and 33,888 incentive stock options outstanding at September 30, 2018

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 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. 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. A $10.0 million charge related to additional FDIC premiums pertaining to prior periods' deposit insurance assessments and related interest is included in the Corporate and Reconciling category for the nine months ended September 30, 2018. See Note 1 to the Condensed Consolidated Financial Statements included in Item 1 of this report for additional information. 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: (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total At September 30, 2018 $ 10,327,878 $ 71,172 $ 8,730,295 $ 8,216,972 $ 27,346,317 At December 31, 2017 9,350,028 76,308 8,909,671 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 September 30, 2018 (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 91,243 $ 36,731 $ 101,952 $ 446 $ 230,372 Provision (benefit) for loan and lease losses 8,207 — 2,293 — 10,500 Net interest income (expense) after provision for loan and lease losses 83,036 36,731 99,659 446 219,872 Non-interest income 18,305 22,159 26,848 4,972 72,284 Non-interest expense 44,506 30,753 95,769 7,755 178,783 Income (loss) before income tax expense 56,835 28,137 30,738 (2,337 ) 113,373 Income tax expense (benefit) 13,981 7,316 6,117 (13,714 ) 13,700 Net income (loss) $ 42,854 $ 20,821 $ 24,621 $ 11,377 $ 99,673 Three months ended September 30, 2017 (In thousands) Commercial Banking HSA Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 81,925 $ 26,713 $ 96,859 $ (4,593 ) $ 200,904 Provision (benefit) for loan and lease losses 12,073 — (1,923 ) — 10,150 Net interest income (expense) after provision for loan and lease losses 69,852 26,713 98,782 (4,593 ) 190,754 Non-interest income 13,207 19,371 27,079 6,189 65,846 Non-interest expense 38,339 27,222 92,478 3,784 161,823 Income (loss) before income tax expense 44,720 18,862 33,383 (2,188 ) 94,777 Income tax expense (benefit) 14,363 6,006 10,605 (693 ) 30,281 Net income (loss) $ 30,357 $ 12,856 $ 22,778 $ (1,495 ) $ 64,496 Nine months ended September 30, 2018 (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 264,353 $ 104,920 $ 302,782 $ (2,505 ) $ 669,550 Provision for loan and lease losses 26,300 — 5,700 — 32,000 Net interest income (expense) after provision for loan and lease losses 238,053 104,920 297,082 (2,505 ) 637,550 Non-interest income 48,662 67,710 78,421 14,612 209,405 Non-interest expense 128,730 93,488 287,795 20,844 530,857 Income (loss) before income tax expense 157,985 79,142 87,708 (8,737 ) 316,098 Income tax expense (benefit) 38,864 20,577 17,454 (22,377 ) 54,518 Net income $ 119,121 $ 58,565 $ 70,254 $ 13,640 $ 261,580 Nine months ended September 30, 2017 (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 239,118 $ 76,339 $ 286,351 $ (10,453 ) $ 591,355 Provision (benefit) for loan and lease losses 29,562 — (1,662 ) — 27,900 Net interest income (expense) after provision for loan and lease losses 209,556 76,339 288,013 (10,453 ) 563,455 Non-interest income 39,163 58,392 80,516 15,368 193,439 Non-interest expense 113,767 84,211 281,979 10,069 490,026 Income (loss) before income tax expense 134,952 50,520 86,550 (5,154 ) 266,868 Income tax expense (benefit) 41,125 15,395 26,374 (1,572 ) 81,322 Net income (loss) $ 93,827 $ 35,125 $ 60,176 $ (3,582 ) $ 185,546

Revenue from Contracts with Cus

Revenue from Contracts with Customers Revenue from Contracts with customers	9 Months Ended
	Sep. 30, 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 the 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 is 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 September 30, 2018 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 3,211 $ 21,294 $ 16,107 $ (11 ) $ 40,601 Wealth and investment services 2,577 — 5,843 (8 ) 8,412 Other income — 865 352 — 1,217 Revenue from contracts with customers 5,788 22,159 22,302 (19 ) 50,230 Non-interest income within the scope of other GAAP topics 12,517 — 4,546 4,991 22,054 Total non-interest income $ 18,305 $ 22,159 $ 26,848 $ 4,972 $ 72,284 Three months ended September 30, 2017 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 3,119 $ 18,658 $ 16,435 $ 109 $ 38,321 Wealth and investment services 2,471 — 5,288 (9 ) 7,750 Other income — 713 216 — 929 Revenue from contracts with customers 5,590 19,371 21,939 100 47,000 Non-interest income within the scope of other GAAP topics 7,617 — 5,140 6,089 18,846 Total non-interest income $ 13,207 $ 19,371 $ 27,079 $ 6,189 $ 65,846 Nine months ended September 30, 2018 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 9,613 $ 65,112 $ 47,079 $ 107 $ 121,911 Wealth and investment services 7,703 — 17,060 (25 ) 24,738 Other income — 2,598 1,485 — 4,083 Revenue from contracts with customers 17,316 67,710 65,624 82 150,732 Non-interest income within the scope of other GAAP topics 31,346 — 12,797 14,530 58,673 Total non-interest income $ 48,662 $ 67,710 $ 78,421 $ 14,612 $ 209,405 Nine months ended September 30, 2017 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 9,012 $ 56,176 $ 48,046 $ 285 $ 113,519 Wealth and investment services 7,288 — 15,638 (26 ) 22,900 Other income — 2,216 603 — 2,819 Revenue from contracts with customers 16,300 58,392 64,287 259 139,238 Non-interest income within the scope of other GAAP topics 22,863 — 16,229 15,109 54,201 Total non-interest income $ 39,163 $ 58,392 $ 80,516 $ 15,368 $ 193,439 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	9 Months Ended
	Sep. 30, 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 September 30, 2018 At December 31, 2017 Commitments to extend credit $ 5,683,275 $ 5,567,687 Standby letter of credit 185,859 195,902 Commercial letter of credit 36,393 43,200 Total credit-related financial instruments with off-balance sheet risk $ 5,905,527 $ 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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 2,596 $ 2,544 $ 2,362 $ 2,287 Provision charged to expense 28 — 262 257 Ending balance $ 2,624 $ 2,544 $ 2,624 $ 2,544 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 September 30, 2018

Subsequent Events (Notes)

Subsequent Events (Notes)	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events The Company has evaluated events from the date of the Condensed Consolidated Financial Statements and accompanying Notes thereto, September 30, 2018 , through the issuance of this Quarterly Report on Form 10-Q and determined that no significant events were identified requiring recognition or disclosure, except as identified below. The sale of six banking center locations closed on October 5, 2018. Deposits of approximately $105 million

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 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. Use of Estimates
New Accounting Pronouncements, Policy [Policy Text Block]	Accounting Standards Adopted During 2018 Effective January 1, 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 held within the portfolio. The Update accelerates the Company's recognition of premium amortization on those debt securities. The Company adopted 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. 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) - Recognition and Measurement of Financial Assets and Financial Liabilities. 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) and 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. 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. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract The Update aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The updated guidance also requires an entity to amortize the capitalized implementation costs as an expense over the term of the hosting arrangement and to present in the same income statement line item as the fees associated with the hosting arrangement. This Update is effective for the Company on January 1, 2020, with early adoption permitted. The Company does not intend to early adopt this Update. The Company will apply the amendments in this update prospectively to all implementation costs incurred after the date of adoption. The Company does not expect this Update to have a material impact on its consolidated financial statements. ASU No. 2018-14, Compensation-Retirement Benefits - Defined Benefit Plan - General (Subtopic 715-20) - Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans The Update modifies the disclosure requirements for defined benefit pension plans and other postretirement plans. This updated guidance will be effective for the Company on January 1, 2021. The Company does not expect this Update to have a material impact on its consolidated financial statements. ASU No. 2018-13, Fair Value Measurement (Topic 820) - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement The Update modifies the disclosure requirements on fair value measurements. The updated guidance will no longer require entities to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. However, it will require public companies to disclose changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 measurements. This Update is effective for the Company on January 1, 2020, and earlier adoption is permitted. The Company does not expect this Update to have a material impact on its consolidated financial statements. 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. The Company does not expect the new guidance to have a material impact on its consolidated financial statements. 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 is effective for the Company on January 1, 2020 and early adoption is permitted. The Update must be applied prospectively. The Company does not expect the new guidance to have a material impact on its consolidated 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 may 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 empowered 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. Through these 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, treasury, and accounting. These work streams are collectively assessing required resources, use of existing and new models, and data availability. The Company expects that the new credit models will include additional assumptions used to calculate credit losses over the estimated life of the financial assets and will include expected future changes in macroeconomic conditions. The Company contracted with system solution providers and is in the process of implementing the selected solutions that will be used to run its credit loss models. The Update is effective for the Company on January 1, 2020. The impact of adopting the Update is expected to be influenced by assessment of the composition, characteristics, and credit quality of our loan and securities portfolios as well as the economic conditions in effect at the adoption date. Therefore, we are unable to reasonably estimate the impact of adopting the Update at this time. ASU No. 2016-02, Leases (Topic 842) and subsequent ASUs issued to amend this Topic. 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. During Q3 2018, the FASB issued a subsequent Update which, among other issues, incorporates a new transition method option that would allow the Company to use the effective date, January 1, 2019 for the Company, as the date of initial application of the new leases standard and recognize cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company currently expects to elect this transition method. The Company is in the process of reviewing its existing leases, and certain service contracts for embedded leases, to evaluate the impact of these Updates on the consolidated financial statements. The Company has engaged a third party consultant to assist with the implementation efforts and has selected a third party software solution to assist with the accounting under these Updates.

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 $ 9,215 $ — $ (1 ) $ 9,214 $ 1,247 $ — $ — $ 1,247 Agency CMO 254,549 79 (8,162 ) 246,466 308,989 1,158 (3,814 ) 306,333 Agency MBS 1,466,973 641 (57,883 ) 1,409,731 1,124,960 2,151 (19,270 ) 1,107,841 Agency CMBS 610,411 — (39,862 ) 570,549 608,276 — (20,250 ) 588,026 CMBS 404,104 850 (52 ) 404,902 358,984 2,157 (74 ) 361,067 CLO 127,743 202 (284 ) 127,661 209,075 910 (134 ) 209,851 Single issuer-trust preferred — — — — 7,096 — (46 ) 7,050 Corporate debt 56,032 361 (963 ) 55,430 56,504 797 (679 ) 56,622 Available-for-sale $ 2,929,027 $ 2,133 $ (107,207 ) $ 2,823,953 $ 2,675,131 $ 7,173 $ (44,267 ) $ 2,638,037 Held-to-maturity: Agency CMO $ 218,351 $ 143 $ (9,192 ) $ 209,302 $ 260,114 $ 664 $ (4,824 ) $ 255,954 Agency MBS 2,535,043 8,256 (110,035 ) 2,433,264 2,569,735 16,989 (37,442 ) 2,549,282 Agency CMBS 672,505 — (28,222 ) 644,283 696,566 — (10,011 ) 686,555 Municipal bonds and notes 684,587 804 (26,487 ) 658,904 711,381 8,584 (6,558 ) 713,407 CMBS 221,969 380 (3,746 ) 218,603 249,273 2,175 (620 ) 250,828 Private Label MBS 3 — — 3 323 1 — 324 Held-to-maturity $ 4,332,458 $ 9,583 $ (177,682 ) $ 4,164,359 $ 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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 1,103 $ 3,231 $ 1,364 $ 3,243 Reduction for investment securities called (281 ) (1,028 ) (542 ) (1,166 ) Additions for OTTI not previously recognized in earnings — — — 126 Ending balance $ 822 $ 2,203 $ 822 $ 2,203
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 September 30, 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: U.S. Treasury Bills $ 9,214 $ (1 ) $ — $ — 2 $ 9,214 $ (1 ) Agency CMO 108,055 (2,046 ) 123,570 (6,116 ) 43 231,625 (8,162 ) Agency MBS 632,866 (13,665 ) 751,739 (44,218 ) 185 1,384,605 (57,883 ) Agency CMBS 28,075 (1,074 ) 542,474 (38,788 ) 37 570,549 (39,862 ) CMBS 68,695 (52 ) — — 14 68,695 (52 ) CLO 41,156 (143 ) 15,009 (141 ) 3 56,165 (284 ) Single issuer-trust preferred — — — — — — — Corporate debt 8,862 (72 ) 17,157 (891 ) 5 26,019 (963 ) Available-for-sale in an unrealized loss position $ 896,923 $ (17,053 ) $ 1,449,949 $ (90,154 ) 289 $ 2,346,872 $ (107,207 ) Held-to-maturity: Agency CMO $ 31,749 $ (959 ) $ 155,428 $ (8,233 ) 26 $ 187,177 $ (9,192 ) Agency MBS 757,451 (20,783 ) 1,467,605 (89,252 ) 274 2,225,056 (110,035 ) Agency CMBS 43,474 (697 ) 600,808 (27,525 ) 57 644,282 (28,222 ) Municipal bonds and notes 343,560 (11,463 ) 216,401 (15,024 ) 272 559,961 (26,487 ) CMBS 160,047 (3,256 ) 17,152 (490 ) 21 177,199 (3,746 ) Held-to-maturity in an unrealized loss position $ 1,336,281 $ (37,158 ) $ 2,457,394 $ (140,524 ) 650 $ 3,793,675 $ (177,682 ) 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: U.S. Treasury Bills $ — $ — $ — $ — — $ — $ — 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 September 30, 2018 Available-for-Sale Held-to-Maturity (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 29,730 $ 29,750 $ 6,352 $ 6,378 Due after one year through five years 31,012 31,092 4,244 4,272 Due after five through ten years 276,583 276,143 40,016 39,933 Due after ten years 2,591,702 2,486,968 4,281,846 4,113,776 Total debt securities $ 2,929,027 $ 2,823,953 $ 4,332,458 $ 4,164,359

