Webster Financial (WBS) 10-K 1 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	WBS
Entity Registrant Name	WEBSTER FINANCIAL CORPORATION
Entity Central Index Key	801,337
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		92,111,033
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 4.7

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets [Abstract]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 231,158	$ 190,663
Interest-bearing deposits	25,628	29,461
Securities available-for-sale, at fair value	2,638,037	2,991,091
Investment securities held-to-maturity (fair value of $4,456,350 and $4,125,125)	4,487,392	4,160,658
Federal Home Loan Bank and Federal Reserve Bank stock	151,566	194,646
Loans held for sale (valued under fair value option $20,888 and $60,260)	20,888	67,577
Loans and leases	17,523,858	17,026,588
Allowance for loan and lease losses	(199,994)	(194,320)
Loans and leases, net	17,323,864	16,832,268
Deferred tax assets, net	92,630	84,391
Premises and equipment, net	130,001	137,413
Goodwill	538,373	538,373
Other intangible assets, net	29,611	33,674
Cash surrender value of life insurance policies	531,820	517,852
Accrued interest receivable and other assets	286,677	294,462
Total assets	26,487,645	26,072,529
Liabilities and Equity [Abstract]
Non-interest-bearing	4,191,496	4,021,061
Interest-bearing	16,802,233	15,282,796
Total deposits	20,993,729	19,303,857
Securities sold under agreements to repurchase and other borrowings	643,269	949,526
Federal Home Loan Bank advances	1,677,105	2,842,908
Long-term debt	225,767	225,514
Accrued expenses and other liabilities	245,817	223,712
Total liabilities	23,785,687	23,545,517
Shareholders’ equity:
Common stock, $.01 par value: Authorized - 200,000,000 shares; (Issued 93,651,601 shares)	937	937
Paid-in capital	1,122,164	1,125,937
Retained earnings	1,595,762	1,425,320
Treasury stock, at cost (1,658,526 and 1,899,502 shares)	(70,430)	(70,899)
Accumulated other comprehensive loss, net of tax	(91,531)	(76,993)
Total shareholders' equity	2,701,958	2,527,012
Total liabilities and shareholders' equity	26,487,645	26,072,529
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) Series E issued and outstanding (5,060 shares)Series F issued and outstanding(6,000)Series E issued and outstanding (5,060 shares)	145,056	0
Series E Preferred Stock [Member]
Shareholders’ equity:
Preferred stock, $.01 par value; Authorized - 3,000,000 shares: Series E issued and outstanding (5,060 shares) Series E issued and outstanding (5,060 shares)Series F issued and outstanding(6,000)Series E issued and outstanding (5,060 shares)	$ 0	$ 122,710

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Security held-to-maturity, fair value	$ 4,456,350	$ 4,125,125
LHFS, at fair value option	$ 20,888	$ 60,260
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Common stock par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued		93,651,601
Treasury stock, shares	1,658,526	1,899,502
Series E Preferred Stock [Member]
Preferred stock, shares issued		5,060
Preferred Stock, Shares Outstanding		5,060
Series F Preferred Stock [Member]
Preferred stock, shares issued	6,000
Preferred Stock, Shares Outstanding	6,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Income:
Interest and fees on loans and leases	$ 708,566	$ 621,028	$ 552,441
Taxable interest and dividends on securities	181,131	180,346	190,061
Non-taxable interest on securities	22,874	19,090	15,948
Loans held for sale	1,034	1,449	1,590
Interest Expense:
Deposits	62,253	49,858	46,031
Securities sold under agreements to repurchase and other borrowings	14,365	14,528	16,861
Federal Home Loan Bank advances	30,320	29,033	22,858
Long-term debt	10,380	9,981	9,665
Total interest expense	117,318	103,400	95,415
Total interest income	913,605	821,913	760,040
Net interest income	796,287	718,513	664,625
Provision for loan and lease losses	40,900	56,350	49,300
Net interest income (loss) after provision for loan and lease losses	755,387	662,163	615,325
Non-interest Income:
Deposit service fees	151,137	140,685	135,057
Loan and lease related fees	26,448	26,581	25,594
Wealth and investment services	31,055	28,962	32,486
Mortgage banking activities	9,937	14,635	7,795
Increase in cash surrender value of life insurance policies	14,627	14,759	13,020
Gain on sale of investment securities, net	0	414	609
Impairment loss on securities recognized in earnings	(126)	(149)	(110)
Other income	26,400	38,591	23,326
Total non-interest income	259,478	264,478	237,777
Non-interest Expense:
Compensation and benefits	359,926	332,127	297,517
Occupancy	60,490	61,110	48,836
Technology and equipment	89,464	79,882	80,813
Intangible assets amortization	4,062	5,652	6,340
Marketing	17,421	19,703	16,053
Professional and outside services	16,858	14,801	11,156
Deposit insurance	25,649	26,006	24,042
Other expense	87,205	83,910	70,584
Total non-interest expense	661,075	623,191	555,341
Income before income tax expense	353,790	303,450	297,761
Income tax expense	98,351	96,323	93,032
Net income	255,439	207,127	204,729
Preferred stock dividends and other	(8,608)	(8,704)	(9,368)
Earnings applicable to common shareholders	$ 246,831	$ 198,423	$ 195,361
Earnings per common share:
Earnings per common share, Basic (in dollars per share)	$ 2.68	$ 2.17	$ 2.15
Earnings per common share, Diluted (in dollars per share)	$ 2.67	$ 2.16	$ 2.13

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 69,893	$ 64,496	$ 61,579	$ 59,471	$ 57,660	$ 51,817	$ 50,603	$ 47,047	$ 255,439	$ 207,127	$ 204,729
Other comprehensive (loss) income, net of tax:
Total available-for-sale and transferred securities									(7,590)	(9,069)	(22,828)
Total derivative instruments									4,565	5,912	2,550
Total defined benefit pension and postretirement benefit plans									4,135	4,270	(1,567)
Other comprehensive income (loss), net of tax									1,110	1,113	(21,845)
Comprehensive income									$ 256,549	$ 208,240	$ 182,884

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Series A Preferred Stock [Member]	Series E Preferred Stock [Member]	Series F Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member]Series E 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 A Preferred Stock [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, 2014	$ 2,322,815				$ 151,649			$ 936	$ 1,127,534	$ 1,202,251				$ (103,294)	$ (56,261)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	204,729									204,729
Other comprehensive income (loss), net of tax	(21,845)														(21,845)
Dividends and dividend equivalents declared on common stock	(81,197)								119	(81,316)
Dividends on preferred stock		$ (615)	$ (8,096)								$ (615)	$ (8,096)
Common stock issued	0							1	(1)	0				0
Preferred stock conversion					(28,939)				(3,429)					32,368
Stock-based compensation, net of tax impact	12,947								2,906	(1,005)				11,046
Exercise of stock options	3,060								(2,781)					5,841
Common shares acquired related to stock compensation plan activity	(5,251)													(5,251)
Common stock repurchase program	(12,564)													(12,564)
Common stock warrants repurchased	(23)								(23)
Ending Balance at Dec. 31, 2015	2,413,960				122,710			937	1,124,325	1,315,948				(71,854)	(78,106)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	207,127									207,127
Other comprehensive income (loss), net of tax	1,113														1,113
Dividends and dividend equivalents declared on common stock	(89,913)								149	(90,062)
Dividends on preferred stock			(8,096)									(8,096)
Stock-based compensation, net of tax impact	14,092								2,976	403				10,713
Exercise of stock options	11,762								(1,350)					13,112
Common shares acquired related to stock compensation plan activity	(11,664)													(11,664)
Common stock repurchase program	(11,206)													(11,206)
Common stock warrants repurchased	(163)								(163)
Ending 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	255,439									255,439
Other comprehensive income (loss), net of tax	1,110														1,110
Dividends and dividend equivalents declared on common stock	(94,929)								168	(95,097)
Dividends on preferred stock			(8,096)	$ (88)								$ (8,096)	$ (88)
Common stock issued				$ 145,056			$ 145,056
Stock-based compensation, net of tax impact	14,184								0	2,636				11,548
Exercise of stock options	8,259								(3,941)					12,200
Common shares acquired related to stock compensation plan activity	(11,694)													(11,694)
Common stock repurchase program	(11,585)													(11,585)
Stock Redeemed or Called During Period, Value			$ (122,710)			$ (122,710)
Ending 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]
Cumulative Effect of New Accounting Principle in Period of Adoption										$ 15,648					$ (15,648)

Consolidated Statements of Sha7

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends on common stock and dividend equivalents declared, per share	$ 1.03	$ 0.98	$ 0.89
Series A Preferred Stock [Member]
Dividends on preferred stock, per share			21.25
Series E Preferred Stock [Member]
Dividends on preferred stock, per share	$ 1,600	$ 1,600	$ 1,600

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities:
Net income	$ 255,439	$ 207,127	$ 204,729
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	40,900	56,350	49,300
Deferred tax (benefit) expense	(9,074)	17,700	(15,513)
Depreciation and amortization	37,172	36,449	34,678
Amortization of earning assets and funding premium/discount, net	45,444	57,331	54,555
Stock-based compensation	12,276	11,438	10,935
Gain on sale, net of write-down, on foreclosed and repossessed assets	(784)	(976)	(311)
(Gain on sale) write-down, net on premises and equipment	(15)	397	(244)
Impairment loss on securities recognized in earnings	126	149	110
Gain on the sale of investment securities, net	0	(414)	(609)
Increase in cash surrender value of life insurance policies	(14,627)	(14,759)	(13,020)
Mortgage banking activities	(9,937)	(14,635)	(7,795)
Proceeds from sale of loans held for sale	333,027	438,925	452,590
Originations of loans held for sale	(287,634)	(452,886)	(449,048)
Net decrease (increase) in derivative contract assets net of liabilities	32,763	27,929	(6,489)
Gain (Loss) on Disposition of Other Assets	0	7,331	0
Net (increase) decrease in accrued interest receivable and other assets	(19,790)	54,269	(44,554)
Net increase (decrease) in accrued expenses and other liabilities	29,680	(18,918)	33,478
Net cash provided by operating activities	444,966	398,145	302,792
Investing Activities:
Net decrease (increase) in interest-bearing deposits	3,833	126,446	(23,212)
Purchases of available-for-sale securities	(660,106)	(980,870)	(903,240)
Proceeds from maturities and principal payments of available-for-sale securities	984,732	672,965	558,301
Proceeds from sales of available-for-sale securities	0	259,283	123,270
Purchases of held-to-maturity securities	(1,043,278)	(1,066,156)	(761,033)
Proceeds from maturities and principal payments of held-to-maturity securities	687,439	795,953	681,124
Net proceeds (purchase) of Federal Home Loan Bank stock	43,080	(6,299)	4,943
Purchases of intercompany debt securities	873	(381)	458
Net increase in loans	(549,213)	(1,440,141)	(1,813,811)
Proceeds from loans not originated for sale	14,679	34,170	33,644
Purchase of life insurance policies	0	0	(50,000)
Proceeds from life insurance policies	746	0	3,912
Proceeds from the sale of foreclosed properties and repossessed assets	7,603	9,205	10,511
Proceeds from the sale of premises and equipment	3,357	1,550	650
Additions to premises and equipment	(28,546)	(40,731)	(36,115)
Proceeds from Sale of Other Assets	7,581	0	0
Acquisition of business, net cash acquired	0	0	1,396,414
Net cash provided by (used for) investing activities	(527,220)	(1,635,006)	(774,184)
Financing Activities:
Net increase in deposits	1,690,197	1,351,609	853,921
Proceeds from Other Debt	0	5,000	0
Proceeds from Federal Home Loan Bank advances	12,255,000	19,630,000	13,505,000
Repayments of Federal Home Loan Bank advances	(13,420,791)	(19,451,219)	(13,700,279)
Net decrease in securities sold under agreements to repurchase and other borrowings	(306,257)	(201,874)	(99,356)
Payments for Repurchase of Redeemable Preferred Stock	(122,710)	0	0
Proceeds from Issuance of Redeemable Preferred Stock	145,056	0	0
Dividends paid to common shareholders	(94,630)	(89,522)	(80,964)
Dividends paid to preferred shareholders	(8,096)	(8,096)	(8,711)
Exercise of stock options	8,259	11,762	3,060
Excess tax benefits from stock-based compensation	0	3,204	2,338
Common stock repurchased	(11,585)	(11,206)	(12,564)
Shares acquired related to employee share-based compensation plans	(11,694)	(11,664)	(5,251)
Common stock warrants repurchased	0	(163)	(23)
Net cash (used for) provided by financing activities	122,749	1,227,831	457,171
Net decrease in cash and due from banks	40,495	(9,030)	(14,221)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	190,663	199,693	213,914
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	231,158	190,663	199,693
Supplemental disclosure of cash flow information:
Interest paid	114,046	102,438	95,428
Income taxes paid	109,059	80,143	106,991
Noncash investing and financing activities:
Transfer of loans and leases to foreclosed properties and repossessed assets	8,972	6,769	8,714
Transfer of loans from portfolio to loans held for sale	7,234	39,383	585
Deposits assumed in business acquisition	0	0	1,446,899
Preferred stock conversion	$ 0	$ 0	$ 28,939

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	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 December 31, 2017 , Webster Financial Corporation's principal asset is all of the outstanding capital stock of 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 Consolidated Financial Statements and the accompanying Notes thereto include the accounts of Webster Financial Corporation and all other entities in which it has a controlling financial interest. Intercompany accounts and transactions have been eliminated in consolidation. Webster's accounting and financial reporting policies conform, in all material respects, to GAAP and to general practices within the financial services industry. Assets that the Company holds or manages in a fiduciary or agency capacity for customers, typically referred to as assets under administration or assets under management are not included in the accompanying Consolidated Balance Sheets since those assets are not Webster's, and the Company is not the primary beneficiary. Certain prior period amounts have been reclassified to conform to the current year's presentation. These reclassifications had an immaterial effect on net income, comprehensive income, total assets, total liabilities, total shareholders' equity, net cash provided by operating activities, and net cash used for investing activities. Variable Interest Entities A variable interest entity (VIE) is an entity that has either a total equity investment that is insufficient to finance its activities without additional subordinated financial support or whose equity investors lack the ability to control the entity’s activities or lack the ability to receive expected benefits or absorb obligations in a manner that’s consistent with their investment in the entity. The Company evaluates each VIE to understand the purpose and design of the entity, and its involvement in the ongoing activities of the VIE. The Company will consolidate the VIE if it has: • the power to direct the activities of the VIE that most significantly affect the VIE's economic performance; and • an obligation to absorb losses of the VIE, or the right to receive benefits from the VIE, that could potentially be significant to the VIE. See Note 2: Variable Interest Entities for further information. Use of Estimates The preparation of financial statements in accordance with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the financial statements as well as income and expense during the period. The allowance for loan and lease losses, the fair value measurements for valuation of investments and other financial instruments, evaluation of investments for OTTI, valuation of goodwill and other intangible assets, and assessing the realizability of deferred tax assets and the measurement of uncertain tax position, as well as the status of contingencies, are particularly subject to change. Actual results could differ from those estimates. Cash Equivalents Cash equivalents have a maturity of three months or less. Cash and due from banks. Cash equivalents, including cash on hand, certain cash due from banks, and deposits at the FRB of Boston, are referenced as cash and due from banks in the accompanying Consolidated Balance Sheets and Consolidated Statements of Cash Flows. Interest-bearing deposits. Cash equivalents, primarily representing deposits at the FRB of Boston in excess of reserve requirements, and federal funds sold, which essentially represent uncollateralized loans to other financial institutions, are referenced as interest-bearing deposits in the accompanying Consolidated Balance Sheets and Consolidated Statements of Cash Flows. The Company regularly evaluates the credit risk associated with those financial institutions to assess that Webster is not exposed to any significant credit risk on cash equivalents. Investment Securities Investment securities are classified as available-for-sale or held-to-maturity at the time of purchase. Any classification change subsequent to trade date is reviewed for compliance with corporate objectives and accounting policy. Debt securities classified as held-to-maturity are those which Webster has the ability and intent to hold to maturity. Securities classified as held-to-maturity are recorded at amortized cost net of unamortized premiums and discounts. Discount accretion income and premium amortization expense are recognized as interest income according to a constant yield methodology, with consideration given to prepayment assumptions on mortgage backed securities. Securities classified as available-for-sale are recorded at fair value with unrealized gains and losses recorded as a component of other comprehensive income (OCI)/other comprehensive loss (OCL). Securities transferred from available-for-sale to held-to-maturity are recorded at fair value at the time of transfer, and the respective gain or loss is recorded as a separate component of OCI/OCL and amortized as an adjustment to interest income over the remaining life of the security. Securities classified as available-for-sale or held-to-maturity and in an unrealized loss position are evaluated for OTTI on a quarterly basis. The evaluation considers several qualitative factors, including the period of time the security has been in a loss position, and the amount of the unrealized loss. If the Company intends to sell the security or it is more likely than not the Company will be required to sell the security prior to recovery of its amortized cost basis, the security is written down to fair value, and the loss is recognized in non-interest income in the accompanying Consolidated Statements of Income. If the Company does not intend to sell the security and it is more likely than not that the Company will not be required to sell the security prior to recovery of its amortized cost basis, only the credit component of the unrealized loss is recorded as an impairment charge to a debt security and recognized as a loss. The remaining loss component would be recorded to accumulated other comprehensive loss, net of tax (AOCL) in the accompanying Consolidated Balance Sheets. The entire amount of an unrealized loss position of an equity security that is considered OTTI is recorded as an impairment loss in non-interest income in the accompanying Consolidated Statements of Income. The specific identification method is used to determine realized gains and losses on sales of securities. See Note 3: Investment Securities for further information. Federal Home Loan Bank and Federal Reserve Bank Stock Webster Bank is a member of the FHLB and the Federal Reserve System, and is required to maintain an investment in capital stock of the FHLB of Boston and FRB of Boston. Based on redemption provisions, the stock of both the FHLB and the FRB has no quoted market value and is carried at cost. Membership stock is reviewed for impairment as economic circumstances warrant special review. Loans Held for Sale Effective January 1, 2016, on a loan by loan election, residential mortgage loans that are classified as held for sale are accounted for under either the fair value option method of accounting or the lower of cost or fair value method of accounting with the election being made at the time the asset is first recognized. The Company has elected the fair value option to mitigate accounting mismatches between held for sale derivative commitments and loan valuations. Prior to January 1, 2016, residential mortgage loans that were classified as held for sale were accounted for at the lower of cost or fair value method of accounting and were valued on an individual asset basis. Loans not originated for sale but subsequently transferred to held for sale continue to be valued at the lower of cost or fair value method of accounting and are valued on an individual asset basis. Any cost amount in excess of fair value is recorded as a valuation allowance and recognized as a reduction of other income in the Consolidated Statements of Income. Gains or losses on the sale of loans held for sale are recorded as mortgage banking activities. Cash flows from sale of loans made by the Company that were acquired specifically for resale are presented as operating cash flows. All other cash flows from sale of loans are presented as investing cash flows. See Note 5: Transfers of Financial Assets for further information. Transfers and Servicing of Financial Assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is generally considered to have been surrendered when: (i) the transferred assets are legally isolated from the Company or its consolidated affiliates, even in bankruptcy or other receivership; (ii) the transferee has the right to pledge or exchange the assets with no conditions that constrain the transferee and provide more than a trivial benefit to the Company; and (iii) the Company does not maintain the obligation or unilateral ability to reclaim or repurchase the assets. The Company sells financial assets in the normal course of business, the majority of which are residential mortgage loan sales primarily to government-sponsored enterprises through established programs, commercial loan sales through participation agreements, and other individual or portfolio loan and securities sales. In accordance with accounting guidance for asset transfers, the Company considers any ongoing involvement with transferred assets in determining whether the assets can be derecognized from the balance sheet. With the exception of servicing and certain performance-based guarantees, the Company’s continuing involvement with financial assets sold is minimal and generally limited to market customary representation and warranty clauses covering certain characteristics of the mortgage loans sold and the Company's origination process. The gain or loss on sale depends on the previous carrying amount of the transferred financial assets, the consideration received, and any other assets obtained or liabilities incurred in exchange for the transferred assets. When the Company sells financial assets, it may retain servicing rights and/or other interests in the financial assets. Servicing assets and any other interests held by the Company are recorded at fair value upon transfer, and thereafter are carried at the lower of cost or fair value. See Note 5: Transfers of Financial Assets for further information. Loans and Leases Loans and leases are stated at the principal amount outstanding, net of amounts charged off, unearned income, unamortized premiums and discounts, and deferred loan and lease fees/costs which are recognized as yield adjustments using the interest method. These yield adjustments are amortized over the contractual life of the related loans and leases adjusted for prepayments when applicable. Interest on loans and leases is credited to interest income as earned based on the interest rate applied to principal amounts outstanding. Prepayment fees are recognized in non-interest income. Cash flows from loans and leases are presented as investing cash flows. Loans and leases are placed on non-accrual status when collection of principal and interest in accordance with contractual terms is doubtful, generally when principal or interest payments become 90 days delinquent, unless the loan or lease is well secured and in process of collection, or sooner if management concludes circumstances indicate that the borrower may be unable to meet contractual principal or interest payments. Residential real estate loans, excluding loans fully insured against loss and in the process of collection, and consumer loans are placed on non-accrual status at 90 days past due, or at the date when the Company is notified that the borrower is discharged in bankruptcy. A charge-off for the balance in excess of the fair value of the collateral less cost to sell, is recorded at 180 days if the loan balance exceeds the fair value of the collateral less costs to sell. Residential loans that are more than 90 days past due, fully insured against loss, and in the process of collection, remain accruing and are reported as 90 days or more past due and accruing. Commercial, commercial real estate loans, and equipment finance loans or leases are subject to a detailed review when 90 days past due to determine accrual status, or when payment is uncertain and a specific consideration is made to put a loan or lease on non-accrual status. When loans and leases are placed on non-accrual status, the accrual of interest is discontinued, and any unpaid accrued interest is reversed and charged against interest income. If ultimate repayment of a non-accrual loan or lease is expected, any payments received are applied in accordance with contractual terms. If ultimate repayment is not expected on commercial, commercial real estate, and equipment finance loans and leases, any payment received on a non-accrual loan or lease is applied to principal until the unpaid balance has been fully recovered. Any excess is then credited to interest income when received. If the Company determines, through a current valuation analysis, that principal can be repaid on residential real estate and consumer loans, interest payments may be taken into income as received on a cash basis. Except for loans discharged under Chapter 7 of the U.S. bankruptcy code, loans are removed from non-accrual status when they become current as to principal and interest or demonstrate a period of performance under contractual terms and, in the opinion of management, are fully collectible as to principal and interest. Pursuant to regulatory guidance, a Chapter 7 discharged bankruptcy loan is removed from non-accrual status when the bank expects full repayment of the remaining pre-discharged contractual principal and interest, the loan is a closed-end amortizing loan, it is fully collateralized, and post-discharge the loan had at least six consecutive months of current payments. See Note 4: Loans and Leases for further information. Allowance for Loan and Lease Losses The ALLL is a reserve established through a provision for loan and lease losses charged to expense and represents management’s best estimate of probable losses that may be incurred within the existing loan and lease portfolio as of the balance sheet date. The level of the allowance reflects management’s view of trends in losses, current portfolio quality, and present economic, political, and regulatory conditions. The ALLL may be allocated for specific portfolio segments; however, the entire allowance balance is available to absorb credit losses inherent in the total loan and lease portfolio. A charge-off is recorded when all or a portion of the loan or lease is deemed to be uncollectible. Back-testing is performed to compare original estimated losses and actual observed losses, resulting in ongoing refinements. While management utilizes its best judgment based on the information available at the time, the ultimate adequacy of the allowance is dependent upon a variety of factors that are beyond the Company’s control, which include the performance of the Company’s portfolio, economic conditions, interest rate sensitivity, and other external factors. The ALLL consists of the following three elements: (i) specific valuation allowances established for probable losses on impaired loans and leases; (ii) quantitative valuation allowances calculated using loss experience for like loans and leases with similar characteristics and trends, adjusted, as necessary, to reflect the impact of current conditions; and (iii) qualitative factors determined based on general economic conditions and other factors that may be internal or external to the Company. Loans and leases are considered impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impairment is evaluated on a pooled basis for smaller-balance homogeneous residential, consumer loans and small business loans. Commercial, commercial real estate, and equipment financing loans and leases over a specific dollar amount and all TDR are evaluated individually for impairment. A loan identified as a TDR is considered an impaired loan for the entire term of the loan, with few exceptions. If a loan is impaired, a specific valuation allowance may be established, and the loan is reported net, at the present value of estimated future cash flows using the loan’s original interest rate or at the fair value of collateral less cost to sell if repayment is expected from collateral liquidation. Interest payments on non-accruing impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Loans and leases, or portions thereof, are charged off when deemed uncollectible. Factors considered by management in determining impairment include payment status, collateral value, discharged bankruptcy, and the likelihood of collecting scheduled principal and interest payments. The current or weighted-average (for multiple notes within a commercial borrowing arrangement) interest rate of the loan is used as the discount rate, for determining net present value of the loan evaluated for impairment, when the interest rate floats with a specified index. A change in terms or payments would be included in the impairment calculation. See Note 4: Loans and Leases for further information. Reserve for Unfunded Commitments The reserve for unfunded commitments provides for probable losses inherent with funding the unused portion of legal commitments to lend. The unfunded reserve calculation includes factors that are consistent with the ALLL methodology for funded loans using the PD, LGD, and a draw down factor applied to the underlying borrower risk and facility grades. The reserve for unfunded credit commitments is included within other liabilities in the accompanying Consolidated Balance Sheets, and changes in the reserve are reported as a component of other expense in the accompanying Consolidated Statements of Income. See Note 20: Commitments and Contingencies for further information. Troubled Debt Restructurings A modified loan is considered a TDR when the following two conditions are met: (i) the borrower is experiencing financial difficulties; and (ii) the modification constitutes a concession. The Company considers all aspects of the restructuring in determining whether a concession has been granted, including the debtor's ability to access funds at a market rate. In general, a concession exists when the modified terms of the loan are more attractive to the borrower than standard market terms. Modified terms are dependent upon the financial position and needs of the individual borrower. The most common types of modifications include covenant modifications and forbearance. Loans for which the borrower has been discharged under Chapter 7 bankruptcy are considered collateral dependent TDR, impaired at the date of discharge, and charged down to the fair value of collateral less cost to sell, if management considers that loss potential likely exists. The Company’s policy is to place consumer loan TDR, except those that were performing prior to TDR status, on non-accrual status for a minimum period of six months. Commercial TDR are evaluated on a case-by-case basis for determination of whether or not to place them on non-accrual status. Loans qualify for return to accrual status once they have demonstrated performance with the restructured terms of the loan agreement for a minimum of six months. Initially, all TDRs are reported as impaired. Generally, TDRs are classified as impaired loans and reported as TDR for the remaining life of the loan. Impaired and TDR classification may be removed if the borrower demonstrates compliance with the modified terms for a minimum of six months and through a fiscal year-end and the restructuring agreement specifies a market rate of interest equal to that which would be provided to a borrower with similar credit at the time of restructuring. In the limited circumstance that a loan is removed from TDR classification, it is the Company’s policy to continue to base its measure of loan impairment on the contractual terms specified by the loan agreement. The Company’s loan and lease portfolio includes loans that have been restructured into an A-Note/B-Note structure as a result of evaluating the cash flow of the borrowers to support repayment. Following these restructurings, Webster immediately charged off the balances of the B-Notes. The restructuring agreements specify a market interest rate equal to that which would be provided to a borrower with similar credit at the time of restructuring. See Note 4: Loans and Leases for further information. Foreclosed and Repossessed Assets Real estate acquired through foreclosure or completion of a deed in lieu of foreclosure and other assets acquired through repossession are carried at the lower of cost or market value less estimated selling costs and are included within other assets in the accompanying Consolidated Balance Sheets. Independent appraisals generally are obtained to substantiate fair value and may be subject to adjustment based upon historical experience or specific geographic trends impacting the property. Within 90 days of a loan being foreclosed upon, the excess of loan balance over fair value less cost to sell is charged off against the ALLL. Subsequent write-downs in value, maintenance costs as incurred, and gains or losses upon sale are charged to non-interest expense in the accompanying Consolidated Statements of Income. Premises and Equipment Premises and equipment are carried at cost, less accumulated depreciation. Depreciation of premises and equipment is computed on a straight-line basis over the estimated useful lives of the assets, as follows: Minimum Maximum Building and Improvements 5 - 40 years Leasehold improvements 5 - 20 years (or term or lease, if shorter) Fixtures and equipment 5 - 10 years Data processing and software 3 - 7 years Repairs and maintenance costs are charged to non-interest expense as incurred. Premises and equipment being actively marketed for sale are reclassified as assets held for disposition. The cost and accumulated depreciation relating to premises and equipment retired or otherwise disposed of are eliminated, and any resulting losses are charged to non-interest expense. See Note 6: Premises and Equipment for further information. Goodwill Goodwill represents the excess purchase price of businesses acquired over the fair value of the identifiable net assets acquired and is assigned to specific reporting units. Goodwill is not subject to amortization but rather is evaluated for impairment annually, or more frequently in interim periods if events occur or circumstances change indicating it would more likely than not result in a reduction of the fair value of a reporting unit below its carrying value. Goodwill is evaluated for impairment by either performing a qualitative evaluation or a two-step quantitative test. The qualitative evaluation is an assessment of factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, including goodwill. The Company utilizes an equally weighted combined income and market approach to arrive at an indicated fair value range for the reporting unit. In Step 1, the fair value of a reporting unit is compared to its carrying amount, including goodwill, to ascertain if a goodwill impairment exists. If the fair value of the reporting unit exceeds its carrying amount, goodwill of the reporting unit is not considered impaired, and it is not necessary to continue to Step 2 of the impairment process. Otherwise, Step 2 is performed where the implied fair value of goodwill is compared to the carrying value of goodwill in the reporting unit. If a reporting unit's carrying value exceeds fair value, the difference is charged to non-interest expense. See Note 7: Goodwill and Other Intangible Assets for further information. Other Intangible Assets Other intangible assets represent purchased assets that lack physical substance but can be distinguished from goodwill because of contractual or other legal rights, or because the asset is capable of being sold or exchanged either separately or in combination with a related contract, asset, or liability. Other intangible assets with finite useful lives are amortized to non-interest expense over their estimated useful lives and are evaluated for impairment whenever events occur or circumstances change indicating the carrying amount of the asset may not be recoverable. Core deposit and customer relationship intangible assets are amortized over their estimated useful lives. See Note 7: Goodwill and Other Intangible Assets for further information. Cash Surrender Value of Life Insurance The investment in life insurance represents the cash surrender value of life insurance policies on certain current and former officers of Webster. Increases in the cash surrender value are recorded as non-interest income. Decreases are the result of collection on the policies due to the death of an insured. Death benefit proceeds in excess of cash surrender value are recorded in other non-interest income when realized. Securities Sold Under Agreements to Repurchase These agreements are accounted for as secured financing transactions since Webster maintains effective control over the transferred investment securities and the transfer meets the other criteria for such accounting. Obligations to repurchase the sold investment securities are reflected as a liability in the accompanying Consolidated Balance Sheets. The investment securities underlying the agreements are delivered to a custodial account for the benefit of the dealer or bank with whom each transaction is executed. The dealers or banks, which may sell, loan, or otherwise hypothecate such securities to other parties in the normal course of their operations, agree to resell to Webster the same securities at the maturity date of the agreements. The investment securities underlying the agreements with Bank customers are pledged; however, the customer does not have ability to hypothecate the underlying securities. See Note 10: Borrowings for further information. Share-Based Compensation Webster maintains stock compensation plans under which non-qualified stock options, incentive stock options, restricted stock, restricted stock units, or stock appreciation rights may be granted to employees and directors. Share awards are issued from available treasury shares. Share-based compensation cost is recognized over the vesting period, is based on the grant-date fair value, net of a reduction for estimated forfeitures which is adjusted for actual forfeitures as they occur, and is reported as a component of compensation and benefits expense. Awards are generally subject to a 3 -year vesting period, while certain conditions provide for a 1 -year vesting period. Excess tax benefits result when tax return deductions exceed recognized compensation cost determined using the grant-date fair value approach for financial statement purposes. For time-based restricted stock and restricted stock unit awards, fair value is measured using the Company's common stock closing price at the date of grant. For performance-based restricted stock awards, fair value is measured using the Monte Carlo valuation methodology, which provides for the 3 -year performance period. Awards ultimately vest in a range from zero to 150% of the target number of shares under the grant. 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. For stock option awards the Black-Scholes Option-Pricing Model was used to measure fair value at the date of grant. Dividends are paid on the time-based shares upon grant and are non-forfeitable, while dividends are accrued on the performance-based awards and paid on earned shares when the performance target is met. See Note 18: Share-Based Plans for further information. Income Taxes Income tax expense, or benefit, is comprised of two components, current and deferred. The current component reflects taxes payable or refundable for a current period based on applicable tax laws, and the deferred component represents the tax effects of temporary differences between amounts recognized for financial accounting and tax purposes. Deferred tax assets and liabilities reflect the tax effects of such differences that are anticipated to result in taxable or deductible amounts in the future, when the temporary differences reverse. DTAs are recognized if it is more likely than not they will be realized, and may be reduced by a valuation allowance if it is more likely than not that all or some portion will not be realized. Tax positions that are uncertain but meet a more likely than not recognition threshold are initially and subsequently measured as the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position meets the more likely than not recognition threshold considers the facts, circumstances, and information available at the reporting date and is subject to management's judgment. Webster recognizes interest expense and penalties on uncertain tax positions as a component of income tax expense and recognizes interest income on refundable income taxes as a component of other non-interest income. See Note 8: Income Taxes for further information. Earnings Per Common Share Earnings per common share is computed under the two-class method. Basic earnings per common share is computed by dividing earnings allocated to common shareholders by the weighted-average number of common shares outstanding during the applicable period, excluding outstanding non-participating securities. Certain non-vested restricted stock awards are participating securities as they have non-forfeitable rights to dividends or dividend equivalents. Diluted earnings per common share is computed using the weighted-average number of shares determined for the basic earnings per common share computation plus the dilutive effect of stock compensation and warrants for common stock using the treasury stock method. A reconciliation of the weighted-average shares used in calculating basic earnings per common share and the weighted-average common shares used in calculating diluted earnings per common share is provided in Note 14: Earnings Per Common Share . Comprehensive Income Comprehensive income includes all changes in shareholders’ equity during a period, except those resulting from transactions with shareholders. Comprehensive income consists of net income, and the after-tax effect of the following items; changes in net unrealized gain/loss on securities available for sale, changes in net unrealized gain/loss on derivative instruments, and changes in net actuarial gain/loss and prior service cost for defined benefit pension and other postretirement benefit plans. Comprehensive income is reported in the accompanying Consolidated Statements of Shareholders' Equity, Consolidated Statements of Comprehensive Income, and Note 12: Accumulated Other Comprehensive Loss, Net of Tax . Derivative Instruments and Hedging Activities Derivatives are recognize