Loans and Leases (Tables)

Loans and Leases (Tables)	9 Months Ended
	Sep. 30, 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 September 30, At December 31, 2017 Residential $ 4,415,063 $ 4,490,878 Consumer 2,441,181 2,590,225 Commercial 6,174,396 5,368,694 Commercial Real Estate 4,771,325 4,523,828 Equipment Financing 519,054 550,233 Loans and leases (1) (2) $ 18,321,019 $ 17,523,858 (1) Loans and leases include net deferred fees and net premiums/discounts of $13.6 million and $20.6 million at September 30, 2018 and December 31, 2017 , respectively. (2) At September 30, 2018 the Company had pledged $7.1 billion
Past Due Financing Receivables	The following tables summarize the aging of loans and leases: At September 30, 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 $ 9,023 $ 5,510 $ — $ 49,469 $ 64,002 $ 4,351,061 $ 4,415,063 Consumer: Home equity 9,519 3,442 — 35,174 48,135 2,165,340 2,213,475 Other consumer 1,819 898 — 1,490 4,207 223,499 227,706 Commercial: Commercial non-mortgage 659 543 147 55,040 56,389 5,148,962 5,205,351 Asset-based — — — 1,029 1,029 968,016 969,045 Commercial real estate: Commercial real estate 2,715 35 — 7,254 10,004 4,564,320 4,574,324 Commercial construction — — — — — 197,001 197,001 Equipment financing 1,371 3,617 — 3,339 8,327 510,727 519,054 Total $ 25,106 $ 14,045 $ 147 $ 152,795 $ 192,093 $ 18,128,926 $ 18,321,019 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 September 30, 2018 Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 19,007 $ 31,759 $ 95,340 $ 55,833 $ 5,383 $ 207,322 Provision (benefit) charged to expense 407 474 5,686 4,146 (213 ) 10,500 Charge-offs (874 ) (4,863 ) (740 ) (1,922 ) (136 ) (8,535 ) Recoveries 133 1,827 431 143 11 2,545 Balance, end of period $ 18,673 $ 29,197 $ 100,717 $ 58,200 $ 5,045 $ 211,832 At or for the three months ended September 30, 2017 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total ALLL: Balance, beginning of period $ 18,427 $ 42,488 $ 79,964 $ 52,402 $ 6,297 $ 199,578 (Benefit) provision charged to expense (348 ) (41 ) 12,166 (2,129 ) 502 10,150 Charge-offs (585 ) (6,197 ) (3,002 ) (749 ) (121 ) (10,654 ) Recoveries 280 1,894 466 10 79 2,729 Balance, end of period $ 17,774 $ 38,144 $ 89,594 $ 49,534 $ 6,757 $ 201,803 At or for the nine months ended September 30, 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 1,316 2,967 17,596 10,678 (557 ) 32,000 Charge-offs (2,545 ) (14,844 ) (7,869 ) (2,039 ) (246 ) (27,543 ) Recoveries 844 4,884 1,457 154 42 7,381 Balance, end of period $ 18,673 $ 29,197 $ 100,717 $ 58,200 $ 5,045 $ 211,832 Individually evaluated for impairment $ 4,319 $ 1,428 $ 10,491 $ 1,544 $ 15 $ 17,797 Collectively evaluated for impairment $ 14,354 $ 27,769 $ 90,226 $ 56,656 $ 5,030 $ 194,035 Loan and lease balances: Individually evaluated for impairment $ 105,600 $ 39,808 $ 104,353 $ 9,767 $ 6,489 $ 266,017 Collectively evaluated for impairment 4,309,463 2,401,373 6,070,043 4,761,558 512,565 18,055,002 Loans and leases $ 4,415,063 $ 2,441,181 $ 6,174,396 $ 4,771,325 $ 519,054 $ 18,321,019 At or for the nine months ended September 30, 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 (4,436 ) 6,847 21,905 2,987 597 27,900 Charge-offs (1,940 ) (18,273 ) (5,321 ) (951 ) (425 ) (26,910 ) Recoveries 924 4,337 1,105 21 106 6,493 Balance, end of period $ 17,774 $ 38,144 $ 89,594 $ 49,534 $ 6,757 $ 201,803 Individually evaluated for impairment $ 4,925 $ 1,689 $ 10,844 $ 290 $ 38 $ 17,786 Collectively evaluated for impairment $ 12,849 $ 36,455 $ 78,750 $ 49,244 $ 6,719 $ 184,017 Loan and lease balances: Individually evaluated for impairment $ 116,706 $ 46,224 $ 85,385 $ 18,199 $ 3,642 $ 270,156 Collectively evaluated for impairment 4,382,735 2,520,759 5,262,918 4,446,718 563,135 17,176,265 Loans and leases $ 4,499,441 $ 2,566,983 $ 5,348,303 $ 4,464,917 $ 566,777 $ 17,446,421
Impaired Loans	The following tables summarize impaired loans and leases: At September 30, 2018 (In thousands) Unpaid Principal Balance Total Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential $ 115,959 $ 105,600 $ 66,484 $ 39,116 $ 4,319 Consumer - home equity 45,299 39,808 30,924 8,884 1,428 Commercial : Commercial non-mortgage 117,223 103,324 65,968 37,356 10,491 Asset-based 1,074 1,029 1,029 — — Commercial real estate 12,239 9,767 2,561 7,206 1,544 Equipment financing 6,536 6,489 6,164 325 15 Total $ 298,330 $ 266,017 $ 173,130 $ 92,887 $ 17,797 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 11,994 11,226 6,387 4,839 272 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 September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Average Recorded Investment Accrued Interest Income Cash Basis Interest Income Average Accrued Cash Basis Interest Income Average Recorded Investment Accrued Cash Basis Interest Income Average Recorded Investment Accrued Cash Basis Interest Income Residential $ 107,618 $ 923 $ 301 $ 118,841 $ 1,027 $ 285 $ 109,948 $ 2,852 $ 819 $ 118,065 $ 3,133 $ 986 Consumer - home equity 40,722 292 238 46,753 341 246 42,622 876 738 45,972 998 808 Commercial: Commercial non-mortgage 94,618 847 — 81,816 249 — 87,603 2,257 — 64,932 704 — Asset based 1,095 — — 4,279 — — 809 — — 4,279 — — Commercial real estate: Commercial real estate 11,222 30 — 20,249 96 — 10,497 164 — 20,647 329 — Commercial construction — — — 828 — — — — — 831 12 — Equipment financing 6,337 41 — 4,895 30 — 4,907 112 — 5,031 168 — Total $ 261,612 $ 2,133 $ 539 $ 277,661 $ 1,743 $ 531 $ 256,386 $ 6,261 $ 1,557 $ 259,757 $ 5,344 $ 1,794
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 September 30, At December 31, At September 30, At December 31, At September 30, At December 31, (1) - (6) Pass $ 5,742,170 $ 5,048,162 $ 4,561,901 $ 4,355,916 $ 499,167 $ 525,105 (7) Special Mention 188,905 104,594 105,778 62,065 1,574 8,022 (8) Substandard 236,246 206,883 103,646 105,847 18,313 17,106 (9) Doubtful 7,075 9,055 — — — — Total $ 6,174,396 $ 5,368,694 $ 4,771,325 $ 4,523,828 $ 519,054 $ 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 September 30, At December 31, 2017 Accrual status $ 145,219 $ 147,113 Non-accrual status 95,154 74,291 Total recorded investment of TDRs $ 240,373 $ 221,404 Specific reserves for TDRs included in the balance of ALLL $ 16,338 $ 12,384 Additional funds committed to borrowers in TDR status 2,926 2,736 For the portion of TDRs deemed to be uncollectible, Webster charged off $1.1 million and $0.4 million for the three months ended September 30, 2018 and 2017 , respectively, and $6.3 million , and $3.0 million for the nine months ended September 30, 2018 and 2017 , respectively. The following table provides information on the type of concession for loans and leases modified as TDRs: Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Number of Post- (1) Number of Post- (1) Number of Post- (1) Number of Post- (1) (Dollars in thousands) Residential Extended Maturity 1 $ 20 — $ — 1 $ 20 9 $ 1,390 Adjusted Interest Rate — — — — — — 2 335 Maturity/Rate Combined 4 440 4 570 7 716 9 1,416 Other (2) 3 356 6 1,357 16 2,798 32 5,471 Consumer - home equity Extended Maturity 1 148 2 158 3 341 8 822 Adjusted Interest Rate — — 1 247 — — 1 247 Maturity/Rate Combined 3 170 2 399 6 618 13 3,212 Other (2) 5 258 12 839 30 1,951 55 3,733 Commercial non - mortgage Extended Maturity 4 537 — — 7 622 8 813 Maturity/Rate Combined 8 8,185 8 299 10 8,236 13 9,153 Other (2) 8 10,585 — — 17 39,328 1 4 Commercial real estate Extended Maturity — — — — 2 97 — — Maturity/Rate Combined — — — — 1 245 — — Other (2) — — — — 1 5,111 — — Total TDRs 37 $ 20,699 35 $ 3,869 101 $ 60,083 151 $ 26,596 (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. Loans and leases modified as TDRs within the previous 12 months and for which there was a payment default, consisted of 1 residential loan with an recorded investment of $241 thousand and 1 residential loan with an recorded investment $248 thousand for the three months ended September 30, 2018 and 2017 , respectively, and 2 residential loans with an recorded investment of $261 thousand and 1 residential loan with an recorded investment $248 thousand for the nine months ended September 30, 2018 and 2017 , respectively. The recorded investment of TDRs in commercial, commercial real estate, and equipment financing segregated by risk rating exposure is as follows: (In thousands) At September 30, 2018 At December 31, 2017 (1) - (6) Pass $ 12,733 $ 8,268 (7) Special Mention 334 355 (8) Substandard 74,822 53,050 (9) Doubtful 7,075 — Total $ 94,964 $ 61,673

Transfers of Financial Assets (

Transfers of Financial Assets (Tables)	9 Months Ended
	Sep. 30, 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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 674 $ 843 $ 872 $ 790 Provision (benefit) charged to expense 18 25 (172 ) 78 Repurchased loans and settlements charged off (10 ) (18 ) (18 ) (18 ) Ending balance $ 682 $ 850 $ 682 $ 850 Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 2,596 $ 2,544 $ 2,362 $ 2,287 Provision charged to expense 28 — 262 257 Ending balance $ 2,624 $ 2,544 $ 2,624 $ 2,544
Transfer of Financial Assets Accounted for as Sales [Table Text Block]	The following table provides information for mortgage banking activities: Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Residential mortgage loans held for sale: Proceeds from sale $ 57,042 $ 88,691 $ 147,105 $ 262,029 Loans sold with servicing rights retained 51,014 79,690 130,740 239,357 Net gain on sale 1,051 1,979 2,732 4,356 Ancillary fees 463 682 1,275 2,091 Fair value option adjustment (209 ) (240 ) (323 ) 1,591
Servicing Asset at Amortized Cost [Table Text Block]	The following table presents the changes in carrying value for mortgage servicing assets: Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 23,341 $ 24,708 $ 25,139 $ 24,466 Additions 1,428 2,576 3,878 7,063 Amortization (2,125 ) (2,144 ) (6,373 ) (6,389 ) Ending balance $ 22,644 $ 25,140 $ 22,644 $ 25,140

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 $ (10,283 ) $ 11,717 $ 22,000 $ (8,610 ) $ 13,390 HSA Bank - Customer relationships 21,000 (5,991 ) 15,009 21,000 (4,779 ) 16,221 Total other intangible assets $ 43,000 $ (16,274 ) $ 26,726 $ 43,000 $ (13,389 ) $ 29,611
Schedule Of Expected Amortization Expense, Next Four Years	As of September 30, 2018 , the remaining estimated aggregate future amortization expense for intangible assets is as follows: (In thousands) Remainder of 2018 $ 962 2019 3,847 2020 3,847 2021 3,847 2022 3,847 Thereafter 10,376

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2018
Banking and Thrift [Abstract]
Deposit Liabilities, Type [Table Text Block]	A summary of deposits by type follows: (In thousands) At September 30, At December 31, Non-interest-bearing: Demand $ 4,231,505 $ 4,191,496 Interest-bearing: Health savings accounts 5,599,596 5,038,681 Checking 2,587,679 2,736,952 Money market 2,376,649 2,209,492 Savings 4,106,942 4,348,700 Time deposits 3,095,252 2,468,408 Total interest-bearing 17,766,118 16,802,233 Total deposits $ 21,997,623 $ 20,993,729 Time deposits and interest-bearing checking, included in above balances, obtained through brokers $ 938,092 $ 898,157 Time deposits, included in above balance, that exceed the FDIC limit 506,955 561,512 Deposit overdrafts reclassified as loan balances 1,761 2,210
Time Deposit Maturities [Table Text Block]	The scheduled maturities of time deposits are as follows: (In thousands) At September 30, Remainder of 2018 $ 683,421 2019 1,771,721 2020 437,240 2021 125,265 2022 49,295 Thereafter 28,310 Total time deposits $ 3,095,252

Borrowings (Tables)

Borrowings (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Repurchase Agreements	The following table summarizes securities sold under agreements to repurchase and other borrowings: At September 30, At December 31, (In thousands) Amount Rate Amount Rate Securities sold under agreements to repurchase (1) : Original maturity of one year or less $ 264,488 0.29 % $ 288,269 0.17 % Original maturity of greater than one year, non-callable 100,000 2.50 300,000 3.10 Total securities sold under agreements to repurchase 364,488 0.89 588,269 1.66 Fed funds purchased 200,000 2.25 55,000 1.37 Securities sold under agreements to repurchase and other borrowings $ 564,488 1.37 $ 643,269 1.64
Federal Home Loan Bank, Advances	The following table provides information for FHLB advances: At September 30, At December 31, (Dollars in thousands) Amount Weighted- Average Contractual Coupon Rate Amount Weighted- Average Contractual Coupon Rate Maturing within 1 year $ 948,731 2.18 % $ 1,150,000 1.48 % After 1 but within 2 years 259,295 1.79 103,026 1.81 After 2 but within 3 years 75,000 1.51 215,000 1.73 After 3 but within 4 years 150,049 3.27 200,000 2.06 (1) After 4 but within 5 years 193 1.69 170 — After 5 years 8,616 2.64 8,909 2.65 (1) FHLB advances and overall rate $ 1,441,884 2.19 $ 1,677,105 1.61 (1) Aggregate carrying value of assets pledged as collateral $ 6,773,182 $ 6,402,066 Remaining borrowing capacity 3,018,052 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 reported in the Company's 2017 Annual Report on Form 10-K 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 September 30, 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 (638 ) (727 ) Debt issuance cost on senior fixed-rate notes (725 ) (826 ) Long-term debt $ 225,957 $ 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 plus 2.95% , was 5.28% at September 30, 2018 and 4.55% at December 31, 2017

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss, Net of Tax (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2018 Nine months ended September 30, 2018 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (64,617 ) $ (10,814 ) $ (46,505 ) $ (121,936 ) $ (27,947 ) $ (15,016 ) $ (48,568 ) $ (91,531 ) (OCL) OCI before reclassifications (13,811 ) 197 — (13,614 ) (50,481 ) 1,620 — (48,861 ) Amounts reclassified from AOCL — 1,438 2,548 3,986 — 4,217 4,611 8,828 Net current-period OCI/(OCL) (13,811 ) 1,635 2,548 (9,628 ) (50,481 ) 5,837 4,611 (40,033 ) Ending balance $ (78,428 ) $ (9,179 ) $ (43,957 ) $ (131,564 ) $ (78,428 ) $ (9,179 ) $ (43,957 ) $ (131,564 ) Three months ended September 30, 2017 Nine months ended September 30, 2017 (In thousands) Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Securities Available For Sale Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Beginning balance $ (14,501 ) $ (15,258 ) $ (42,323 ) $ (72,082 ) $ (15,476 ) $ (17,068 ) $ (44,449 ) $ (76,993 ) OCI/(OCL) before reclassifications 872 (34 ) — 838 1,847 (445 ) — 1,402 Amounts reclassified from AOCL — 1,145 1,001 2,146 — 3,366 3,127 6,493 Net current-period OCI 872 1,111 1,001 2,984 1,847 2,921 3,127 7,895 Ending balance $ (13,629 ) $ (14,147 ) $ (41,322 ) $ (69,098 ) $ (13,629 ) $ (14,147 ) $ (41,322 ) $ (69,098 )
Schedule of Accumulated Other Comprehensive Loss	The following tables provide information for the items reclassified from AOCL: (In thousands) Three months ended September 30, Nine months ended September 30, Associated Line Item in the Condensed Consolidated Statements of Income AOCL Components 2018 2017 2018 2017 Derivative instruments: Cash flow hedges $ (1,932 ) $ (1,810 ) $ (5,664 ) $ (5,316 ) Total interest expense Tax benefit 494 665 1,447 1,950 Income tax expense Net of tax $ (1,438 ) $ (1,145 ) $ (4,217 ) $ (3,366 ) Defined benefit pension and other postretirement benefit plans: Amortization of net loss $ (3,431 ) $ (1,587 ) $ (6,209 ) $ (4,959 ) (1) Tax benefit 883 586 1,598 1,832 Income tax expense Net of tax $ (2,548 ) $ (1,001 ) $ (4,611 ) $ (3,127 )

Regulatory Matters (Tables)

Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2018 Actual Minimum Requirement Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio Webster Financial Corporation CET1 risk-based capital $ 2,215,456 11.23 % $ 887,910 4.5 % $ 1,282,537 6.5 % Total risk-based capital 2,652,270 13.44 1,578,507 8.0 1,973,133 10.0 Tier 1 risk-based capital 2,360,493 11.96 1,183,880 6.0 1,578,507 8.0 Tier 1 leverage capital 2,360,493 8.89 1,061,977 4.0 1,327,471 5.0 Webster Bank CET1 risk-based capital $ 2,137,249 10.84 % $ 887,232 4.5 % $ 1,281,558 6.5 % Total risk-based capital 2,351,706 11.93 1,577,302 8.0 1,971,628 10.0 Tier 1 risk-based capital 2,137,249 10.84 1,182,977 6.0 1,577,302 8.0 Tier 1 leverage capital 2,137,249 8.05 1,061,427 4.0 1,326,784 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)	9 Months Ended
	Sep. 30, 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 September 30, Nine Months Ended September 30, (In thousands, except per share data) 2018 2017 2018 2017 Earnings for basic and diluted earnings per common share: Net income $ 99,673 $ 64,496 $ 261,580 $ 185,546 Less: Preferred stock dividends 1,968 2,024 5,884 6,072 Net income available to common shareholders 97,705 62,472 255,696 179,474 Less: Earnings applicable to participating securities 245 46 656 212 Earnings applicable to common shareholders $ 97,460 $ 62,426 $ 255,040 $ 179,262 Shares: Weighted-average common shares outstanding - basic 91,959 92,125 91,912 92,003 Effect of dilutive securities: Stock options and restricted stock 243 372 303 403 Warrants 6 6 6 6 Weighted-average common shares outstanding - diluted 92,208 92,503 92,221 92,412 Earnings per common share: Basic $ 1.06 $ 0.68 $ 2.77 $ 1.95 Diluted 1.06 0.67 2.77 1.94
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Potential common shares from non-participating restricted stock, of 97 thousand and 80 thousand for the three months ended September 30, 2018 and 2017 , respectively, and 54 thousand and 61 thousand for the nine months ended September 30, 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 Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 cash flow hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) $ 325,000 $ 4,951 $ — $ — $ 325,000 $ 2,770 $ — $ — Not designated as hedging instruments: Positions subject to a master netting agreement (1) Interest rate derivatives (2) 3,852,438 13,226 76,789 215 2,791,760 5,977 721,048 1,968 Mortgage banking derivatives (3) 52,067 223 3,063 7 28,497 421 39,230 110 Other 24,879 199 23,927 435 7,914 258 30,328 419 Positions not subject to a master netting agreement (4) Interest rate derivatives 677,679 3,090 3,242,821 83,142 1,366,299 23,009 2,146,518 25,631 RPAs 84,702 19 100,294 43 93,713 80 116,882 111 Other 6,918 300 2,517 47 — — 2,073 184 Total not designated as hedging instruments 4,698,683 17,057 3,449,411 83,889 4,288,183 29,745 3,056,079 28,423 Gross derivative instruments, before netting $ 5,023,683 22,008 $ 3,449,411 83,889 $ 4,613,183 32,515 $ 3,056,079 28,423 Less: Legally enforceable master netting agreements 586 586 2,245 2,245 Less: Cash collateral posted 17,709 — 6,704 — Total derivative instruments, after netting $ 3,713 $ 83,303 $ 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) Balances related to CME are presented as a single unit of account. Notional amounts of interest rate swaps cleared through CME include; $2.7 billion and $1.9 billion for asset derivatives and $47 million and $595 million for liability derivatives at September 30, 2018 and December 31, 2017, respectively, with related fair values of approximately zero . (3) Notional amounts include mandatory forward commitments of $33.0 million , while notional amounts do not include approved floating rate commitments of $9.1 million , at September 30, 2018
Other Derivatives Not Designated For Hedge Accounting	Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Designated as cash flow hedging instruments: Interest rate derivatives (1) $ 1,667 $ 1,928 $ 5,158 $ 5,953 Not designated as hedging instruments: Interest rate derivatives (2) $ 1,623 $ 2,955 $ 7,372 $ 5,850 RPAs 22 51 117 157 Mortgage banking derivatives (26 ) (219 ) (95 ) (1,886 ) Other (2) (226 ) (756 ) 1,113 (1,748 ) Total not designated as hedging instruments (2) (3) $ 1,393 $ 2,031 $ 8,507 $ 2,373
Offsetting Liabilities	The following table presents the transition from a gross basis to net basis, due to the application of counterparty netting agreements: At September 30, 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 $ 4,951 $ — $ 4,951 $ — $ 2,770 $ 91 $ 2,679 $ — Non-hedge accounting 13,425 586 12,758 81 6,222 2,154 4,025 43 Total assets $ 18,376 $ 586 $ 17,709 $ 81 $ 8,992 $ 2,245 $ 6,704 $ 43 Derivative instrument losses: Hedge accounting $ — $ — $ — $ — $ — $ — $ — $ — Non-hedge accounting 651 586 — 65 2,387 2,245 — 142 Total liabilities $ 651 $ 586 $ — $ 65 $ 2,387 $ 2,245 $ — $ 142

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Option, Disclosures	The following table presents the fair value, unpaid principal balance, and accrual status, of assets accounted for under the fair value option: At September 30, 2018 At December 31, 2017 (In thousands) Fair Value Unpaid Principal Balance Difference Fair Value Unpaid Principal Balance Difference Originated loans held for sale $ 17,137 $ 17,288 $ (151 ) $ 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.
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 September 30, 2018 (In thousands) Level 1 Level 2 Level 3 NAV Total Financial assets held at fair value: U.S. Treasury Bills $ 9,214 $ — $ — $ — $ 9,214 Agency CMO — 246,466 — — 246,466 Agency MBS — 1,409,731 — — 1,409,731 Agency CMBS — 570,549 — — 570,549 CMBS — 404,902 — — 404,902 CLO — 127,661 — — 127,661 Single issuer-trust preferred — — — — — Corporate debt — 55,430 — — 55,430 Total available-for-sale investment securities 9,214 2,814,739 — — 2,823,953 Gross derivative instruments, before netting (1) 498 21,510 — — 22,008 Originated loans held for sale — 17,137 — — 17,137 Investments held in Rabbi Trust 4,930 — — — 4,930 Alternative investments — — — 2,073 2,073 Total financial assets held at fair value $ 14,642 $ 2,853,386 $ — $ 2,073 $ 2,870,101 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 462 $ 83,427 $ — $ — $ 83,889 At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 NAV 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 — — — 3,495 3,495 Total financial assets held at fair value $ 6,306 $ 2,689,935 $ — $ 3,495 $ 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 Valuation Methodology And Unobservable Inputs	assets measured at fair value on a non-recurring basis.
Summary Of Estimated Fair Values Of Significant Financial Instruments	The estimated fair values of selected financial instruments and servicing assets are as follows: At September 30, 2018 At December 31, 2017 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Level 2 Held-to-maturity investment securities $ 4,332,458 $ 4,164,359 $ 4,487,392 $ 4,456,350 Level 3 Loans and leases, net 18,109,187 17,913,452 17,323,864 17,211,619 Mortgage servicing assets 22,644 48,661 25,139 45,309 Liabilities: Level 2 Deposit liabilities $ 18,902,371 $ 18,902,371 $ 18,525,321 $ 18,525,321 Time deposits 3,095,252 3,067,487 2,468,408 2,455,245 Securities sold under agreements to repurchase and other borrowings 564,488 564,396 643,269 644,084 FHLB advances 1,441,884 1,439,155 1,677,105 1,678,070 Long-term debt (1) 225,957 229,336 225,767 234,359 (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)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Summary of Net Periodic Benefit Cost	The following table summarizes the components of net periodic benefit cost: Three months ended September 30, 2018 2017 (In thousands) Pension Plan SERP Other Benefits Pension Plan SERP Other Benefits Service cost $ — $ — $ — $ 12 $ — $ — Interest cost on benefit obligations 1,857 35 20 1,829 96 19 Expected return on plan assets (3,178 ) — — (3,074 ) — — Amortization of prior service cost — — — — — — Recognized net loss 1,160 2,271 — 1,466 136 (15 ) Net periodic benefit cost $ (161 ) $ 2,306 $ 20 $ 233 $ 232 $ 4 Nine months ended September 30, 2018 2017 (In thousands) Pension Plan SERP Other Benefits Pension Plan SERP Other Benefits Service cost $ — $ — $ — $ 37 $ — $ — Interest cost on benefit obligations 5,577 201 59 5,486 281 69 Expected return on plan assets (9,538 ) — — (9,222 ) — — Amortization of prior service cost — — — — — — Recognized net loss 3,480 2,729 — 4,398 561 — Net periodic benefit cost $ (481 ) $ 2,930 $ 59 $ 699 $ 842 $ 69