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2017
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 December 31, 2017 2016 (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 $ 1,247 $ — $ — $ 1,247 $ 734 $ — $ — $ 734 Agency CMO 308,989 1,158 (3,814 ) 306,333 419,865 3,344 (3,503 ) 419,706 Agency MBS 1,124,960 2,151 (19,270 ) 1,107,841 969,460 4,398 (19,509 ) 954,349 Agency CMBS 608,276 — (20,250 ) 588,026 587,776 63 (14,567 ) 573,272 CMBS 358,984 2,157 (74 ) 361,067 473,974 4,093 (702 ) 477,365 CLO 209,075 910 (134 ) 209,851 425,083 2,826 (519 ) 427,390 Single issuer-trust preferred 7,096 — (46 ) 7,050 30,381 — (1,748 ) 28,633 Corporate debt 56,504 797 (679 ) 56,622 108,490 1,502 (350 ) 109,642 Total available-for-sale $ 2,675,131 $ 7,173 $ (44,267 ) $ 2,638,037 $ 3,015,763 $ 16,226 $ (40,898 ) $ 2,991,091 Held-to-maturity: Agency CMO $ 260,114 $ 664 $ (4,824 ) $ 255,954 $ 339,455 $ 1,977 $ (3,824 ) $ 337,608 Agency MBS 2,569,735 16,989 (37,442 ) 2,549,282 2,317,449 26,388 (41,768 ) 2,302,069 Agency CMBS 696,566 — (10,011 ) 686,555 547,726 694 (1,348 ) 547,072 Municipal bonds and notes 711,381 8,584 (6,558 ) 713,407 655,813 4,389 (25,749 ) 634,453 CMBS 249,273 2,175 (620 ) 250,828 298,538 4,107 (411 ) 302,234 Private Label MBS 323 1 — 324 1,677 12 — 1,689 Total held-to-maturity $ 4,487,392 $ 28,413 $ (59,455 ) $ 4,456,350 $ 4,160,658 $ 37,567 $ (73,100 ) $ 4,125,125 Other-Than-Temporary Impairment The balance of OTTI, included in the amortized cost columns above, is related to certain CLO positions that were previously considered Covered Funds as defined by Section 619 of the Dodd-Frank Act commonly known as the Volcker Rule. The Company has taken measures to bring its CLO positions into conformance with the Volcker Rule. To the extent that changes occur in interest rates, credit movements, and other factors that impact fair value and expected recovery of amortized cost of its investment securities, the Company may be required to recognize OTTI in earnings, in future periods. The following table presents the changes in OTTI: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 3,243 $ 3,288 $ 3,696 Reduction for securities sold or called (2,005 ) (194 ) (518 ) Additions for OTTI not previously recognized 126 149 110 Ending balance $ 1,364 $ 3,243 $ 3,288 Fair Value and Unrealized Losses The following tables provide information on fair value and unrealized losses for the individual securities with an unrealized loss, aggregated by investment security type and length of time that the individual securities have been in a continuous unrealized loss position: At December 31, 2017 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 81,001 $ (449 ) $ 119,104 $ (3,365 ) 27 $ 200,105 $ (3,814 ) Agency MBS 416,995 (2,920 ) 606,021 (16,350 ) 135 1,023,016 (19,270 ) Agency CMBS 54,182 (851 ) 533,844 (19,399 ) 36 588,026 (20,250 ) CMBS 23,869 (74 ) — — 6 23,869 (74 ) CLO 56,335 (134 ) — — 3 56,335 (134 ) Single issuer-trust preferred 7,050 (46 ) — — 1 7,050 (46 ) Corporate debt 11,082 (395 ) 6,265 (284 ) 4 17,347 (679 ) Total 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 ) Total held-to-maturity in an unrealized loss position $ 1,536,069 $ (13,687 ) $ 1,655,375 $ (45,768 ) 388 $ 3,191,444 $ (59,455 ) At December 31, 2016 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 107,853 $ (2,168 ) $ 67,351 $ (1,335 ) 15 $ 175,204 $ (3,503 ) Agency MBS 512,075 (10,503 ) 252,779 (9,006 ) 97 764,854 (19,509 ) Agency CMBS 554,246 (14,567 ) — — 32 554,246 (14,567 ) CMBS 12,427 (24 ) 63,930 (678 ) 12 76,357 (702 ) CLO 49,946 (54 ) 50,237 (465 ) 5 100,183 (519 ) Single issuer-trust preferred — — 28,633 (1,748 ) 5 28,633 (1,748 ) Corporate debt — — 7,384 (350 ) 2 7,384 (350 ) Total available-for-sale in an unrealized loss position $ 1,236,547 $ (27,316 ) $ 470,314 $ (13,582 ) 168 $ 1,706,861 $ (40,898 ) Held-to-maturity: Agency CMO $ 163,439 $ (3,339 ) $ 17,254 $ (485 ) 16 $ 180,693 $ (3,824 ) Agency MBS 1,394,623 (32,942 ) 273,779 (8,826 ) 150 1,668,402 (41,768 ) Agency CMBS 347,725 (1,348 ) — — 25 347,725 (1,348 ) Municipal bonds and notes 384,795 (25,745 ) 1,192 (4 ) 196 385,987 (25,749 ) CMBS 60,768 (411 ) — — 8 60,768 (411 ) Total held-to-maturity in an unrealized loss position $ 2,351,350 $ (63,785 ) $ 292,225 $ (9,315 ) 395 $ 2,643,575 $ (73,100 ) Impairment Analysis The following impairment analysis by investment security type, summarizes the basis for evaluating if investment securities within the Company’s available-for-sale and held-to-maturity portfolios have been impacted by OTTI. Unless otherwise noted for an investment security type, management does not intend to sell these investments and has determined, based upon available evidence, that it is more likely than not that the Company will not be required to sell these securities before the recovery of their amortized cost. As such, based on the following impairment analysis, the Company does not consider these securities, in unrealized loss positions, to be other-than-temporarily impaired at December 31, 2017 . Available-for-Sale Securities Agency CMO. There were unrealized losses of $3.8 million on the Company’s investment in Agency CMO at December 31, 2017 , compared to $3.5 million at December 31, 2016 . Unrealized losses increased slightly due to higher market rates while principal balances decreased for this asset class since December 31, 2016 . 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 $19.3 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at December 31, 2017 , compared to $19.5 million at December 31, 2016 . Unrealized losses decreased slightly due to paydowns and purchase activity, while principal balances increased for this asset class since December 31, 2016 . These investments are issued by a government or government sponsored agency and therefore, are backed by certain government guarantees, either direct or implicit. There has been no change in the credit quality, and the contractual cash flows are performing as expected. Agency CMBS. There were unrealized losses of $20.3 million on the Company's investment in commercial mortgage-backed securities issued by government agencies at December 31, 2017 , compared to $14.6 million at December 31, 2016 . Unrealized losses increased due to higher market rates while principal balances increased for this asset class since December 31, 2016 . 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 $74 thousand on the Company’s investment in CMBS at December 31, 2017 , compared to $702 thousand at December 31, 2016 . The portfolio of mainly floating rate CMBS experienced reduced market spreads which resulted in higher market prices and smaller unrealized losses at December 31, 2017 compared to December 31, 2016 . 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 $134 thousand on the Company’s investments in CLO at December 31, 2017 compared to $519 thousand unrealized losses at December 31, 2016 . Unrealized losses decreased due to reduced market spreads while principal balances decreased since December 31, 2016 . Internal stress tests are performed on individual bonds to monitor potential losses under stress scenarios. Contractual cash flows for the bonds continue to perform as expected. Single issuer-trust preferred. There were unrealized losses of $46 thousand on the Company's investment in single issuer-trust preferred at December 31, 2017 , compared to $1.7 million at December 31, 2016 . Unrealized losses decreased due to lower principal balances for this asset class as a conversion feature for two securities was exercised by the issuer resulting in the reclassification of those securities into corporate debt. Single issuer-trust preferred consists of one investment issued by a large capitalization money center financial institution, which continues to service its debt. The Company performs periodic credit reviews of the issuer to assess the likelihood for ultimate recovery of amortized cost. Corporate debt. There were $679 thousand unrealized losses on the Company's corporate debt portfolio at December 31, 2017 , compared to $350 thousand at December 31, 2016 . Unrealized losses increased as reclassified security balances with unrealized losses exceeded maturing corporate debt balances since December 31, 2016 . The Company performs periodic credit reviews of the issuer to assess the likelihood for ultimate recovery of amortized cost. Held-to-Maturity Securities Agency CMO. There were unrealized losses of $4.8 million on the Company’s investment in Agency CMO at December 31, 2017 , compared to $3.8 million at December 31, 2016 . Unrealized losses increased due to higher market rates while principal balances decreased since December 31, 2016 . 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 $37.4 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at December 31, 2017 , compared to $41.8 million at December 31, 2016 . Unrealized losses decreased due to paydowns and purchase activity while principal balances increased for this asset class since December 31, 2016 . 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 $10.0 million on the Company’s investment in commercial mortgage-backed securities issued by government agencies at December 31, 2017 , compared to $1.3 million at December 31, 2016 . Unrealized losses increased due to higher market rates while principal balances increased since December 31, 2016 . 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 $6.6 million on the Company’s investment in municipal bonds and notes at December 31, 2017 , compared to $25.7 million at December 31, 2016 . Unrealized losses decreased due to lower market spreads while principal balances increased since December 31, 2016 . The Company performs periodic credit reviews of the issuers and the securities are currently performing as expected. CMBS. There were unrealized losses of $620 thousand on the Company’s investment in CMBS at December 31, 2017 , compared to $411 thousand unrealized losses at December 31, 2016 . Unrealized losses increased due to higher market rates on mainly seasoned fixed rate conduit transactions while principal balances decreased since December 31, 2016 . Internal stress tests are performed on individual bonds to monitor potential losses under stress scenarios. Sales of Available-for Sale Securities The following table provides information on sales of available-for-sale securities: Years ended December 31, (In thousands) 2017 2016 2015 Proceeds from sales (1) $ — $ 259,273 $ 95,101 Gross realized gains on sales $ — $ 2,891 $ 1,029 Less: Gross realized losses on sales — 2,477 420 Gain on sale of investment securities, net $ — $ 414 $ 609 (1) There were no sales during the year ended December 31, 2017 . Contractual Maturities The amortized cost and fair value of debt securities by contractual maturity, including called securities, are set forth below: At December 31, 2017 Available-for-Sale Held-to-Maturity (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 1,247 $ 1,247 $ 33,654 $ 34,145 Due after one year through five years 40,066 40,447 3,839 3,857 Due after five through ten years 332,558 333,931 37,870 38,450 Due after ten years 2,301,260 2,262,412 4,412,029 4,379,898 Total debt securities $ 2,675,131 $ 2,638,037 $ 4,487,392 $ 4,456,350 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 December 31, 2017 , the Company had a carrying value of $1.2 billion in callable 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 do not reflect actual duration which are impacted by prepayments. Investment securities with a carrying value totaling $2.4 billion at December 31, 2017 and $2.5 billion at December 31, 2016

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	The Company has an investment interest in several entities that meet the definition of a VIE. The following discussion provides information about the Company's VIEs. 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 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 Consolidated Statements of Income. Refer to Note 16: Fair Value Measurements for additional information. Non-Consolidated Securitized Investments. The Company, through normal investment activities, makes passive investments in securities issued by VIEs for which Webster is not the manager. The investment securities consist of Agency CMO, Agency MBS, Agency CMBS, CLO, and single issuer-trust preferred. The Company has not provided financial or other support with respect to these investment securities other than its original investment. For these investment securities, the Company determined it is not the primary beneficiary due to the relative size of its investment in comparison to the principal amount of the structured securities issued by the VIEs, the level of credit subordination which reduces the Company’s obligation to absorb losses or right to receive benefits and its inability to direct the activities that most significantly impact the economic performance of the VIEs. The Company’s maximum exposure to loss is limited to the amount of its investment in the VIEs. Refer to 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 December 31, 2017 and December 31, 2016 , the aggregate carrying value of the Company's tax credit-finance investments were $33.5 million and $22.8 million , respectively, which represents the Company's maximum exposure to loss. At December 31, 2017 and December 31, 2016 , unfunded commitments have been recognized, totaling $17.3 million and $14.0 million , respectively, and are included in accrued expenses and other liabilities in the accompanying 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 and therefore, is not consolidated. 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 Consolidated Balance Sheets, and the related interest expense is reported as interest expense on long-term debt in the accompanying Consolidated Statements of Income. Other Investments. The Company invests in various alternative investments in which it holds a variable interest. Alternative investments are non-public entities which cannot be redeemed since the Company’s investment is distributed as the underlying equity is liquidated. For these investments, the Company has determined it is not the primary beneficiary due to its inability to direct the activities that most significantly impact the economic performance of the VIEs. At December 31, 2017 and December 31, 2016 , the aggregate carrying value of the Company's other investments in VIEs was $13.8 million and $12.3 million , respectively, and the maximum exposure to loss of the Company's other investments in VIEs, including unfunded commitments, was $22.9 million and $19.9 million , respectively. Refer to Note 16: Fair Value Measurements for additional information.

Loans and Leases

Loans and Leases	12 Months Ended
	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	Loans and Leases The following table summarizes loans and leases: At December 31, (In thousands) 2017 2016 Residential $ 4,490,878 $ 4,254,682 Consumer 2,590,225 2,684,500 Commercial 5,368,694 4,940,931 Commercial Real Estate 4,523,828 4,510,846 Equipment Financing 550,233 635,629 Loans and leases (1) (2) $ 17,523,858 $ 17,026,588 (1) Loans and leases include net deferred fees and net premiums and discounts of $20.6 million and $17.3 million at December 31, 2017 and December 31, 2016 , respectively. (2) At December 31, 2017 , the Company had pledged $6.7 billion of eligible loans as collateral to support borrowing capacity at the FHLB of Boston and the FRB of Boston. Loans and Leases Portfolio Aging The following tables summarize the aging of loans and leases: At December 31, 2017 (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 and Leases 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 At December 31, 2016 (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 and Leases Residential $ 8,631 $ 2,609 $ — $ 47,279 $ 58,519 $ 4,196,163 $ 4,254,682 Consumer: Home equity 8,831 5,782 — 35,926 50,539 2,359,354 2,409,893 Other consumer 2,233 1,485 — 1,663 5,381 269,226 274,607 Commercial: Commercial non-mortgage 1,382 577 749 38,190 40,898 4,094,727 4,135,625 Asset-based — — — — — 805,306 805,306 Commercial real estate: Commercial real estate 6,357 1,816 — 9,871 18,044 4,117,742 4,135,786 Commercial construction — — — 662 662 374,398 375,060 Equipment financing 903 693 — 225 1,821 633,808 635,629 Total $ 28,337 $ 12,962 $ 749 $ 133,816 $ 175,864 $ 16,850,724 $ 17,026,588 Interest on non-accrual loans and leases that would have been recorded as additional interest income for the years ended December 31, 2017 , 2016 , and 2015 , had the loans and leases been current in accordance with their original terms, totaled $8.4 million , $11.0 million , and $8.2 million , 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 ALLL: At or for the Year ended December 31, 2017 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total Allowance for loan and lease losses: Balance at January 1, 2017 $ 23,226 $ 45,233 $ 71,905 $ 47,477 $ 6,479 $ 194,320 Provision (benefit) charged to expense (2,692 ) 9,367 23,417 11,040 (232 ) 40,900 Losses charged off (2,500 ) (24,447 ) (8,147 ) (9,275 ) (558 ) (44,927 ) Recoveries 1,024 6,037 2,358 165 117 9,701 Balance at December 31, 2017 $ 19,058 $ 36,190 $ 89,533 $ 49,407 $ 5,806 $ 199,994 Individually evaluated for impairment $ 4,805 $ 1,668 $ 9,786 $ 272 $ 23 $ 16,554 Collectively evaluated for impairment $ 14,253 $ 34,522 $ 79,747 $ 49,135 $ 5,783 $ 183,440 Loan and lease balances: Individually evaluated for impairment $ 114,295 $ 45,436 $ 72,471 $ 11,226 $ 3,325 $ 246,753 Collectively evaluated for impairment 4,376,583 2,544,789 5,296,223 4,512,602 546,908 17,277,105 Loans and leases $ 4,490,878 $ 2,590,225 $ 5,368,694 $ 4,523,828 $ 550,233 $ 17,523,858 At or for the Year ended December 31, 2016 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total Allowance for loan and lease losses: Balance at January 1, 2016 $ 25,876 $ 42,052 $ 59,977 $ 41,598 $ 5,487 $ 174,990 Provision (benefit) charged to expense 230 18,507 28,662 7,930 1,021 56,350 Losses charged off (4,636 ) (20,669 ) (18,360 ) (2,682 ) (565 ) (46,912 ) Recoveries 1,756 5,343 1,626 631 536 9,892 Balance at December 31, 2016 $ 23,226 $ 45,233 $ 71,905 $ 47,477 $ 6,479 $ 194,320 Individually evaluated for impairment $ 8,090 $ 2,903 $ 7,422 $ 169 $ 9 $ 18,593 Collectively evaluated for impairment $ 15,136 $ 42,330 $ 64,483 $ 47,308 $ 6,470 $ 175,727 Loan and lease balances: Individually evaluated for impairment $ 119,424 $ 45,719 $ 53,037 $ 24,755 $ 6,420 $ 249,355 Collectively evaluated for impairment 4,135,258 2,638,781 4,887,894 4,486,091 629,209 16,777,233 Loans and leases $ 4,254,682 $ 2,684,500 $ 4,940,931 $ 4,510,846 $ 635,629 $ 17,026,588 At or for the Year ended December 31, 2015 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total Allowance for loan and lease losses: Balance at January 1, 2015 $ 25,452 $ 43,518 $ 47,068 $ 37,148 $ 6,078 $ 159,264 Provision (benefit) charged to expense 6,057 11,847 21,693 11,381 (1,678 ) 49,300 Losses charged off (6,508 ) (17,679 ) (11,522 ) (7,578 ) (273 ) (43,560 ) Recoveries 875 4,366 2,738 647 1,360 9,986 Balance at December 31, 2015 $ 25,876 $ 42,052 $ 59,977 $ 41,598 $ 5,487 $ 174,990 Individually evaluated for impairment $ 10,364 $ 3,477 $ 5,197 $ 3,163 $ 3 $ 22,204 Collectively evaluated for impairment $ 15,512 $ 38,575 $ 54,780 $ 38,435 $ 5,484 $ 152,786 Loan and lease balances: Individually evaluated for impairment $ 134,448 $ 48,425 $ 56,581 $ 39,295 $ 422 $ 279,171 Collectively evaluated for impairment 3,926,553 2,654,135 4,259,418 3,952,354 600,104 15,392,564 Loans and leases $ 4,061,001 $ 2,702,560 $ 4,315,999 $ 3,991,649 $ 600,526 $ 15,671,735 Impaired Loans and Leases The following tables summarize impaired loans and leases: At December 31, 2017 (In thousands) Unpaid Principal Balance Total Recorded Investment Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential: 1-4 family $ 125,352 $ 114,295 $ 69,759 $ 44,536 $ 4,805 Consumer home equity 50,809 45,436 34,418 11,018 1,668 Commercial: Commercial non-mortgage 79,900 71,882 27,313 44,569 9,786 Asset-based 3,272 589 589 — — Commercial real estate: Commercial real estate 11,994 11,226 6,387 4,839 272 Commercial construction — — — — — Equipment financing 3,409 3,325 2,932 393 23 Total $ 274,736 $ 246,753 $ 141,398 $ 105,355 $ 16,554 At December 31, 2016 (In thousands) Unpaid Principal Balance Total Recorded Investment Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential: 1-4 family $ 131,468 $ 119,424 $ 21,068 $ 98,356 $ 8,090 Consumer home equity 52,432 45,719 22,746 22,973 2,903 Commercial: Commercial non-mortgage 57,732 53,037 26,006 27,031 7,422 Asset based — — — — — Commercial real estate: Commercial real estate 24,146 23,568 19,591 3,977 169 Commercial construction 1,188 1,187 1,187 — — Equipment financing 6,398 6,420 6,197 223 9 Total $ 273,364 $ 249,355 $ 96,795 $ 152,560 $ 18,593 The following table summarizes the average recorded investment and interest income recognized for impaired loans and leases: Years ended December 31, 2017 2016 2015 (In thousands) Average Recorded Investment Accrued Interest Income Cash Basis Interest Income Average Recorded Investment Accrued Interest Income Cash Basis Interest Income Average Accrued Cash Basis Interest Income Residential $ 116,859 $ 4,138 $ 1,264 $ 126,936 $ 4,377 $ 1,200 $ 138,215 $ 4,473 $ 1,139 Consumer home equity 45,578 1,323 1,046 47,072 1,361 985 49,337 1,451 1,099 Commercial Commercial non-mortgage 62,459 1,095 — 54,708 1,540 — 46,379 1,319 — Asset based 295 — — — — — — — — Commercial real estate: Commercial real estate 17,397 417 — 28,451 511 — 64,495 1,165 — Commercial construction 594 12 — 3,574 92 — 6,062 133 — Equipment financing 4,872 207 — 3,421 184 — 527 16 — Total $ 248,054 $ 7,192 $ 2,310 $ 264,162 $ 8,065 $ 2,185 $ 305,015 $ 8,557 $ 2,238 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 PD and the 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 loss. 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 borrowers’ 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 At December 31, At December 31, At December 31, (In thousands) 2017 2016 2017 2016 2017 2016 (1) - (6) Pass $ 5,048,162 $ 4,655,007 $ 4,355,916 $ 4,357,458 $ 525,105 $ 618,084 (7) Special Mention 104,594 56,240 62,065 69,023 8,022 1,324 (8) Substandard 206,883 226,603 105,847 84,365 17,106 16,221 (9) Doubtful 9,055 3,081 — — — — Total $ 5,368,694 $ 4,940,931 $ 4,523,828 $ 4,510,846 $ 550,233 $ 635,629 For residential and consumer loans, the Company considers factors such as past due status, updated FICO scores, employment status, collateral, geography, loans discharged in bankruptcy, and the status of first lien position loans on second lien position loans as credit quality indicators. 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 TDRs: At December 31, (Dollars in thousands) 2017 2016 Accrual status $ 147,113 $ 147,809 Non-accrual status 74,291 75,719 Total recorded investment of TDR (1) $ 221,404 $ 223,528 Specific reserves for TDR included in the balance of ALLL $ 12,384 $ 14,583 Additional funds committed to borrowers in TDR status 2,736 459 (1) Total recorded investment of TDRs exclude $0.1 million and $0.7 million at December 31, 2017 and December 31, 2016 , respectively, of accrued interest receivable. For years ended December 31, 2017 , 2016 and 2015 , Webster charged off $3.2 million , $18.6 million , and $11.8 million , respectively, for the portion of TDRs deemed to be uncollectible. The following table provides information on the type of concession for loans and leases modified as TDRs: Years ended December 31, 2017 2016 2015 Number of Loans and Leases Post- Modification Recorded Investment (1) Number of Loans and Leases Post- Modification Recorded Investment (1) Number of Loans and Leases Post- Modification Recorded Investment (1) (Dollars in thousands) Residential: Extended Maturity 16 $ 2,569 17 $ 2,801 27 $ 4,909 Adjusted Interest rates 2 335 2 528 3 573 Combination Rate and Maturity 12 1,733 13 1,537 26 5,315 Other (2) 39 6,200 24 4,090 30 4,366 Consumer home equity: Extended Maturity 12 976 11 484 12 1,012 Adjusted Interest rates 1 247 — — — — Combination Rate and Maturity 14 3,469 15 1,156 12 945 Other (2) 73 4,907 52 3,131 68 3,646 Commercial non mortgage: Extended Maturity 12 1,233 12 14,883 3 254 Adjusted Interest rates — — — — 1 24 Combination Rate and Maturity 18 9,592 2 648 7 5,361 Other (2) 4 6,375 13 1,767 20 22,048 Commercial real estate: Extended Maturity — — 3 4,921 1 315 Adjusted Interest rates — — 1 237 — — Combination Rate and Maturity — — 2 335 1 42 Other (2) — — 1 509 1 405 Equipment Financing Extended Maturity — — 7 6,642 — — Total 203 $ 37,636 175 $ 43,669 212 $ 49,215 (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, and/or other concessions. The were no significant amounts of loans and leases modified as TDRs within the previous 12 months and for which there was a payment default for the years ended December 31, 2017 , 2016 and 2015 . The recorded investment of TDRs in commercial, commercial real estate, and equipment financing segregated by risk rating exposure is as follows: At December 31, (In thousands) 2017 2016 (1) - (6) Pass $ 8,268 $ 10,210 (7) Special Mention 355 7 (8) Substandard 53,050 45,509 (9) Doubtful — 2,738 Total $ 61,673 $ 58,464

Transfers of Financial Assets

Transfers of Financial Assets	12 Months Ended
	Dec. 31, 2017
Transfers and Servicing [Abstract]
Transfers of Financial Assets	Transfers of Financial Assets Transfers of Financial Assets The Company sells financial assets in the normal course of business, primarily residential mortgage loans sold to government-sponsored enterprises through established programs and securitizations. The gain or loss on residential mortgage loans sold and the fair value adjustment to loans held for sale are included as mortgage banking activities in the accompanying 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 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 may also 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 Consolidated Statements of Income. The following table provides a summary of activity in the reserve for loan repurchases: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 790 $ 1,192 $ 1,059 Provision (benefit) charged to expense 100 (303 ) 133 Repurchased loans and settlements charged off (18 ) (99 ) — Ending balance $ 872 $ 790 $ 1,192 The following table provides information for mortgage banking activities: Years ended December 31, (In thousands) 2017 2016 2015 Residential mortgage loans held for sale: Proceeds from sale $ 335,656 $ 438,925 $ 452,590 Loans sold with servicing rights retained 304,788 399,318 416,277 Net gain on sale 6,211 11,629 7,795 Ancillary fees 2,629 3,532 — Fair value option adjustment 1,097 (526 ) — The Company has retained servicing rights on residential mortgage loans totaling $2.6 billion at both December 31, 2017 and 2016 . The following table presents the changes in carrying value for mortgage servicing assets: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 24,466 $ 20,698 $ 19,379 Additions 9,249 11,312 8,027 Amortization (8,576 ) (7,544 ) (6,708 ) Ending balance $ 25,139 $ 24,466 $ 20,698 Loan servicing fees, net of mortgage servicing rights amortization, were $0.8 million , $1.1 million , and $1.5 million , for the years ended December 31, 2017 , 2016 , and 2015 , respectively, and are included as a component of loan related fees in the accompanying Consolidated Statements of Income. See Note 16: 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, except as noted, for cash proceeds of $7.4 million for certain residential loans and for cash proceeds of $7.2 million for certain commercial loans for the year ended December 31, 2017 ; for cash proceeds of $26.5 million , resulting in a gain of $2.1 million , for certain commercial loans and for cash proceeds of $7.6 million for certain residential loans for the year ended December 31, 2016 ; and for cash proceeds of $0.7 million for certain commercial loans and for cash proceeds of $32.9 million for certain consumer loans for the year ended December 31, 2015

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment A summary of premises and equipment follows: At December 31, (In thousands) 2017 2016 Land $ 11,302 $ 12,595 Buildings and improvements 80,646 83,903 Leasehold improvements 82,067 83,971 Fixtures and equipment 76,665 76,146 Data processing and software 234,667 220,002 Total premises and equipment 485,347 476,617 Less: Accumulated depreciation and amortization (355,346 ) (339,204 ) Premises and equipment, net $ 130,001 $ 137,413 Depreciation and amortization of premises and equipment was $33.1 million , $30.8 million , and $28.4 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The following table provides a summary of activity for assets held for disposition: Years ended December 31, (In thousands) 2017 2016 Beginning balance $ 637 $ 637 Additions 2,006 — Write-downs (529 ) — Sales (1,970 ) — Ending balance $ 144 $ 637

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
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 December 31, 2017 2016 (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 $ 516,560 $ 516,560 HSA Bank 21,813 21,813 21,813 21,813 Total goodwill $ 538,373 $ 538,373 $ 538,373 $ 538,373 Other intangible assets: HSA Bank - Core deposit intangible assets $ 22,000 $ (8,610 ) $ 13,390 $ 22,000 $ (6,162 ) $ 15,838 HSA Bank - Customer relationships 21,000 (4,779 ) 16,221 21,000 (3,164 ) 17,836 Total other intangible assets $ 43,000 $ (13,389 ) $ 29,611 $ 43,000 $ (9,326 ) $ 33,674 As of December 31, 2017 , the remaining estimated aggregate future amortization expense for intangible assets is as follows: (In thousands) 2018 $ 3,847 2019 3,847 2020 3,847 2021 3,847 2022 3,847 Thereafter 10,376