Share-Based Plans (Tables)

Share-Based Plans (Tables)	9 Months Ended
	Sep. 30, 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 nine months ended September 30, 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 January 1, 2018 207,800 $ 43.16 78,916 $ 45.35 673,039 $ 18.75 Granted 145,382 58.36 75,707 55.82 — — Vested restricted stock awards (1) 129,445 44.80 55,112 46.08 — — Forfeited 8,041 52.53 13,847 51.19 — — Exercised options — — — — 180,247 11.71 Outstanding and exercisable, at September 30, 2018 215,696 51.91 85,664 53.19 492,792 21.33 (1)

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 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: (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total At September 30, 2018 $ 10,327,878 $ 71,172 $ 8,730,295 $ 8,216,972 $ 27,346,317 At December 31, 2017 9,350,028 76,308 8,909,671 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 September 30, 2018 (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 91,243 $ 36,731 $ 101,952 $ 446 $ 230,372 Provision (benefit) for loan and lease losses 8,207 — 2,293 — 10,500 Net interest income (expense) after provision for loan and lease losses 83,036 36,731 99,659 446 219,872 Non-interest income 18,305 22,159 26,848 4,972 72,284 Non-interest expense 44,506 30,753 95,769 7,755 178,783 Income (loss) before income tax expense 56,835 28,137 30,738 (2,337 ) 113,373 Income tax expense (benefit) 13,981 7,316 6,117 (13,714 ) 13,700 Net income (loss) $ 42,854 $ 20,821 $ 24,621 $ 11,377 $ 99,673 Three months ended September 30, 2017 (In thousands) Commercial Banking HSA Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 81,925 $ 26,713 $ 96,859 $ (4,593 ) $ 200,904 Provision (benefit) for loan and lease losses 12,073 — (1,923 ) — 10,150 Net interest income (expense) after provision for loan and lease losses 69,852 26,713 98,782 (4,593 ) 190,754 Non-interest income 13,207 19,371 27,079 6,189 65,846 Non-interest expense 38,339 27,222 92,478 3,784 161,823 Income (loss) before income tax expense 44,720 18,862 33,383 (2,188 ) 94,777 Income tax expense (benefit) 14,363 6,006 10,605 (693 ) 30,281 Net income (loss) $ 30,357 $ 12,856 $ 22,778 $ (1,495 ) $ 64,496 Nine months ended September 30, 2018 (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 264,353 $ 104,920 $ 302,782 $ (2,505 ) $ 669,550 Provision for loan and lease losses 26,300 — 5,700 — 32,000 Net interest income (expense) after provision for loan and lease losses 238,053 104,920 297,082 (2,505 ) 637,550 Non-interest income 48,662 67,710 78,421 14,612 209,405 Non-interest expense 128,730 93,488 287,795 20,844 530,857 Income (loss) before income tax expense 157,985 79,142 87,708 (8,737 ) 316,098 Income tax expense (benefit) 38,864 20,577 17,454 (22,377 ) 54,518 Net income $ 119,121 $ 58,565 $ 70,254 $ 13,640 $ 261,580 Nine months ended September 30, 2017 (In thousands) Commercial Banking HSA Bank Community Banking Corporate and Reconciling Consolidated Total Net interest income (expense) $ 239,118 $ 76,339 $ 286,351 $ (10,453 ) $ 591,355 Provision (benefit) for loan and lease losses 29,562 — (1,662 ) — 27,900 Net interest income (expense) after provision for loan and lease losses 209,556 76,339 288,013 (10,453 ) 563,455 Non-interest income 39,163 58,392 80,516 15,368 193,439 Non-interest expense 113,767 84,211 281,979 10,069 490,026 Income (loss) before income tax expense 134,952 50,520 86,550 (5,154 ) 266,868 Income tax expense (benefit) 41,125 15,395 26,374 (1,572 ) 81,322 Net income (loss) $ 93,827 $ 35,125 $ 60,176 $ (3,582 ) $ 185,546

Revenue from Contracts with C_2

Revenue from Contracts with Customers Disaggregation of Revenue (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2018 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 3,211 $ 21,294 $ 16,107 $ (11 ) $ 40,601 Wealth and investment services 2,577 — 5,843 (8 ) 8,412 Other income — 865 352 — 1,217 Revenue from contracts with customers 5,788 22,159 22,302 (19 ) 50,230 Non-interest income within the scope of other GAAP topics 12,517 — 4,546 4,991 22,054 Total non-interest income $ 18,305 $ 22,159 $ 26,848 $ 4,972 $ 72,284 Three months ended September 30, 2017 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 3,119 $ 18,658 $ 16,435 $ 109 $ 38,321 Wealth and investment services 2,471 — 5,288 (9 ) 7,750 Other income — 713 216 — 929 Revenue from contracts with customers 5,590 19,371 21,939 100 47,000 Non-interest income within the scope of other GAAP topics 7,617 — 5,140 6,089 18,846 Total non-interest income $ 13,207 $ 19,371 $ 27,079 $ 6,189 $ 65,846 Nine months ended September 30, 2018 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 9,613 $ 65,112 $ 47,079 $ 107 $ 121,911 Wealth and investment services 7,703 — 17,060 (25 ) 24,738 Other income — 2,598 1,485 — 4,083 Revenue from contracts with customers 17,316 67,710 65,624 82 150,732 Non-interest income within the scope of other GAAP topics 31,346 — 12,797 14,530 58,673 Total non-interest income $ 48,662 $ 67,710 $ 78,421 $ 14,612 $ 209,405 Nine months ended September 30, 2017 (In thousands) Commercial HSA Community Corporate and Consolidated Major Revenue Streams Deposit service fees $ 9,012 $ 56,176 $ 48,046 $ 285 $ 113,519 Wealth and investment services 7,288 — 15,638 (26 ) 22,900 Other income — 2,216 603 — 2,819 Revenue from contracts with customers 16,300 58,392 64,287 259 139,238 Non-interest income within the scope of other GAAP topics 22,863 — 16,229 15,109 54,201 Total non-interest income $ 39,163 $ 58,392 $ 80,516 $ 15,368 $ 193,439

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2018 At December 31, 2017 Commitments to extend credit $ 5,683,275 $ 5,567,687 Standby letter of credit 185,859 195,902 Commercial letter of credit 36,393 43,200 Total credit-related financial instruments with off-balance sheet risk $ 5,905,527 $ 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 September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 674 $ 843 $ 872 $ 790 Provision (benefit) charged to expense 18 25 (172 ) 78 Repurchased loans and settlements charged off (10 ) (18 ) (18 ) (18 ) Ending balance $ 682 $ 850 $ 682 $ 850 Three months ended September 30, Nine months ended September 30, (In thousands) 2018 2017 2018 2017 Beginning balance $ 2,596 $ 2,544 $ 2,362 $ 2,287 Provision charged to expense 28 — 262 257 Ending balance $ 2,624 $ 2,544 $ 2,624 $ 2,544

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Change in Accounting Estimate (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Change in Accounting Estimate [Line Items]
Deposit insurance	$ 9,694	$ 6,344		$ 30,098	$ 19,701
Corporate, Non-Segment [Member]
Change in Accounting Estimate [Line Items]
Deposit insurance				10,000
Corporate, Non-Segment [Member] | Regulatory Reviews of Filings [Member]
Change in Accounting Estimate [Line Items]
Deposit insurance			$ 7,200	$ 10,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies New Accounting Pronouncements or Change in Accounting Principle (Details) $ in Millions	Sep. 30, 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

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	Sep. 30, 2018	Dec. 31, 2017
Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 30	$ 33.5
Accounts Payable and Accrued Liabilities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	10.7	17.3
Other Investments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	16.4	13.8
Unfunded Loan Commitment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 28.7	$ 22.9

Investment Securities (Summary

Investment Securities (Summary Of Investment Securities) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	$ 2,929,027	$ 2,675,131
Unrealized Gains	2,133	7,173
Unrealized Losses	(107,207)	(44,267)
Fair Value	2,823,953	2,638,037
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	4,332,458	4,487,392
Unrealized Gains	9,583	28,413
Unrealized Losses	(177,682)	(59,455)
Fair Value	4,164,359	4,456,350
US Treasury Bill Securities [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	9,215	1,247
Unrealized Gains	0	0
Unrealized Losses	(1)	0
Fair Value	9,214	1,247
Agency CMO [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	254,549	308,989
Unrealized Gains	79	1,158
Unrealized Losses	(8,162)	(3,814)
Fair Value	246,466	306,333
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	218,351	260,114
Unrealized Gains	143	664
Unrealized Losses	(9,192)	(4,824)
Fair Value	209,302	255,954
Agency MBS [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	1,466,973	1,124,960
Unrealized Gains	641	2,151
Unrealized Losses	(57,883)	(19,270)
Fair Value	1,409,731	1,107,841
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	2,535,043	2,569,735
Unrealized Gains	8,256	16,989
Unrealized Losses	(110,035)	(37,442)
Fair Value	2,433,264	2,549,282
Agency CMBS [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	610,411	608,276
Unrealized Gains	0	0
Unrealized Losses	(39,862)	(20,250)
Fair Value	570,549	588,026
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	672,505	696,566
Unrealized Gains	0	0
Unrealized Losses	(28,222)	(10,011)
Fair Value	644,283	686,555
Non-agency CMBS [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	404,104	358,984
Unrealized Gains	850	2,157
Unrealized Losses	(52)	(74)
Fair Value	404,902	361,067
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	221,969	249,273
Unrealized Gains	380	2,175
Unrealized Losses	(3,746)	(620)
Fair Value	218,603	250,828
CLO [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	127,743	209,075
Unrealized Gains	202	910
Unrealized Losses	(284)	(134)
Fair Value	127,661	209,851
Single issuer trust preferred securities [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	0	7,096
Unrealized Gains	0	0
Unrealized Losses	0	(46)
Fair Value	0	7,050
Corporate debt securities [Member]
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	56,032	56,504
Unrealized Gains	361	797
Unrealized Losses	(963)	(679)
Fair Value	55,430	56,622
Municipal bonds and notes [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	684,587	711,381
Unrealized Gains	804	8,584
Unrealized Losses	(26,487)	(6,558)
Fair Value	658,904	713,407
Private Label MBS [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	3	323
Unrealized Gains	0	1
Unrealized Losses	0	0
Fair Value	$ 3	$ 324

Investment Securities (Other Th

Investment Securities (Other Than Temporary Impairment Credit Losses Recognized In Earnings) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of OTTI, beginning of period	$ 1,103	$ 3,231	$ 1,364	$ 3,243
Reduction for securities sold, called	(281)	(1,028)	(542)	(1,166)
Balance of OTTI, end of period	822	2,203	822	2,203
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses	$ 0	$ 0	$ 0	$ 126

Investment Securities (Summar_2

Investment Securities (Summary Of Gross Unrealized Losses Not Considered OTTI) (Detail) $ in Thousands	Sep. 30, 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	$ 896,923	$ 650,514
Available for sale, Unrealized Losses - Less Than Twelve Months	(17,053)	(4,869)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,449,949	1,265,234
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (90,154)	$ (39,398)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	289	212
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 2,346,872	$ 1,915,748
Available for sale, Unrealized Losses - Total	(107,207)	(44,267)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,336,281	1,536,069
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(37,158)	(13,687)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	2,457,394	1,655,375
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (140,524)	$ (45,768)
Held-to-maturity, Number of Holdings - Total | holding	650	388
Held-to-maturity, Fair Value - Total	$ 3,793,675	$ 3,191,444
Held-to-maturity, Unrealized Losses - Total	(177,682)	(59,455)
US Treasury Bill Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	9,214
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (1)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 9,214
Available for sale, Unrealized Losses - Total	(1)
Agency CMO [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	108,055	81,001
Available for sale, Unrealized Losses - Less Than Twelve Months	(2,046)	(449)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	123,570	119,104
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (6,116)	$ (3,365)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	43	27
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 231,625	$ 200,105
Available for sale, Unrealized Losses - Total	(8,162)	(3,814)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	31,749	98,090
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(959)	(1,082)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	155,428	106,775
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (8,233)	$ (3,742)
Held-to-maturity, Number of Holdings - Total | holding	26	22
Held-to-maturity, Fair Value - Total	$ 187,177	$ 204,865
Held-to-maturity, Unrealized Losses - Total	(9,192)	(4,824)
Agency MBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	632,866	416,995
Available for sale, Unrealized Losses - Less Than Twelve Months	(13,665)	(2,920)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	751,739	606,021
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (44,218)	$ (16,350)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	185	135
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 1,384,605	$ 1,023,016
Available for sale, Unrealized Losses - Total	(57,883)	(19,270)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	757,451	762,107
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(20,783)	(4,555)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	1,467,605	1,197,839
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (89,252)	$ (32,887)
Held-to-maturity, Number of Holdings - Total | holding	274	205
Held-to-maturity, Fair Value - Total	$ 2,225,056	$ 1,959,946
Held-to-maturity, Unrealized Losses - Total	(110,035)	(37,442)
Agency CMBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	28,075	54,182
Available for sale, Unrealized Losses - Less Than Twelve Months	(1,074)	(851)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	542,474	533,844
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (38,788)	$ (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	$ 570,549	$ 588,026
Available for sale, Unrealized Losses - Total	(39,862)	(20,250)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	43,474	576,770
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(697)	(7,599)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	600,808	109,785
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (27,525)	$ (2,412)
Held-to-maturity, Number of Holdings - Total | holding	57	56
Held-to-maturity, Fair Value - Total	$ 644,282	$ 686,555
Held-to-maturity, Unrealized Losses - Total	(28,222)	(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	68,695	23,869
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (52)	$ (74)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	14	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 68,695	$ 23,869
Available for sale, Unrealized Losses - Total	(52)	(74)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	160,047	92,670
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(3,256)	(413)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	17,152	14,115
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (490)	$ (207)
Held-to-maturity, Number of Holdings - Total | holding	21	13
Held-to-maturity, Fair Value - Total	$ 177,199	$ 106,785
Held-to-maturity, Unrealized Losses - Total	(3,746)	(620)
CLO [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	41,156	56,335
Available for sale, Unrealized Losses - Less Than Twelve Months	(143)	$ (134)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	15,009
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (141)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	3	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 56,165	$ 56,335
Available for sale, Unrealized Losses - Total	(284)	(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		7,050
Available for sale, Unrealized Losses - Less Than Twelve Months		$ (46)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		$ 7,050
Available for sale, Unrealized Losses - Total		(46)
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	8,862	11,082
Available for sale, Unrealized Losses - Less Than Twelve Months	(72)	(395)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	17,157	6,265
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (891)	$ (284)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | holding	5	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 26,019	$ 17,347
Available for sale, Unrealized Losses - Total	(963)	(679)
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	343,560	6,432
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(11,463)	(38)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	216,401	226,861
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (15,024)	$ (6,520)
Held-to-maturity, Number of Holdings - Total | holding	272	92
Held-to-maturity, Fair Value - Total	$ 559,961	$ 233,293
Held-to-maturity, Unrealized Losses - Total	$ (26,487)	$ (6,558)

Investment Securities (Summar_3

Investment Securities (Summary Of Debt Securities By Contractual Maturity) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available-for-sale, Amortized Cost - Due in one year or less	$ 29,730
Available-for-sale, Amortized Cost - Due after one year through five years	31,012
Available-for-sale, Amortized Cost - Due after five through ten years	276,583
Available-for-sale, Amortized Cost - Due after ten years	2,591,702
Available-for-sale, Amortized Cost - Total debt securities	2,929,027	$ 2,675,131
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale, Fair Value - Due in one year or less	29,750
Available-for-sale, Fair Value - Due after one year through five years	31,092
Available-for-sale, Fair Value - Due after five through ten years	276,143
Available-for-sale, Fair Value - Due after ten years	2,486,968
Debt Securities, Available-for-sale	2,823,953	2,638,037
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Held-to-maturity, Amortized Cost - Due in one year or less	6,352
Held-to-maturity, Amortized Cost - Due after one year through five years	4,244
Held-to-maturity, Amortized Cost - Due after five through ten years	40,016
Held-to-maturity, Amortized Cost - Due after ten years	4,281,846
Amortized Cost	4,332,458	4,487,392
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, Fair Value - Due in one year or less	6,378
Held-to-maturity, Fair Value - Due after one year through five years	4,272
Held to maturity, Fair Value - Due after five through ten years	39,933
Held to maturity, Fair Value - Due after ten years	4,113,776
Fair Value	$ 4,164,359	$ 4,456,350

Investment Securities Investmen

Investment Securities Investment Securities (Narrative) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	$ (107,207)	$ (44,267)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Unrealized Losses	(177,682)	(59,455)
Investment securities available-for-sale, at fair value	2,823,953	2,638,037
Pledged Financial Instruments, Not Separately Reported, Securities	2,500,000
Agency CMO [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	(8,162)	(3,814)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Unrealized Losses	(9,192)	(4,824)
Agency MBS [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	(57,883)	(19,270)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Unrealized Losses	(110,035)	(37,442)
Agency CMBS [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	(39,862)	(20,250)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		20,300
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Unrealized Losses	(28,222)	(10,011)
Non-agency CMBS [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	(52)	(74)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Unrealized Losses	(3,746)	(620)
CLO [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	(284)	(134)
Single issuer trust preferred securities [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	0	(46)
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Abstract]
Unrealized Losses	(963)	(679)
Municipal Bonds [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Unrealized Losses	(26,487)	$ (6,558)
Callable at the option of the counterparty [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Investment securities available-for-sale, at fair value	$ 1,100,000

Investment Securities (Narrativ

Investment Securities (Narrative) (Summary Of Realized Gain (Loss) on Investments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Gain (Loss) on Investments [Line Items]
Proceeds from Sale of Debt Securities, Available-for-sale	$ 0	$ 0	$ 0	$ 0

Loans and Leases (Detail)

Loans and Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 18,321,019	$ 17,523,858	$ 17,446,421
Unamortized premiums	13,600	20,600
Pledged Financial Instruments, Not Separately Reported, Loans Receivable Pledged as Collateral	7,100,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,415,063	4,490,878	4,499,441
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,441,181	2,590,225	2,566,983
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	6,174,396	5,368,694	5,348,303
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,771,325	4,523,828	4,464,917
Finance Leases Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 519,054	$ 550,233	$ 566,777

Loans and Leases (Summary Of Lo

Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 192,093	$ 172,360
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	147	892
Financing Receivable, Recorded Investment, Nonaccrual Status	152,795	126,513
Financing Receivable, Recorded Investment, Current	18,128,926	17,351,498
Loans and leases	18,321,019	17,523,858	$ 17,446,421
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	25,106	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	14,045	13,666
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	64,002	58,270
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	49,469	44,481
Financing Receivable, Recorded Investment, Current	4,351,061	4,432,608
Loans and leases	4,415,063	4,490,878	4,499,441
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	9,023	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	5,510	5,146
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	2,441,181	2,590,225	2,566,983
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	48,135	54,083
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	35,174	35,645
Financing Receivable, Recorded Investment, Current	2,165,340	2,298,185
Loans and leases	2,213,475	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	9,519	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	3,442	5,770
Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	4,207	5,707
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	1,490	1,707
Financing Receivable, Recorded Investment, Current	223,499	232,250
Loans and leases	227,706	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	1,819	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	898	1,444
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	6,174,396	5,368,694	5,348,303
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	56,389	45,673
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	147	644
Financing Receivable, Recorded Investment, Nonaccrual Status	55,040	39,214
Financing Receivable, Recorded Investment, Current	5,148,962	4,488,242
Loans and leases	5,205,351	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	659	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	543	603
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,029	589
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	1,029	589
Financing Receivable, Recorded Investment, Current	968,016	834,190
Loans and leases	969,045	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	4,771,325	4,523,828	4,464,917
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	197,001	279,554
Loans and leases	197,001	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	10,004	5,287
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	248
Financing Receivable, Recorded Investment, Nonaccrual Status	7,254	4,484
Financing Receivable, Recorded Investment, Current	4,564,320	4,238,987
Loans and leases	4,574,324	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	2,715	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	35	77
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	8,327	2,751
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	3,339	393
Financing Receivable, Recorded Investment, Current	510,727	547,482
Loans and leases	519,054	550,233	$ 566,777
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	1,371	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	$ 3,617	$ 626

Loans and Leases (Narrative) (D

Loans and Leases (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	$ 4.3	$ 2.8	$ 7.9	$ 6.4
Write-down of TDR's	$ (1.1)	$ (0.4)	$ (6.3)	$ (3)

Loans and Leases (Allowance For

Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 1,100	$ 400	$ 6,300	$ 3,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	207,322	199,578	199,994	194,320
Provision (benefit) charged to expense	10,500	10,150	32,000	27,900
Charge-offs	(8,535)	(10,654)	(27,543)	(26,910)
Recoveries	2,545	2,729	7,381	6,493
Balance, end of period	207,322	199,578	199,994	194,320	$ 211,832	$ 199,994	$ 201,803
ALLL, Individually evaluated for impairment					17,797		17,786
ALLL, Collectively evaluated for impairment					194,035		184,017
Loan and lease balances, Individually evaluated for impairment					266,017		270,156
Loan and lease balances, Collectively evaluated for impairment					18,055,002		17,176,265
Loans and leases					18,321,019	17,523,858	17,446,421
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	19,007	18,427	19,058	23,226
Provision (benefit) charged to expense	407	(348)	1,316	(4,436)
Charge-offs	(874)	(585)	(2,545)	(1,940)
Recoveries	133	280	844	924
Balance, end of period	19,007	18,427	19,058	23,226	18,673	19,058	17,774
ALLL, Individually evaluated for impairment					4,319		4,925
ALLL, Collectively evaluated for impairment					14,354		12,849
Loan and lease balances, Individually evaluated for impairment					105,600		116,706
Loan and lease balances, Collectively evaluated for impairment					4,309,463		4,382,735
Loans and leases					4,415,063	4,490,878	4,499,441
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	31,759	42,488	36,190	45,233
Provision (benefit) charged to expense	474	(41)	2,967	6,847
Charge-offs	(4,863)	(6,197)	(14,844)	(18,273)
Recoveries	1,827	1,894	4,884	4,337
Balance, end of period	31,759	42,488	36,190	45,233	29,197	36,190	38,144
ALLL, Individually evaluated for impairment					1,428		1,689
ALLL, Collectively evaluated for impairment					27,769		36,455
Loan and lease balances, Individually evaluated for impairment					39,808		46,224
Loan and lease balances, Collectively evaluated for impairment					2,401,373		2,520,759
Loans and leases					2,441,181	2,590,225	2,566,983
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	95,340	79,964	89,533	71,905
Provision (benefit) charged to expense	5,686	12,166	17,596	21,905
Charge-offs	(740)	(3,002)	(7,869)	(5,321)
Recoveries	431	466	1,457	1,105
Balance, end of period	95,340	79,964	89,533	71,905	100,717	89,533	89,594
ALLL, Individually evaluated for impairment					10,491		10,844
ALLL, Collectively evaluated for impairment					90,226		78,750
Loan and lease balances, Individually evaluated for impairment					104,353		85,385
Loan and lease balances, Collectively evaluated for impairment					6,070,043		5,262,918
Loans and leases					6,174,396	5,368,694	5,348,303
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	55,833	52,402	49,407	47,477
Provision (benefit) charged to expense	4,146	(2,129)	10,678	2,987
Charge-offs	(1,922)	(749)	(2,039)	(951)
Recoveries	143	10	154	21
Balance, end of period	55,833	52,402	49,407	47,477	58,200	49,407	49,534
ALLL, Individually evaluated for impairment					1,544		290
ALLL, Collectively evaluated for impairment					56,656		49,244
Loan and lease balances, Individually evaluated for impairment					9,767		18,199
Loan and lease balances, Collectively evaluated for impairment					4,761,558		4,446,718
Loans and leases					4,771,325	4,523,828	4,464,917
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	5,383	6,297	5,806	6,479
Provision (benefit) charged to expense	(213)	502	(557)	597
Charge-offs	(136)	(121)	(246)	(425)
Recoveries	11	79	42	106
Balance, end of period	$ 5,383	$ 6,297	$ 5,806	$ 6,479	5,045	5,806	6,757
ALLL, Individually evaluated for impairment					15		38
ALLL, Collectively evaluated for impairment					5,030		6,719
Loan and lease balances, Individually evaluated for impairment					6,489		3,642
Loan and lease balances, Collectively evaluated for impairment					512,565		563,135
Loans and leases					$ 519,054	$ 550,233	$ 566,777