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense reflects the following expense (benefit) components: Years ended December 31, (In thousands) 2017 2016 2015 Current: Federal $ 96,364 $ 73,194 $ 97,575 State and local 11,061 5,429 10,970 Total current 107,425 78,623 108,545 Deferred: Federal 39,568 12,542 (7,279 ) State and local (48,642 ) 5,158 (8,234 ) Total deferred (9,074 ) 17,700 (15,513 ) Total federal 135,932 85,736 90,296 Total state and local (37,581 ) 10,587 2,736 Income tax expense $ 98,351 $ 96,323 $ 93,032 The Company's deferred state and local benefit in 2017 includes $47.5 million related to a reduction in its beginning-of-year valuation allowance for SALT DTA's, or $37.5 million net of deferred federal expense of $10.0 million . The deferred state and local benefit in 2017 also includes $1.8 million from other SALT DTA adjustments, net of federal effects. The Company's deferred federal expense in 2017 also includes $31.5 million from a re-measurement of its DTA upon the enactment of the Tax Act. Due to a $10.6 million impact of the Tax Act on the $39.3 million of net SALT DTA adjustments noted above, the Company reported a $20.9 million expense attributable to the Tax Act, and a $28.7 million net benefit from SALT DTAs, for a net benefit of $7.8 million in its results for the quarter ended December 31, 2017. Included in the Company's income tax expense for the years ended December 31, 2017 , 2016 , and 2015 , are benefits of operating loss carryforwards of $25.1 million , none , and $3.0 million , and net tax credits of $1.6 million , $1.0 million , and $2.1 million , respectively, exclusive of Tax Act impacts. The following table reflects a reconciliation of reported income tax expense to the amount that would result from applying the federal statutory rate of 35.0% : Years ended December 31, 2017 2016 2015 (Dollars in thousands) Amount Percent Amount Percent Amount Percent Income tax expense at federal statutory rate $ 123,826 35.0 % $ 106,208 35.0 % $ 104,217 35.0 % Reconciliation to reported income tax expense: SALT expense, net of federal 8,189 2.3 6,882 2.3 7,563 2.5 Tax-exempt interest income, net (10,826 ) (3.1 ) (8,917 ) (2.9 ) (7,117 ) (2.4 ) SALT DTA adjustments, net of federal (28,724 ) (8.1 ) — — (5,785 ) (1.9 ) Tax Act impacts, net 20,891 5.9 — — — — Excess tax benefits, net (6,349 ) (1.8 ) — — — — Increase in cash surrender value of life insurance (5,120 ) (1.4 ) (5,166 ) (1.7 ) (4,557 ) (1.5 ) Other, net (3,536 ) (1.0 ) (2,684 ) (1.0 ) (1,289 ) (0.5 ) Income tax expense and effective tax rate $ 98,351 27.8 % $ 96,323 31.7 % $ 93,032 31.2 % The following table reflects the significant components of the DTAs, net: At December 31, (In thousands) 2017 2016 Deferred tax assets: Allowance for loan and lease losses $ 51,203 $ 77,908 Net operating loss and credit carry forwards 71,813 64,644 Compensation and employee benefit plans 25,023 46,433 Net losses on derivative instruments 3,767 8,624 Net unrealized loss on securities available for sale 9,548 9,898 Other 12,273 17,682 Gross deferred tax assets 173,627 225,189 Valuation allowance (38,292 ) (71,474 ) Total deferred tax assets, net of valuation allowance $ 135,335 $ 153,715 Deferred tax liabilities: Equipment-financing leases $ 27,955 $ 41,910 Deferred income on repurchase of debt 1,275 4,251 Intangible assets 6,164 9,952 Mortgage servicing assets 4,445 7,313 Other 2,866 5,898 Gross deferred tax liabilities 42,705 69,324 Deferred tax assets, net $ 92,630 $ 84,391 The Company's DTA, net increased by $8.2 million during 2017 , reflecting primarily the $9.1 million deferred tax benefit and a $0.7 million expense allocated directly to shareholders equity. The $38.3 million valuation allowance at December 31, 2017 consisted of $38.2 million attributable to SALT net operating loss carryforwards and $0.1 million to a capital loss carryforward. The $33.2 million net decrease in the valuation allowance includes: (i) a $27.0 million reduction in the beginning-of-year valuation allowance applicable to a change in the estimated realizability of SALT DTAs in future years, (ii) a $3.5 million decrease applicable to the estimated utilization and expiration of capital loss carryforwards of $2.1 million and $1.4 million , respectively, and (iii) a $2.7 million net decrease in SALT net DTAs, including Tax Act-related impacts. The reduction in the Company's valuation allowance for SALT DTAs noted above resulted from the completion of a review of its current and projected multi-jurisdictional SALT structure reflecting Webster's continued business expansion and growth. In connection with the review, an evaluation of the Company's net SALT DTAs, including valuation allowances previously established for DTAs not expected to be realized, was performed and a change in their estimated realizability was recognized. Management believes it is more likely than not that the results of future operations will generate sufficient taxable income to realize its total DTA, net of the valuation allowance. Although taxable income in prior years is no longer able to be included as a source of taxable income, due to the general repeal of the carryback of net operating losses under the Tax Act, significant positive evidence remains in support of management's conclusion regarding the realizability of Webster's DTAs, including projected future reversals of existing taxable temporary differences and book-taxable income levels in recent and projected future years. There can, however, be no assurance that any specific level of future income will be generated or that the Company’s DTAs will ultimately be realized. A capital loss carryforward of $1.1 million exists at December 31, 2017 and is scheduled to expire in 2018. A valuation allowance of $0.1 million has been established for the $0.4 million portion of the carryforward scheduled to expire. SALT net operating loss carryforwards approximating $1.2 billion at December 31, 2017 are scheduled to expire in varying amounts during tax years 2023 through 2032, and credits, totaling $0.8 million at December 31, 2017 , have a five-year carryover period, with excess credits subject to expiration annually. A valuation allowance of $38.2 million has been established for approximately $644 million of those net operating loss carryforwards estimated to expire. A deferred tax liability of $14.9 million has not been recognized for certain thrift bad-debt reserves, established before 1988, that would become taxable upon the occurrence of certain events: distributions by Webster Bank in excess of certain earnings and profits; the redemption of Webster Bank’s stock; or liquidation. Webster does not expect any of those events to occur. At December 31, 2017 the cumulative taxable temporary differences applicable to those reserves approximated $58.0 million . The following table reflects a reconciliation of the beginning and ending balances of unrecognized tax benefits (UTBs): Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 3,847 $ 5,094 $ 4,593 Additions as a result of tax positions taken during the current year 584 613 865 Additions as a result of tax positions taken during prior years 7 — 1,254 Reductions as a result of tax positions taken during prior years (61 ) (625 ) (247 ) Reductions relating to settlements with taxing authorities (392 ) (693 ) (992 ) Reductions as a result of lapse of statute of limitation periods (390 ) (542 ) (379 ) Ending balance $ 3,595 $ 3,847 $ 5,094 At December 31, 2017 , 2016 , and 2015 , there are $2.8 million , $2.5 million , and $3.3 million , respectively, of UTBs that, if recognized, would affect the effective tax rate. Webster recognizes interest and penalties related to UTBs, where applicable, in income tax expense. During the years ended December 31, 2017 , 2016 , and 2015 , Webster recognized an expense of $0.2 million , a benefit of $0.2 million , and an expense of $1.1 million , respectively. At December 31, 2017 and 2016 , the Company had accrued interest and penalties related to UTBs of $1.9 million and $1.7 million , respectively. Webster has determined it is reasonably possible that its total UTBs could decrease by an amount in the range of $0.6 million to $1.8 million by the end of 2018, primarily as a result of potential settlements with state and local taxing authorities concerning apportionment and tax-base determinations and/or potential lapses in statute-of-limitation periods.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Deposits	Deposits A summary of deposits by type follows: At December 31, (In thousands) 2017 2016 Non-interest-bearing: Demand $ 4,191,496 $ 4,021,061 Interest-bearing: Checking 2,736,952 2,528,274 Health savings accounts 5,038,681 4,362,503 Money market 2,209,492 2,047,121 Savings 4,348,700 4,320,090 Time deposits 2,468,408 2,024,808 Total interest-bearing 16,802,233 15,282,796 Total deposits $ 20,993,729 $ 19,303,857 Time deposits and interest-bearing checking, included in above balances, obtained through brokers $ 898,157 $ 848,618 Time deposits, included in above balance, that meet or exceed the FDIC limit 561,512 490,721 Demand deposit overdrafts reclassified as loan balances 2,210 1,885 The scheduled maturities of time deposits are as follows: (In thousands) At December 31, 2017 2018 $ 1,381,899 2019 693,554 2020 236,955 2021 106,042 2022 49,831 Thereafter 127 Total time deposits $ 2,468,408

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowings	Borrowings Total borrowings of $2.5 billion at December 31, 2017 and $4.0 billion at December 31, 2016 , are described in detail below. The following table summarizes securities sold under agreements to repurchase and other borrowings: At December 31, (In thousands) 2017 2016 Total Outstanding Rate Total Outstanding Rate Securities sold under agreements to repurchase: Original maturity of one year or less $ 288,269 0.17 $ 340,526 0.16 Original maturity of greater than one year, non-callable 300,000 3.10 400,000 3.09 Total securities sold under agreements to repurchase 588,269 1.66 740,526 1.82 Fed funds purchased 55,000 1.37 209,000 0.46 Securities sold under agreements to repurchase and other borrowings $ 643,269 1.64 $ 949,526 1.53 Repurchase agreements are used as a source of borrowed funds and are collateralized by U.S. Government agency mortgage-backed securities which are delivered to broker/dealers. Repurchase agreements counterparties are limited to primary dealers in government securities and commercial/municipal customers through Webster’s Treasury Unit. Dealer counterparties have the right to pledge, transfer, or hypothecate purchased securities during the term of the transaction. The Company has right of offset with respect to all repurchase agreement assets and liabilities. Total securities sold under agreements to repurchase represents the gross amount for these transactions, as only liabilities are outstanding for the periods presented. The following table provides information for FHLB advances: At December 31, 2017 2016 (Dollars in thousands) Total Outstanding Weighted- Average Contractual Coupon Rate Total Outstanding Weighted- Average Contractual Coupon Rate Maturing within 1 year $ 1,150,000 1.48 % $ 2,130,500 0.71 % After 1 but within 2 years 103,026 1.81 200,000 1.36 After 2 but within 3 years 215,000 1.73 128,026 1.73 After 3 but within 4 years 200,000 4.13 175,000 1.77 After 4 but within 5 years 170 — 200,000 1.81 After 5 years 8,909 1.96 9,370 2.59 1,677,105 1.85 2,842,896 0.95 Premiums on advances — 12 Federal Home Loan Bank advances $ 1,677,105 $ 2,842,908 Aggregate carrying value of assets pledged as collateral $ 6,402,066 $ 5,967,318 Remaining borrowing capacity $ 2,600,624 $ 1,192,758 Webster Bank was 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: At December 31, (Dollars in thousands) 2017 2016 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 (727 ) (845 ) Debt issuance cost on senior fixed-rate notes (826 ) (961 ) Long-term debt $ 225,767 $ 225,514 (1) The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month LIBOR plus 2.95% , was 4.55% at December 31, 2017 and 3.94% at December 31, 2016

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity Share activity during the year ended December 31, 2017 is as follows: Preferred Stock Series E Preferred Stock Series F Common Stock Issued Treasury Stock Held Common Stock Outstanding Balance at January 1, 2017 5,060 — 93,651,601 1,899,502 91,752,099 Restricted share activity — — — (124,800 ) 124,800 Stock options exercised — — — (338,176 ) 338,176 Common stock repurchased — — — 222,000 (222,000 ) Warrant exercise — — 28,690 — 28,690 Series F Preferred Stock issuance — 6,000 — — — Series E Preferred Stock redemption (5,060 ) — — — — Balance at December 31, 2017 — 6,000 93,680,291 1,658,526 92,021,765 Common Stock On October 24, 2017, Webster announced that its Board of Directors had authorized a $100 million common stock repurchase program under which shares may be repurchased from time to time in the open market or in privately negotiated transactions, subject to market conditions and other factors. This program is in addition to an existing common stock repurchase program authorized on December 6, 2012, under which $100 million had been authorized. Common stock repurchased during 2017 was acquired, at an average cost of $52.18 per common share, which results in a remaining repurchase authority for the common stock repurchase programs of $103.9 million at December 31, 2017 . On June 8, 2011, the U.S. Treasury closed an underwritten public offering of 3,282,276 warrants issued in connection with the Company’s participation in the Capital Purchase Program, each representing the right to purchase one share of Webster common stock, $0.01 par value per share. The warrants have an exercise price of $18.28 , and expire on November 21, 2018. Concurrent with the U.S. Treasury's action, the Board of Directors approved the repurchase of a significant number of warrants in a public auction conducted on behalf of the U.S. Treasury. The board approved plan provides for additional repurchases from time-to-time, as permitted by securities laws and other legal requirements. During 2017 , there were 44,275 warrants exercised in cashless exchange transactions leaving 8,752 warrants outstanding and exercisable at December 31, 2017 . Preferred Stock On December 15, 2017, Webster exercised its right to redeem all of the outstanding shares of 6.40% Series E Non-Cumulative Perpetual Preferred Stock, par value $0.01 per share, for the per share cash redemption price of $25,400 which includes the quarterly per share dividend amount that otherwise would have been paid on that date. On December 12, 2017, Webster closed on a public offering of 6,000,000 depository shares, each representing 1/1000th ownership interest in a share of Webster's 5.25% Series F Non-Cumulative Perpetual Preferred Stock, par value $0.01 per share, with a liquidation preference of $25,000 per share (equivalent to $25 per depository share) (the "Series F Preferred Stock"). Webster will pay dividends as declared by the Board of Directors or a duly authorized committee of the Board. Dividends are payable at a rate of 5.25% per annum, quarterly in arrears, on the fifteenth day of each March, June, September, and December. Dividends on the Series F Preferred Stock are not cumulative and are not mandatory. If for any reason the Board of Directors or a duly authorized committee of the Board does not declare a dividend on the Series F Preferred Stock for any dividend period, such dividend will not accrue or be payable, and Webster will have no obligation to pay dividends for such dividend period, whether or not dividends are declared for any future dividend periods. The terms of the Series F Preferred Stock prohibit the Company from declaring or paying any cash dividends on its common stock, unless Webster has declared and paid full dividends on the Series F Preferred Stock for the most recently completed dividend period.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss, Net of Tax	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive Loss, Net of Tax	Accumulated Other Comprehensive Loss, Net of Tax The following table summarizes the changes in AOCL by component: (In thousands) Available For Sale and Transferred Securities Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Balance at December 31, 2014 $ 16,421 $ (25,530 ) $ (47,152 ) $ (56,261 ) Other comprehensive (loss) income before reclassifications (22,512 ) (3,136 ) (5,500 ) (31,148 ) Amounts reclassified from accumulated other comprehensive (loss) income (316 ) 5,686 3,933 9,303 Net current-period other comprehensive (loss) income, net of tax (22,828 ) 2,550 (1,567 ) (21,845 ) Balance at December 31, 2015 (6,407 ) (22,980 ) (48,719 ) (78,106 ) Other comprehensive (loss) income before reclassifications (8,901 ) 825 (232 ) (8,308 ) Amounts reclassified from accumulated other comprehensive (loss) income (168 ) 5,087 4,502 9,421 Net current-period other comprehensive (loss) income, net of tax (9,069 ) 5,912 4,270 1,113 Balance at December 31, 2016 (15,476 ) (17,068 ) (44,449 ) (76,993 ) Adoption of ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from AOCI (4,881 ) (2,513 ) (8,254 ) (15,648 ) Other comprehensive (loss) income before reclassifications (7,590 ) 181 98 (7,311 ) Amounts reclassified from accumulated other comprehensive (loss) income — 4,384 4,037 8,421 Net current-period other comprehensive (loss) income, net of tax (7,590 ) 4,565 4,135 1,110 Balance at December 31, 2017 $ (27,947 ) $ (15,016 ) $ (48,568 ) $ (91,531 ) The following table provides information for the items reclassified from AOCL: Years ended December 31, Accumulated Other Comprehensive Loss Components 2017 2016 2015 Associated Line Item in the Consolidated Statements Of Income (In thousands) Available-for-sale and transferred securities: Unrealized gains on investments $ — $ 414 $ 609 Gain on sale of investment securities, net Unrealized losses on investments — (149 ) (110 ) Impairment loss recognized in earnings Total before tax — 265 499 Tax expense — (97 ) (183 ) Income tax expense Net of tax $ — $ 168 $ 316 Derivative instruments: Cash flow hedges $ (7,160 ) $ (8,020 ) $ (8,965 ) Total interest expense Tax benefit 2,776 2,933 3,279 Income tax expense Net of tax $ (4,384 ) $ (5,087 ) $ (5,686 ) Defined benefit pension and other postretirement benefit plans: Amortization of net loss $ (6,612 ) $ (7,126 ) $ (6,161 ) (1) Prior service costs — (14 ) (73 ) (1) Total before tax (6,612 ) (7,140 ) (6,234 ) Tax benefit 2,575 2,638 2,301 Income tax expense Net of tax $ (4,037 ) $ (4,502 ) $ (3,933 ) (1) These accumulated other comprehensive income components are included in the computation of net periodic benefit cost (see Note 17 Retirement Benefit Plans for further details). The following tables summarize the items and related tax effects for each component of OCI/OCL, net of tax: Year ended December 31, 2017 (In thousands) Pre-Tax Amount Tax Benefit (Expense) Net of Tax Amount Available-for-sale and transferred securities: Net unrealized loss during the period $ (12,423 ) $ 4,833 $ (7,590 ) Reclassification for net gain included in net income — — — Net non-credit other-than-temporary impairment — — — Amortization of unrealized loss on securities transferred to held-to-maturity — — — Total available-for-sale and transferred securities (12,423 ) 4,833 (7,590 ) Derivative instruments: Net unrealized gain during the period 291 (110 ) 181 Reclassification adjustment for net loss included in net income 7,160 (2,776 ) 4,384 Total derivative instruments 7,451 (2,886 ) 4,565 Defined benefit pension and other postretirement benefit plans: Current year actuarial loss 155 (57 ) 98 Reclassification adjustment for amortization of net loss included in net income 6,612 (2,575 ) 4,037 Reclassification adjustment for prior service cost included in net income — — — Total defined benefit pension and postretirement benefit plans 6,767 (2,632 ) 4,135 Other comprehensive income, net of tax $ 1,795 $ (685 ) $ 1,110 Year ended December 31, 2016 (In thousands) Pre-Tax Amount Tax Benefit (Expense) Net of Tax Amount Available-for-sale and transferred securities: Net unrealized loss during the period $ (14,113 ) $ 5,212 $ (8,901 ) Reclassification for net gain included in net income (414 ) 152 (262 ) Net non-credit other-than-temporary impairment 149 (55 ) 94 Amortization of unrealized loss on securities transferred to held-to-maturity — — — Total available-for-sale and transferred securities (14,378 ) 5,309 (9,069 ) Derivative instruments: Net unrealized loss during the period 1,331 (506 ) 825 Reclassification adjustment for net loss included in net income 8,020 (2,933 ) 5,087 Total derivative instruments 9,351 (3,439 ) 5,912 Defined benefit pension and other postretirement benefit plans: Current year actuarial loss (368 ) 136 (232 ) Reclassification adjustment for amortization of net loss included in net income 7,126 (2,633 ) 4,493 Reclassification adjustment for prior service cost included in net income 14 (5 ) 9 Total defined benefit pension and postretirement benefit plans 6,772 (2,502 ) 4,270 Other comprehensive loss, net of tax $ 1,745 $ (632 ) $ 1,113 Year ended December 31, 2015 (In thousands) Pre-Tax Amount Tax Benefit (Expense) Net of Tax Amount Available-for-sale and transferred securities: Net unrealized gain during the period $ (35,701 ) $ 13,166 $ (22,535 ) Reclassification for net gain included in net income (609 ) 223 (386 ) Net non-credit other-than-temporary impairment 110 (40 ) 70 Amortization of unrealized loss on securities transferred to held-to-maturity 37 (14 ) 23 Total available-for-sale and transferred securities (36,163 ) 13,335 (22,828 ) Derivative instruments: Net unrealized loss during the period (4,945 ) 1,809 (3,136 ) Reclassification adjustment for net loss included in net income 8,965 (3,279 ) 5,686 Total derivative instruments 4,020 (1,470 ) 2,550 Defined benefit pension and other postretirement benefit plans: Current year actuarial loss (8,719 ) 3,219 (5,500 ) Reclassification adjustment for amortization of net loss included in net income 6,161 (2,274 ) 3,887 Reclassification adjustment for prior service cost included in net income 73 (27 ) 46 Total defined benefit pension and postretirement benefit plans (2,485 ) 918 (1,567 ) Other comprehensive loss, net of tax $ (34,628 ) $ 12,783 $ (21,845 )

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2017
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 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. Under 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 and other intangibles adjusted for certain deferred tax liabilities. Webster's 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: Actual Capital Requirements Minimum Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio At December 31, 2017 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 At December 31, 2016 Webster Financial Corporation CET1 risk-based capital $ 1,932,171 10.52 % $ 826,504 4.5 % $ 1,193,840 6.5 % Total risk-based capital 2,328,808 12.68 1,469,341 8.0 1,836,677 10.0 Tier 1 risk-based capital 2,054,881 11.19 1,102,006 6.0 1,469,341 8.0 Tier 1 leverage capital 2,054,881 8.13 1,010,857 4.0 1,263,571 5.0 Webster Bank CET1 risk-based capital $ 1,945,332 10.61 % $ 825,228 4.5 % $ 1,191,995 6.5 % Total risk-based capital 2,141,939 11.68 1,467,071 8.0 1,833,839 10.0 Tier 1 risk-based capital 1,945,332 10.61 1,100,304 6.0 1,467,071 8.0 Tier 1 leverage capital 1,945,332 7.70 1,010,005 4.0 1,262,507 5.0 Dividend Restrictions Webster Financial Corporation is dependent upon dividends from Webster Bank to provide funds for its cash requirements, including payments of dividends to shareholders. Banking regulations may limit the amount of dividends that may be paid. Approval by regulatory authorities is required if the effect of dividends declared would cause the regulatory capital of Webster Bank to fall below specified minimum levels, or if dividends declared exceed the net income for that year combined with the undistributed net income for the preceding two years. In addition, the OCC has discretion to prohibit any otherwise permitted capital distribution on general safety and soundness grounds. Dividends paid by Webster Bank to Webster Financial Corporation totaled $120 million and $145 million during the years ended December 31, 2017 and 2016 , respectively. Cash Restrictions Webster Bank is required by Federal Reserve System regulations to hold cash reserve balances, on hand or with Federal Reserve Banks. Pursuant to this requirement, the Bank held $82.3 million and $58.6 million at December 31, 2017 and 2016

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2017
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: Years ended December 31, (In thousands, except per share data) 2017 2016 2015 Earnings for basic and diluted earnings per common share: Net income $ 255,439 $ 207,127 $ 204,729 Less: Preferred stock dividends 8,184 8,096 8,711 Net income available to common shareholders 247,255 199,031 196,018 Less: Earnings applicable to participating securities 424 608 657 Earnings applicable to common shareholders $ 246,831 $ 198,423 $ 195,361 Shares: Weighted-average common shares outstanding - basic 91,965 91,367 90,968 Effect of dilutive securities: Stock options and restricted stock 385 461 524 Warrants 6 28 41 Weighted-average common shares outstanding - diluted 92,356 91,856 91,533 Earnings per common share: Basic $ 2.68 $ 2.17 $ 2.15 Diluted 2.67 2.16 2.13 Potential common shares excluded from the effect of dilutive securities because they would have been anti-dilutive, are as follows: Years ended December 31, (In thousands) 2017 2016 2015 Stock options (shares with exercise price greater than market price) — 41 213 Restricted stock (due to performance conditions on non-participating shares) 58 125 92 Basic weighted-average common shares outstanding includes the effect of conversion of the Series A Preferred Stock which occurred on June 1, 2015. Prior to that, the Series A Preferred Stock was considered to be anti-dilutive. Refer to Note 11: Shareholders' Equity and Note 18: Share-Based Plans

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments Risk Management Objective of Using Derivatives Webster manages economic risks, including interest rate, liquidity, and credit risk 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 receipt or payment of, both future 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 the fair value of 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 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 Consolidated Statements of Income, are described in the following paragraphs. Interest rate swap and cap contracts are sold to commercial and other customers who wish to modify loan interest rate sensitivity. These contracts are offset with dealer counterparty transactions structured with matching terms. As a result, there is minimal impact on earnings, except for fee income earned in such transactions. 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 a lead bank in a loan syndication. Other derivatives include foreign currency forward contracts related to lending arrangements, a VISA equity swap transaction, and mortgage banking derivatives such as mortgage-backed securities related to residential loan commitments and loans held for sale. Mortgage banking derivatives are utilized by Webster in its efforts to manage risk of loss associated with its mortgage loan commitments and mortgage loans held for sale. Prior to closing and funding certain single-family residential mortgage loans interest rate lock commitments are generally extended to the borrowers. During the period from commitment date to closing date, Webster is subject to the risk that market rates of interest may change. If market rates rise, investors generally will pay less to purchase such loans causing a reduction in the anticipated gain on sale of the loans and 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. Fair Value of Derivative Instruments The following table presents the notional amounts and fair values of derivative positions: At December 31, 2017 At December 31, 2016 Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives (In thousands) Notional Fair Notional Fair Notional Fair Notional Fair Designated as hedging instruments: Positions subject to master netting agreements (1) Interest rate derivatives $ 325,000 $ 2,770 $ — $ — $ 225,000 $ 3,270 $ 100,000 $ 792 Not designated as hedging instruments: Positions subject to master netting agreements (1) Interest rate derivatives 2,791,760 5,977 721,048 1,968 1,943,485 32,226 1,242,937 24,388 Mortgage banking derivatives (2) 28,497 421 39,230 110 103,440 3,084 59,895 711 Other 7,914 258 30,328 419 10,634 231 14,265 120 Positions not subject to master netting agreements Interest rate derivatives 1,366,299 23,009 2,146,518 25,631 1,734,679 38,668 1,451,762 19,001 RPAs 93,713 80 116,882 111 86,037 139 87,273 166 Other — — 2,073 184 1,438 19 181 11 Total not designated as hedging instruments 4,288,183 29,745 3,056,079 28,423 3,879,713 74,367 2,856,313 44,397 Gross derivative instruments, before netting $ 4,613,183 32,515 $ 3,056,079 28,423 $ 4,104,713 77,637 $ 2,956,313 45,189 Less: Legally enforceable master netting agreements 2,245 2,245 24,252 24,254 Less: Cash collateral posted 6,704 — 11,475 600 Total derivative instruments, after netting $ 23,566 $ 26,178 $ 41,910 $ 20,335 (1) One of Webster's counterparty relationships was impacted by a Chicago Mercantile Exchange rulebook amendment, resulting in the presentation of that relationship on a settlement basis, as a single unit of account. (2) Notional amounts include mandatory forward commitments of $39.0 million , while notional amounts do not include approved floating rate commitments of $11.3 million , at December 31, 2017 . Changes in Fair Value Changes in the fair value of derivatives not qualifying for hedge accounting treatment are reported as a component of other non-interest income in the accompanying Consolidated Statements of Income as follows: Years ended December 31, (In thousands) 2017 2016 2015 Interest rate derivatives $ 2,702 $ 8,668 $ 4,361 RPA 242 (361 ) (33 ) Mortgage banking derivatives (2,062 ) 1,553 801 Other (768 ) (67 ) (63 ) Total impact on other non-interest income $ 114 $ 9,793 $ 5,066 Amounts for the effective portion of changes in the fair value of derivatives are reclassified to interest expense as interest payments are made on Webster's variable-rate debt. Over the next twelve months, the Company estimates that $0.8 million will be reclassified from AOCL as an increase to interest expense. Webster records gains and losses related to swap terminations as OCI. These balances are subsequently amortized into interest expense over the respective terms of the hedged debt instruments. At December 31, 2017 , the remaining unamortized loss on the termination of cash flow hedges is $14.9 million . Over the next twelve months, the Company estimates that $6.2 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 12: Accumulated Other Comprehensive Loss, Net of Tax . Information about the valuation methods used to measure fair value is provided in Note 16: Fair Value Measurements . Offsetting Derivatives Webster has entered into transactions with counterparties that are subject to a legally enforceable master netting agreement. Derivatives subject to a legally enforceable master netting agreement are reported on a net basis, net of cash collateral. Net positions are recorded in other assets for a net gain position and in other liabilities for a net loss position in the accompanying Consolidated Balance Sheets. In addition, there was $406 thousand cash collateral posted, that was not offset, at December 31, 2017 . The following table is presented on a gross basis, prior to the application of counterparty netting agreements: At December 31, 2017 At December 31, 2016 (In thousands) Gross Amount Relationship Offset Cash Collateral Offset Net Amount Gross Amount Relationship Offset Cash Collateral Offset Net Amount Derivative instrument assets Hedged Accounting $ 2,770 $ 91 $ 2,679 $ — $ 3,270 $ 2,335 $ 935 $ — Non-Hedged Accounting 6,222 2,154 4,025 43 32,457 21,917 10,540 — Total $ 8,992 $ 2,245 $ 6,704 $ 43 $ 35,727 $ 24,252 $ 11,475 $ — Derivative instrument liabilities Hedged Accounting $ — $ — $ — $ — $ 792 $ 792 $ — $ — Non-Hedged Accounting 2,387 2,245 — 142 24,508 23,462 600 446 Total $ 2,387 $ 2,245 $ — $ 142 $ 25,300 $ 24,254 $ 600 $ 446 Counterparty Credit Risk Use of derivative contracts may expose the bank to counterparty credit risk. The Company has International Swaps Derivative Association (ISDA) master agreements, including a Credit Support Annex, with all derivative counterparties. The ISDA master agreements provide that on each payment date, all amounts otherwise owing the same currency under the same transaction are netted so that only a single amount is owed in that currency. The ISDA provides, if the parties so elect, for such netting of amounts in the same currency among all transactions identified as being subject to such election that have common payment dates and booking offices. Under the Credit Support Annex, daily net exposure in excess of a negotiated threshold is secured by posted cash collateral. The Company has negotiated a zero threshold with the majority of its approved financial institution counterparties. In accordance with Webster policies, institutional counterparties must be analyzed and approved through the Company’s credit approval process. The Company’s credit exposure on interest rate derivatives with non-dealer counterparties is limited to the net favorable value, including accrued interest, of all such instruments, reduced by the amount of collateral pledged by the counterparties. The Company's credit exposure related to derivatives with dealer counterparties is significantly mitigated with cash collateral equal to, or in excess of, the market value of the instrument updated daily. In accordance with counterparty credit agreements and derivative clearing rules, the Company had approximately $3.1 million in net margin collateral received from financial counterparties at December 31, 2017 , comprised of $32.0 million in initial margin posted and $35.1 million in variation margin collateral received from financial counterparties or the derivative clearing organization. Collateral levels for approved financial institution counterparties are monitored daily and adjusted as necessary. In the event of default, should the collateral not be returned, the exposure would be offset by terminating the transaction. The Company regularly evaluates the credit risk of its counterparties, taking into account the likelihood of default, net exposures, and remaining contractual life, among other related factors. The Company's net current credit exposure relating to interest rate derivatives with Webster Bank customers was $23.0 million at December 31, 2017 . 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 $28.2 million at December 31, 2017