Loans and Leases (Impaired Loan

Loans and Leases (Impaired Loans And Leases By Class) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 298,330	$ 274,736
Total Recorded Investment	266,017	246,753
Recorded Investment No Allowance	173,130	141,398
Recorded Investment With Allowance	92,887	105,355
Related Valuation Allowance	17,797	16,554
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	115,959	125,352
Total Recorded Investment	105,600	114,295
Recorded Investment No Allowance	66,484	69,759
Recorded Investment With Allowance	39,116	44,536
Related Valuation Allowance	4,319	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	45,299
Total Recorded Investment	39,808
Recorded Investment No Allowance	30,924
Recorded Investment With Allowance	8,884
Related Valuation Allowance	1,428
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	117,223	79,900
Total Recorded Investment	103,324	71,882
Recorded Investment No Allowance	65,968	27,313
Recorded Investment With Allowance	37,356	44,569
Related Valuation Allowance	10,491	9,786
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	1,074	3,272
Total Recorded Investment	1,029	589
Recorded Investment No Allowance	1,029	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	12,239	11,994
Total Recorded Investment	9,767	11,226
Recorded Investment No Allowance	2,561	6,387
Recorded Investment With Allowance	7,206	4,839
Related Valuation Allowance	1,544	272
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	6,536	3,409
Total Recorded Investment	6,489	3,325
Recorded Investment No Allowance	6,164	2,932
Recorded Investment With Allowance	325	393
Related Valuation Allowance	$ 15	$ 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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 261,612	$ 277,661	$ 256,386	$ 259,757
Accrued Interest Income	2,133	1,743	6,261	5,344
Cash Basis Interest Income	539	531	1,557	1,794
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	107,618	118,841	109,948	118,065
Accrued Interest Income	923	1,027	2,852	3,133
Cash Basis Interest Income	301	285	819	986
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	40,722	46,753	42,622	45,972
Accrued Interest Income	292	341	876	998
Cash Basis Interest Income	238	246	738	808
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	94,618	81,816	87,603	64,932
Accrued Interest Income	847	249	2,257	704
Cash Basis Interest Income	0	0	0	0
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,095	4,279	809	4,279
Accrued Interest Income	0	0	0	0
Cash Basis Interest Income	0	0	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	11,222	20,249	10,497	20,647
Accrued Interest Income	30	96	164	329
Cash Basis Interest Income	0	0	0	0
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	828	0	831
Accrued Interest Income	0	0	0	12
Cash Basis Interest Income	0	0	0	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	6,337	4,895	4,907	5,031
Accrued Interest Income	41	30	112	168
Cash Basis Interest Income	$ 0	$ 0	$ 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	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 18,321,019	$ 17,523,858	$ 17,446,421
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	6,174,396	5,368,694	5,348,303
Commercial Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	5,742,170	5,048,162
Commercial Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	188,905	104,594
Commercial Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	236,246	206,883
Commercial Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	7,075	9,055
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	4,771,325	4,523,828	4,464,917
Commercial Real Estate Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	4,561,901	4,355,916
Commercial Real Estate Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	105,778	62,065
Commercial Real Estate Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	103,646	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	519,054	550,233	$ 566,777
Finance Leases Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	499,167	525,105
Finance Leases Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	1,574	8,022
Finance Leases Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	18,313	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	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 240,373		$ 221,404
Specific reserves for TDRs included in the balance of ALLL	211,832	$ 207,322	199,994	$ 201,803	$ 199,578	$ 194,320
Additional funds committed to borrowers in TDR status	2,926		2,736
Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	145,219		147,113
Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	95,154		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	$ 16,338		$ 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		9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	37	35	101	151
Post-Modification Recorded Investment | $	$ 20,699	$ 3,869	$ 60,083	$ 26,596
Home Equity Loan [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	0	1
Post-Modification Recorded Investment | $	$ 0	$ 247
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	1	0	1	9
Post-Modification Recorded Investment | $	$ 20	$ 0	$ 20	$ 1,390
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	0	0	0	2
Post-Modification Recorded Investment | $	$ 0	$ 0	$ 0	$ 335
Residential Portfolio Segment [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	4	4	7	9
Post-Modification Recorded Investment | $	$ 440	$ 570	$ 716	$ 1,416
Residential Portfolio Segment [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	3	6	16	32
Post-Modification Recorded Investment | $	$ 356	$ 1,357	$ 2,798	$ 5,471
Consumer Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan			0	1
Post-Modification Recorded Investment | $			$ 0	$ 247
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	1	2	3	8
Post-Modification Recorded Investment | $	$ 148	$ 158	$ 341	$ 822
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	3	2	6	13
Post-Modification Recorded Investment | $	$ 170	$ 399	$ 618	$ 3,212
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	5	12	30	55
Post-Modification Recorded Investment | $	$ 258	$ 839	$ 1,951	$ 3,733
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	4	0	7	8
Post-Modification Recorded Investment | $	$ 537	$ 0	$ 622	$ 813
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	8	8	10	13
Post-Modification Recorded Investment | $	$ 8,185	$ 299	$ 8,236	$ 9,153
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	8	0	17	1
Post-Modification Recorded Investment | $	$ 10,585	$ 0	$ 39,328	$ 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	0	0	2	0
Post-Modification Recorded Investment | $	$ 0	$ 0	$ 97	$ 0
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	0	0	1	0
Post-Modification Recorded Investment | $	$ 0	$ 0	$ 245	$ 0
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	0	0	1	0
Post-Modification Recorded Investment | $	$ 0	$ 0	$ 5,111	$ 0

Loans and Leases (Information_2

Loans and Leases (Information on Loans and Leases Modified as TDR within the Previous 12 Months with payment default) (Narrative) (Detail) - Residential Portfolio Segment [Member] $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	1	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 241		$ 261	$ 248

Loans and Leases (Investments i

Loans and Leases (Investments in TDRs, Segregated by Risk Rating Exposure) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 240,373	$ 221,404
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	94,964	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	12,733	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	334	355
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (8) Substandard [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	74,822	53,050
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (9) Doubtful [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 7,075	$ 0

Transfers of Financial Assets_2

Transfers of Financial Assets (Reserve for loan repurchases) (Detail) - SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 674	$ 843	$ 872	$ 790
Provision (benefit) charged to expense	18	25	(172)	78
Repurchased loans and settlements charged off	(10)	(18)	(18)	(18)
Ending balance	$ 682	$ 850	$ 682	$ 850

Transfers of Financial Assets_3

Transfers of Financial Assets (Loans sold) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gain on sale	$ 1,305	$ 2,421	$ 3,684	$ 8,038
Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale	57,042	88,691	147,105	262,029
Loans sold with servicing rights retained	51,014	79,690	130,740	239,357
Net gain on sale	1,051	1,979	2,732	4,356
Ancillary Fee Income Generated by Servicing Financial Assets, Amount	463	682	1,275	2,091
Fair value option adjustment	$ (209)	$ (240)	$ (323)	$ 1,591

Transfers of Financial Assets_4

Transfers of Financial Assets (Mortgage Servicing Assets) (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 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			$ 674	$ 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	$ 2,500,000		2,500,000		$ 2,600,000
Contractually Specified Servicing Fees, Amount	$ 300	$ 200	900	600
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			$ 674

Transfers of Financial Assets S

Transfers of Financial Assets Servicing Assets at Amortized Cost Roll Forward (Details) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Beginning Balance	$ 23,341	$ 24,708	$ 25,139	$ 24,466
Additions	1,428	2,576	3,878	7,063
Amortization	(2,125)	(2,144)	(6,373)	(6,389)
Ending Balance	$ 22,644	$ 25,140	$ 22,644	$ 25,140

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Gross Carrying Value And Accumulated Amortization Of Other Intangible Assets) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 538,373	$ 538,373
Gross Carrying Amount	43,000	43,000
Accumulated Amortization	(16,274)	(13,389)
Net Carrying Amount	26,726	29,611
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	(10,283)	(8,610)
Net Carrying Amount	11,717	13,390
Customer Relationships [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,000	21,000
Accumulated Amortization	(5,991)	(4,779)
Net Carrying Amount	$ 15,009	$ 16,221

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Schedule Of Expected Future Amortization Expense) (Detail) $ in Thousands	Sep. 30, 2018USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2018	$ 962
2,019	3,847
2,020	3,847
2,021	3,847
2,022	3,847
Thereafter	$ 10,376

Deposits (Summary Of Deposits)

Deposits (Summary Of Deposits) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Non-interest-bearing:
Demand	$ 4,231,505	$ 4,191,496
Interest-bearing:
HSA	5,599,596	5,038,681
Checking	2,587,679	2,736,952
Money market	2,376,649	2,209,492
Savings	4,106,942	4,348,700
Time deposits	3,095,252	2,468,408
Total interest-bearing	17,766,118	16,802,233
Total deposits	21,997,623	20,993,729
Time deposits and interest-bearing checking, included in above balances, obtained through brokers	938,092	898,157
Time deposits, included in above balance, that exceed the FDIC limit	506,955	561,512
Deposit overdrafts reclassified as loan balances	$ 1,761	$ 2,210

Deposits (Scheduled Maturities

Deposits (Scheduled Maturities Of Time Deposits) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Remainder of 2017	$ 683,421
2,018	1,771,721
2,019	437,240
2,020	125,265
2,021	49,295
Thereafter	28,310
Total time deposits	$ 3,095,252	$ 2,468,408

Borrowings Borrowings - (Narrat

Borrowings Borrowings - (Narrative) (Details) - USD ($) $ in Billions	Sep. 30, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Total borrowings	$ 2.2	$ 2.5

Borrowings (Summary Of Securiti

Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 364,488	$ 588,269
Fed funds purchased	200,000	55,000
Securities sold under agreements to repurchase and other borrowings	$ 564,488	$ 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	0.89%	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	2.25%	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	1.37%	1.64%
Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 264,488	$ 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	0.29%	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	$ 100,000	$ 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	2.50%	3.10%

Borrowings (Federal Home Loan A

Borrowings (Federal Home Loan Advances) (Details) - USD ($) $ in Thousands	Sep. 30, 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)	2.18%	1.48%
FHLB advances maturing after 1 but within 2 years, Weighted Average Contractual Coupon Rate (as a percent)	1.79%	1.81%
FHLB advances maturing after 2 but within 3 years, Weighted Average Contractual Coupon Rate (as a percent)	1.51%	1.73%
FHLB advances maturing after 3 but within 4 years, Weighted Average Contractual Coupon Rate (as a percent)	3.27%	2.06%
FHLB advances maturing after 4 but within 5 years, Weighted Average Contractual Coupon Rate (as a percent)	1.69%	0.00%
FHLB advances maturing after 5 years, Weighted Average Contractual Coupon Rate (as a percent)	2.64%	2.65%
Federal Home Loan Bank, Advances, Weighted Average Contractual Coupon Rate (as a percent)	2.19%	1.61%
Federal Home Loan Bank, Advances, Maturity, Rolling Year [Abstract]
FHLB advances maturing within 1 year, Total Outstanding	$ 948,731	$ 1,150,000
FHLB advances maturing after 1 but within 2 years, Total Outstanding	259,295	103,026
FHLB advances maturing after 2 but within 3 years, Total Outstanding	75,000	215,000
FHLB advances maturing after 3 but within 4 years, Total Outstanding	150,049	200,000
FHLB advances maturing after 4 but within 5 years, Total Outstanding	193	170
FHLB advances maturing after 5 years, Total Outstanding	8,616	8,909
Federal Home Loan Bank, Advances	1,441,884	1,677,105
Pledged Financial Instruments, Not Separately Reported, Loans Receivable, for Federal Home Loan Bank Debt	6,773,182	6,402,066
Remaining borrowing capacity	$ 3,018,052	$ 2,600,624
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 ($)		Sep. 30, 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		(725,000)	(826,000)
Long-term debt		$ 225,957,000	$ 225,767,000
Variable interest rate		5.28%	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		$ (638,000)	$ (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 plus 2.95% , was 5.28% at September 30, 2018 and 4.55% at December 31, 2017

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Other Comprehensive Income (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 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	$ (9,628)	$ 2,984	(40,033)	7,895
Ending Balance	2,816,198	2,638,787	2,816,198	2,638,787
Available For Sale and Transferred Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(64,617)	(14,501)	(27,947)	(15,476)
(OCL) OCI before reclassifications	(13,811)	872	(50,481)	1,847
Amounts reclassified from AOCL	0	0	0	0
Other comprehensive income (loss), net of tax	(13,811)	872	(50,481)	1,847
Ending Balance	(78,428)	(13,629)	(78,428)	(13,629)
Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(10,814)	(15,258)	(15,016)	(17,068)
(OCL) OCI before reclassifications	197	(34)	1,620	(445)
Amounts reclassified from AOCL	1,438	1,145	4,217	3,366
Other comprehensive income (loss), net of tax	1,635	1,111	5,837	2,921
Ending Balance	(9,179)	(14,147)	(9,179)	(14,147)
Defined Benefit Pension and Other Postretirement Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(46,505)	(42,323)	(48,568)	(44,449)
(OCL) OCI before reclassifications	0	0	0	0
Amounts reclassified from AOCL	2,548	1,001	4,611	3,127
Other comprehensive income (loss), net of tax	2,548	1,001	4,611	3,127
Ending Balance	(43,957)	(41,322)	(43,957)	(41,322)
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(121,936)	(72,082)	(91,531)	(76,993)
(OCL) OCI before reclassifications	(13,614)	838	(48,861)	1,402
Amounts reclassified from AOCL	3,986	2,146	8,828	6,493
Other comprehensive income (loss), net of tax	(9,628)	2,984	(40,033)	7,895
Ending Balance	$ (131,564)	$ (69,098)	$ (131,564)	$ (69,098)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Accumulated Other Comprehensive Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ (13,700)	$ (30,281)	$ (54,518)	$ (81,322)
Earnings applicable to common shareholders	97,460	62,426	255,040	179,262
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	0	0	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	(1,438)	(1,145)	(4,217)	(3,366)
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	494	665	1,447	1,950
Earnings applicable to common shareholders	(1,438)	(1,145)	(4,217)	(3,366)
Total interest expense	(1,932)	(1,810)	(5,664)	(5,316)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(3,431)	(1,587)	(6,209)	(4,959)
Defined benefit pension and postretirement benefit plans [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	883	586	1,598	1,832
Net of tax	$ (2,548)	$ (1,001)	$ (4,611)	$ (3,127)