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is best determined using quoted market prices. However, in many instances, quoted market prices are not available. In such instances, fair values are determined using appropriate valuation techniques. Various assumptions and observable inputs must be relied upon in applying these techniques. Accordingly, categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. As such, the fair value estimates may not be realized in an immediate transfer of the respective asset or liability. Fair value estimates are made at a specific point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the entire holdings or any part of a particular financial instrument. Fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments, and other factors. These factors are subjective in nature and involve uncertainties and matters of significant judgment and therefore, cannot be determined with precision. Changes in assumptions could significantly affect the estimates. Fair Value Hierarchy The three levels within the fair value hierarchy are as follows: • Level 1: Valuation is based upon unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. • Level 2: Fair value is calculated using significant inputs other than quoted market prices that are directly or indirectly observable for the asset or liability. The valuation may rely on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit ratings, etc.), or inputs that are derived principally or corroborated by market data, by correlation, or other means. • Level 3: Inputs for determining the fair value of the respective assets or liabilities are not observable. Level 3 valuations are reliant upon pricing models and techniques that require significant management judgment or estimation. Assets and Liabilities Measured at Fair Value on a Recurring Basis Available-for-Sale Investment Securities. When quoted prices are available in an active market, the Company classifies investment securities within Level 1 of the valuation hierarchy. U.S. Treasury Bills are classified within Level 1 of the fair value hierarchy. When quoted market prices are not available, the Company employs an independent pricing service that utilizes matrix pricing to calculate fair value. Such fair value measurements consider observable data such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayments speeds, credit information, and respective terms and conditions for debt instruments. Management maintains procedures to monitor the pricing service's assumptions and establishes processes to challenge the pricing service's valuations that appear unusual unexpected. Available-for-Sale investment securities which include Agency CMO, Agency MBS, Agency CMBS, CMBS, CLO, single issuer-trust preferred, and corporate debt, are classified within Level 2 of the fair value hierarchy. Derivative Instruments. Foreign exchange contracts are valued based on unadjusted quoted prices in active markets and classified within Level 1 of the fair value hierarchy. All other derivative instruments are valued using third-party valuation software, which considers the present value of cash flows discounted using observable forward rate assumptions. The Chicago Mercantile Exchange have amended their rulebooks to legally characterize variation margin payments for over-the-counter derivatives that clear as settlements rather than collateral, effective January 3, 2017. One of Webster's counterparty relationships was impacted by this change, resulting in the fair value of the instrument including cash collateral as a single unit of account. The resulting fair values are validated against valuations performed by independent third parties and are classified within Level 2 of the fair value hierarchy. In determining if any fair value adjustment related to credit risk is required, Webster evaluates the credit risk of its counterparties by considering factors such as the likelihood of default by the counterparties, its net exposures, the remaining contractual life, as well as the amount of collateral securing the position. Webster reviews its counterparty exposure on a regular basis, and, when necessary, appropriate business actions are taken to adjust 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 change in value of derivative assets and liabilities attributable to credit risk was not significant during the reported periods. Mortgage Banking Derivatives. Forward sales of mortgage loans and mortgage-backed securities are utilized by the Company in its efforts to manage risk of loss associated with its mortgage loan commitments and mortgage loans held for sale. Prior to closing and funding certain single-family residential mortgage loans, an interest rate lock commitment is generally extended to the borrower. During the period from commitment date to closing date, the Company is subject to the risk that market rates of interest may change. If market rates rise, investors generally will pay less to purchase such loans resulting in a reduction in the gain on sale of the loans or, possibly, a loss. In an effort to mitigate such risk, forward delivery sales commitments are established, under which the Company agrees to deliver whole mortgage loans to various investors or issue mortgage-backed securities. The fair value of mortgage banking derivatives is determined based on current market prices for similar assets in the secondary market and, therefore, classified within Level 2 of the fair value hierarchy. Investments Held in Rabbi Trust. Investments held in the Rabbi Trust primarily include mutual funds that invest in equity and fixed income securities. Shares of mutual funds are valued based on net asset value, which represents quoted market prices for the underlying shares held in the mutual funds. Therefore, investments held in the Rabbi Trust are classified within Level 1 of the fair value hierarchy. Webster has elected to measure the investments held in the Rabbi Trust at fair value. The cost basis of the investments held in the Rabbi Trust is $2.2 million as of December 31, 2017 . Alternative Investments. Alternative investments are non-public entities that cannot be redeemed since the Company’s investment is distributed as the underlying equity is liquidated. Alternative investments in which the ownership percentage is greater than 3% are fair valued on a recurring basis based upon the net asset value of the respective fund. Alternative investments in which the ownership percentage is less than 3% are fair valued on a non-recurring basis. These alternative investments are recorded at cost, subject to impairment testing. Both recurring and non-recurring alternative investments are classified within Level 3 of the fair value hierarchy, as they are non-public entities that cannot be redeemed since the Company's investment is distributed as the underlying investments are liquidated. At December 31, 2017 , the alternative investments book value was $18.0 million and there was $9.1 million in remaining unfunded commitments. 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 generally records residential mortgage loans held for sale under the fair value option of ASC Topic 825 "Financial Instruments." 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, such loans are classified within Level 2 of the fair value hierarchy. Summaries of the fair values of assets and liabilities measured at fair value on a recurring basis are as follows: At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 1,247 $ — $ — $ 1,247 Agency CMO — 306,333 — 306,333 Agency MBS — 1,107,841 — 1,107,841 Agency CMBS — 588,026 — 588,026 CMBS — 361,067 — 361,067 CLO — 209,851 — 209,851 Single issuer-trust preferred — 7,050 — 7,050 Corporate debt — 56,622 — 56,622 Total available-for-sale investment securities 1,247 2,636,790 — 2,638,037 Gross derivative instruments, before netting (1) 258 32,257 — 32,515 Investments held in Rabbi Trust 4,801 — — 4,801 Alternative investments — — 7,460 7,460 Originated loans held for sale — 20,888 — 20,888 Total financial assets held at fair value $ 6,306 $ 2,689,935 $ 7,460 $ 2,703,701 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 587 $ 27,836 $ — $ 28,423 At December 31, 2016 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 734 $ — $ — $ 734 Agency CMO — 419,706 — 419,706 Agency MBS — 954,349 — 954,349 Agency CMBS — 573,272 — 573,272 CMBS — 477,365 — 477,365 CLO — 427,390 — 427,390 Single issuer-trust preferred — 28,633 — 28,633 Corporate debt — 109,642 — 109,642 Total available-for-sale investment securities 734 2,990,357 — 2,991,091 Gross derivative instruments, before netting (1) 250 77,387 — 77,637 Investments held in Rabbi Trust 5,119 — — 5,119 Alternative investments — — 5,502 5,502 Originated loans held for sale — 60,260 — 60,260 Total financial assets held at fair value $ 6,103 $ 3,128,004 $ 5,502 $ 3,139,609 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 120 $ 45,069 $ — $ 45,189 (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 15: Derivative Financial Instruments . The following table presents the changes in Level 3 assets and liabilities that are measured at fair value on a recurring basis: (In thousands) Alternative Investments Balance at January 1, 2017 $ 5,502 Unrealized gain included in net income 613 Purchases/capital funding 1,399 Payments (54 ) Balance at December 31, 2017 $ 7,460 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. Transferred Loans Held For Sale. Certain loans are transferred to loans held for sale once a decision has been made to sell such loans. These loans are accounted for at the lower of cost or market and are considered to be recognized at fair value when they are recorded at below cost. This activity is primarily commercial loans with observable inputs and are classified within Level 2. On the occasion should these loans include adjustments for changes in loan characteristics using unobservable inputs, the loans would be classified within Level 3. Collateral Dependent Impaired Loans and Leases. Impaired loans and leases for which repayment is expected to be provided solely by the value of the underlying collateral are considered collateral dependent and are valued based on the estimated fair value of such collateral using customized discounting criteria. As such, collateral dependent impaired loans and leases are classified as Level 3 of the fair value hierarchy. Other Real Estate Owned and Repossessed Assets. The total book value of OREO and repossessed assets was $6.1 million at December 31, 2017 . OREO and repossessed assets are accounted for at the lower of cost or market and are considered to be recognized at fair value when they are recorded at below cost. The fair value of OREO is based on independent appraisals or internal valuation methods, less estimated selling costs. The valuation may consider available pricing guides, auction results, and price opinions. Certain assets require assumptions about factors that are not observable in an active market in the determination of fair value, as such, OREO and repossessed assets are classified within Level 3 of the fair value hierarchy. The table below presents the valuation methodology and unobservable inputs for Level 3 assets measured at fair value on a non-recurring basis as of December 31, 2017 : (Dollars in thousands) Asset Fair Value Valuation Methodology Unobservable Inputs Range of Inputs Collateral dependent impaired loans and leases $ 12,556 Real Estate Appraisals Discount for appraisal type 0% - 15 % Discount for costs to sell 0% - 8 % OREO $ 1,077 Real Estate Appraisals Discount for appraisal type 0% - 20 % Discount for costs to sell 8% Fair Value of Financial Instruments and Servicing Assets The Company is required to disclose the estimated fair value of financial instruments, both assets and liabilities, for which it is practicable to estimate fair value. The following is a description of valuation methodologies used for those assets and liabilities. Cash, Due from Banks, and Interest-bearing Deposits. The carrying amount of cash, due from banks, and interest-bearing deposits is used to approximate fair value, given the short time frame to maturity and, as such, these assets do not present unanticipated credit concerns. Cash, due from banks, and interest-bearing deposits are classified within Level 1 of the fair value hierarchy. Held-to-Maturity Investment Securities. When quoted market prices are not available, the Company employs an independent pricing service that utilizes matrix pricing to calculate fair value. Such fair value measurements consider observable data such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayments speeds, credit information, and respective terms and conditions for debt instruments. Management maintains procedures to monitor the pricing service's assumptions and establishes processes to challenge the pricing service's valuations 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. The fair values of all other borrowings are estimated using discounted cash flow analysis based on current market rates adjusted, as appropriate, for associated credit risks. Securities sold under agreements to repurchase and other borrowings are classified within Level 2 of the fair value hierarchy. Federal Home Loan Bank Advances and Long-Term Debt. The fair value of FHLB advances and long-term debt is estimated using a discounted cash flow technique. Discount rates are matched with the time period of the expected cash flow and are adjusted, as appropriate, to reflect credit risk. FHLB advances and long-term debt are classified within Level 2 of the fair value hierarchy. Mortgage Servicing Assets. Mortgage servicing assets are accounted for at cost, subject to impairment testing. Mortgage servicing assets are considered to be recognized at fair value when they are recorded at below cost. Changes in fair value are included as a component of other non-interest income in the accompanying 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 December 31, 2017 2016 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Financial Assets: Level 2 Held-to-maturity investment securities $ 4,487,392 $ 4,456,350 $ 4,160,658 $ 4,125,125 Transferred loans held for sale — — 7,317 7,444 Level 3 Loans and leases, net 17,323,864 17,211,619 16,832,268 16,678,106 Mortgage servicing assets 25,139 45,309 24,466 52,075 Alternative investments 10,562 12,940 11,034 13,189 Financial Liabilities: Level 2 Deposit liabilities, other than time deposits $ 18,525,321 $ 18,525,321 $ 17,279,049 $ 17,279,049 Time deposits 2,468,408 2,455,245 2,024,808 2,024,395 Securities sold under agreements to repurchase and other borrowings 643,269 644,084 949,526 955,660 FHLB advances (1) 1,677,105 1,678,070 2,842,908 2,825,101 Long-term debt (1) 225,767 234,359 225,514 225,514 (1) The following adjustments to the carrying amount are not included for determination of fair value, see Note 10: Borrowings : • FHLB advances - unamortized premiums on advances •

Retirement Benefit Plans

Retirement Benefit Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Benefit Plans	Retirement Benefit Plans Defined benefit pension and other postretirement benefits Webster Bank offered a defined benefit noncontributory pension plan through December 31, 2007 for eligible employees who met certain minimum service and age requirements. Pension plan benefits are based upon employee earnings during the period of credited service. A supplemental defined benefit retirement plan (SERP) was also offered to certain employees who were at the Executive Vice President level or above through December 31, 2007. The SERP provides eligible participants with additional pension benefits. Webster Bank also provides other postretirement healthcare benefits to certain retired employees. The Webster Bank Pension Plan and the SERP were frozen as of December 31, 2007. No additional benefits have been accrued since that time. Employees hired on or after January 1, 2007 receive no qualified or supplemental retirement income under the plans. All other employees accrue no additional qualified or supplemental retirement income after January 1, 2008, and the amount of their qualified and supplemental retirement income will not exceed the amount of benefits determined as of December 31, 2007. There were $122 thousand and $124 thousand in company contributions to the SERP for the years ended December 31, 2017 and 2016 , respectively. The mortality assumptions used in the pension liability assessment for the year ended December 31, 2017 were the RP-2014 adjusted to 2006 dataset mortality table projected to measurement date with Mercer's mortality improvement scale MMP-2017. The measurement date is December 31 for the Webster Bank Pension Plan, SERP, and other postretirement healthcare benefits. The following table sets forth changes in benefit obligation, changes in plan assets, and the funded status of the defined benefit pension and other postretirement benefits at December 31: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2017 2016 2017 2016 Change in benefit obligation: Beginning balance $ 211,508 $ 203,645 $ 11,806 $ 10,518 $ 3,852 $ 3,853 Service cost 50 45 — — — — Interest cost 7,314 8,441 375 389 92 125 Actuarial loss (gain) 18,396 6,108 1,037 1,023 (631 ) 59 Benefits paid and administrative expenses (7,950 ) (6,731 ) (122 ) (124 ) (219 ) (185 ) Ending balance (1) 229,318 211,508 13,096 11,806 3,094 3,852 Change in plan assets: Beginning balance 192,922 161,369 — — — — Actual return on plan assets 31,253 18,284 — — — — Employer contributions — 20,000 122 124 219 185 Benefits paid and administrative expenses (7,950 ) (6,731 ) (122 ) (124 ) (219 ) (185 ) Ending balance 216,225 192,922 — — — — Funded status of the plan at year end (2) $ (13,093 ) $ (18,586 ) $ (13,096 ) $ (11,806 ) $ (3,094 ) $ (3,852 ) (1) The accumulated benefit obligation for the defined benefit pension and other postretirement benefits was $245.5 million and $227.2 million at December 31, 2017 and 2016 , respectively. (2) The underfunded status amounts are included in accrued expense and other liabilities in the accompanying Consolidated Balance Sheets. The Company expects that $5.1 million in net actuarial loss will be recognized as a component of net periodic benefit cost in 2018 . The components of AOCL related to the defined benefit pension and other postretirement benefits at December 31, 2017 and 2016 are summarized below: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2017 2016 2017 2016 Net actuarial loss (gain) $ 59,433 $ 65,857 $ 3,299 $ 3,009 $ (16 ) $ 616 Prior service cost — — — — — — Total pre-tax amounts included in AOCL 59,433 65,857 3,299 3,009 (16 ) 616 Deferred tax benefit 13,407 23,727 744 1,084 (3 ) 222 Amounts included in accumulated AOCL, net of tax $ 46,026 $ 42,130 $ 2,555 $ 1,925 $ (13 ) $ 394 Expected future benefit payments for the defined benefit pension and other postretirement benefits are presented below: (In thousands) Pension Plan SERP Other Benefits 2018 $ 9,009 $ 11,371 $ 354 2019 8,630 130 342 2020 9,065 132 328 2021 9,792 132 311 2022 10,425 131 292 2023-2027 55,206 651 1,125 The components of the net periodic benefit cost (benefit) for the defined benefit pension and other postretirement benefits were as follows for the years ended December 31: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Service cost $ 50 $ 45 $ 45 $ — $ — $ — $ — $ — $ — Interest cost on benefit obligations 7,314 8,441 8,008 375 389 345 92 125 123 Expected return on plan assets (12,296 ) (11,461 ) (11,873 ) — — — — — — Amortization of prior service cost — — — — — — — 14 73 Recognized net loss 5,864 6,665 5,724 748 426 390 — 35 47 Net periodic benefit cost (benefit) $ 932 $ 3,690 $ 1,904 $ 1,123 $ 815 $ 735 $ 92 $ 174 $ 243 Changes in funded status related to the defined benefit pension and other postretirement benefits and recognized as a component of OCI in the accompanying Consolidated Statements of Comprehensive Income as follows for the years ended December 31: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Net (gain) loss $ (561 ) $ (715 ) $ 8,525 $ 1,037 $ 1,023 $ 372 $ (631 ) $ 60 $ (178 ) Amounts reclassified from AOCL (5,864 ) (6,665 ) (5,724 ) (748 ) (426 ) (390 ) — (35 ) (47 ) Amortization of prior service cost — — — — — — — (14 ) (73 ) Total (gain) loss recognized in OCI $ (6,425 ) $ (7,380 ) $ 2,801 $ 289 $ 597 $ (18 ) $ (631 ) $ 11 $ (298 ) Fair Value Measurements The following is a description of the valuation methodologies used for the pension plan assets measured at fair value, including the general classification of such instruments pursuant to the valuation hierarchy: Registered investment companies. Exchange traded funds are quoted at market prices in an exchange and active market, which represent the net asset values of shares held by the plan at year end. Money market funds are shown at cost, which approximates fair value. The exchange traded fund is benchmarked against the Standard & Poor's 500 Index. Common collective trust funds. The net asset value (NAV), as provided by the trustee, is used as the fair value of the investments. The NAV is based on the fair value of the underlying investments held by the fund less its liabilities. Plan transactions (purchases and sales) may occur daily. Were the Plan to initiate a full redemption of the collective trust, the investment adviser reserves the right to temporarily delay withdrawal from the trust in order to ensure that securities liquidations will be carried out in an orderly business manner. The common collective trust funds performance are benchmarked against the Standard and Poor’s 500 Stock Index, the S&P 400 Mid Cap Index, the Russell 2000 Index, the MSCI ACWI ex U.S. Index, and the Barclays Capital U.S. Long Credit Index. Investment contract with insurance company. These investments are valued at fair value by discounting the related cash flows based on current yields of similar instruments with comparable durations considering the credit-worthiness of the issuer. Holdings of insurance company investment contracts are classified as Level 3 investments. A summary of the fair value and hierarchy classification of financial assets of the pension plan is as follows: At December 31, 2017 2016 (In thousands) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Registered investment companies: Exchange traded funds $ 37,848 $ — $ — $ 37,848 $ 31,526 $ — $ — $ 31,526 Cash and cash equivalents 1,115 — — 1,115 701 — — 701 Common collective trust funds: Fixed Income funds — 107,430 — 107,430 — 96,429 — 96,429 Equity Funds — 69,832 — 69,832 — 63,285 — 63,285 Insurance company investment contract — — — — — — 793 793 Total $ 38,963 $ 177,262 $ — $ 216,225 $ 32,227 $ 159,714 $ 793 $ 192,734 The following table sets forth a summary of changes in the fair value of Level 3 assets of the pension plan: Years ended December 31, (In thousands) 2017 2016 Beginning balance $ 793 $ 934 Employer contributions 78 — Unrealized gains relating to instruments still held at the reporting date — (10 ) Benefit payments, administrative expenses (166 ) (131 ) Asset sales (705 ) — Ending balance $ — $ 793 Asset Management The following table presents the target allocation and the pension plan asset allocation for the periods indicated, by asset category: Target Allocation Percentage of Pension Plan assets 2018 2017 2016 Fixed income investments 55 % 50 % 51 % Equity investments 45 50 49 Total 100 % 100 % 100 % The Retirement Plan Committee is a fiduciary under ERISA and is charged with the responsibility for directing and monitoring the investment management of the pension plan. To assist the Retirement Plan Committee in this function, it engages the services of investment managers and advisors who possess the necessary expertise to manage the pension plan assets within the established investment policy guidelines and objectives. The investment policy guidelines and objectives is reviewed at a minimum annually by the Retirement Plan Committee. The primary objective of the pension plan investment strategy is to provide long-term total return through capital appreciation and dividend and interest income. The Plan invests in registered investment companies and bank collective trusts. The volatility, as measured by standard deviation, of the pension plan assets should not exceed that of the Composite Index. The investment policy guidelines allow the pension plan assets to be invested in certain types of cash equivalents, fixed income securities, equity securities, mutual funds, and collective trusts. Investments in mutual funds and collective trust funds are substantially limited to funds with the securities characteristic of their assigned benchmarks. The pension plan investment strategy is designed to maintain a diversified portfolio, with a target average long-term rate of 6.50% , however, there is no certainty that the portfolio will perform to expectations. Asset allocations are monitored monthly, and the portfolio is rebalanced as needed. Weighted-average assumptions used to determine benefit obligations at December 31 are as follows: Pension Plan SERP Other Benefits 2017 2016 2017 2016 2017 2016 Discount rate 3.50 % 4.01 % 3.30 % 3.63 % 3.00 % 3.27 % Rate of compensation increase n/a n/a n/a n/a n/a n/a Weighted-average assumptions used to determine net periodic benefit cost for the years ended December 31 are as follows: Pension Plan SERP Other Benefits 2017 2016 2015 2017 2016 2015 2017 2016 2015 Discount rate 4.01 % 4.20 % 3.85 % 3.63 % 3.75 % 3.50 % 3.27 % 3.35 % 3.15 % Expected long-term return on assets 6.50 % 7.00 % 7.00 % n/a n/a n/a n/a n/a n/a Rate of compensation increase n/a n/a n/a n/a n/a n/a n/a n/a n/a Assumed healthcare cost trend n/a n/a n/a n/a n/a n/a 7.50 % 8.25 % 8.00 % The assumed healthcare cost-trend rate is 7.50% for 2017 and 2018, declining 1.0% each year thereafter until 2024 when the rate will be 4.60% . An increase of 1.0% in the assumed healthcare cost-trend rate for 2017 would have increased the net periodic postretirement benefit cost by $5 thousand and increased the accumulated benefit obligation by $148 thousand . A decrease of 1.0% in the assumed healthcare cost trend rate for 2017 would have decreased the net periodic postretirement benefit cost by $5 thousand and decreased the accumulated postretirement benefit obligation by $134 thousand . Multiple-employer plan Webster Bank, for the benefit of former employees of a bank acquired by the Company, is a sponsor of a multiple-employer pension plan that does not segregate the assets or liabilities of its employers participating in the plan. According to the plan administrator, as of July 1, 2017 , the date of the latest actuarial valuation, Webster Bank’s portion of this plan was under-funded by $0.8 million . The following table sets forth contributions and funding status of Webster Bank's portion of this plan: (Dollars in thousands) Contributions by Webster Bank for the year ended December 31, Funded Status of the Plan at December 31, Plan Name Employer Identification Number Plan Number 2017 2016 2015 2017 2016 Pentegra Defined Benefit Plan for Financial Institutions 13-5645888 333 $614 $690 $340 At least 80 percent At least 80 percent Multi-employer accounting is applied to the Fund. As a multiple-employer pension plan, there are no collective bargained contracts affecting its contribution or benefit provisions. Any shortfall amortization basis is being amortized over seven years, as required by the Pension Protection Act. All benefit accruals were frozen as of September 1, 2004. The Company's contributions to this plan did not exceed more than 5% of total contributions in the plan for the years ended December 31, 2017 , 2016 , and 2015 . Webster Bank Retirement Savings Plan Webster Bank provides an employee retirement savings plan governed by section 401(k) of the Internal Revenue Code. Webster Bank matches 100% of the first 2% and 50% of the next 6% of employees’ pre-tax contributions based on annual compensation. If a participant fails to make a pre-tax contribution election within 90 days of his or her date of hire, automatic pre-tax contributions will commence 90 days after his or her date of hire at a rate equal to 3% of compensation. Compensation and benefit expense included $12.0 million , $11.1 million , and $10.9 million for the years ended December 31, 2017 , 2016 , and 2015

Share-Based Plans

Share-Based Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Plans	Share-Based Plans Stock compensation plans Webster maintains stock compensation plans under which non-qualified stock options, incentive stock options, restricted stock, restricted stock units, or stock appreciation rights may be granted to employees and directors. The Company believes these share awards better align the interests of its employees with those of its shareholders. Stock compensation cost is recognized over the required service vesting period for the awards, based on the grant-date fair value, net of estimated forfeitures, and is included as a component of compensation and benefits reflected in non-interest expense. The Plans have shareholder approval for up to 13.4 million shares of common stock. At December 31, 2017 , there were 2.6 million common shares remaining available for grant, while no stock appreciation rights have been granted. The following table provides a summary of stock compensation expense and income tax benefits associated with stock compensation recognized in the accompanying Consolidated Statements of Income: Years ended December 31, (In thousands) 2017 2016 2015 Stock options $ — $ 43 $ 379 Restricted stock 12,276 11,395 10,556 Total stock compensation expense $ 12,276 $ 11,438 $ 10,935 Income tax benefit (1) $ 11,849 $ 4,132 $ 3,903 (1) The income tax benefit in 2017 includes $7.1 million of excess tax benefits recognized under ASU No. 2016-09, Compensation - Stock Compensation (Topic 718) - Improvements to Employee Share Based Payment Accounting, which the Company adopted effective January 1, 2017. At December 31, 2017 there was $13.5 million of unrecognized stock compensation expense for restricted stock, expected to be recognized over a weighted-average period of 1.9 years . The following table provides a summary of the activity under the stock compensation plans for the year ended December 31, 2017 : Unvested Restricted Stock Awards Stock Options Outstanding Time-Based Performance-Based Number of Shares Weighted-Average Grant Date Fair Value Number of Units Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Exercise Price Balance at January 1, 2017 253,361 $ 32.24 2,158 $ 32.89 116,184 $ 33.62 1,072,974 $ 21.24 Granted 168,369 54.76 8,129 56.07 89,581 56.18 — — Exercised options — — — — — — 399,935 25.42 Vested restricted stock awards (1) 194,986 37.16 10,287 51.21 117,695 42.09 — — Forfeited 18,944 35.58 — — 9,154 43.10 — — Balance at December 31, 2017 207,800 $ 43.16 — $ — 78,916 $ 45.35 673,039 $ 18.75 (1) Vested for purposes of recording compensation expense. Time-based restricted stock . Time-based restricted stock awards vest over the applicable service period ranging from 1 to 5 years. The number of time-based awards that may be granted to an eligible individual in a calendar year is limited to 100,000 shares. Compensation expense is recorded over the vesting period based on 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 zero to 150% . For the performance-based shares granted in 2017 , 50% vest based upon Webster's ranking for total shareholder return versus Webster's compensation peer group companies and 50% vest 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. The total fair value of restricted stock awards vested during the years ended December 31, 2017 , 2016 , and 2015 was $12.7 million , $11.6 million , and $11.6 million , respectively. Stock options . Stock option awards have an exercise price equal to the market price of Webster's stock on the date of grant. Each option grants the holder the right to acquire a share of Webster common stock over a contractual life of up to 10 years. There have been no stock options granted since 2013. All awarded options have vested. There were 639,151 non-qualified stock options and 33,888 incentive stock options outstanding at December 31, 2017 . Aggregate intrinsic value represents the total pretax intrinsic value (the difference between Webster's closing stock price on the last trading day of the year and the weighted-average exercise price, multiplied by the number of shares) that would have been received by the option holders had they all exercised their options at that time. At December 31, 2017 , as all awarded options have vested, all of the outstanding options are exercisable, and the aggregate intrinsic value of these options was $25.2 million . The total intrinsic value of options exercised during the years ended December 31, 2017 , 2016 , and 2015 was $11.1 million , $6.4 million , and $4.3 million , respectively. The following table summarizes information for options, all of which are both outstanding and exercisable, at December 31, 2017 : Range of Exercise Prices Number of Shares Weighted-Average Remaining Contractual Life (years) Weighted-Average Exercise Price $ 5.14 - 12.85 222,947 1.2 $ 9.43 $ 22.04 - 25.15 450,092 4.5 23.37 673,039 3.4 $ 18.75

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2017
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. 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 ALCO. Webster allocates the provision for loan and lease losses to each segment based on management’s estimate of the inherent loss content in each of the specific loan and lease portfolios. Provision expense for certain elements of risk that are not deemed specifically attributable to a reportable segment, such as the provision for the consumer liquidating portfolio, is shown as part of the Corporate and Reconciling category. Webster allocates a majority of non-interest expense to each reportable segment using a full-absorption costing process. Costs, including corporate overhead, are analyzed, pooled by process, and assigned to the appropriate reportable segment. Income tax expense is allocated to each reportable segment based on the consolidated effective income tax rate for the period shown. Segment Reporting Modifications The 2016 segment results have been adjusted for comparability to the 2017 segment presentation for the following changes. • To further strengthen Webster's ability to deliver the totality of its products and services to the owners and executives of commercial clients and other high net worth individuals, an organizational change was made during the second quarter of 2017. Effective April 1, 2017, the head of Private Banking reports directly to the head of Commercial Banking. The current organizational structure reflects how executive management responsibilities are assigned and reviewed. As a result of this change, the Private Banking and Commercial Banking operating segments are aggregated into one reportable segment, Commercial Banking. • In late 2007 Webster discontinued its indirect residential construction lending and its indirect home equity lending outside of its primary New England market area referred to as National Wholesale Lending. Webster placed these two portfolios into a liquidating loan portfolio included within the Corporate and Reconciling category. The balance of the home equity liquidating loan portfolio was $65.0 million at December 31, 2016 . As the remainder of this portfolio has been performing in the same manner as the continuing home equity portfolio, management has decided to combine the liquidating loan portfolio with the continuing home equity loan portfolio. The combined portfolio is included in the Community Banking reportable segment. The following tables present the operating results, including all appropriate allocations, for Webster’s reportable segments and the Corporate and Reconciling category: Year ended December 31, 2017 (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated Net interest income (loss) $ 322,393 $ 383,700 $ 104,704 $(14,510) $ 796,287 Provision (benefit) for loan and lease losses 38,518 2,382 — — 40,900 Net interest income (loss) after provision for loan and lease losses 283,875 381,318 104,704 (14,510) 755,387 Non-interest income 55,194 107,368 77,378 19,538 259,478 Non-interest expense 154,037 373,081 113,143 20,814 661,075 Income (loss) before income tax expense 185,032 115,605 68,939 (15,786) 353,790 Income tax expense (benefit) 51,438 32,137 19,165 (4,389) 98,351 Net income (loss) $ 133,594 $ 83,468 $ 49,774 $(11,397) $ 255,439 Year ended December 31, 2016 (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated Net interest income (loss) $ 287,596 $ 367,137 $ 81,451 $ (17,671 ) $ 718,513 Provision (benefit) for loan and lease losses 37,455 18,895 — — 56,350 Net interest income (loss) after provision for loan and lease losses 250,141 348,242 81,451 (17,671 ) 662,163 Non-interest income 57,253 110,197 71,710 25,318 264,478 Non-interest expense 138,379 369,132 97,152 18,528 623,191 Income (loss) before income tax expense 169,015 89,307 56,009 (10,881 ) 303,450 Income tax expense (benefit) 53,649 28,348 17,779 (3,453 ) 96,323 Net income (loss) $ 115,366 $ 60,959 $ 38,230 $ (7,428 ) $ 207,127 Year ended December 31, 2015 (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated Net interest income (loss) $ 266,085 $ 356,881 $ 73,433 $ (31,774 ) $ 664,625 Provision (benefit) for loan and lease losses 30,546 18,754 — — 49,300 Net interest income (loss) after provision for loan and lease losses 235,539 338,127 73,433 (31,774 ) 615,325 Non-interest income 46,967 108,647 62,475 19,688 237,777 Non-interest expense 129,499 335,834 81,449 8,559 555,341 Income (loss) before income tax expense 153,007 110,940 54,459 (20,645 ) 297,761 Income tax expense (benefit) 47,804 34,605 17,016 (6,393 ) 93,032 Net income (loss) $ 105,203 $ 76,335 $ 37,443 $ (14,252 ) $ 204,729 The following table presents total assets for Webster's reportable segments and the Corporate and Reconciling category: Total Assets (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated At December 31, 2017 $ 9,350,028 $ 8,909,671 $ 76,308 $ 8,151,638 $ 26,487,645 At December 31, 2016 9,069,445 8,721,046 83,987 8,198,051 26,072,529

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments Webster is obligated under various non-cancelable operating leases for properties used as banking centers and other office facilities. The leases contain renewal options and escalation clauses which provide for increased rental expense, or for equipment upgrades. Rental expense under the leases was $31.1 million , $30.4 million , and $21.5 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively, and is recorded as a component of occupancy expense in the accompanying Consolidated Statements of Income. Rental income from sub-leases on certain of these properties is netted as a component of occupancy expense, while rental income under various non-cancelable operating leases for properties owned is recorded as a component of other non-interest income in the accompanying Consolidated Statements of Income. Rental income was $0.7 million , $0.8 million , and $0.8 million for the years ended December 31, 2017 , 2016 , and 2015 . The following table summarizes future minimum rental payments and receipts under lease agreements: At December 31, 2017 (In thousands) Rental Payments Rental Receipts 2018 $ 29,181 $ 717 2019 28,035 592 2020 26,254 488 2021 24,552 395 2022 20,885 353 Thereafter 77,541 1,438 Total future minimum rental payments and receipts $ 206,448 $ 3,983 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: At December 31, (In thousands) 2017 2016 Commitments to extend credit $ 5,567,687 $ 5,224,280 Standby letter of credit 195,902 128,985 Commercial letter of credit 43,200 46,497 Total credit-related financial instruments with off-balance sheet risk $ 5,806,789 $ 5,399,762 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 they relate to. These commitments subject the Company to potential exposure in excess of 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 Consolidated Balance Sheets. The following table provides a summary of activity in the reserve for unfunded credit commitments: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 2,287 $ 2,119 $ 5,151 Provision (benefit) 75 168 (3,032 ) Ending balance $ 2,362 $ 2,287 $ 2,119 The change in the provision is attributable to a benefit recorded in 2015. The benefit was the result of a change in a key assumption used in calculating expected incremental utilization of credit. The updated assumption is based on a more detailed analysis of customer behavior and performance in the months prior to a charge-off, rather than a general overall utilization rate, which should result in a better estimate of potential loss on credit-related financial instruments. 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 accruals for litigation and claims when a loss contingency is considered probable and the related amount is reasonably estimable. These accruals are 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 accruals, Webster believes that at December 31, 2017

Parent Company Information

Parent Company Information	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Information	Parent Company Information Financial information for the Parent Company only is presented in the following tables: Condensed Balance Sheets December 31, (In thousands) 2017 2016 Assets: Cash and due from banks $ 181,085 $ 152,947 Intercompany debt securities 150,000 150,000 Investment in subsidiaries 2,585,955 2,425,398 Alternative investments 2,939 4,275 Other assets 13,252 24,659 Total assets $ 2,933,231 $ 2,757,279 Liabilities and shareholders’ equity: Senior notes $ 148,447 $ 148,194 Junior subordinated debt 77,320 77,320 Accrued interest payable 2,616 2,589 Due to subsidiaries 575 365 Other liabilities 2,315 1,799 Total liabilities 231,273 230,267 Shareholders’ equity 2,701,958 2,527,012 Total liabilities and shareholders’ equity $ 2,933,231 $ 2,757,279 Condensed Statements of Income Years ended December 31, (In thousands) 2017 2016 2015 Operating Income: Dividend income from bank subsidiary $ 120,000 $ 145,000 $ 110,000 Interest on securities and deposits 4,477 1,911 546 Loss on sale of investment securities — (2,410 ) — Alternative investments income 1,504 176 2,274 Other non-interest income 204 7,485 152 Total operating income 126,185 152,162 112,972 Operating Expense: Interest expense on borrowings 10,380 9,981 9,665 Compensation and benefits 12,425 11,461 10,965 Other non-interest expense 10,583 6,278 6,005 Total operating expense 33,388 27,720 26,635 Income before income tax benefit and equity in undistributed earnings of subsidiaries and associated companies 92,797 124,442 86,337 Income tax benefit 3,004 3,086 2,929 Equity in undistributed earnings of subsidiaries and associated companies 159,638 79,599 115,463 Net income $ 255,439 $ 207,127 $ 204,729 Condensed Statements of Comprehensive Income Years ended December 31, (In thousands) 2017 2016 2015 Net income $ 255,439 $ 207,127 $ 204,729 Other comprehensive income (loss), net of tax: Net unrealized gains (losses) on available for sale securities — 584 (2,109 ) Net unrealized gains (losses) on derivative instruments 1,216 1,223 1,223 Other comprehensive loss of subsidiaries and associated companies (106 ) (694 ) (20,959 ) Other comprehensive income (loss), net of tax 1,110 1,113 (21,845 ) Comprehensive income $ 256,549 $ 208,240 $ 182,884 Condensed Statements of Cash Flows Years ended December 31, (In thousands) 2017 2016 2015 Operating activities: Net income $ 255,439 $ 207,127 $ 204,729 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed earnings of subsidiaries and associated companies (159,638 ) (79,599 ) (115,463 ) Stock-based compensation 12,276 11,438 10,935 Gain on redemption of other assets — (7,331 ) — Other, net 7,880 (3,736 ) 9,066 Net cash provided by operating activities 115,957 127,899 109,267 Investing activities: Proceeds from sale of available for sale securities — 1,089 — Purchases of intercompany debt securities — (150,000 ) — Proceeds from the sale of other assets 7,581 — — Net cash provided by (used for) investing activities 7,581 (148,911 ) — Financing activities: Preferred stock issued 145,056 — — Preferred stock redeemed (122,710 ) — — Cash dividends paid to common shareholders (94,630 ) (89,522 ) (80,964 ) Cash dividends paid to preferred shareholders (8,096 ) (8,096 ) (8,711 ) Exercise of stock options 8,259 11,762 3,060 Excess tax benefits from stock-based compensation — 3,204 2,338 Common stock repurchased/shares acquired related to employee share-based plans (23,279 ) (22,870 ) (17,815 ) Common stock warrants repurchased — (163 ) (23 ) Net cash used for financing activities (95,400 ) (105,685 ) (102,115 ) Increase (decrease) in cash and due from banks 28,138 (126,697 ) 7,152 Cash and due from banks at beginning of year 152,947 279,644 272,492 Cash and due from banks at end of year $ 181,085 $ 152,947 $ 279,644

Selected Quarterly Consolidated

Selected Quarterly Consolidated Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Selected Quarterly Consolidated Financial Information (Unaudited)	Selected Quarterly Consolidated Financial Information (Unaudited) 2017 (In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Interest income $ 219,680 $ 226,789 $ 231,021 $ 236,115 Interest expense 27,016 29,002 30,117 31,183 Net interest income 192,664 197,787 200,904 204,932 Provision for loan and lease losses 10,500 7,250 10,150 13,000 Non-interest income 63,042 64,551 65,846 66,039 Non-interest expense 163,784 164,419 161,823 171,049 Income before income tax expense 81,422 90,669 94,777 86,922 Income tax expense 21,951 29,090 30,281 17,029 Net income $ 59,471 $ 61,579 $ 64,496 $ 69,893 Earnings applicable to common shareholders $ 57,342 $ 59,485 $ 62,426 $ 67,710 Earnings per common share: Basic $ 0.62 $ 0.65 $ 0.68 $ 0.74 Diluted 0.62 0.64 0.67 0.73 2016 (In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Interest income $ 202,335 $ 202,431 $ 205,715 $ 211,432 Interest expense 26,183 25,526 25,518 26,173 Net interest income 176,152 176,905 180,197 185,259 Provision for loan and lease losses 15,600 14,000 14,250 12,500 Non-interest income 62,374 65,075 66,412 70,617 Non-interest expense 152,445 152,778 156,097 161,871 Income before income tax expense 70,481 75,202 76,262 81,505 Income tax expense 23,434 24,599 24,445 23,845 Net income $ 47,047 $ 50,603 $ 51,817 $ 57,660 Earnings applicable to common shareholders $ 44,921 $ 48,398 $ 49,634 $ 55,501 Earnings per common share: Basic $ 0.49 $ 0.53 $ 0.54 $ 0.61 Diluted 0.49 0.53 0.54 0.60

Summary of Significant Accoun31

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The Consolidated Financial Statements and the accompanying Notes thereto include the accounts of Webster Financial Corporation and all other entities in which it has a controlling financial interest. Intercompany accounts and transactions have been eliminated in consolidation. Webster's accounting and financial reporting policies conform, in all material respects, to GAAP and to general practices within the financial services industry. Assets that the Company holds or manages in a fiduciary or agency capacity for customers, typically referred to as assets under administration or assets under management are not included in the accompanying Consolidated Balance Sheets since those assets are not Webster's, and the Company is not the primary beneficiary.
Variable Interest Entities	Variable Interest Entities A variable interest entity (VIE) is an entity that has either a total equity investment that is insufficient to finance its activities without additional subordinated financial support or whose equity investors lack the ability to control the entity’s activities or lack the ability to receive expected benefits or absorb obligations in a manner that’s consistent with their investment in the entity. The Company evaluates each VIE to understand the purpose and design of the entity, and its involvement in the ongoing activities of the VIE. The Company will consolidate the VIE if it has: • the power to direct the activities of the VIE that most significantly affect the VIE's economic performance; and • an obligation to absorb losses of the VIE, or the right to receive benefits from the VIE, that could potentially be significant to the VIE.
Use of Estimates	Use of EstimatesThe preparation of financial statements in accordance with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the financial statements as well as income and expense during the period. The allowance for loan and lease losses, the fair value measurements for valuation of investments and other financial instruments, evaluation of investments for OTTI, valuation of goodwill and other intangible assets, and assessing the realizability of deferred tax assets and the measurement of uncertain tax position, as well as the status of contingencies, are particularly subject to change. Actual results could differ from those estimates.
Cash Equivalents	Cash Equivalents Cash equivalents have a maturity of three months or less. Cash and due from banks. Cash equivalents, including cash on hand, certain cash due from banks, and deposits at the FRB of Boston, are referenced as cash and due from banks in the accompanying Consolidated Balance Sheets and Consolidated Statements of Cash Flows. Interest-bearing deposits. Cash equivalents, primarily representing deposits at the FRB of Boston in excess of reserve requirements, and federal funds sold, which essentially represent uncollateralized loans to other financial institutions, are referenced as interest-bearing deposits in the accompanying Consolidated Balance Sheets and Consolidated Statements of Cash Flows. The Company regularly evaluates the credit risk associated with those financial institutions to assess that Webster is not exposed to any significant credit risk on cash equivalents.
Investment Securities	Investment Securities Investment securities are classified as available-for-sale or held-to-maturity at the time of purchase. Any classification change subsequent to trade date is reviewed for compliance with corporate objectives and accounting policy. Debt securities classified as held-to-maturity are those which Webster has the ability and intent to hold to maturity. Securities classified as held-to-maturity are recorded at amortized cost net of unamortized premiums and discounts. Discount accretion income and premium amortization expense are recognized as interest income according to a constant yield methodology, with consideration given to prepayment assumptions on mortgage backed securities. Securities classified as available-for-sale are recorded at fair value with unrealized gains and losses recorded as a component of other comprehensive income (OCI)/other comprehensive loss (OCL). Securities transferred from available-for-sale to held-to-maturity are recorded at fair value at the time of transfer, and the respective gain or loss is recorded as a separate component of OCI/OCL and amortized as an adjustment to interest income over the remaining life of the security. Securities classified as available-for-sale or held-to-maturity and in an unrealized loss position are evaluated for OTTI on a quarterly basis. The evaluation considers several qualitative factors, including the period of time the security has been in a loss position, and the amount of the unrealized loss. If the Company intends to sell the security or it is more likely than not the Company will be required to sell the security prior to recovery of its amortized cost basis, the security is written down to fair value, and the loss is recognized in non-interest income in the accompanying Consolidated Statements of Income. If the Company does not intend to sell the security and it is more likely than not that the Company will not be required to sell the security prior to recovery of its amortized cost basis, only the credit component of the unrealized loss is recorded as an impairment charge to a debt security and recognized as a loss. The remaining loss component would be recorded to accumulated other comprehensive loss, net of tax (AOCL) in the accompanying Consolidated Balance Sheets. The entire amount of an unrealized loss position of an equity security that is considered OTTI is recorded as an impairment loss in non-interest income in the accompanying Consolidated Statements of Income.
Loans Held for Sale	Loans Held for Sale Effective January 1, 2016, on a loan by loan election, residential mortgage loans that are classified as held for sale are accounted for under either the fair value option method of accounting or the lower of cost or fair value method of accounting with the election being made at the time the asset is first recognized. The Company has elected the fair value option to mitigate accounting mismatches between held for sale derivative commitments and loan valuations. Prior to January 1, 2016, residential mortgage loans that were classified as held for sale were accounted for at the lower of cost or fair value method of accounting and were valued on an individual asset basis. Loans not originated for sale but subsequently transferred to held for sale continue to be valued at the lower of cost or fair value method of accounting and are valued on an individual asset basis. Any cost amount in excess of fair value is recorded as a valuation allowance and recognized as a reduction of other income in the Consolidated Statements of Income.
Transfers and Servicing of Financial Assets	Transfers and Servicing of Financial Assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is generally considered to have been surrendered when: (i) the transferred assets are legally isolated from the Company or its consolidated affiliates, even in bankruptcy or other receivership; (ii) the transferee has the right to pledge or exchange the assets with no conditions that constrain the transferee and provide more than a trivial benefit to the Company; and (iii) the Company does not maintain the obligation or unilateral ability to reclaim or repurchase the assets. The Company sells financial assets in the normal course of business, the majority of which are residential mortgage loan sales primarily to government-sponsored enterprises through established programs, commercial loan sales through participation agreements, and other individual or portfolio loan and securities sales. In accordance with accounting guidance for asset transfers, the Company considers any ongoing involvement with transferred assets in determining whether the assets can be derecognized from the balance sheet. With the exception of servicing and certain performance-based guarantees, the Company’s continuing involvement with financial assets sold is minimal and generally limited to market customary representation and warranty clauses covering certain characteristics of the mortgage loans sold and the Company's origination process. The gain or loss on sale depends on the previous carrying amount of the transferred financial assets, the consideration received, and any other assets obtained or liabilities incurred in exchange for the transferred assets.
Loans and Leases	Loans and Leases Loans and leases are stated at the principal amount outstanding, net of amounts charged off, unearned income, unamortized premiums and discounts, and deferred loan and lease fees/costs which are recognized as yield adjustments using the interest method. These yield adjustments are amortized over the contractual life of the related loans and leases adjusted for prepayments when applicable. Interest on loans and leases is credited to interest income as earned based on the interest rate applied to principal amounts outstanding. Prepayment fees are recognized in non-interest income. Cash flows from loans and leases are presented as investing cash flows. Loans and leases are placed on non-accrual status when collection of principal and interest in accordance with contractual terms is doubtful, generally when principal or interest payments become 90 days delinquent, unless the loan or lease is well secured and in process of collection, or sooner if management concludes circumstances indicate that the borrower may be unable to meet contractual principal or interest payments. Residential real estate loans, excluding loans fully insured against loss and in the process of collection, and consumer loans are placed on non-accrual status at 90 days past due, or at the date when the Company is notified that the borrower is discharged in bankruptcy. A charge-off for the balance in excess of the fair value of the collateral less cost to sell, is recorded at 180 days if the loan balance exceeds the fair value of the collateral less costs to sell. Residential loans that are more than 90 days past due, fully insured against loss, and in the process of collection, remain accruing and are reported as 90 days or more past due and accruing. Commercial, commercial real estate loans, and equipment finance loans or leases are subject to a detailed review when 90 days past due to determine accrual status, or when payment is uncertain and a specific consideration is made to put a loan or lease on non-accrual status.
Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments	Allowance for Loan and Lease Losses The ALLL is a reserve established through a provision for loan and lease losses charged to expense and represents management’s best estimate of probable losses that may be incurred within the existing loan and lease portfolio as of the balance sheet date. The level of the allowance reflects management’s view of trends in losses, current portfolio quality, and present economic, political, and regulatory conditions. The ALLL may be allocated for specific portfolio segments; however, the entire allowance balance is available to absorb credit losses inherent in the total loan and lease portfolio. A charge-off is recorded when all or a portion of the loan or lease is deemed to be uncollectible. Back-testing is performed to compare original estimated losses and actual observed losses, resulting in ongoing refinements. While management utilizes its best judgment based on the information available at the time, the ultimate adequacy of the allowance is dependent upon a variety of factors that are beyond the Company’s control, which include the performance of the Company’s portfolio, economic conditions, interest rate sensitivity, and other external factors. The ALLL consists of the following three elements: (i) specific valuation allowances established for probable losses on impaired loans and leases; (ii) quantitative valuation allowances calculated using loss experience for like loans and leases with similar characteristics and trends, adjusted, as necessary, to reflect the impact of current conditions; and (iii) qualitative factors determined based on general economic conditions and other factors that may be internal or external to the Company. Loans and leases are considered impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impairment is evaluated on a pooled basis for smaller-balance homogeneous residential, consumer loans and small business loans. Commercial, commercial real estate, and equipment financing loans and leases over a specific dollar amount and all TDR are evaluated individually for impairment. A loan identified as a TDR is considered an impaired loan for the entire term of the loan, with few exceptions. If a loan is impaired, a specific valuation allowance may be established, and the loan is reported net, at the present value of estimated future cash flows using the loan’s original interest rate or at the fair value of collateral less cost to sell if repayment is expected from collateral liquidation. Interest payments on non-accruing impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Loans and leases, or portions thereof, are charged off when deemed uncollectible. Factors considered by management in determining impairment include payment status, collateral value, discharged bankruptcy, and the likelihood of collecting scheduled principal and interest payments. The current or weighted-average (for multiple notes within a commercial borrowing arrangement) interest rate of the loan is used as the discount rate, for determining net present value of the loan evaluated for impairment, when the interest rate floats with a specified index. A change in terms or payments would be included in the impairment calculation. See Note 4: Loans and Leases for further information. Reserve for Unfunded Commitments
Troubled Debt Restructurings	Troubled Debt Restructurings A modified loan is considered a TDR when the following two conditions are met: (i) the borrower is experiencing financial difficulties; and (ii) the modification constitutes a concession. The Company considers all aspects of the restructuring in determining whether a concession has been granted, including the debtor's ability to access funds at a market rate. In general, a concession exists when the modified terms of the loan are more attractive to the borrower than standard market terms. Modified terms are dependent upon the financial position and needs of the individual borrower. The most common types of modifications include covenant modifications and forbearance. Loans for which the borrower has been discharged under Chapter 7 bankruptcy are considered collateral dependent TDR, impaired at the date of discharge, and charged down to the fair value of collateral less cost to sell, if management considers that loss potential likely exists.
Foreclosed and Repossessed Assets	Foreclosed and Repossessed Assets Real estate acquired through foreclosure or completion of a deed in lieu of foreclosure and other assets acquired through repossession are carried at the lower of cost or market value less estimated selling costs and are included within other assets in the accompanying Consolidated Balance Sheets. Independent appraisals generally are obtained to substantiate fair value and may be subject to adjustment based upon historical experience or specific geographic trends impacting the property. Within 90 days
Premises and Equipment	Premises and Equipment Premises and equipment are carried at cost, less accumulated depreciation. Depreciation of premises and equipment is computed on a straight-line basis over the estimated useful lives of the assets, as follows: Minimum Maximum Building and Improvements 5 - 40 years Leasehold improvements 5 - 20 years (or term or lease, if shorter) Fixtures and equipment 5 - 10 years Data processing and software 3 - 7 years
Goodwill	Goodwill Goodwill represents the excess purchase price of businesses acquired over the fair value of the identifiable net assets acquired and is assigned to specific reporting units. Goodwill is not subject to amortization but rather is evaluated for impairment annually, or more frequently in interim periods if events occur or circumstances change indicating it would more likely than not result in a reduction of the fair value of a reporting unit below its carrying value.
Other Intangible Assets	Other Intangible AssetsOther intangible assets represent purchased assets that lack physical substance but can be distinguished from goodwill because of contractual or other legal rights, or because the asset is capable of being sold or exchanged either separately or in combination with a related contract, asset, or liability. Other intangible assets with finite useful lives are amortized to non-interest expense over their estimated useful lives and are evaluated for impairment whenever events occur or circumstances change indicating the carrying amount of the asset may not be recoverable. Core deposit and customer relationship intangible assets are amortized over their estimated useful lives.
Cash Surrender Value of Life Insurance	Cash Surrender Value of Life InsuranceThe investment in life insurance represents the cash surrender value of life insurance policies on certain current and former officers of Webster. Increases in the cash surrender value are recorded as non-interest income. Decreases are the result of collection on the policies due to the death of an insured. Death benefit proceeds in excess of cash surrender value are recorded in other non-interest income when realized.
Securities Sold Under Agreements to Repurchase	Securities Sold Under Agreements to RepurchaseThese agreements are accounted for as secured financing transactions since Webster maintains effective control over the transferred investment securities and the transfer meets the other criteria for such accounting. Obligations to repurchase the sold investment securities are reflected as a liability in the accompanying Consolidated Balance Sheets. The investment securities underlying the agreements are delivered to a custodial account for the benefit of the dealer or bank with whom each transaction is executed. The dealers or banks, which may sell, loan, or otherwise hypothecate such securities to other parties in the normal course of their operations, agree to resell to Webster the same securities at the maturity date of the agreements. The investment securities underlying the agreements with Bank customers are pledged; however, the customer does not have ability to hypothecate the underlying securities.
Share-based Compensation	Share-Based Compensation Webster maintains stock compensation plans under which non-qualified stock options, incentive stock options, restricted stock, restricted stock units, or stock appreciation rights may be granted to employees and directors. Share awards are issued from available treasury shares. Share-based compensation cost is recognized over the vesting period, is based on the grant-date fair value, net of a reduction for estimated forfeitures which is adjusted for actual forfeitures as they occur, and is reported as a component of compensation and benefits expense. Awards are generally subject to a 3 -year vesting period, while certain conditions provide for a 1 -year vesting period. Excess tax benefits result when tax return deductions exceed recognized compensation cost determined using the grant-date fair value approach for financial statement purposes. For time-based restricted stock and restricted stock unit awards, fair value is measured using the Company's common stock closing price at the date of grant. For performance-based restricted stock awards, fair value is measured using the Monte Carlo valuation methodology, which provides for the 3 -year performance period. Awards ultimately vest in a range from zero to 150% of the target number of shares under the grant. 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. For stock option awards the Black-Scholes Option-Pricing Model was used to measure fair value at the date of grant. Dividends are paid on the time-based shares upon grant and are non-forfeitable, while dividends are accrued on the performance-based awards and paid on earned shares when the performance target is met. See Note 18: Share-Based Plans
Income Taxes	Income Taxes Income tax expense, or benefit, is comprised of two components, current and deferred. The current component reflects taxes payable or refundable for a current period based on applicable tax laws, and the deferred component represents the tax effects of temporary differences between amounts recognized for financial accounting and tax purposes. Deferred tax assets and liabilities reflect the tax effects of such differences that are anticipated to result in taxable or deductible amounts in the future, when the temporary differences reverse. DTAs are recognized if it is more likely than not they will be realized, and may be reduced by a valuation allowance if it is more likely than not that all or some portion will not be realized.
Earnings Per Common Share	Earnings Per Common Share Earnings per common share is computed under the two-class method. Basic earnings per common share is computed by dividing earnings allocated to common shareholders by the weighted-average number of common shares outstanding during the applicable period, excluding outstanding non-participating securities. Certain non-vested restricted stock awards are participating securities as they have non-forfeitable rights to dividends or dividend equivalents. Diluted earnings per common share is computed using the weighted-average number of shares determined for the basic earnings per common share computation plus the dilutive effect of stock compensation and warrants for common stock using the treasury stock method. A reconciliation of the weighted-average shares used in calculating basic earnings per common share and the weighted-average common shares used in calculating diluted earnings per common share is provided in Note 14: Earnings Per Common Share
Comprehensive Income	Comprehensive Income Comprehensive income includes all changes in shareholders’ equity during a period, except those resulting from transactions with shareholders. Comprehensive income consists of net income, and the after-tax effect of the following items; changes in net unrealized gain/loss on securities available for sale, changes in net unrealized gain/loss on derivative instruments, and changes in net actuarial gain/loss and prior service cost for defined benefit pension and other postretirement benefit plans. Comprehensive income is reported in the accompanying Consolidated Statements of Shareholders' Equity, Consolidated Statements of Comprehensive Income, and Note 12: Accumulated Other Comprehensive Loss, Net of Tax
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Derivatives are recognized as assets and liabilities in the accompanying Consolidated Balance Sheets and measured at fair value. For exchange-traded contracts, fair value is based on quoted market prices. For non-exchange traded contracts, fair value is based on dealer quotes, pricing models, discounted cash flow methodologies, or similar techniques for which the determination of fair value may require management judgment or estimation, relating to future rates and credit activities. Interest Rate Swap Agreements. For asset/liability management purposes, the Company may use interest rate swaps or interest rate caps to hedge various exposures or to modify interest rate characteristics of various balance sheet accounts. Interest rate swaps are contracts in which a series of interest rate flows are exchanged over a prescribed period of time. The notional amount on which the interest payments are based is not exchanged. Swap agreements entered into for hedge purposes are derivative instruments and generally convert a portion of the Company’s variable-rate debt to a fixed-rate (cash flow hedge), or convert a portion of its fixed-rate debt to a variable-rate (fair value hedge). Webster uses forward-settle interest rate swaps to 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. Forward-settle swaps typically have a future effective date that coincides with the expected debt issuance date. The forward-settle swaps are typically terminated and cash settled upon hedge debt issuance date. The gain or loss on a derivative designated and qualifying as a fair value hedging instrument, as well as the offsetting gain or loss on the hedged item attributable to the risk being hedged, is recognized currently in earnings in the same accounting period. The effective portion of the gain or loss on a derivative designated and qualifying as a cash flow hedging instrument is initially reported as a component of AOCL and subsequently reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. The ineffective portion of the gain or loss on the derivative instrument, if any, is recognized in non-interest income. Interest rate derivative financial instruments receive hedge accounting treatment only if they are qualified and properly designated as hedges and are expected to be, and are, effective in substantially reducing interest rate risk arising from specifically identified assets and liabilities. A hedging instrument is expected at inception to be highly effective at offsetting changes in the hedged transactions attributable to the changes in the hedged risk. The Company expects that the hedging relationship will be highly effective; however, it does not assume there is no ineffectiveness. The Company performs quarterly prospective and retrospective assessments of the hedge effectiveness to ensure the hedging relationship continues to be highly effective and that hedge accounting can continue to be applied. Those derivative financial instruments that do not meet specified hedging criteria are recorded at fair value with changes in fair value recorded in income. Cash flows from derivative financial instruments designated for hedge accounting are classified in the cash flow statement in the same category as the cash flows of the asset or liability being hedged. Derivative Loan Commitments. Mortgage loan commitments related to the origination of mortgages that will be held for sale upon funding are considered derivative instruments. Loan commitments that are derivatives are recognized at fair value on the Consolidated Balance Sheets in other assets and other liabilities with changes in their fair values recorded in non-interest income. Counterparty Credit Risk. The Company's exposure from bilateral, non-cleared derivatives is collateralized and subject to daily margin call settlements. Credit exposure related to non-cleared derivatives may be offset by the amount of collateral pledged by the counterparty. The Company's credit exposure on interest rate swaps consists of the net favorable value plus interest payments of all swaps by each of the counterparties. Cleared derivative transactions are with our selected clearing exchange, Chicago Mercantile Exchange, and exposure is settled to market on a daily basis. There is additional credit exposure related to initial margin collateral pledged to Chicago Mercantile Exchange at trade execution.
Offsetting Assets and Liabilities	Offsetting Assets and LiabilitiesThe Company presents derivative receivables and derivative payables with the same counterparty and the related variation margin of cash collateral receivables and payables on a net basis on the Consolidated Balance Sheets when a legally enforceable master netting agreement exists. The cash collateral, relating to the initial margin, is included within accrued interest receivable and other assets in the Consolidated Balance Sheets.
Fair Value Measurements	Fair Value Measurements The Company measures many of its assets and liabilities on a fair value basis, in accordance with ASC Topic 820, " Fair Value Measurement. " Fair value is used on a recurring basis for certain assets and liabilities in which fair value is the primary basis of accounting. Examples of these include derivative instruments, available-for-sale securities and loans held for sale where the Company has elected the fair value option. Additionally, fair value is used on a non-recurring basis to evaluate assets or liabilities for impairment. Examples of these include impaired loans and leases, mortgage servicing assets, long-lived assets, goodwill, and loans not originated for sale but subsequently transferred to held for sale, which are accounted for at the lower of cost or fair value. Further information regarding the Company's policies and methodology used to measure fair value is presented in Note 16: Fair Value Measurements
Employee Retirement Benefit Plan	Employee Retirement Benefit Plan Webster Bank maintains a noncontributory defined benefit pension plan covering all employees that were participants on or before December 31, 2007. Costs related to this qualified plan, based upon actuarial computations of current and future benefits for eligible employees, are charged to non-interest expense and are funded in accordance with the requirements of the Employee Retirement Income Security Act. An asset is recognized for an overfunded plan and a liability is recognized for an underfunded plan. A supplemental retirement plan is also maintained for select executive level employees that were participants on or before December 31, 2007. Webster Bank also provides postretirement healthcare benefits to certain retired employees. In December 2016, the Company elected to change the approach to estimating service and interest components of net periodic pension cost for the retirement benefit plans. Effective January 2017, a full yield curve approach was utilized to measure the benefit obligation. The Company changed to the new estimate method to improve the correlation between projected benefit cash flows and the corresponding yield spot rates and to provide a more precise measurement of service and interest costs.
Fee Revenue	Fee RevenueGenerally, fee revenue from deposit service charges and loans is recorded when earned, except where ultimate collection is uncertain, in which case revenue is recognized as received. Trust revenue is recorded as earned on individual accounts based upon a percentage of asset value. Fee income on managed institutional accounts is recognized as earned and collected quarterly based on the quarter-end value of assets managed.
Marketing Costs	Marketing CostsMarketing costs are expensed as incurred over the projected benefit period.
Recently Adopted and Issued Accounting Standards Updates	Recently Adopted Accounting Standards Updates Effective January 1, 2017 , the following new accounting guidance was adopted by the Company: ASU No. 2016-09, Compensation - Stock Compensation (Topic 718) - Improvements to Employee Share Based Payment Accounting. The Update impacted the accounting for employee share-based payment transactions, including the income tax consequences, and classification on the statement of cash flows. The Update requires the Company to recognize the income tax effects of awards in the income statement on a prospective basis when the awards vest or are settled, compared to within additional paid-in capital. As a result, applicable excess tax benefits and tax deficiencies are recorded as an income tax benefit or expense, respectively. The Company elected to present the classification on the statement of cash flows on a prospective basis to better align this presentation with the income tax effects. The impact of the Update will vary from period to period based on the Company's stock price and the quantity of shares that vest or are settled within a given period. The Update also requires the Company to elect the accounting for forfeitures of share-based payments by either (i) recognizing forfeitures of awards as they occur or (ii) estimating the number of awards expected to be forfeited and adjusting the estimate when it is likely to change, as is currently required. The Company elected to account for forfeitures of share-based payments by estimating the number of awards expected to be forfeited and adjusting the estimate when it is likely to change, which is in accordance with the Company's previous accounting practices. The adoption of this accounting standard did not have a material impact on the Company's financial statements. ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The Update issued in February 2018, provides for the reclassification of the effect of remeasuring deferred tax balances related to items within accumulated other comprehensive loss, net of tax to retained earnings resulting from the Tax Act. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company elected to early adopt the Update during the fourth quarter 2017. As a result, the Company reclassified $15.6 million from accumulated other comprehensive loss, net of tax to retained earnings. Accounting Standards Issued but not yet Adopted The following list identifies ASUs applicable to the Company that have been issued by the FASB but are not yet effective: ASU No. 2017-12, Derivatives and Hedging (Topic 815) - Targeted Improvements to Accounting for Hedging Activities. The purpose of the Update is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. The update requires a modified retrospective transition method in which the Company will recognize a cumulative effect of the change on the opening balance for each affected component of equity in the financial statements as of the date of adoption. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company is in the process of assessing all potential impacts of the standard including the potential to early adopt the Update. ASU No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities. The Update is intended to enhance the accounting for the amortization of premiums for purchased callable debt securities. Specifically, 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. The Update is being issued in response to concerns from stakeholders that, current GAAP excludes certain callable debt securities from consideration of early repayment of principal even if the holder is certain that the call will be exercised. The Update, upon adoption, is expected to accelerate the Company’s recognition of premium amortization on debt securities held within the portfolio. The amendments in the Update will be applied on a modified retrospective basis through a cumulative-effect adjustment directly through retained earnings upon adoption. Management is in the process of evaluating the full impact of adopting the Update including, but not limited to the following: • Modifying system amortization requirements; • Evaluation of premiums associated with debt securities to determine the appropriate cumulative-effect adjustment; and • Establishing new accounting policies pertaining to premium amortization on purchased callable debt securities. The Update is effective for the Company on January 1, 2019 and early adoption is permitted. The Company is evaluating the potential to early adopt the Update. 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 part of compensation expense and the other components of net periodic benefit cost separately from service cost in the Company's Consolidated Statements of Income. The Company currently includes all components of net periodic benefit cost in "compensation and benefits" expense in the Consolidated Statements of Income. Upon adoption of this Update in the first quarter 2018, only service cost will remain in compensation and benefits expense, and the other components (interest cost on benefit obligations, expected return on plan assets, amortization of prior service cost, and recognized net loss) will be included in "other expense" in the Consolidated Statements of Income. The other components of net periodic benefit cost were $3.4 million and $6.1 million for the years ended December 31, 2017 and 2016, respectively. 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 to the goodwill impairment analysis which involves calculating the implied fair value of goodwill determined in the same manner as the amount of goodwill recognized in a business combination upon acquisition. Entities will still have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The update must be applied prospectively and is effective for the Company on January 1, 2020. Early adoption is permitted. The Company does not expect the new guidance to have a material impact on its financial statements. ASU No. 2016-15, Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments. The Update addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The Update addresses the following eight issues: 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 Update will be implemented using a retrospective transition approach during the first quarter 2018, and will not have a significant impact on the Company's financial statements. ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments. Current GAAP requires an "incurred loss" methodology for recognizing credit losses. This approach delays recognition until it is probable a loss has been incurred. Both financial institutions and users of their financial statements expressed concern that current GAAP restricts the ability to record credit losses that are expected, but do not yet meet the "probable" threshold. The main objective of this Update is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in this Update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The Change from an "incurred loss" method to an "expected loss" method represents a fundamental shift from existing GAAP, and is likely to result in a material increase to the Company's accounting for credit losses on financial instruments. To prepare for implementation of the new standard the Company has established a project lead and has formalized a cross functional steering committee comprised of members from different disciplines including Credit, Finance and Treasury as well as specific working groups to focus on key components of the development process. In addition, through one of the working groups, the Company has begun to evaluate the effect that this Update will have on its financial statements and related disclosures. An implementation project plan has been created and is made up of targeted work streams focused on credit models, data management, accounting, and governance. These work streams are collectively assessing resources that may be required, use of existing and new models, data availability, and system solutions to facilitate implementation. The Update will be effective for the Company on January 1, 2020. While we are currently unable to reasonably estimate the impact of adopting the Update, we expect the impact of adoption will be significantly influenced by the composition, characteristics and quality of our loan and securities portfolios as well as the economic conditions as of the adoption date. ASU No. 2016-02, Leases (Topic 842). The Update introduces a lessee model that brings most leases onto the balance sheet. The Update also aligns certain of the underlying principles of the new lessor model with those in ASC 606 "Revenue from Contracts with Customers", the FASB’s new revenue recognition standard (e.g., evaluating how collectability should be considered and determining when profit can be recognized). Furthermore, the Update addresses other concerns including the elimination of the required use of bright-line tests for determining lease classification. Lessors are required to provide additional transparency into the exposure to the changes in value of their residual assets and how they manage that exposure. The Update is effective for the Company on January 1, 2019. A modified retrospective transition approach is required for leases existing at or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company is in the early assessment stage and will continue to review the existing lease portfolio to evaluate the impact of the new accounting guidance on the financial statements. ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities. This Update 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 practicability exception, 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. With the exception of disclosure requirements that will be adopted prospectively, the Update must be adopted on a modified retrospective basis. The Update also emphasizes the existing requirement to use exit prices to measure fair value for disclosure purposes and clarifies that entities should not make use of a practicability exception in determining the fair value of loans. The Company will adopt the Update during the first quarter of 2018 and will not have a material impact on the Company's financial statements. ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). Also, subsequent ASUs issued to clarify this Topic. In May 2014, the FASB issued new accounting guidance for recognizing revenue from contracts with customers, which is effective on January 1, 2018. ASU 2014-09 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 current revenue recognition guidance, including industry-specific guidance. The Update is 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 Update is effective for the first quarter of 2018, and can be adopted through either a full retrospective transition, or a modified retrospective transition approach. The Update excludes 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). As a result a substantial amount of the Company's revenue will not be affected.