Regulatory Matters (Information

Regulatory Matters (Information On The Capital Ratios) (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,215,456		$ 2,093,116
Common Equity Tier One Capital Ratio	11.23%		11.14%
Common Equity Tier One Capital Required for Capital Adequacy	$ 887,910		$ 845,389
Common Equity Tier One Capital Required to be Well-Capitalized	1,282,537		1,221,118
Total risk-based capital, Actual Amount	$ 2,652,270		$ 2,517,848
Total risk-based capital, Actual Ratio	13.44%		13.40%
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,578,507		$ 1,502,914
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%		8.00%
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,973,133		$ 1,878,643
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%		10.00%
Tier 1 capital, Actual Amount	$ 2,360,493		$ 2,238,172
Tier 1 capital, Actual Ratio	11.96%		11.91%
Tier 1 capital, Capital Requirements, Minimum Amount	$ 1,183,880		$ 1,127,186
Tier 1 capital, Capital Requirements, Minimum Ratio	6.00%		6.00%
Tier 1 capital, Capital Requirements, Well Capitalized Amount	$ 1,578,507		$ 1,502,914
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	8.00%		8.00%
Tier 1 leverage capital ratio, Actual Amount	$ 2,360,493		$ 2,238,172
Tier 1 leverage capital ratio, Actual Ratio	8.89%		8.63%
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	$ 1,061,977		$ 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	$ 1,327,471		$ 1,296,021
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	5.00%		5.00%
Dividends paid	$ 220,000	$ 80,000
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,137,249		$ 2,114,224
Common Equity Tier One Capital Ratio	10.84%		11.26%
Common Equity Tier One Capital Required for Capital Adequacy	$ 887,232		$ 844,693
Common Equity Tier One Capital Required to be Well-Capitalized	1,281,558		1,220,113
Total risk-based capital, Actual Amount	$ 2,351,706		$ 2,316,580
Total risk-based capital, Actual Ratio	11.93%		12.34%
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,577,302		$ 1,501,677
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%		8.00%
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,971,628		$ 1,877,097
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%		10.00%
Tier 1 capital, Actual Amount	$ 2,137,249		$ 2,114,224
Tier 1 capital, Actual Ratio	10.84%		11.26%
Tier 1 capital, Capital Requirements, Minimum Amount	$ 1,182,977		$ 1,126,258
Tier 1 capital, Capital Requirements, Minimum Ratio	6.00%		6.00%
Tier 1 capital, Capital Requirements, Well Capitalized Amount	$ 1,577,302		$ 1,501,677
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	8.00%		8.00%
Tier 1 leverage capital ratio, Actual Amount	$ 2,137,249		$ 2,114,224
Tier 1 leverage capital ratio, Actual Ratio	8.05%		8.14%
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	$ 1,061,427		$ 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	$ 1,326,784		$ 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	$ 98,600		$ 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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings for basic and diluted earnings per common share:
Net income	$ 99,673	$ 64,496	$ 261,580	$ 185,546
Less: Preferred stock dividends	1,968	2,024	5,884	6,072
Undistributed Earnings, Basic	97,705	62,472	255,696	179,474
Net income available to common shareholders	97,705	62,472	255,696	179,474
Less: Earnings applicable to participating securities	245	46	656	212
Less: Earnings applicable to participating securities	245	46	656	212
Earnings applicable to common shareholders	97,460	62,426	255,040	179,262
Earnings applicable to common shareholders	$ 97,460	$ 62,426	$ 255,040	$ 179,262
Shares:
Weighted average common shares outstanding - basic (in shares)	91,959	92,125	91,912	92,003
Effect of dilutive securities:
Stock options and restricted stock (in shares)	243	372	303	403
Warrants (in shares)	6	6	6	6
Weighted-average common shares outstanding - diluted (in shares)	92,208	92,503	92,221	92,412
Earnings per common share:
Basic (in dollars per share)	$ 1.06	$ 0.68	$ 2.77	$ 1.95
Diluted (in dollars per share)	$ 1.06	$ 0.67	$ 2.77	$ 1.94

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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 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	97	80	54	61

Derivative Financial Instrume_3

Derivative Financial Instruments (Schedule fair value of derivative instruments) (Detail) - USD ($)		Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative instrument assets, Gross Amount		$ 18,376,000	$ 8,992,000
Asset Derivatives, Fair Value, Less: Cash collateral posted		36,300,000
Derivative Asset		81,000	43,000
Liability Derivatives, Fair Value, Gross Liability		651,000	2,387,000
Derivative liability		65,000	142,000
CME [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		0
Subject to and not subject to Master Netting Agreements [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts		5,023,683,000	4,613,183,000
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		22,008,000	32,515,000
Asset Derivatives, Fair Value, Less: Legally enforceable master netting agreements		586,000	2,245,000
Asset Derivatives, Fair Value, Less: Cash collateral posted		17,709,000	6,704,000
Derivative Asset		3,713,000	23,566,000
Liability Derivatives, Notional Amount		3,449,411,000	3,056,079,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		83,889,000	28,423,000
Liability Derivatives, Fair Value, Less: Legally enforceable master netting agreements		586,000	2,245,000
Liability Derivatives, Fair Value, Less: Cash collateral posted		0	0
Derivative liability		83,303,000	26,178,000
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instrument assets, Gross Amount		4,951,000	2,770,000
Asset Derivatives, Fair Value, Less: Legally enforceable master netting agreements		0	91,000
Asset Derivatives, Fair Value, Less: Cash collateral posted		4,951,000	2,679,000
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]	325,000,000	325,000,000
Derivative instrument assets, Gross Amount	[1]	4,951,000	2,770,000
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		13,425,000	6,222,000
Asset Derivatives, Fair Value, Less: Legally enforceable master netting agreements		586,000	2,154,000
Asset Derivatives, Fair Value, Less: Cash collateral posted		12,758,000	4,025,000
Derivative Asset		81,000	43,000
Liability Derivatives, Fair Value, Gross Liability		651,000	2,387,000
Liability Derivatives, Fair Value, Less: Legally enforceable master netting agreements		586,000	2,245,000
Liability Derivatives, Fair Value, Less: Cash collateral posted		0	0
Derivative liability		65,000	142,000
Not Designated as Hedging Instrument [Member] | CME [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	[1]	2,700,000,000	1,900,000,000
Liability Derivatives, Notional Amount	[1]	47,000,000	595,000,000
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]	3,852,438,000	2,791,760,000
Derivative instrument assets, Gross Amount	[1]	13,226,000	5,977,000
Liability Derivatives, Notional Amount	[1]	76,789,000	721,048,000
Liability Derivatives, Fair Value, Gross Liability	[1]	215,000	1,968,000
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		52,067,000	28,497,000
Derivative instrument assets, Gross Amount		223,000	421,000
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		3,063,000	39,230,000
Liability Derivatives, Fair Value, Gross Liability		7,000	110,000
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]	24,879,000	7,914,000
Derivative instrument assets, Gross Amount	[1]	199,000	258,000
Liability Derivatives, Notional Amount	[1]	23,927,000	30,328,000
Liability Derivatives, Fair Value, Gross Liability	[1]	435,000	419,000
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		4,698,683,000	4,288,183,000
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		17,057,000	29,745,000
Liability Derivatives, Notional Amount		3,449,411,000	3,056,079,000
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		83,889,000	28,423,000
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		677,679,000	1,366,299,000
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		3,090,000	23,009,000
Liability Derivatives, Notional Amount		3,242,821,000	2,146,518,000
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		83,142,000	25,631,000
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		84,702,000	93,713,000
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		19,000	80,000
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		100,294,000	116,882,000
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		43,000	111,000
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		6,918,000	0
Asset Derivatives, Fair Value, Positions not subject to master netting agreement		300,000	0
Liability Derivatives, Notional Amount		2,517,000	2,073,000
Liability Derivatives, Fair Value, Positions not subject to master netting agreement		47,000	$ 184,000
Loan Origination Commitments [Member]
Derivatives, Fair Value [Line Items]
Other Commitment		33,000,000
Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Other Commitment		$ 9,100,000
[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 Instrume_4

Derivative Financial Instruments (Schedule of the changes in the fair value of non-hedge accounting derivatives) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 1,393	$ 2,031	$ 8,507	$ 2,373
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	1,667	1,928	5,158	5,953
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	1,623	2,955	7,372	5,850
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	22	51	117	157
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	(26)	(219)	(95)	(1,886)
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	$ (226)	$ (756)	$ 1,113	$ (1,748)

Derivative Financial Instrume_5

Derivative Financial Instruments (AOCI Related to Cash Flow Hedges) (Narrative) (Detail) - Cash Flow Hedging [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Estimate of amount to be reclassified from AOCL	$ (4,300)
Remaining unamortized gain (loss) on termination of cash flow hedges	(10,100)
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Estimate of amount to be reclassified from AOCL	$ (264)

Derivative Financial Instrume_6

Derivative Financial Instruments (Offsetting Derivatives) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 1,393	$ 2,031	$ 8,507	$ 2,373
Derivative instrument assets, Gross Amount	18,376		18,376		$ 8,992
Derivative instrument asset, Amount Offset	36,300		36,300
Derivative Asset	81		81		43
Liability Derivatives, Fair Value, Gross Liability	651		651		2,387
Derivative liability	65		65		142
Hedge Accounting Positions [Member]
Derivative [Line Items]
Derivative instrument assets, Gross Amount	4,951		4,951		2,770
Derivative instrument asset, Amount Offset, Total	0		0		(91)
Derivative instrument asset, Amount Offset	4,951		4,951		2,679
Derivative Asset	0		0		0
Liability Derivatives, Fair Value, Gross Liability	0		0		0
Derivative instrument liability, Amount Offset, Total	0		0		0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0		0
Derivative liability	0		0		0
Non-Hedged Accounting Positions [Member]
Derivative [Line Items]
Derivative instrument assets, Gross Amount	13,425		13,425		6,222
Derivative instrument asset, Amount Offset, Total	(586)		(586)		(2,154)
Derivative instrument asset, Amount Offset	12,758		12,758		4,025
Derivative Asset	81		81		43
Liability Derivatives, Fair Value, Gross Liability	651		651		2,387
Derivative instrument liability, Amount Offset, Total	(586)		(586)		(2,245)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0		0
Derivative liability	65		65		142
Subject to and not subject to Master Netting Agreements [Member]
Derivative [Line Items]
Derivative instrument asset, Amount Offset, Total	(586)		(586)		(2,245)
Derivative instrument asset, Amount Offset	17,709		17,709		6,704
Derivative Asset	3,713		3,713		23,566
Derivative instrument liability, Amount Offset, Total	(586)		(586)		(2,245)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0		0
Derivative liability	83,303		83,303		$ 26,178
Interest Rate Derivatives [Member] | Operating Expense [Member] | Hedge Accounting Positions [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	1,667	1,928	5,158	5,953
Interest Rate Derivatives [Member] | Operating Expense [Member] | Non-Hedged Accounting Positions [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 1,623	$ 2,955	$ 7,372	$ 5,850

Derivative Financial Instrume_7

Derivative Financial Instruments (Counterparty Credit Risk Narrative) (Detail) $ in Millions	Sep. 30, 2018USD ($)
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 3.1
Valuation, Market Approach [Member]
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 31.7

Derivative Financial Instrume_8

Derivative Financial Instruments Offsetting Liabilities (Details) $ in Millions	Sep. 30, 2018USD ($)
Offsetting Liabilities [Line Items]
Derivative instrument asset, Amount Offset	$ 36.3
Derivative, Collateral, Right to Reclaim Cash	(80)
Exchange Cleared [Member]
Offsetting Liabilities [Line Items]
Derivative, Collateral, Right to Reclaim Cash	(98.2)
Over the Counter [Member]
Offsetting Liabilities [Line Items]
Derivative, Collateral, Right to Reclaim Cash	$ (18.1)

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Detail) $ in Millions	Sep. 30, 2018USD ($)
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	$ 5.3
Rabbi Trust [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	2
Alternative investments [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	$ 3.6