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Property, Plant and Equipment	Premises and equipment are carried at cost, less accumulated depreciation. Depreciation of premises and equipment is computed on a straight-line basis over the estimated useful lives of the assets, as follows: Minimum Maximum Building and Improvements 5 - 40 years Leasehold improvements 5 - 20 years (or term or lease, if shorter) Fixtures and equipment 5 - 10 years Data processing and software 3 - 7 years At December 31, (In thousands) 2017 2016 Land $ 11,302 $ 12,595 Buildings and improvements 80,646 83,903 Leasehold improvements 82,067 83,971 Fixtures and equipment 76,665 76,146 Data processing and software 234,667 220,002 Total premises and equipment 485,347 476,617 Less: Accumulated depreciation and amortization (355,346 ) (339,204 ) Premises and equipment, net $ 130,001 $ 137,413 Depreciation and amortization of premises and equipment was $33.1 million , $30.8 million , and $28.4 million for the years ended December 31, 2017 , 2016 , and 2015

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2017
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 December 31, 2017 2016 (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 $ 1,247 $ — $ — $ 1,247 $ 734 $ — $ — $ 734 Agency CMO 308,989 1,158 (3,814 ) 306,333 419,865 3,344 (3,503 ) 419,706 Agency MBS 1,124,960 2,151 (19,270 ) 1,107,841 969,460 4,398 (19,509 ) 954,349 Agency CMBS 608,276 — (20,250 ) 588,026 587,776 63 (14,567 ) 573,272 CMBS 358,984 2,157 (74 ) 361,067 473,974 4,093 (702 ) 477,365 CLO 209,075 910 (134 ) 209,851 425,083 2,826 (519 ) 427,390 Single issuer-trust preferred 7,096 — (46 ) 7,050 30,381 — (1,748 ) 28,633 Corporate debt 56,504 797 (679 ) 56,622 108,490 1,502 (350 ) 109,642 Total available-for-sale $ 2,675,131 $ 7,173 $ (44,267 ) $ 2,638,037 $ 3,015,763 $ 16,226 $ (40,898 ) $ 2,991,091 Held-to-maturity: Agency CMO $ 260,114 $ 664 $ (4,824 ) $ 255,954 $ 339,455 $ 1,977 $ (3,824 ) $ 337,608 Agency MBS 2,569,735 16,989 (37,442 ) 2,549,282 2,317,449 26,388 (41,768 ) 2,302,069 Agency CMBS 696,566 — (10,011 ) 686,555 547,726 694 (1,348 ) 547,072 Municipal bonds and notes 711,381 8,584 (6,558 ) 713,407 655,813 4,389 (25,749 ) 634,453 CMBS 249,273 2,175 (620 ) 250,828 298,538 4,107 (411 ) 302,234 Private Label MBS 323 1 — 324 1,677 12 — 1,689 Total held-to-maturity $ 4,487,392 $ 28,413 $ (59,455 ) $ 4,456,350 $ 4,160,658 $ 37,567 $ (73,100 ) $ 4,125,125
Other than Temporary Impairment, Credit Losses Recognized in Earnings	The following table presents the changes in OTTI: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 3,243 $ 3,288 $ 3,696 Reduction for securities sold or called (2,005 ) (194 ) (518 ) Additions for OTTI not previously recognized 126 149 110 Ending balance $ 1,364 $ 3,243 $ 3,288
Summary of Gross Unrealized Losses not Considered OTTI	The following tables provide information on fair value and unrealized losses for the individual securities with an unrealized loss, aggregated by investment security type and length of time that the individual securities have been in a continuous unrealized loss position: At December 31, 2017 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 81,001 $ (449 ) $ 119,104 $ (3,365 ) 27 $ 200,105 $ (3,814 ) Agency MBS 416,995 (2,920 ) 606,021 (16,350 ) 135 1,023,016 (19,270 ) Agency CMBS 54,182 (851 ) 533,844 (19,399 ) 36 588,026 (20,250 ) CMBS 23,869 (74 ) — — 6 23,869 (74 ) CLO 56,335 (134 ) — — 3 56,335 (134 ) Single issuer-trust preferred 7,050 (46 ) — — 1 7,050 (46 ) Corporate debt 11,082 (395 ) 6,265 (284 ) 4 17,347 (679 ) Total 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 ) Total held-to-maturity in an unrealized loss position $ 1,536,069 $ (13,687 ) $ 1,655,375 $ (45,768 ) 388 $ 3,191,444 $ (59,455 ) At December 31, 2016 Less Than Twelve Months Twelve Months or Longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses # of Holdings Fair Value Unrealized Losses Available-for-sale: Agency CMO $ 107,853 $ (2,168 ) $ 67,351 $ (1,335 ) 15 $ 175,204 $ (3,503 ) Agency MBS 512,075 (10,503 ) 252,779 (9,006 ) 97 764,854 (19,509 ) Agency CMBS 554,246 (14,567 ) — — 32 554,246 (14,567 ) CMBS 12,427 (24 ) 63,930 (678 ) 12 76,357 (702 ) CLO 49,946 (54 ) 50,237 (465 ) 5 100,183 (519 ) Single issuer-trust preferred — — 28,633 (1,748 ) 5 28,633 (1,748 ) Corporate debt — — 7,384 (350 ) 2 7,384 (350 ) Total available-for-sale in an unrealized loss position $ 1,236,547 $ (27,316 ) $ 470,314 $ (13,582 ) 168 $ 1,706,861 $ (40,898 ) Held-to-maturity: Agency CMO $ 163,439 $ (3,339 ) $ 17,254 $ (485 ) 16 $ 180,693 $ (3,824 ) Agency MBS 1,394,623 (32,942 ) 273,779 (8,826 ) 150 1,668,402 (41,768 ) Agency CMBS 347,725 (1,348 ) — — 25 347,725 (1,348 ) Municipal bonds and notes 384,795 (25,745 ) 1,192 (4 ) 196 385,987 (25,749 ) CMBS 60,768 (411 ) — — 8 60,768 (411 ) Total held-to-maturity in an unrealized loss position $ 2,351,350 $ (63,785 ) $ 292,225 $ (9,315 ) 395 $ 2,643,575 $ (73,100 )
Summary of Sale Proceeds of Available for Sale Securities	The following table provides information on sales of available-for-sale securities: Years ended December 31, (In thousands) 2017 2016 2015 Proceeds from sales (1) $ — $ 259,273 $ 95,101 Gross realized gains on sales $ — $ 2,891 $ 1,029 Less: Gross realized losses on sales — 2,477 420 Gain on sale of investment securities, net $ — $ 414 $ 609
Summary of Debt Securities by Contractual Maturity	The amortized cost and fair value of debt securities by contractual maturity, including called securities, are set forth below: At December 31, 2017 Available-for-Sale Held-to-Maturity (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 1,247 $ 1,247 $ 33,654 $ 34,145 Due after one year through five years 40,066 40,447 3,839 3,857 Due after five through ten years 332,558 333,931 37,870 38,450 Due after ten years 2,301,260 2,262,412 4,412,029 4,379,898 Total debt securities $ 2,675,131 $ 2,638,037 $ 4,487,392 $ 4,456,350

Loans and Leases (Tables)

Loans and Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	The following table summarizes loans and leases: At December 31, (In thousands) 2017 2016 Residential $ 4,490,878 $ 4,254,682 Consumer 2,590,225 2,684,500 Commercial 5,368,694 4,940,931 Commercial Real Estate 4,523,828 4,510,846 Equipment Financing 550,233 635,629 Loans and leases (1) (2) $ 17,523,858 $ 17,026,588 (1) Loans and leases include net deferred fees and net premiums and discounts of $20.6 million and $17.3 million at December 31, 2017 and December 31, 2016 , respectively. (2) At December 31, 2017 , the Company had pledged $6.7 billion of eligible loans as collateral to support borrowing capacity at the FHLB of Boston and the FRB of Boston.
Past Due Financing Receivables	The following tables summarize the aging of loans and leases: At December 31, 2017 (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 and Leases 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 At December 31, 2016 (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 and Leases Residential $ 8,631 $ 2,609 $ — $ 47,279 $ 58,519 $ 4,196,163 $ 4,254,682 Consumer: Home equity 8,831 5,782 — 35,926 50,539 2,359,354 2,409,893 Other consumer 2,233 1,485 — 1,663 5,381 269,226 274,607 Commercial: Commercial non-mortgage 1,382 577 749 38,190 40,898 4,094,727 4,135,625 Asset-based — — — — — 805,306 805,306 Commercial real estate: Commercial real estate 6,357 1,816 — 9,871 18,044 4,117,742 4,135,786 Commercial construction — — — 662 662 374,398 375,060 Equipment financing 903 693 — 225 1,821 633,808 635,629 Total $ 28,337 $ 12,962 $ 749 $ 133,816 $ 175,864 $ 16,850,724 $ 17,026,588
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 ALLL: At or for the Year ended December 31, 2017 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total Allowance for loan and lease losses: Balance at January 1, 2017 $ 23,226 $ 45,233 $ 71,905 $ 47,477 $ 6,479 $ 194,320 Provision (benefit) charged to expense (2,692 ) 9,367 23,417 11,040 (232 ) 40,900 Losses charged off (2,500 ) (24,447 ) (8,147 ) (9,275 ) (558 ) (44,927 ) Recoveries 1,024 6,037 2,358 165 117 9,701 Balance at December 31, 2017 $ 19,058 $ 36,190 $ 89,533 $ 49,407 $ 5,806 $ 199,994 Individually evaluated for impairment $ 4,805 $ 1,668 $ 9,786 $ 272 $ 23 $ 16,554 Collectively evaluated for impairment $ 14,253 $ 34,522 $ 79,747 $ 49,135 $ 5,783 $ 183,440 Loan and lease balances: Individually evaluated for impairment $ 114,295 $ 45,436 $ 72,471 $ 11,226 $ 3,325 $ 246,753 Collectively evaluated for impairment 4,376,583 2,544,789 5,296,223 4,512,602 546,908 17,277,105 Loans and leases $ 4,490,878 $ 2,590,225 $ 5,368,694 $ 4,523,828 $ 550,233 $ 17,523,858 At or for the Year ended December 31, 2016 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total Allowance for loan and lease losses: Balance at January 1, 2016 $ 25,876 $ 42,052 $ 59,977 $ 41,598 $ 5,487 $ 174,990 Provision (benefit) charged to expense 230 18,507 28,662 7,930 1,021 56,350 Losses charged off (4,636 ) (20,669 ) (18,360 ) (2,682 ) (565 ) (46,912 ) Recoveries 1,756 5,343 1,626 631 536 9,892 Balance at December 31, 2016 $ 23,226 $ 45,233 $ 71,905 $ 47,477 $ 6,479 $ 194,320 Individually evaluated for impairment $ 8,090 $ 2,903 $ 7,422 $ 169 $ 9 $ 18,593 Collectively evaluated for impairment $ 15,136 $ 42,330 $ 64,483 $ 47,308 $ 6,470 $ 175,727 Loan and lease balances: Individually evaluated for impairment $ 119,424 $ 45,719 $ 53,037 $ 24,755 $ 6,420 $ 249,355 Collectively evaluated for impairment 4,135,258 2,638,781 4,887,894 4,486,091 629,209 16,777,233 Loans and leases $ 4,254,682 $ 2,684,500 $ 4,940,931 $ 4,510,846 $ 635,629 $ 17,026,588 At or for the Year ended December 31, 2015 (In thousands) Residential Consumer Commercial Commercial Real Estate Equipment Financing Total Allowance for loan and lease losses: Balance at January 1, 2015 $ 25,452 $ 43,518 $ 47,068 $ 37,148 $ 6,078 $ 159,264 Provision (benefit) charged to expense 6,057 11,847 21,693 11,381 (1,678 ) 49,300 Losses charged off (6,508 ) (17,679 ) (11,522 ) (7,578 ) (273 ) (43,560 ) Recoveries 875 4,366 2,738 647 1,360 9,986 Balance at December 31, 2015 $ 25,876 $ 42,052 $ 59,977 $ 41,598 $ 5,487 $ 174,990 Individually evaluated for impairment $ 10,364 $ 3,477 $ 5,197 $ 3,163 $ 3 $ 22,204 Collectively evaluated for impairment $ 15,512 $ 38,575 $ 54,780 $ 38,435 $ 5,484 $ 152,786 Loan and lease balances: Individually evaluated for impairment $ 134,448 $ 48,425 $ 56,581 $ 39,295 $ 422 $ 279,171 Collectively evaluated for impairment 3,926,553 2,654,135 4,259,418 3,952,354 600,104 15,392,564 Loans and leases $ 4,061,001 $ 2,702,560 $ 4,315,999 $ 3,991,649 $ 600,526 $ 15,671,735
Impaired Loans	The following tables summarize impaired loans and leases: At December 31, 2017 (In thousands) Unpaid Principal Balance Total Recorded Investment Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential: 1-4 family $ 125,352 $ 114,295 $ 69,759 $ 44,536 $ 4,805 Consumer home equity 50,809 45,436 34,418 11,018 1,668 Commercial: Commercial non-mortgage 79,900 71,882 27,313 44,569 9,786 Asset-based 3,272 589 589 — — Commercial real estate: Commercial real estate 11,994 11,226 6,387 4,839 272 Commercial construction — — — — — Equipment financing 3,409 3,325 2,932 393 23 Total $ 274,736 $ 246,753 $ 141,398 $ 105,355 $ 16,554 At December 31, 2016 (In thousands) Unpaid Principal Balance Total Recorded Investment Recorded Investment No Allowance Recorded Investment With Allowance Related Valuation Allowance Residential: 1-4 family $ 131,468 $ 119,424 $ 21,068 $ 98,356 $ 8,090 Consumer home equity 52,432 45,719 22,746 22,973 2,903 Commercial: Commercial non-mortgage 57,732 53,037 26,006 27,031 7,422 Asset based — — — — — Commercial real estate: Commercial real estate 24,146 23,568 19,591 3,977 169 Commercial construction 1,188 1,187 1,187 — — Equipment financing 6,398 6,420 6,197 223 9 Total $ 273,364 $ 249,355 $ 96,795 $ 152,560 $ 18,593 The following table summarizes the average recorded investment and interest income recognized for impaired loans and leases: Years ended December 31, 2017 2016 2015 (In thousands) Average Recorded Investment Accrued Interest Income Cash Basis Interest Income Average Recorded Investment Accrued Interest Income Cash Basis Interest Income Average Accrued Cash Basis Interest Income Residential $ 116,859 $ 4,138 $ 1,264 $ 126,936 $ 4,377 $ 1,200 $ 138,215 $ 4,473 $ 1,139 Consumer home equity 45,578 1,323 1,046 47,072 1,361 985 49,337 1,451 1,099 Commercial Commercial non-mortgage 62,459 1,095 — 54,708 1,540 — 46,379 1,319 — Asset based 295 — — — — — — — — Commercial real estate: Commercial real estate 17,397 417 — 28,451 511 — 64,495 1,165 — Commercial construction 594 12 — 3,574 92 — 6,062 133 — Equipment financing 4,872 207 — 3,421 184 — 527 16 — Total $ 248,054 $ 7,192 $ 2,310 $ 264,162 $ 8,065 $ 2,185 $ 305,015 $ 8,557 $ 2,238
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 At December 31, At December 31, At December 31, (In thousands) 2017 2016 2017 2016 2017 2016 (1) - (6) Pass $ 5,048,162 $ 4,655,007 $ 4,355,916 $ 4,357,458 $ 525,105 $ 618,084 (7) Special Mention 104,594 56,240 62,065 69,023 8,022 1,324 (8) Substandard 206,883 226,603 105,847 84,365 17,106 16,221 (9) Doubtful 9,055 3,081 — — — — Total $ 5,368,694 $ 4,940,931 $ 4,523,828 $ 4,510,846 $ 550,233 $ 635,629
Troubled Debt Restructurings on Financing Receivables	Troubled Debt Restructurings The following table summarizes information for TDRs: At December 31, (Dollars in thousands) 2017 2016 Accrual status $ 147,113 $ 147,809 Non-accrual status 74,291 75,719 Total recorded investment of TDR (1) $ 221,404 $ 223,528 Specific reserves for TDR included in the balance of ALLL $ 12,384 $ 14,583 Additional funds committed to borrowers in TDR status 2,736 459 (1) Total recorded investment of TDRs exclude $0.1 million and $0.7 million at December 31, 2017 and December 31, 2016 , respectively, of accrued interest receivable. For years ended December 31, 2017 , 2016 and 2015 , Webster charged off $3.2 million , $18.6 million , and $11.8 million , respectively, for the portion of TDRs deemed to be uncollectible. The following table provides information on the type of concession for loans and leases modified as TDRs: Years ended December 31, 2017 2016 2015 Number of Loans and Leases Post- Modification Recorded Investment (1) Number of Loans and Leases Post- Modification Recorded Investment (1) Number of Loans and Leases Post- Modification Recorded Investment (1) (Dollars in thousands) Residential: Extended Maturity 16 $ 2,569 17 $ 2,801 27 $ 4,909 Adjusted Interest rates 2 335 2 528 3 573 Combination Rate and Maturity 12 1,733 13 1,537 26 5,315 Other (2) 39 6,200 24 4,090 30 4,366 Consumer home equity: Extended Maturity 12 976 11 484 12 1,012 Adjusted Interest rates 1 247 — — — — Combination Rate and Maturity 14 3,469 15 1,156 12 945 Other (2) 73 4,907 52 3,131 68 3,646 Commercial non mortgage: Extended Maturity 12 1,233 12 14,883 3 254 Adjusted Interest rates — — — — 1 24 Combination Rate and Maturity 18 9,592 2 648 7 5,361 Other (2) 4 6,375 13 1,767 20 22,048 Commercial real estate: Extended Maturity — — 3 4,921 1 315 Adjusted Interest rates — — 1 237 — — Combination Rate and Maturity — — 2 335 1 42 Other (2) — — 1 509 1 405 Equipment Financing Extended Maturity — — 7 6,642 — — Total 203 $ 37,636 175 $ 43,669 212 $ 49,215 (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, and/or other concessions. The were no significant amounts of loans and leases modified as TDRs within the previous 12 months and for which there was a payment default for the years ended December 31, 2017 , 2016 and 2015 . The recorded investment of TDRs in commercial, commercial real estate, and equipment financing segregated by risk rating exposure is as follows: At December 31, (In thousands) 2017 2016 (1) - (6) Pass $ 8,268 $ 10,210 (7) Special Mention 355 7 (8) Substandard 53,050 45,509 (9) Doubtful — 2,738 Total $ 61,673 $ 58,464

Transfers of Financial Assets (

Transfers of Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 790 $ 1,192 $ 1,059 Provision (benefit) charged to expense 100 (303 ) 133 Repurchased loans and settlements charged off (18 ) (99 ) — Ending balance $ 872 $ 790 $ 1,192 Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 2,287 $ 2,119 $ 5,151 Provision (benefit) 75 168 (3,032 ) Ending balance $ 2,362 $ 2,287 $ 2,119
Schedule of Loan Sale Activity [Table Text Block]	The following table provides information for mortgage banking activities: Years ended December 31, (In thousands) 2017 2016 2015 Residential mortgage loans held for sale: Proceeds from sale $ 335,656 $ 438,925 $ 452,590 Loans sold with servicing rights retained 304,788 399,318 416,277 Net gain on sale 6,211 11,629 7,795 Ancillary fees 2,629 3,532 — Fair value option adjustment 1,097 (526 ) —
Servicing Asset at Amortized Cost	The following table presents the changes in carrying value for mortgage servicing assets: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 24,466 $ 20,698 $ 19,379 Additions 9,249 11,312 8,027 Amortization (8,576 ) (7,544 ) (6,708 ) Ending balance $ 25,139 $ 24,466 $ 20,698

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Premises and equipment are carried at cost, less accumulated depreciation. Depreciation of premises and equipment is computed on a straight-line basis over the estimated useful lives of the assets, as follows: Minimum Maximum Building and Improvements 5 - 40 years Leasehold improvements 5 - 20 years (or term or lease, if shorter) Fixtures and equipment 5 - 10 years Data processing and software 3 - 7 years At December 31, (In thousands) 2017 2016 Land $ 11,302 $ 12,595 Buildings and improvements 80,646 83,903 Leasehold improvements 82,067 83,971 Fixtures and equipment 76,665 76,146 Data processing and software 234,667 220,002 Total premises and equipment 485,347 476,617 Less: Accumulated depreciation and amortization (355,346 ) (339,204 ) Premises and equipment, net $ 130,001 $ 137,413 Depreciation and amortization of premises and equipment was $33.1 million , $30.8 million , and $28.4 million for the years ended December 31, 2017 , 2016 , and 2015
Disclosure of Long Lived Assets Held-for-sale	The following table provides a summary of activity for assets held for disposition: Years ended December 31, (In thousands) 2017 2016 Beginning balance $ 637 $ 637 Additions 2,006 — Write-downs (529 ) — Sales (1,970 ) — Ending balance $ 144 $ 637

Goodwill and Other Intangible37

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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 December 31, 2017 2016 (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 $ 516,560 $ 516,560 HSA Bank 21,813 21,813 21,813 21,813 Total goodwill $ 538,373 $ 538,373 $ 538,373 $ 538,373 Other intangible assets: HSA Bank - Core deposit intangible assets $ 22,000 $ (8,610 ) $ 13,390 $ 22,000 $ (6,162 ) $ 15,838 HSA Bank - Customer relationships 21,000 (4,779 ) 16,221 21,000 (3,164 ) 17,836 Total other intangible assets $ 43,000 $ (13,389 ) $ 29,611 $ 43,000 $ (9,326 ) $ 33,674
Schedule Of Expected Amortization Expense, Next Four Years	As of December 31, 2017 , the remaining estimated aggregate future amortization expense for intangible assets is as follows: (In thousands) 2018 $ 3,847 2019 3,847 2020 3,847 2021 3,847 2022 3,847 Thereafter 10,376

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Income tax expense reflects the following expense (benefit) components: Years ended December 31, (In thousands) 2017 2016 2015 Current: Federal $ 96,364 $ 73,194 $ 97,575 State and local 11,061 5,429 10,970 Total current 107,425 78,623 108,545 Deferred: Federal 39,568 12,542 (7,279 ) State and local (48,642 ) 5,158 (8,234 ) Total deferred (9,074 ) 17,700 (15,513 ) Total federal 135,932 85,736 90,296 Total state and local (37,581 ) 10,587 2,736 Income tax expense $ 98,351 $ 96,323 $ 93,032
Schedule of Effective Income Tax Rate Reconciliation	The following table reflects a reconciliation of reported income tax expense to the amount that would result from applying the federal statutory rate of 35.0% : Years ended December 31, 2017 2016 2015 (Dollars in thousands) Amount Percent Amount Percent Amount Percent Income tax expense at federal statutory rate $ 123,826 35.0 % $ 106,208 35.0 % $ 104,217 35.0 % Reconciliation to reported income tax expense: SALT expense, net of federal 8,189 2.3 6,882 2.3 7,563 2.5 Tax-exempt interest income, net (10,826 ) (3.1 ) (8,917 ) (2.9 ) (7,117 ) (2.4 ) SALT DTA adjustments, net of federal (28,724 ) (8.1 ) — — (5,785 ) (1.9 ) Tax Act impacts, net 20,891 5.9 — — — — Excess tax benefits, net (6,349 ) (1.8 ) — — — — Increase in cash surrender value of life insurance (5,120 ) (1.4 ) (5,166 ) (1.7 ) (4,557 ) (1.5 ) Other, net (3,536 ) (1.0 ) (2,684 ) (1.0 ) (1,289 ) (0.5 ) Income tax expense and effective tax rate $ 98,351 27.8 % $ 96,323 31.7 % $ 93,032 31.2 %
Schedule of Deferred Tax Assets and Liabilities	The following table reflects the significant components of the DTAs, net: At December 31, (In thousands) 2017 2016 Deferred tax assets: Allowance for loan and lease losses $ 51,203 $ 77,908 Net operating loss and credit carry forwards 71,813 64,644 Compensation and employee benefit plans 25,023 46,433 Net losses on derivative instruments 3,767 8,624 Net unrealized loss on securities available for sale 9,548 9,898 Other 12,273 17,682 Gross deferred tax assets 173,627 225,189 Valuation allowance (38,292 ) (71,474 ) Total deferred tax assets, net of valuation allowance $ 135,335 $ 153,715 Deferred tax liabilities: Equipment-financing leases $ 27,955 $ 41,910 Deferred income on repurchase of debt 1,275 4,251 Intangible assets 6,164 9,952 Mortgage servicing assets 4,445 7,313 Other 2,866 5,898 Gross deferred tax liabilities 42,705 69,324 Deferred tax assets, net $ 92,630 $ 84,391
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible	The following table reflects a reconciliation of the beginning and ending balances of unrecognized tax benefits (UTBs): Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 3,847 $ 5,094 $ 4,593 Additions as a result of tax positions taken during the current year 584 613 865 Additions as a result of tax positions taken during prior years 7 — 1,254 Reductions as a result of tax positions taken during prior years (61 ) (625 ) (247 ) Reductions relating to settlements with taxing authorities (392 ) (693 ) (992 ) Reductions as a result of lapse of statute of limitation periods (390 ) (542 ) (379 ) Ending balance $ 3,595 $ 3,847 $ 5,094

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Deposit Liabilities, Type [Table Text Block]	A summary of deposits by type follows: At December 31, (In thousands) 2017 2016 Non-interest-bearing: Demand $ 4,191,496 $ 4,021,061 Interest-bearing: Checking 2,736,952 2,528,274 Health savings accounts 5,038,681 4,362,503 Money market 2,209,492 2,047,121 Savings 4,348,700 4,320,090 Time deposits 2,468,408 2,024,808 Total interest-bearing 16,802,233 15,282,796 Total deposits $ 20,993,729 $ 19,303,857 Time deposits and interest-bearing checking, included in above balances, obtained through brokers $ 898,157 $ 848,618 Time deposits, included in above balance, that meet or exceed the FDIC limit 561,512 490,721 Demand deposit overdrafts reclassified as loan balances 2,210 1,885
Time Deposit Maturities [Table Text Block]	The scheduled maturities of time deposits are as follows: (In thousands) At December 31, 2017 2018 $ 1,381,899 2019 693,554 2020 236,955 2021 106,042 2022 49,831 Thereafter 127 Total time deposits $ 2,468,408

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Repurchase Agreements	The following table summarizes securities sold under agreements to repurchase and other borrowings: At December 31, (In thousands) 2017 2016 Total Outstanding Rate Total Outstanding Rate Securities sold under agreements to repurchase: Original maturity of one year or less $ 288,269 0.17 $ 340,526 0.16 Original maturity of greater than one year, non-callable 300,000 3.10 400,000 3.09 Total securities sold under agreements to repurchase 588,269 1.66 740,526 1.82 Fed funds purchased 55,000 1.37 209,000 0.46 Securities sold under agreements to repurchase and other borrowings $ 643,269 1.64 $ 949,526 1.53
Federal Home Loan Bank, Advances	The following table provides information for FHLB advances: At December 31, 2017 2016 (Dollars in thousands) Total Outstanding Weighted- Average Contractual Coupon Rate Total Outstanding Weighted- Average Contractual Coupon Rate Maturing within 1 year $ 1,150,000 1.48 % $ 2,130,500 0.71 % After 1 but within 2 years 103,026 1.81 200,000 1.36 After 2 but within 3 years 215,000 1.73 128,026 1.73 After 3 but within 4 years 200,000 4.13 175,000 1.77 After 4 but within 5 years 170 — 200,000 1.81 After 5 years 8,909 1.96 9,370 2.59 1,677,105 1.85 2,842,896 0.95 Premiums on advances — 12 Federal Home Loan Bank advances $ 1,677,105 $ 2,842,908 Aggregate carrying value of assets pledged as collateral $ 6,402,066 $ 5,967,318 Remaining borrowing capacity $ 2,600,624 $ 1,192,758
Schedule of Long-Term Debt	The following table summarizes long-term debt: At December 31, (Dollars in thousands) 2017 2016 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 (727 ) (845 ) Debt issuance cost on senior fixed-rate notes (826 ) (961 ) Long-term debt $ 225,767 $ 225,514 (1) The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month LIBOR plus 2.95% , was 4.55% at December 31, 2017 and 3.94% at December 31, 2016 .

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Stock by Class	Share activity during the year ended December 31, 2017 is as follows: Preferred Stock Series E Preferred Stock Series F Common Stock Issued Treasury Stock Held Common Stock Outstanding Balance at January 1, 2017 5,060 — 93,651,601 1,899,502 91,752,099 Restricted share activity — — — (124,800 ) 124,800 Stock options exercised — — — (338,176 ) 338,176 Common stock repurchased — — — 222,000 (222,000 ) Warrant exercise — — 28,690 — 28,690 Series F Preferred Stock issuance — 6,000 — — — Series E Preferred Stock redemption (5,060 ) — — — — Balance at December 31, 2017 — 6,000 93,680,291 1,658,526 92,021,765

Accumulated Other Comprehensi42

Accumulated Other Comprehensive Loss, Net of Tax (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Other Comprehensive Income (Loss)	The following table summarizes the changes in AOCL by component: (In thousands) Available For Sale and Transferred Securities Derivative Instruments Defined Benefit Pension and Other Postretirement Benefit Plans Total Balance at December 31, 2014 $ 16,421 $ (25,530 ) $ (47,152 ) $ (56,261 ) Other comprehensive (loss) income before reclassifications (22,512 ) (3,136 ) (5,500 ) (31,148 ) Amounts reclassified from accumulated other comprehensive (loss) income (316 ) 5,686 3,933 9,303 Net current-period other comprehensive (loss) income, net of tax (22,828 ) 2,550 (1,567 ) (21,845 ) Balance at December 31, 2015 (6,407 ) (22,980 ) (48,719 ) (78,106 ) Other comprehensive (loss) income before reclassifications (8,901 ) 825 (232 ) (8,308 ) Amounts reclassified from accumulated other comprehensive (loss) income (168 ) 5,087 4,502 9,421 Net current-period other comprehensive (loss) income, net of tax (9,069 ) 5,912 4,270 1,113 Balance at December 31, 2016 (15,476 ) (17,068 ) (44,449 ) (76,993 ) Adoption of ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from AOCI (4,881 ) (2,513 ) (8,254 ) (15,648 ) Other comprehensive (loss) income before reclassifications (7,590 ) 181 98 (7,311 ) Amounts reclassified from accumulated other comprehensive (loss) income — 4,384 4,037 8,421 Net current-period other comprehensive (loss) income, net of tax (7,590 ) 4,565 4,135 1,110 Balance at December 31, 2017 $ (27,947 ) $ (15,016 ) $ (48,568 ) $ (91,531 )
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table provides information for the items reclassified from AOCL: Years ended December 31, Accumulated Other Comprehensive Loss Components 2017 2016 2015 Associated Line Item in the Consolidated Statements Of Income (In thousands) Available-for-sale and transferred securities: Unrealized gains on investments $ — $ 414 $ 609 Gain on sale of investment securities, net Unrealized losses on investments — (149 ) (110 ) Impairment loss recognized in earnings Total before tax — 265 499 Tax expense — (97 ) (183 ) Income tax expense Net of tax $ — $ 168 $ 316 Derivative instruments: Cash flow hedges $ (7,160 ) $ (8,020 ) $ (8,965 ) Total interest expense Tax benefit 2,776 2,933 3,279 Income tax expense Net of tax $ (4,384 ) $ (5,087 ) $ (5,686 ) Defined benefit pension and other postretirement benefit plans: Amortization of net loss $ (6,612 ) $ (7,126 ) $ (6,161 ) (1) Prior service costs — (14 ) (73 ) (1) Total before tax (6,612 ) (7,140 ) (6,234 ) Tax benefit 2,575 2,638 2,301 Income tax expense Net of tax $ (4,037 ) $ (4,502 ) $ (3,933 ) (1) These accumulated other comprehensive income components are included in the computation of net periodic benefit cost (see Note 17 Retirement Benefit Plans for further details). The following tables summarize the items and related tax effects for each component of OCI/OCL, net of tax: Year ended December 31, 2017 (In thousands) Pre-Tax Amount Tax Benefit (Expense) Net of Tax Amount Available-for-sale and transferred securities: Net unrealized loss during the period $ (12,423 ) $ 4,833 $ (7,590 ) Reclassification for net gain included in net income — — — Net non-credit other-than-temporary impairment — — — Amortization of unrealized loss on securities transferred to held-to-maturity — — — Total available-for-sale and transferred securities (12,423 ) 4,833 (7,590 ) Derivative instruments: Net unrealized gain during the period 291 (110 ) 181 Reclassification adjustment for net loss included in net income 7,160 (2,776 ) 4,384 Total derivative instruments 7,451 (2,886 ) 4,565 Defined benefit pension and other postretirement benefit plans: Current year actuarial loss 155 (57 ) 98 Reclassification adjustment for amortization of net loss included in net income 6,612 (2,575 ) 4,037 Reclassification adjustment for prior service cost included in net income — — — Total defined benefit pension and postretirement benefit plans 6,767 (2,632 ) 4,135 Other comprehensive income, net of tax $ 1,795 $ (685 ) $ 1,110 Year ended December 31, 2016 (In thousands) Pre-Tax Amount Tax Benefit (Expense) Net of Tax Amount Available-for-sale and transferred securities: Net unrealized loss during the period $ (14,113 ) $ 5,212 $ (8,901 ) Reclassification for net gain included in net income (414 ) 152 (262 ) Net non-credit other-than-temporary impairment 149 (55 ) 94 Amortization of unrealized loss on securities transferred to held-to-maturity — — — Total available-for-sale and transferred securities (14,378 ) 5,309 (9,069 ) Derivative instruments: Net unrealized loss during the period 1,331 (506 ) 825 Reclassification adjustment for net loss included in net income 8,020 (2,933 ) 5,087 Total derivative instruments 9,351 (3,439 ) 5,912 Defined benefit pension and other postretirement benefit plans: Current year actuarial loss (368 ) 136 (232 ) Reclassification adjustment for amortization of net loss included in net income 7,126 (2,633 ) 4,493 Reclassification adjustment for prior service cost included in net income 14 (5 ) 9 Total defined benefit pension and postretirement benefit plans 6,772 (2,502 ) 4,270 Other comprehensive loss, net of tax $ 1,745 $ (632 ) $ 1,113 Year ended December 31, 2015 (In thousands) Pre-Tax Amount Tax Benefit (Expense) Net of Tax Amount Available-for-sale and transferred securities: Net unrealized gain during the period $ (35,701 ) $ 13,166 $ (22,535 ) Reclassification for net gain included in net income (609 ) 223 (386 ) Net non-credit other-than-temporary impairment 110 (40 ) 70 Amortization of unrealized loss on securities transferred to held-to-maturity 37 (14 ) 23 Total available-for-sale and transferred securities (36,163 ) 13,335 (22,828 ) Derivative instruments: Net unrealized loss during the period (4,945 ) 1,809 (3,136 ) Reclassification adjustment for net loss included in net income 8,965 (3,279 ) 5,686 Total derivative instruments 4,020 (1,470 ) 2,550 Defined benefit pension and other postretirement benefit plans: Current year actuarial loss (8,719 ) 3,219 (5,500 ) Reclassification adjustment for amortization of net loss included in net income 6,161 (2,274 ) 3,887 Reclassification adjustment for prior service cost included in net income 73 (27 ) 46 Total defined benefit pension and postretirement benefit plans (2,485 ) 918 (1,567 ) Other comprehensive loss, net of tax $ (34,628 ) $ 12,783 $ (21,845 )

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2017
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: Actual Capital Requirements Minimum Well Capitalized (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio At December 31, 2017 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 At December 31, 2016 Webster Financial Corporation CET1 risk-based capital $ 1,932,171 10.52 % $ 826,504 4.5 % $ 1,193,840 6.5 % Total risk-based capital 2,328,808 12.68 1,469,341 8.0 1,836,677 10.0 Tier 1 risk-based capital 2,054,881 11.19 1,102,006 6.0 1,469,341 8.0 Tier 1 leverage capital 2,054,881 8.13 1,010,857 4.0 1,263,571 5.0 Webster Bank CET1 risk-based capital $ 1,945,332 10.61 % $ 825,228 4.5 % $ 1,191,995 6.5 % Total risk-based capital 2,141,939 11.68 1,467,071 8.0 1,833,839 10.0 Tier 1 risk-based capital 1,945,332 10.61 1,100,304 6.0 1,467,071 8.0 Tier 1 leverage capital 1,945,332 7.70 1,010,005 4.0 1,262,507 5.0

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share Basic And Diluted	Reconciliation of the calculation of basic and diluted earnings per common share follows: Years ended December 31, (In thousands, except per share data) 2017 2016 2015 Earnings for basic and diluted earnings per common share: Net income $ 255,439 $ 207,127 $ 204,729 Less: Preferred stock dividends 8,184 8,096 8,711 Net income available to common shareholders 247,255 199,031 196,018 Less: Earnings applicable to participating securities 424 608 657 Earnings applicable to common shareholders $ 246,831 $ 198,423 $ 195,361 Shares: Weighted-average common shares outstanding - basic 91,965 91,367 90,968 Effect of dilutive securities: Stock options and restricted stock 385 461 524 Warrants 6 28 41 Weighted-average common shares outstanding - diluted 92,356 91,856 91,533 Earnings per common share: Basic $ 2.68 $ 2.17 $ 2.15 Diluted 2.67 2.16 2.13
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Potential common shares excluded from the effect of dilutive securities because they would have been anti-dilutive, are as follows: Years ended December 31, (In thousands) 2017 2016 2015 Stock options (shares with exercise price greater than market price) — 41 213 Restricted stock (due to performance conditions on non-participating shares) 58 125 92

Derivative Financial Instrume45

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
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 values of derivative positions: At December 31, 2017 At December 31, 2016 Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives (In thousands) Notional Fair Notional Fair Notional Fair Notional Fair Designated as hedging instruments: Positions subject to master netting agreements (1) Interest rate derivatives $ 325,000 $ 2,770 $ — $ — $ 225,000 $ 3,270 $ 100,000 $ 792 Not designated as hedging instruments: Positions subject to master netting agreements (1) Interest rate derivatives 2,791,760 5,977 721,048 1,968 1,943,485 32,226 1,242,937 24,388 Mortgage banking derivatives (2) 28,497 421 39,230 110 103,440 3,084 59,895 711 Other 7,914 258 30,328 419 10,634 231 14,265 120 Positions not subject to master netting agreements Interest rate derivatives 1,366,299 23,009 2,146,518 25,631 1,734,679 38,668 1,451,762 19,001 RPAs 93,713 80 116,882 111 86,037 139 87,273 166 Other — — 2,073 184 1,438 19 181 11 Total not designated as hedging instruments 4,288,183 29,745 3,056,079 28,423 3,879,713 74,367 2,856,313 44,397 Gross derivative instruments, before netting $ 4,613,183 32,515 $ 3,056,079 28,423 $ 4,104,713 77,637 $ 2,956,313 45,189 Less: Legally enforceable master netting agreements 2,245 2,245 24,252 24,254 Less: Cash collateral posted 6,704 — 11,475 600 Total derivative instruments, after netting $ 23,566 $ 26,178 $ 41,910 $ 20,335 (1) One of Webster's counterparty relationships was impacted by a Chicago Mercantile Exchange rulebook amendment, resulting in the presentation of that relationship on a settlement basis, as a single unit of account. (2) Notional amounts include mandatory forward commitments of $39.0 million , while notional amounts do not include approved floating rate commitments of $11.3 million , at December 31, 2017
Interest Rate Swaps And Caps Not Designated For Hedge Accounting	Changes in the fair value of derivatives not qualifying for hedge accounting treatment are reported as a component of other non-interest income in the accompanying Consolidated Statements of Income as follows: Years ended December 31, (In thousands) 2017 2016 2015 Interest rate derivatives $ 2,702 $ 8,668 $ 4,361 RPA 242 (361 ) (33 ) Mortgage banking derivatives (2,062 ) 1,553 801 Other (768 ) (67 ) (63 ) Total impact on other non-interest income $ 114 $ 9,793 $ 5,066
Offsetting Assets and Liabilities	The following table is presented on a gross basis, prior to the application of counterparty netting agreements: At December 31, 2017 At December 31, 2016 (In thousands) Gross Amount Relationship Offset Cash Collateral Offset Net Amount Gross Amount Relationship Offset Cash Collateral Offset Net Amount Derivative instrument assets Hedged Accounting $ 2,770 $ 91 $ 2,679 $ — $ 3,270 $ 2,335 $ 935 $ — Non-Hedged Accounting 6,222 2,154 4,025 43 32,457 21,917 10,540 — Total $ 8,992 $ 2,245 $ 6,704 $ 43 $ 35,727 $ 24,252 $ 11,475 $ — Derivative instrument liabilities Hedged Accounting $ — $ — $ — $ — $ 792 $ 792 $ — $ — Non-Hedged Accounting 2,387 2,245 — 142 24,508 23,462 600 446 Total $ 2,387 $ 2,245 $ — $ 142 $ 25,300 $ 24,254 $ 600 $ 446

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Of Assets And Liabilities Measured On Recurring Basis	Summaries of the fair values of assets and liabilities measured at fair value on a recurring basis are as follows: At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 1,247 $ — $ — $ 1,247 Agency CMO — 306,333 — 306,333 Agency MBS — 1,107,841 — 1,107,841 Agency CMBS — 588,026 — 588,026 CMBS — 361,067 — 361,067 CLO — 209,851 — 209,851 Single issuer-trust preferred — 7,050 — 7,050 Corporate debt — 56,622 — 56,622 Total available-for-sale investment securities 1,247 2,636,790 — 2,638,037 Gross derivative instruments, before netting (1) 258 32,257 — 32,515 Investments held in Rabbi Trust 4,801 — — 4,801 Alternative investments — — 7,460 7,460 Originated loans held for sale — 20,888 — 20,888 Total financial assets held at fair value $ 6,306 $ 2,689,935 $ 7,460 $ 2,703,701 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 587 $ 27,836 $ — $ 28,423 At December 31, 2016 (In thousands) Level 1 Level 2 Level 3 Total Financial assets held at fair value: U.S. Treasury Bills $ 734 $ — $ — $ 734 Agency CMO — 419,706 — 419,706 Agency MBS — 954,349 — 954,349 Agency CMBS — 573,272 — 573,272 CMBS — 477,365 — 477,365 CLO — 427,390 — 427,390 Single issuer-trust preferred — 28,633 — 28,633 Corporate debt — 109,642 — 109,642 Total available-for-sale investment securities 734 2,990,357 — 2,991,091 Gross derivative instruments, before netting (1) 250 77,387 — 77,637 Investments held in Rabbi Trust 5,119 — — 5,119 Alternative investments — — 5,502 5,502 Originated loans held for sale — 60,260 — 60,260 Total financial assets held at fair value $ 6,103 $ 3,128,004 $ 5,502 $ 3,139,609 Financial liabilities held at fair value: Gross derivative instruments, before netting (1) $ 120 $ 45,069 $ — $ 45,189 (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 15: Derivative Financial Instruments .
Schedule Of Quantitative Inputs And Assumptions For Items Categorized In Level 3 Of The Fair Value Hierarchy	The following table presents the changes in Level 3 assets and liabilities that are measured at fair value on a recurring basis: (In thousands) Alternative Investments Balance at January 1, 2017 $ 5,502 Unrealized gain included in net income 613 Purchases/capital funding 1,399 Payments (54 ) Balance at December 31, 2017 $ 7,460
Schedule Of Valuation Methodology And Unobservable Inputs	The table below presents the valuation methodology and unobservable inputs for Level 3 assets measured at fair value on a non-recurring basis as of December 31, 2017 : (Dollars in thousands) Asset Fair Value Valuation Methodology Unobservable Inputs Range of Inputs Collateral dependent impaired loans and leases $ 12,556 Real Estate Appraisals Discount for appraisal type 0% - 15 % Discount for costs to sell 0% - 8 % OREO $ 1,077 Real Estate Appraisals Discount for appraisal type 0% - 20 % Discount for costs to sell 8%
Summary Of Estimated Fair Values Of Significant Financial Instruments	The estimated fair values of selected financial instruments and servicing assets are as follows: At December 31, 2017 2016 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Financial Assets: Level 2 Held-to-maturity investment securities $ 4,487,392 $ 4,456,350 $ 4,160,658 $ 4,125,125 Transferred loans held for sale — — 7,317 7,444 Level 3 Loans and leases, net 17,323,864 17,211,619 16,832,268 16,678,106 Mortgage servicing assets 25,139 45,309 24,466 52,075 Alternative investments 10,562 12,940 11,034 13,189 Financial Liabilities: Level 2 Deposit liabilities, other than time deposits $ 18,525,321 $ 18,525,321 $ 17,279,049 $ 17,279,049 Time deposits 2,468,408 2,455,245 2,024,808 2,024,395 Securities sold under agreements to repurchase and other borrowings 643,269 644,084 949,526 955,660 FHLB advances (1) 1,677,105 1,678,070 2,842,908 2,825,101 Long-term debt (1) 225,767 234,359 225,514 225,514 (1) The following adjustments to the carrying amount are not included for determination of fair value, see Note 10: Borrowings : • FHLB advances - unamortized premiums on advances •

Retirement Benefit Plans (Table

Retirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures	The following table sets forth changes in benefit obligation, changes in plan assets, and the funded status of the defined benefit pension and other postretirement benefits at December 31: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2017 2016 2017 2016 Change in benefit obligation: Beginning balance $ 211,508 $ 203,645 $ 11,806 $ 10,518 $ 3,852 $ 3,853 Service cost 50 45 — — — — Interest cost 7,314 8,441 375 389 92 125 Actuarial loss (gain) 18,396 6,108 1,037 1,023 (631 ) 59 Benefits paid and administrative expenses (7,950 ) (6,731 ) (122 ) (124 ) (219 ) (185 ) Ending balance (1) 229,318 211,508 13,096 11,806 3,094 3,852 Change in plan assets: Beginning balance 192,922 161,369 — — — — Actual return on plan assets 31,253 18,284 — — — — Employer contributions — 20,000 122 124 219 185 Benefits paid and administrative expenses (7,950 ) (6,731 ) (122 ) (124 ) (219 ) (185 ) Ending balance 216,225 192,922 — — — — Funded status of the plan at year end (2) $ (13,093 ) $ (18,586 ) $ (13,096 ) $ (11,806 ) $ (3,094 ) $ (3,852 )
Schedule of Net Periodic Benefit Cost Not yet Recognized	The components of AOCL related to the defined benefit pension and other postretirement benefits at December 31, 2017 and 2016 are summarized below: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2017 2016 2017 2016 Net actuarial loss (gain) $ 59,433 $ 65,857 $ 3,299 $ 3,009 $ (16 ) $ 616 Prior service cost — — — — — — Total pre-tax amounts included in AOCL 59,433 65,857 3,299 3,009 (16 ) 616 Deferred tax benefit 13,407 23,727 744 1,084 (3 ) 222 Amounts included in accumulated AOCL, net of tax $ 46,026 $ 42,130 $ 2,555 $ 1,925 $ (13 ) $ 394
Schedule of Expected Benefit Payments	Expected future benefit payments for the defined benefit pension and other postretirement benefits are presented below: (In thousands) Pension Plan SERP Other Benefits 2018 $ 9,009 $ 11,371 $ 354 2019 8,630 130 342 2020 9,065 132 328 2021 9,792 132 311 2022 10,425 131 292 2023-2027 55,206 651 1,125
Summary of Net Periodic Benefit Cost	The components of the net periodic benefit cost (benefit) for the defined benefit pension and other postretirement benefits were as follows for the years ended December 31: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Service cost $ 50 $ 45 $ 45 $ — $ — $ — $ — $ — $ — Interest cost on benefit obligations 7,314 8,441 8,008 375 389 345 92 125 123 Expected return on plan assets (12,296 ) (11,461 ) (11,873 ) — — — — — — Amortization of prior service cost — — — — — — — 14 73 Recognized net loss 5,864 6,665 5,724 748 426 390 — 35 47 Net periodic benefit cost (benefit) $ 932 $ 3,690 $ 1,904 $ 1,123 $ 815 $ 735 $ 92 $ 174 $ 243
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss)	Changes in funded status related to the defined benefit pension and other postretirement benefits and recognized as a component of OCI in the accompanying Consolidated Statements of Comprehensive Income as follows for the years ended December 31: Pension Plan SERP Other Benefits (In thousands) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Net (gain) loss $ (561 ) $ (715 ) $ 8,525 $ 1,037 $ 1,023 $ 372 $ (631 ) $ 60 $ (178 ) Amounts reclassified from AOCL (5,864 ) (6,665 ) (5,724 ) (748 ) (426 ) (390 ) — (35 ) (47 ) Amortization of prior service cost — — — — — — — (14 ) (73 ) Total (gain) loss recognized in OCI $ (6,425 ) $ (7,380 ) $ 2,801 $ 289 $ 597 $ (18 ) $ (631 ) $ 11 $ (298 )
Schedule of Changes in Fair Value of Plan Assets	A summary of the fair value and hierarchy classification of financial assets of the pension plan is as follows: At December 31, 2017 2016 (In thousands) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Registered investment companies: Exchange traded funds $ 37,848 $ — $ — $ 37,848 $ 31,526 $ — $ — $ 31,526 Cash and cash equivalents 1,115 — — 1,115 701 — — 701 Common collective trust funds: Fixed Income funds — 107,430 — 107,430 — 96,429 — 96,429 Equity Funds — 69,832 — 69,832 — 63,285 — 63,285 Insurance company investment contract — — — — — — 793 793 Total $ 38,963 $ 177,262 $ — $ 216,225 $ 32,227 $ 159,714 $ 793 $ 192,734
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets	The following table sets forth a summary of changes in the fair value of Level 3 assets of the pension plan: Years ended December 31, (In thousands) 2017 2016 Beginning balance $ 793 $ 934 Employer contributions 78 — Unrealized gains relating to instruments still held at the reporting date — (10 ) Benefit payments, administrative expenses (166 ) (131 ) Asset sales (705 ) — Ending balance $ — $ 793
Schedule of Allocation of Plan Assets	The following table presents the target allocation and the pension plan asset allocation for the periods indicated, by asset category: Target Allocation Percentage of Pension Plan assets 2018 2017 2016 Fixed income investments 55 % 50 % 51 % Equity investments 45 50 49 Total 100 % 100 % 100 %
Schedule of Assumptions Used	Weighted-average assumptions used to determine benefit obligations at December 31 are as follows: Pension Plan SERP Other Benefits 2017 2016 2017 2016 2017 2016 Discount rate 3.50 % 4.01 % 3.30 % 3.63 % 3.00 % 3.27 % Rate of compensation increase n/a n/a n/a n/a n/a n/a Weighted-average assumptions used to determine net periodic benefit cost for the years ended December 31 are as follows: Pension Plan SERP Other Benefits 2017 2016 2015 2017 2016 2015 2017 2016 2015 Discount rate 4.01 % 4.20 % 3.85 % 3.63 % 3.75 % 3.50 % 3.27 % 3.35 % 3.15 % Expected long-term return on assets 6.50 % 7.00 % 7.00 % n/a n/a n/a n/a n/a n/a Rate of compensation increase n/a n/a n/a n/a n/a n/a n/a n/a n/a Assumed healthcare cost trend n/a n/a n/a n/a n/a n/a 7.50 % 8.25 % 8.00 %
Schedule of Multiemployer Plans	The following table sets forth contributions and funding status of Webster Bank's portion of this plan: (Dollars in thousands) Contributions by Webster Bank for the year ended December 31, Funded Status of the Plan at December 31, Plan Name Employer Identification Number Plan Number 2017 2016 2015 2017 2016 Pentegra Defined Benefit Plan for Financial Institutions 13-5645888 333 $614 $690 $340 At least 80 percent At least 80 percent

Share-Based Plans (Tables)

Share-Based Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Allocation of Stock-based Compensation Expense and Related Tax Benefit	The following table provides a summary of stock compensation expense and income tax benefits associated with stock compensation recognized in the accompanying Consolidated Statements of Income: Years ended December 31, (In thousands) 2017 2016 2015 Stock options $ — $ 43 $ 379 Restricted stock 12,276 11,395 10,556 Total stock compensation expense $ 12,276 $ 11,438 $ 10,935 Income tax benefit (1) $ 11,849 $ 4,132 $ 3,903 (1) The income tax benefit in 2017 includes $7.1 million
Summary of Restricted Stock and Stock Option Activity	The following table provides a summary of the activity under the stock compensation plans for the year ended December 31, 2017 : Unvested Restricted Stock Awards Stock Options Outstanding Time-Based Performance-Based Number of Shares Weighted-Average Grant Date Fair Value Number of Units Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Grant Date Fair Value Number of Shares Weighted-Average Exercise Price Balance at January 1, 2017 253,361 $ 32.24 2,158 $ 32.89 116,184 $ 33.62 1,072,974 $ 21.24 Granted 168,369 54.76 8,129 56.07 89,581 56.18 — — Exercised options — — — — — — 399,935 25.42 Vested restricted stock awards (1) 194,986 37.16 10,287 51.21 117,695 42.09 — — Forfeited 18,944 35.58 — — 9,154 43.10 — — Balance at December 31, 2017 207,800 $ 43.16 — $ — 78,916 $ 45.35 673,039 $ 18.75 (1)
Summary of Options Outstanding and Options Exercisable	The following table summarizes information for options, all of which are both outstanding and exercisable, at December 31, 2017 : Range of Exercise Prices Number of Shares Weighted-Average Remaining Contractual Life (years) Weighted-Average Exercise Price $ 5.14 - 12.85 222,947 1.2 $ 9.43 $ 22.04 - 25.15 450,092 4.5 23.37 673,039 3.4 $ 18.75

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Operating Results And Total Assets Reportable Segments	The following tables present the operating results, including all appropriate allocations, for Webster’s reportable segments and the Corporate and Reconciling category: Year ended December 31, 2017 (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated Net interest income (loss) $ 322,393 $ 383,700 $ 104,704 $(14,510) $ 796,287 Provision (benefit) for loan and lease losses 38,518 2,382 — — 40,900 Net interest income (loss) after provision for loan and lease losses 283,875 381,318 104,704 (14,510) 755,387 Non-interest income 55,194 107,368 77,378 19,538 259,478 Non-interest expense 154,037 373,081 113,143 20,814 661,075 Income (loss) before income tax expense 185,032 115,605 68,939 (15,786) 353,790 Income tax expense (benefit) 51,438 32,137 19,165 (4,389) 98,351 Net income (loss) $ 133,594 $ 83,468 $ 49,774 $(11,397) $ 255,439 Year ended December 31, 2016 (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated Net interest income (loss) $ 287,596 $ 367,137 $ 81,451 $ (17,671 ) $ 718,513 Provision (benefit) for loan and lease losses 37,455 18,895 — — 56,350 Net interest income (loss) after provision for loan and lease losses 250,141 348,242 81,451 (17,671 ) 662,163 Non-interest income 57,253 110,197 71,710 25,318 264,478 Non-interest expense 138,379 369,132 97,152 18,528 623,191 Income (loss) before income tax expense 169,015 89,307 56,009 (10,881 ) 303,450 Income tax expense (benefit) 53,649 28,348 17,779 (3,453 ) 96,323 Net income (loss) $ 115,366 $ 60,959 $ 38,230 $ (7,428 ) $ 207,127 Year ended December 31, 2015 (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated Net interest income (loss) $ 266,085 $ 356,881 $ 73,433 $ (31,774 ) $ 664,625 Provision (benefit) for loan and lease losses 30,546 18,754 — — 49,300 Net interest income (loss) after provision for loan and lease losses 235,539 338,127 73,433 (31,774 ) 615,325 Non-interest income 46,967 108,647 62,475 19,688 237,777 Non-interest expense 129,499 335,834 81,449 8,559 555,341 Income (loss) before income tax expense 153,007 110,940 54,459 (20,645 ) 297,761 Income tax expense (benefit) 47,804 34,605 17,016 (6,393 ) 93,032 Net income (loss) $ 105,203 $ 76,335 $ 37,443 $ (14,252 ) $ 204,729 The following table presents total assets for Webster's reportable segments and the Corporate and Reconciling category: Total Assets (In thousands) Commercial Community Banking HSA Bank Corporate and Consolidated At December 31, 2017 $ 9,350,028 $ 8,909,671 $ 76,308 $ 8,151,638 $ 26,487,645 At December 31, 2016 9,069,445 8,721,046 83,987 8,198,051 26,072,529

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments and Receipts for Leases	The following table summarizes future minimum rental payments and receipts under lease agreements: At December 31, 2017 (In thousands) Rental Payments Rental Receipts 2018 $ 29,181 $ 717 2019 28,035 592 2020 26,254 488 2021 24,552 395 2022 20,885 353 Thereafter 77,541 1,438 Total future minimum rental payments and receipts $ 206,448 $ 3,983
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: At December 31, (In thousands) 2017 2016 Commitments to extend credit $ 5,567,687 $ 5,224,280 Standby letter of credit 195,902 128,985 Commercial letter of credit 43,200 46,497 Total credit-related financial instruments with off-balance sheet risk $ 5,806,789 $ 5,399,762
Reserve For Unfunded Credit Commitments	The following table provides a summary of activity in the reserve for loan repurchases: Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 790 $ 1,192 $ 1,059 Provision (benefit) charged to expense 100 (303 ) 133 Repurchased loans and settlements charged off (18 ) (99 ) — Ending balance $ 872 $ 790 $ 1,192 Years ended December 31, (In thousands) 2017 2016 2015 Beginning balance $ 2,287 $ 2,119 $ 5,151 Provision (benefit) 75 168 (3,032 ) Ending balance $ 2,362 $ 2,287 $ 2,119