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring and Nonrecurring Basis) (Detail) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Financial assets held at fair value:
Debt Securities, Available-for-sale		$ 2,823,953	$ 2,638,037
Investment securities available-for-sale, at fair value		2,823,953	2,638,037
Derivative Asset		81	43
Loans Held-for-sale, Fair Value Disclosure		17,137	20,888
Financial liabilities held at fair value:
Derivative liability		65	142
US Treasury Bill Securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		9,214	1,247
Agency CMO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		246,466	306,333
Agency MBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		1,409,731	1,107,841
Agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		570,549	588,026
Non-agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		404,902	361,067
CLO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		127,661	209,851
Single issuer trust preferred securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	7,050
Corporate debt securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		55,430	56,622
Fair Value, Measurements, Recurring [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		2,823,953
Investment securities available-for-sale, at fair value			2,638,037
Alternative Investment		2,073	3,495
Total financial assets held at fair value		2,870,101	2,699,736
Financial liabilities held at fair value:
Derivative liability	[1]	83,889	28,423
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		9,214
Investment securities available-for-sale, at fair value			1,247
Alternative Investment		0	0
Total financial assets held at fair value		14,642	6,306
Financial liabilities held at fair value:
Derivative liability	[1]	462	587
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		2,814,739
Investment securities available-for-sale, at fair value			2,636,790
Alternative Investment		0	0
Total financial assets held at fair value		2,853,386	2,689,935
Financial liabilities held at fair value:
Derivative liability	[1]	83,427	27,836
Fair Value, Measurements, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			0
Alternative Investment		2,073	3,495
Total financial assets held at fair value		2,073	3,495
Financial liabilities held at fair value:
Derivative liability			0
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]	22,008	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]	498	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]	21,510	32,257
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Derivative Asset			0
Fair Value, Measurements, Recurring [Member] | Investments Held In Rabbi Trust [Member]
Financial assets held at fair value:
Other assets		4,930	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		4,930	4,801
Fair Value, Measurements, Recurring [Member] | Investments Held In Rabbi Trust [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Other assets			0
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		17,137	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:
Loans Held-for-sale, Fair Value Disclosure		0	0
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		17,137	20,888
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		0
Fair Value, Measurements, Recurring [Member] | US Treasury Bill Securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		9,214
Investment securities available-for-sale, at fair value			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:
Debt Securities, Available-for-sale		9,214
Investment securities available-for-sale, at fair value			1,247
Fair Value, Measurements, Recurring [Member] | US Treasury Bill Securities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Agency CMO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		246,466
Investment securities available-for-sale, at fair value			306,333
Fair Value, Measurements, Recurring [Member] | Agency CMO [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		246,466
Investment securities available-for-sale, at fair value			306,333
Fair Value, Measurements, Recurring [Member] | Agency CMO [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		1,409,731
Investment securities available-for-sale, at fair value			1,107,841
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		1,409,731
Investment securities available-for-sale, at fair value			1,107,841
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		570,549
Investment securities available-for-sale, at fair value			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:
Debt Securities, Available-for-sale		0
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		570,549
Investment securities available-for-sale, at fair value			588,026
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		404,902
Investment securities available-for-sale, at fair value			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:
Debt Securities, Available-for-sale		0
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		404,902
Investment securities available-for-sale, at fair value			361,067
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | CLO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		127,661
Investment securities available-for-sale, at fair value			209,851
Fair Value, Measurements, Recurring [Member] | CLO [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		127,661
Investment securities available-for-sale, at fair value			209,851
Fair Value, Measurements, Recurring [Member] | CLO [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			0
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			7,050
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			7,050
Fair Value, Measurements, Recurring [Member] | Single issuer trust preferred securities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			0
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		55,430
Investment securities available-for-sale, at fair value			56,622
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		$ 55,430
Investment securities available-for-sale, at fair value			56,622
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value			$ 0
[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	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 17,137	$ 20,888
Fair Value, Option, Loans Held as Assets, Aggregate Difference	(151)	542
loans held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans and Leases Receivable, Gross, Consumer, Real Estate	$ 17,288	$ 20,346

Fair Value Measurements (Summar

Fair Value Measurements (Summary Of Estimated Fair Values Of Significant Financial Instruments) (Detail) - USD ($) $ in Thousands		Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale		$ 17,137		$ 20,888
Mortgage servicing assets, Carrying Amount		22,644	$ 23,341	25,139	$ 25,140	$ 24,708	$ 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		18,109,187		17,323,864
Securities sold under agreements to repurchase and other borrowings		564,488		643,269
FHLB advances	[1]	1,441,884		1,677,105
Long-term debt	[1]	225,957		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		18,902,371		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		3,095,252		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		4,332,458		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		22,644		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		564,396		644,084
FHLB advances	[1]	1,439,155		1,678,070
Long-term debt	[1]	229,336		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		17,913,452		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		18,902,371		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		3,067,487		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		4,164,359		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		$ 48,661		$ 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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 12	$ 0	$ 37
Interest cost on benefit obligations	1,857	1,829	5,577	5,486
Expected return on plan assets	(3,178)	(3,074)	(9,538)	(9,222)
Amortization of prior service cost	0	0	0	0
Recognized net loss	1,160	1,466	3,480	4,398
Net periodic benefit cost	(161)	233	(481)	699
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost on benefit obligations	35	96	201	281
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Recognized net loss	2,271	136	2,729	561
Net periodic benefit cost	2,306	232	2,930	842
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost on benefit obligations	20	19	59	69
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Recognized net loss	0	(15)	0	0
Net periodic benefit cost	$ 20	$ 4	$ 59	$ 69

Share-Based Plans (Narrative) (

Share-Based Plans (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 2.7	$ 3	$ 8.6	$ 9.1
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock compensation expense	$ 16.4		$ 16.4
Weighted average recognition period			2 years
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	100,000		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)			3 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)	492,792		492,792		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)	458,904		458,904
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	33,888		33,888

Share-Based Plans (Summary of R

Share-Based Plans (Summary of Restricted Stock and Stock Option Activity) (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense		$ 2.7	$ 3	$ 8.6	$ 9.1
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)				207,800
Restricted stock, Granted (in shares)				145,382
Restricted stock, Vested restricted stock awards (in shares)	[1]			129,445
Restricted stock, Forfeited (in shares)				8,041
Restricted stock, Outstanding at end of period (in shares)		215,696		215,696
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)				$ 43.16
Restricted stock, Granted (in dollars per share)				58.36
Restricted stock, Vested restricted stock awards (in dollars per share)	[1]			44.80
Restricted stock, Forfeited (in dollars per share)				52.53
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share)		$ 51.91		$ 51.91
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)				78,916
Restricted stock, Granted (in shares)				75,707
Restricted stock, Vested restricted stock awards (in shares)	[1]			55,112
Restricted stock, Forfeited (in shares)				13,847
Restricted stock, Outstanding at end of period (in shares)		85,664		85,664
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)				$ 45.35
Restricted stock, Granted (in dollars per share)				55.82
Restricted stock, Vested restricted stock awards (in dollars per share)	[1]			46.08
Restricted stock, Forfeited (in dollars per share)				51.19
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share)		$ 53.19		$ 53.19
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				673,039
Options granted, Number of Shares				0
Exercised options, Number of Shares				180,247
Options forfeited, Number of Shares				0
Options outstanding, at end of period, Number of Shares		492,792		492,792
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)				$ 18.75
Options granted, Weighted-Average Exercise Price (in dollars per share)				0
Exercised options, Weighted-Average Exercise Price (in dollars per share)				11.71
Options forfeited, Weighted-Average Exercise Price (in dollars per share)				0
Options, at end of period, Weighted-average Exercise Price (in dollars per share)		$ 21.33		$ 21.33
[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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Assets	$ 27,346,317		$ 27,346,317		$ 26,487,645
Net interest income (expense)	230,372	$ 200,904	669,550	$ 591,355
Provision for Loan and Lease Losses	10,500	10,150	32,000	27,900
Net interest income after provision for loan and lease losses	219,872	190,754	637,550	563,455
Noninterest Income	72,284	65,846	209,405	193,439
Total non-interest expense	178,783	161,823	530,857	490,026
Income (loss) before income tax expense	113,373	94,777	316,098	266,868
Income tax expense	13,700	30,281	54,518	81,322
Net income	99,673	64,496	261,580	185,546
Operating Segments [Member] | Commercial Banking [Member]
Segment Reporting Information [Line Items]
Total Assets	10,327,878		10,327,878		9,350,028
Net interest income (expense)	91,243	81,925	264,353	239,118
Provision for Loan and Lease Losses	8,207	12,073	26,300	29,562
Net interest income after provision for loan and lease losses	83,036	69,852	238,053	209,556
Noninterest Income	18,305	13,207	48,662	39,163
Total non-interest expense	44,506	38,339	128,730	113,767
Income (loss) before income tax expense	56,835	44,720	157,985	134,952
Income tax expense	13,981	14,363	38,864	41,125
Net income	42,854	30,357	119,121	93,827
Operating Segments [Member] | HSA Bank [Member]
Segment Reporting Information [Line Items]
Total Assets	71,172		71,172		76,308
Net interest income (expense)	36,731	26,713	104,920	76,339
Provision for Loan and Lease Losses	0	0	0	0
Net interest income after provision for loan and lease losses	36,731	26,713	104,920	76,339
Noninterest Income	22,159	19,371	67,710	58,392
Total non-interest expense	30,753	27,222	93,488	84,211
Income (loss) before income tax expense	28,137	18,862	79,142	50,520
Income tax expense	7,316	6,006	20,577	15,395
Net income	20,821	12,856	58,565	35,125
Operating Segments [Member] | Community Banking [Member]
Segment Reporting Information [Line Items]
Total Assets	8,730,295		8,730,295		8,909,671
Net interest income (expense)	101,952	96,859	302,782	286,351
Provision for Loan and Lease Losses	2,293	(1,923)	5,700	(1,662)
Net interest income after provision for loan and lease losses	99,659	98,782	297,082	288,013
Noninterest Income	26,848	27,079	78,421	80,516
Total non-interest expense	95,769	92,478	287,795	281,979
Income (loss) before income tax expense	30,738	33,383	87,708	86,550
Income tax expense	6,117	10,605	17,454	26,374
Net income	24,621	22,778	70,254	60,176
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total Assets	8,216,972		8,216,972		$ 8,151,638
Net interest income (expense)	446	(4,593)	(2,505)	(10,453)
Provision for Loan and Lease Losses	0	0	0	0
Net interest income after provision for loan and lease losses	446	(4,593)	(2,505)	(10,453)
Noninterest Income	4,972	6,189	14,612	15,368
Total non-interest expense	7,755	3,784	20,844	10,069
Income (loss) before income tax expense	(2,337)	(2,188)	(8,737)	(5,154)
Income tax expense	(13,714)	(693)	(22,377)	(1,572)
Net income	$ 11,377	$ (1,495)	$ 13,640	$ (3,582)

Segment Reporting Segment Repor

Segment Reporting Segment Reporting Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)Segment	Sep. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | Segment			3
Deposit insurance	$ 9,694	$ 6,344	$ 30,098	$ 19,701
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Deposit insurance			$ 10,000

Revenue from Contracts with C_3

Revenue from Contracts with Customers Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 50,230	$ 47,000	$ 150,732	$ 139,238
Noninterest Income	72,284	65,846	209,405	193,439
Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	40,601	38,321	121,911	113,519
Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	8,412	7,750	24,738	22,900
Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,217	929	4,083	2,819
Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	22,054	18,846	58,673	54,201
Operating Segments [Member] | Commercial Banking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,788	5,590	17,316	16,300
Noninterest Income	18,305	13,207	48,662	39,163
Operating Segments [Member] | Commercial Banking [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,211	3,119	9,613	9,012
Operating Segments [Member] | Commercial Banking [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,577	2,471	7,703	7,288
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	0	0
Operating Segments [Member] | Commercial Banking [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	12,517	7,617	31,346	22,863
Operating Segments [Member] | Community Banking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	22,302	21,939	65,624	64,287
Noninterest Income	26,848	27,079	78,421	80,516
Operating Segments [Member] | Community Banking [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	16,107	16,435	47,079	48,046
Operating Segments [Member] | Community Banking [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,843	5,288	17,060	15,638
Operating Segments [Member] | Community Banking [Member] | Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	352	216	1,485	603
Operating Segments [Member] | Community Banking [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	4,546	5,140	12,797	16,229
Operating Segments [Member] | HSA Bank [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	22,159	19,371	67,710	58,392
Noninterest Income	22,159	19,371	67,710	58,392
Operating Segments [Member] | HSA Bank [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	21,294	18,658	65,112	56,176
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	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	865	713	2,598	2,216
Operating Segments [Member] | HSA Bank [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	0	0	0	0
Corporate, Non-Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(19)	100	82	259
Noninterest Income	4,972	6,189	14,612	15,368
Corporate, Non-Segment [Member] | Deposit service fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(11)	109	107	285
Corporate, Non-Segment [Member] | Wealth and investment services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(8)	(9)	(25)	(26)
Corporate, Non-Segment [Member] | Other non interest income [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Non-interest income within the scope of other GAAP topics [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	$ 4,991	$ 6,089	$ 14,530	$ 15,109

Commitments and Contingencies_2

Commitments and Contingencies (Outstanding Financial Instruments Contract Amounts Represent Credit Risk) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,905,527	$ 5,806,789
Standby letter of credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	185,859	195,902
Commercial letter of credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	36,393	43,200
Commitments to extend credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,683,275	$ 5,567,687

(Reserve for Unfunded Commitmen

(Reserve for Unfunded Commitments) (Detail) - SEC Schedule, 12-09, Allowance, Credit Loss [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 2,596	$ 2,544	$ 2,362	$ 2,287
Provision charged to expense	28	0	262	257
Ending balance	$ 2,624	$ 2,544	$ 2,624	$ 2,544

Subsequent Events Discontinued

Subsequent Events Discontinued Operations and Disposal Groups (Details) - Sale of Banking Centers [Member] - Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] $ in Millions	Sep. 30, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operations Number of Banking Centers	6
Disposal Group, Including Discontinued Operation, Deposits	$ 105