Parent Company Information (Tab

Parent Company Information (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule of Parent Company Information Balance Sheet	Condensed Balance Sheets December 31, (In thousands) 2017 2016 Assets: Cash and due from banks $ 181,085 $ 152,947 Intercompany debt securities 150,000 150,000 Investment in subsidiaries 2,585,955 2,425,398 Alternative investments 2,939 4,275 Other assets 13,252 24,659 Total assets $ 2,933,231 $ 2,757,279 Liabilities and shareholders’ equity: Senior notes $ 148,447 $ 148,194 Junior subordinated debt 77,320 77,320 Accrued interest payable 2,616 2,589 Due to subsidiaries 575 365 Other liabilities 2,315 1,799 Total liabilities 231,273 230,267 Shareholders’ equity 2,701,958 2,527,012 Total liabilities and shareholders’ equity $ 2,933,231 $ 2,757,279
Schedule of Parent Company Information Income Statement	Condensed Statements of Income Years ended December 31, (In thousands) 2017 2016 2015 Operating Income: Dividend income from bank subsidiary $ 120,000 $ 145,000 $ 110,000 Interest on securities and deposits 4,477 1,911 546 Loss on sale of investment securities — (2,410 ) — Alternative investments income 1,504 176 2,274 Other non-interest income 204 7,485 152 Total operating income 126,185 152,162 112,972 Operating Expense: Interest expense on borrowings 10,380 9,981 9,665 Compensation and benefits 12,425 11,461 10,965 Other non-interest expense 10,583 6,278 6,005 Total operating expense 33,388 27,720 26,635 Income before income tax benefit and equity in undistributed earnings of subsidiaries and associated companies 92,797 124,442 86,337 Income tax benefit 3,004 3,086 2,929 Equity in undistributed earnings of subsidiaries and associated companies 159,638 79,599 115,463 Net income $ 255,439 $ 207,127 $ 204,729
Schedule of Parent Company Information Comprehensive Income Statement	Condensed Statements of Comprehensive Income Years ended December 31, (In thousands) 2017 2016 2015 Net income $ 255,439 $ 207,127 $ 204,729 Other comprehensive income (loss), net of tax: Net unrealized gains (losses) on available for sale securities — 584 (2,109 ) Net unrealized gains (losses) on derivative instruments 1,216 1,223 1,223 Other comprehensive loss of subsidiaries and associated companies (106 ) (694 ) (20,959 ) Other comprehensive income (loss), net of tax 1,110 1,113 (21,845 ) Comprehensive income $ 256,549 $ 208,240 $ 182,884
Schedule of Parent Company Information Cash Flow Statement	Condensed Statements of Cash Flows Years ended December 31, (In thousands) 2017 2016 2015 Operating activities: Net income $ 255,439 $ 207,127 $ 204,729 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed earnings of subsidiaries and associated companies (159,638 ) (79,599 ) (115,463 ) Stock-based compensation 12,276 11,438 10,935 Gain on redemption of other assets — (7,331 ) — Other, net 7,880 (3,736 ) 9,066 Net cash provided by operating activities 115,957 127,899 109,267 Investing activities: Proceeds from sale of available for sale securities — 1,089 — Purchases of intercompany debt securities — (150,000 ) — Proceeds from the sale of other assets 7,581 — — Net cash provided by (used for) investing activities 7,581 (148,911 ) — Financing activities: Preferred stock issued 145,056 — — Preferred stock redeemed (122,710 ) — — Cash dividends paid to common shareholders (94,630 ) (89,522 ) (80,964 ) Cash dividends paid to preferred shareholders (8,096 ) (8,096 ) (8,711 ) Exercise of stock options 8,259 11,762 3,060 Excess tax benefits from stock-based compensation — 3,204 2,338 Common stock repurchased/shares acquired related to employee share-based plans (23,279 ) (22,870 ) (17,815 ) Common stock warrants repurchased — (163 ) (23 ) Net cash used for financing activities (95,400 ) (105,685 ) (102,115 ) Increase (decrease) in cash and due from banks 28,138 (126,697 ) 7,152 Cash and due from banks at beginning of year 152,947 279,644 272,492 Cash and due from banks at end of year $ 181,085 $ 152,947 $ 279,644

Selected Quarterly Consolidat52

Selected Quarterly Consolidated Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information	2017 (In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Interest income $ 219,680 $ 226,789 $ 231,021 $ 236,115 Interest expense 27,016 29,002 30,117 31,183 Net interest income 192,664 197,787 200,904 204,932 Provision for loan and lease losses 10,500 7,250 10,150 13,000 Non-interest income 63,042 64,551 65,846 66,039 Non-interest expense 163,784 164,419 161,823 171,049 Income before income tax expense 81,422 90,669 94,777 86,922 Income tax expense 21,951 29,090 30,281 17,029 Net income $ 59,471 $ 61,579 $ 64,496 $ 69,893 Earnings applicable to common shareholders $ 57,342 $ 59,485 $ 62,426 $ 67,710 Earnings per common share: Basic $ 0.62 $ 0.65 $ 0.68 $ 0.74 Diluted 0.62 0.64 0.67 0.73 2016 (In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Interest income $ 202,335 $ 202,431 $ 205,715 $ 211,432 Interest expense 26,183 25,526 25,518 26,173 Net interest income 176,152 176,905 180,197 185,259 Provision for loan and lease losses 15,600 14,000 14,250 12,500 Non-interest income 62,374 65,075 66,412 70,617 Non-interest expense 152,445 152,778 156,097 161,871 Income before income tax expense 70,481 75,202 76,262 81,505 Income tax expense 23,434 24,599 24,445 23,845 Net income $ 47,047 $ 50,603 $ 51,817 $ 57,660 Earnings applicable to common shareholders $ 44,921 $ 48,398 $ 49,634 $ 55,501 Earnings per common share: Basic $ 0.49 $ 0.53 $ 0.54 $ 0.61 Diluted 0.49 0.53 0.54 0.60

Summary of Significant Accoun53

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Narrative) (Loans) (Detail)	12 Months Ended
	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Threshold Period Past Due for Nonperforming Status of Financing Receivables	90 days
Threshold period past due for write-off of financing receivable (in days)	180 days
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Threshold Period Past Due for Nonperforming Status of Financing Receivables	90 days
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Threshold Period Past Due for Nonperforming Status of Financing Receivables	90 days
Other Real Estate Owned [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Threshold period past due for write-off of financing receivable (in days)	90 days

Significant Accounting Policies

Significant Accounting Policies (Premises and Equipment) (Detail)	12 Months Ended
	Dec. 31, 2017
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	40 years
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	20 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	10 years
Data Processing and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Data Processing and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	7 years

Summary of Significant Accoun55

Summary of Significant Accounting Policies (Share Based Compensation) (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Performance Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Award vesting percentage	50.00%
Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	0.00%
Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	150.00%

Investment Securities (Summary

Investment Securities (Summary Of Investment Securities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities [Abstract]
Amortized Cost	$ 2,675,131	$ 3,015,763
Unrealized Gains	7,173	16,226
Unrealized Losses	(44,267)	(40,898)
Fair Value	2,638,037	2,991,091
Held-to-maturity Securities [Abstract]
Amortized Cost	4,487,392	4,160,658
Unrealized Gains	28,413	37,567
Unrealized Losses	(59,455)	(73,100)
Fair Value	4,456,350	4,125,125
US Treasury Bill Securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	1,247	734
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	1,247	734
Collateralized Mortgage Obligations [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	308,989	419,865
Unrealized Gains	1,158	3,344
Unrealized Losses	(3,814)	(3,503)
Fair Value	306,333	419,706
Held-to-maturity Securities [Abstract]
Amortized Cost	260,114	339,455
Unrealized Gains	664	1,977
Unrealized Losses	(4,824)	(3,824)
Fair Value	255,954	337,608
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	1,124,960	969,460
Unrealized Gains	2,151	4,398
Unrealized Losses	(19,270)	(19,509)
Fair Value	1,107,841	954,349
Held-to-maturity Securities [Abstract]
Amortized Cost	2,569,735	2,317,449
Unrealized Gains	16,989	26,388
Unrealized Losses	(37,442)	(41,768)
Fair Value	2,549,282	2,302,069
Agency commercial mortgage-backed securities (agency CMBS) [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	608,276	587,776
Unrealized Gains	0	63
Unrealized Losses	(20,250)	(14,567)
Fair Value	588,026	573,272
Held-to-maturity Securities [Abstract]
Amortized Cost	696,566	547,726
Unrealized Gains	0	694
Unrealized Losses	(10,011)	(1,348)
Fair Value	686,555	547,072
Commercial Mortgage Backed Securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	358,984	473,974
Unrealized Gains	2,157	4,093
Unrealized Losses	(74)	(702)
Fair Value	361,067	477,365
Held-to-maturity Securities [Abstract]
Amortized Cost	249,273	298,538
Unrealized Gains	2,175	4,107
Unrealized Losses	(620)	(411)
Fair Value	250,828	302,234
Collateralized loan obligations (CLO) [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	209,075	425,083
Unrealized Gains	910	2,826
Unrealized Losses	(134)	(519)
Fair Value	209,851	427,390
Trust Preferred Securities Single Issuers [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	7,096	30,381
Unrealized Gains	0	0
Unrealized Losses	(46)	(1,748)
Fair Value	7,050	28,633
Corporate Debt Securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	56,504	108,490
Unrealized Gains	797	1,502
Unrealized Losses	(679)	(350)
Fair Value	56,622	109,642
Municipal Bonds [Member]
Held-to-maturity Securities [Abstract]
Amortized Cost	711,381	655,813
Unrealized Gains	8,584	4,389
Unrealized Losses	(6,558)	(25,749)
Fair Value	713,407	634,453
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Held-to-maturity Securities [Abstract]
Amortized Cost	323	1,677
Unrealized Gains	1	12
Unrealized Losses	0	0
Fair Value	$ 324	$ 1,689

Investment Securities (Other Th

Investment Securities (Other Than Temporary Impairment Credit Losses Recognized In Earnings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of OTTI, beginning of period	$ 3,243	$ 3,288	$ 3,696
Reduction for securities sold, called	(2,005)	(194)	(518)
Additions for OTTI not previously recognized	126	149	110
Balance of OTTI, end of period	$ 1,364	$ 3,243	$ 3,288

Investment Securities (Summar58

Investment Securities (Summary Of Gross Unrealized Losses Not Considered OTTI) (Detail) $ in Thousands	Dec. 31, 2017USD ($)holding	Dec. 31, 2016USD ($)holding
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	$ 650,514	$ 1,236,547
Available for sale, Unrealized Losses - Less Than Twelve Months	(4,869)	(27,316)
Available for sale, Fair Value - Twelve Months or Longer	1,265,234	470,314
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (39,398)	$ (13,582)
Available for sale, Number of Holdings - Total | holding	212	168
Available for sale, Fair Value - Total	$ 1,915,748	$ 1,706,861
Available for sale, Unrealized Losses - Total	(44,267)	(40,898)
Held-to-maturity, Fair Value - Less Than Twelve Months	1,536,069	2,351,350
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(13,687)	(63,785)
Held-to-maturity, Fair Value - Twelve Months or Longer	1,655,375	292,225
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (45,768)	$ (9,315)
Held-to-maturity, Number of Holdings - Total | holding	388	395
Held-to-maturity, Fair Value - Total	$ 3,191,444	$ 2,643,575
Held-to-maturity, Unrealized Losses - Total	(59,455)	(73,100)
Collateralized Mortgage Obligations [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	81,001	107,853
Available for sale, Unrealized Losses - Less Than Twelve Months	(449)	(2,168)
Available for sale, Fair Value - Twelve Months or Longer	119,104	67,351
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (3,365)	$ (1,335)
Available for sale, Number of Holdings - Total | holding	27	15
Available for sale, Fair Value - Total	$ 200,105	$ 175,204
Available for sale, Unrealized Losses - Total	(3,814)	(3,503)
Held-to-maturity, Fair Value - Less Than Twelve Months	98,090	163,439
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(1,082)	(3,339)
Held-to-maturity, Fair Value - Twelve Months or Longer	106,775	17,254
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (3,742)	$ (485)
Held-to-maturity, Number of Holdings - Total | holding	22	16
Held-to-maturity, Fair Value - Total	$ 204,865	$ 180,693
Held-to-maturity, Unrealized Losses - Total	(4,824)	(3,824)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	416,995	512,075
Available for sale, Unrealized Losses - Less Than Twelve Months	(2,920)	(10,503)
Available for sale, Fair Value - Twelve Months or Longer	606,021	252,779
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (16,350)	$ (9,006)
Available for sale, Number of Holdings - Total | holding	135	97
Available for sale, Fair Value - Total	$ 1,023,016	$ 764,854
Available for sale, Unrealized Losses - Total	(19,270)	(19,509)
Held-to-maturity, Fair Value - Less Than Twelve Months	762,107	1,394,623
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(4,555)	(32,942)
Held-to-maturity, Fair Value - Twelve Months or Longer	1,197,839	273,779
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (32,887)	$ (8,826)
Held-to-maturity, Number of Holdings - Total | holding	205	150
Held-to-maturity, Fair Value - Total	$ 1,959,946	$ 1,668,402
Held-to-maturity, Unrealized Losses - Total	(37,442)	(41,768)
Agency commercial mortgage-backed securities (agency CMBS) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	54,182	554,246
Available for sale, Unrealized Losses - Less Than Twelve Months	(851)	$ (14,567)
Available for sale, Fair Value - Twelve Months or Longer	533,844
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (19,399)
Available for sale, Number of Holdings - Total | holding	36	32
Available for sale, Fair Value - Total	$ 588,026	$ 554,246
Available for sale, Unrealized Losses - Total	(20,250)	(14,567)
Held-to-maturity, Fair Value - Less Than Twelve Months	576,770	347,725
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(7,599)	$ (1,348)
Held-to-maturity, Fair Value - Twelve Months or Longer	109,785
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (2,412)
Held-to-maturity, Number of Holdings - Total | holding	56	25
Held-to-maturity, Fair Value - Total	$ 686,555	$ 347,725
Held-to-maturity, Unrealized Losses - Total	(10,011)	(1,348)
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	23,869	12,427
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (74)	(24)
Available for sale, Fair Value - Twelve Months or Longer		63,930
Available for sale, Unrealized Losses - Twelve Months or Longer		$ (678)
Available for sale, Number of Holdings - Total | holding	6	12
Available for sale, Fair Value - Total	$ 23,869	$ 76,357
Available for sale, Unrealized Losses - Total	(74)	(702)
Held-to-maturity, Fair Value - Less Than Twelve Months	92,670	60,768
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(413)	$ (411)
Held-to-maturity, Fair Value - Twelve Months or Longer	14,115
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (207)
Held-to-maturity, Number of Holdings - Total | holding	13	8
Held-to-maturity, Fair Value - Total	$ 106,785	$ 60,768
Held-to-maturity, Unrealized Losses - Total	(620)	(411)
Collateralized loan obligations (CLO) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	56,335	49,946
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (134)	(54)
Available for sale, Fair Value - Twelve Months or Longer		50,237
Available for sale, Unrealized Losses - Twelve Months or Longer		$ (465)
Available for sale, Number of Holdings - Total | holding	3	5
Available for sale, Fair Value - Total	$ 56,335	$ 100,183
Available for sale, Unrealized Losses - Total	(134)	(519)
Trust Preferred Securities Single Issuers [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	7,050	0
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (46)
Available for sale, Fair Value - Twelve Months or Longer		28,633
Available for sale, Unrealized Losses - Twelve Months or Longer		$ (1,748)
Available for sale, Number of Holdings - Total | holding	1	5
Available for sale, Fair Value - Total	$ 7,050	$ 28,633
Available for sale, Unrealized Losses - Total	(46)	(1,748)
Municipal Bonds [Member]
Schedule of Investments [Line Items]
Held-to-maturity, Fair Value - Less Than Twelve Months	6,432	384,795
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(38)	(25,745)
Held-to-maturity, Fair Value - Twelve Months or Longer	226,861	1,192
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (6,520)	$ (4)
Held-to-maturity, Number of Holdings - Total | holding	92	196
Held-to-maturity, Fair Value - Total	$ 233,293	$ 385,987
Held-to-maturity, Unrealized Losses - Total	(6,558)	(25,749)
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	11,082
Available for sale, Unrealized Losses - Less Than Twelve Months	(395)
Available for sale, Fair Value - Twelve Months or Longer	6,265	7,384
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (284)	$ (350)
Available for sale, Number of Holdings - Total | holding	4	2
Available for sale, Fair Value - Total	$ 17,347	$ 7,384
Available for sale, Unrealized Losses - Total	$ (679)	$ (350)

Investment Securities (Narrativ

Investment Securities (Narrative) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Unrealized Losses	$ (44,267)	$ (40,898)
Held-to-maturity securities, accumulated unrealized holding loss	(59,455)	(73,100)
Securities available-for-sale, at fair value	2,638,037	2,991,091
Securities pledged to secure public funds, carrying value	2,400,000	2,500,000
Collateralized Mortgage Obligations [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(3,814)	(3,503)
Held-to-maturity securities, accumulated unrealized holding loss	(4,824)	(3,824)
Securities available-for-sale, at fair value	306,333	419,706
Agency mortgage-backed securities (agency MBS) [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(19,270)	(19,509)
Held-to-maturity securities, accumulated unrealized holding loss	(37,442)	(41,768)
Securities available-for-sale, at fair value	1,107,841	954,349
Agency commercial mortgage-backed securities (agency CMBS) [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(20,250)	(14,567)
Held-to-maturity securities, accumulated unrealized holding loss	(10,011)	(1,348)
Securities available-for-sale, at fair value	588,026	573,272
Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(74)	(702)
Held-to-maturity securities, accumulated unrealized holding loss	(620)	(411)
Securities available-for-sale, at fair value	361,067	477,365
Collateralized loan obligations (CLO) [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(134)	(519)
Securities available-for-sale, at fair value	209,851	427,390
Trust Preferred Securities Single Issuers [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(46)	(1,748)
Securities available-for-sale, at fair value	7,050	28,633
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Unrealized Losses	(679)	(350)
Securities available-for-sale, at fair value	56,622	109,642
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity securities, accumulated unrealized holding loss	(6,558)	$ (25,749)
Callable at the option of the counterparty [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	$ 1,200,000

Investment Securities (Summar60

Investment Securities (Summary Of Sale Proceeds Of Available For Sale Securities) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales (1)	$ 0	$ 259,273	$ 95,101
Gains	0	2,891	1,029
Losses	0	2,477	420
Available-for-sale Securities, Gross Realized Gain (Loss)	$ 0	$ 414	$ 609

Investment Securities (Summar61

Investment Securities (Summary Of Debt Securities By Contractual Maturity) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	$ 1,247
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	40,066
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	332,558
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	2,301,260
Available-for-sale Debt Securities, Amortized Cost Basis	2,675,131
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	1,247
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	40,447
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	333,931
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	2,262,412
Available for Sale, Fair Value - Total debt securities	2,638,037
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	33,654
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	3,839
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	37,870
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	4,412,029
Amortized Cost	4,487,392	$ 4,160,658
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	34,145
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	3,857
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	38,450
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	4,379,898
Held-to-maturity Securities, Fair Value	$ 4,456,350	$ 4,125,125

Variable Interest Entities (Det

Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Assets [Member]
Variable Interest Entity [Line Items]
Variable interest entities, investments, carrying value	$ 33.5	$ 22.8
Accounts Payable and Accrued Liabilities [Member]
Variable Interest Entity [Line Items]
Variable interest entities, unfunded commitments	17.3	14
Other Investments [Member]
Variable Interest Entity [Line Items]
Variable interest entities, investments, carrying value	13.8	12.3
Unfunded Loan Commitment [Member]
Variable Interest Entity [Line Items]
Variable interest entities, total exposure of other investments including unfunded commitments	$ 22.9	$ 19.9

Loans and Leases (Detail)

Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 17,523,858	$ 17,026,588	$ 15,671,735
Unamortized premiums	20,600	17,300
Pledged loans as collateral	6,700,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	4,490,878	4,254,682	4,061,001
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	2,590,225	2,684,500	2,702,560
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	5,368,694	4,940,931	4,315,999
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	4,523,828	4,510,846	3,991,649
Finance Leases Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 550,233	$ 635,629	$ 600,526

Loans and Leases (Summary Of Lo

Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	$ 172,360	$ 175,864
90 or More Days Past Due and Accruing	892	749
Non-accrual	126,513	133,816
Current	17,351,498	16,850,724
Total Loans and Leases	17,523,858	17,026,588	$ 15,671,735
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	58,270	58,519
90 or More Days Past Due and Accruing	0	0
Non-accrual	44,481	47,279
Current	4,432,608	4,196,163
Total Loans and Leases	4,490,878	4,254,682	4,061,001
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans and Leases	2,590,225	2,684,500	2,702,560
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	54,083	50,539
90 or More Days Past Due and Accruing	0	0
Non-accrual	35,645	35,926
Current	2,298,185	2,359,354
Total Loans and Leases	2,352,268	2,409,893
Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	5,707	5,381
90 or More Days Past Due and Accruing	0	0
Non-accrual	1,707	1,663
Current	232,250	269,226
Total Loans and Leases	237,957	274,607
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans and Leases	5,368,694	4,940,931	4,315,999
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	45,673	40,898
90 or More Days Past Due and Accruing	644	749
Non-accrual	39,214	38,190
Current	4,488,242	4,094,727
Total Loans and Leases	4,533,915	4,135,625
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	589	0
90 or More Days Past Due and Accruing	0	0
Non-accrual	589	0
Current	834,190	805,306
Total Loans and Leases	834,779	805,306
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans and Leases	4,523,828	4,510,846	3,991,649
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	0	662
90 or More Days Past Due and Accruing	0	0
Non-accrual	0	662
Current	279,554	374,398
Total Loans and Leases	279,554	375,060
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	5,287	18,044
90 or More Days Past Due and Accruing	248	0
Non-accrual	4,484	9,871
Current	4,238,987	4,117,742
Total Loans and Leases	4,244,274	4,135,786
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	2,751	1,821
90 or More Days Past Due and Accruing	0	0
Non-accrual	393	225
Current	547,482	633,808
Total Loans and Leases	550,233	635,629	$ 600,526
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	31,289	28,337
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	8,643	8,631
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	12,668	8,831
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	2,556	2,233
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	5,212	1,382
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	478	6,357
Financing Receivables, 30 to 59 Days Past Due [Member] | Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	1,732	903
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	13,666	12,962
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	5,146	2,609
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	5,770	5,782
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	1,444	1,485
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	603	577
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	77	1,816
Financing Receivables, 60 to 89 Days Past Due [Member] | Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual	$ 626	$ 693

Loans and Leases (Narrative) (D

Loans and Leases (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Interest on non-accrual loans that would have been recorded as additional interest income	$ 8.4	$ 11	$ 8.2
Write-down of TDR's	$ (3.2)	$ (18.6)	$ (11.8)

Loans and Leases (Allowance For

Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period				$ 194,320	$ 194,320			$ 174,990	$ 194,320	$ 174,990	$ 159,264
Provision (benefit) charged to expense	$ 13,000	$ 10,150	$ 7,250	10,500	12,500	$ 14,250	$ 14,000	15,600	40,900	56,350	49,300
Losses charged off									(44,927)	(46,912)	(43,560)
Recoveries									9,701	9,892	9,986
Balance, end of period	199,994			194,320	194,320	194,320		174,990	194,320	174,990	159,264	$ 194,320	$ 174,990
Individually evaluated for impairment	16,554					18,593							22,204
Collectively evaluated for impairment	183,440					175,727							152,786
Individually evaluated for impairment	246,753											249,355	279,171
Collectively evaluated for impairment	17,277,105											16,777,233	15,392,564
Total Loans and Leases	17,523,858											17,026,588	15,671,735
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period				23,226	23,226			25,876	23,226	25,876	25,452
Provision (benefit) charged to expense									(2,692)	230	6,057
Losses charged off									(2,500)	(4,636)	(6,508)
Recoveries									1,024	1,756	875
Balance, end of period	19,058			23,226	23,226	23,226		25,876	23,226	25,876	25,452	23,226	25,876
Individually evaluated for impairment	4,805					8,090							10,364
Collectively evaluated for impairment	14,253					15,136							15,512
Individually evaluated for impairment	114,295											119,424	134,448
Collectively evaluated for impairment	4,376,583											4,135,258	3,926,553
Total Loans and Leases	4,490,878											4,254,682	4,061,001
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period				45,233	45,233			42,052	45,233	42,052	43,518
Provision (benefit) charged to expense									9,367	18,507	11,847
Losses charged off									(24,447)	(20,669)	(17,679)
Recoveries									6,037	5,343	4,366
Balance, end of period	36,190			45,233	45,233	45,233		42,052	45,233	42,052	43,518	45,233	42,052
Individually evaluated for impairment	1,668					2,903							3,477
Collectively evaluated for impairment	34,522					42,330							38,575
Individually evaluated for impairment	45,436											45,719	48,425
Collectively evaluated for impairment	2,544,789											2,638,781	2,654,135
Total Loans and Leases	2,590,225											2,684,500	2,702,560
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period				71,905	71,905			59,977	71,905	59,977	47,068
Provision (benefit) charged to expense									23,417	28,662	21,693
Losses charged off									(8,147)	(18,360)	(11,522)
Recoveries									2,358	1,626	2,738
Balance, end of period	89,533			71,905	71,905	71,905		59,977	71,905	59,977	47,068	71,905	59,977
Individually evaluated for impairment	9,786					7,422							5,197
Collectively evaluated for impairment	79,747					64,483							54,780
Individually evaluated for impairment	72,471											53,037	56,581
Collectively evaluated for impairment	5,296,223											4,887,894	4,259,418
Total Loans and Leases	5,368,694											4,940,931	4,315,999
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period				47,477	47,477			41,598	47,477	41,598	37,148
Provision (benefit) charged to expense									11,040	7,930	11,381
Losses charged off									(9,275)	(2,682)	(7,578)
Recoveries									165	631	647
Balance, end of period	49,407			47,477	47,477	47,477		41,598	47,477	41,598	37,148	47,477	41,598
Individually evaluated for impairment	272					169							3,163
Collectively evaluated for impairment	49,135					47,308							38,435
Individually evaluated for impairment	11,226											24,755	39,295
Collectively evaluated for impairment	4,512,602											4,486,091	3,952,354
Total Loans and Leases	4,523,828											4,510,846	3,991,649
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period				6,479	6,479			5,487	6,479	5,487	6,078
Provision (benefit) charged to expense									(232)	1,021	(1,678)
Losses charged off									(558)	(565)	(273)
Recoveries									117	536	1,360
Balance, end of period	5,806			$ 6,479	$ 6,479	6,479		$ 5,487	$ 6,479	$ 5,487	$ 6,078	6,479	5,487
Individually evaluated for impairment	23					9							3
Collectively evaluated for impairment	5,783					$ 6,470							5,484
Individually evaluated for impairment	3,325											6,420	422
Collectively evaluated for impairment	546,908											629,209	600,104
Total Loans and Leases	$ 550,233											$ 635,629	$ 600,526

Loans and Leases (Impaired Loan

Loans and Leases (Impaired Loans And Leases By Class) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 274,736	$ 273,364
Total Recorded Investment	246,753	249,355
Recorded Investment No Allowance	141,398	96,795
Recorded Investment With Allowance	105,355	152,560
Related Valuation Allowance	16,554	18,593
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	125,352	131,468
Total Recorded Investment	114,295	119,424
Recorded Investment No Allowance	69,759	21,068
Recorded Investment With Allowance	44,536	98,356
Related Valuation Allowance	4,805	8,090
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance		52,432
Total Recorded Investment		45,719
Recorded Investment No Allowance		22,746
Recorded Investment With Allowance		22,973
Related Valuation Allowance		2,903
Consumer Portfolio Segment [Member] | Home Equity Loan [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
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	79,900	57,732
Total Recorded Investment	71,882	53,037
Recorded Investment No Allowance	27,313	26,006
Recorded Investment With Allowance	44,569	27,031
Related Valuation Allowance	9,786	7,422
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,272	0
Total Recorded Investment	589	0
Recorded Investment No Allowance	589	0
Recorded Investment With Allowance	0	0
Related Valuation Allowance	0	0
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	1,188
Total Recorded Investment	0	1,187
Recorded Investment No Allowance	0	1,187
Recorded Investment With Allowance	0	0
Related Valuation Allowance	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	11,994	24,146
Total Recorded Investment	11,226	23,568
Recorded Investment No Allowance	6,387	19,591
Recorded Investment With Allowance	4,839	3,977
Related Valuation Allowance	272	169
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,409	6,398
Total Recorded Investment	3,325	6,420
Recorded Investment No Allowance	2,932	6,197
Recorded Investment With Allowance	393	223
Related Valuation Allowance	$ 23	$ 9

Loans and Leases (Interest Inco

Loans and Leases (Interest Income From Impaired Loans And Leases, By Class) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 248,054	$ 264,162	$ 305,015
Accrued Interest Income	7,192	8,065	8,557
Cash Basis Interest Income	2,310	2,185	2,238
Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Cash Basis Interest Income	0	0	0
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	116,859	126,936	138,215
Accrued Interest Income	4,138	4,377	4,473
Cash Basis Interest Income	1,264	1,200	1,139
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			49,337
Accrued Interest Income			1,451
Cash Basis Interest Income			1,099
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	45,578	47,072
Accrued Interest Income	1,323	1,361
Cash Basis Interest Income	1,046	985
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	62,459	54,708	46,379
Accrued Interest Income	1,095	1,540	1,319
Cash Basis Interest Income	0	0	0
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	295	0	0
Accrued Interest Income	0	0	0
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			64,495
Accrued Interest Income			1,165
Cash Basis Interest Income	0	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	17,397	28,451
Accrued Interest Income	417	511
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	594	3,574	6,062
Accrued Interest Income	12	92	133
Cash Basis Interest Income	0	0	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	4,872	3,421	527
Accrued Interest Income	207	184	16
Cash Basis Interest Income	$ 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	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	$ 17,523,858	$ 17,026,588	$ 15,671,735
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	5,368,694	4,940,931	4,315,999
Commercial Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	5,048,162	4,655,007
Commercial Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	104,594	56,240
Commercial Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	206,883	226,603
Commercial Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	9,055	3,081
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	4,523,828	4,510,846	3,991,649
Commercial Real Estate Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	4,355,916	4,357,458
Commercial Real Estate Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	62,065	69,023
Commercial Real Estate Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	105,847	84,365
Commercial Real Estate Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	0	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	550,233	635,629	$ 600,526
Finance Leases Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	525,105	618,084
Finance Leases Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	8,022	1,324
Finance Leases Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Total Loans and Leases	17,106	16,221
Finance Leases Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Total 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	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDR	$ 221,404	$ 223,528
Specific reserves for TDR included in the balance of ALLL	199,994	194,320	$ 194,320	$ 174,990	$ 159,264
Additional funds committed to borrowers in TDR status	2,736	459
Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDR	147,113	147,809
Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDR	74,291	75,719
Troubled Debt Restructures [Member]
Financing Receivable, Modifications [Line Items]
Interest receivable	100	700
Troubled Debt Restructures [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Specific reserves for TDR included in the balance of ALLL	$ 12,384	$ 14,583

Loans and Leases (Information o

Loans and Leases (Information on How Loans and Leases were Modified as a TDR) (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)loan	Dec. 31, 2015USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		203	175	212
Post-Modification Recorded Investment | $		$ 37,636	$ 43,669	$ 49,215	[1]
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		16	17	27
Post-Modification Recorded Investment | $		$ 2,569	$ 2,801	$ 4,909	[1]
Residential Portfolio Segment [Member] | Adjusted Interest Rates [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		2	2	3
Post-Modification Recorded Investment | $		$ 335	$ 528	$ 573	[1]
Residential Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		12	13	26
Post-Modification Recorded Investment | $		$ 1,733	$ 1,537	$ 5,315	[1]
Residential Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		39	24	30	[2]
Post-Modification Recorded Investment | $		$ 6,200	$ 4,090	$ 4,366	[1],[2]
Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan				12
Post-Modification Recorded Investment | $	[1]			$ 1,012
Consumer Portfolio Segment [Member] | Adjusted Interest Rates [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		1	0	0
Post-Modification Recorded Investment | $		$ 247	$ 0	$ 0	[1]
Consumer Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan				12
Post-Modification Recorded Investment | $	[1]			$ 945
Consumer Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]			68
Post-Modification Recorded Investment | $	[1],[2]			$ 3,646
Commercial Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan				3
Post-Modification Recorded Investment | $	[1]			$ 254
Commercial Portfolio Segment [Member] | Adjusted Interest Rates [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	0	1
Post-Modification Recorded Investment | $		$ 0	$ 0	$ 24	[1]
Commercial Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan				7
Post-Modification Recorded Investment | $	[1]			$ 5,361
Commercial Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]			20
Post-Modification Recorded Investment | $	[1],[2]			$ 22,048
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan				1
Post-Modification Recorded Investment | $	[1]			$ 315
Commercial Real Estate Portfolio Segment [Member] | Adjusted Interest Rates [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	1	0
Post-Modification Recorded Investment | $	[1]	$ 0	$ 237	$ 0
Commercial Real Estate Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan				1
Post-Modification Recorded Investment | $	[1]			$ 42
Commercial Real Estate Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]			1
Post-Modification Recorded Investment | $	[1],[2]			$ 405
Finance Leases Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	7	0
Post-Modification Recorded Investment | $		$ 0	$ 6,642	$ 0	[1]
Home Equity Loan [Member] | Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		12	11
Post-Modification Recorded Investment | $		$ 976	$ 484
Home Equity Loan [Member] | Consumer Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		14	15
Post-Modification Recorded Investment | $		$ 3,469	$ 1,156
Home Equity Loan [Member] | Consumer Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		73	52
Post-Modification Recorded Investment | $		$ 4,907	$ 3,131
Real Estate Loan [Member] | Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	3
Post-Modification Recorded Investment | $		$ 0	$ 4,921
Real Estate Loan [Member] | Commercial Real Estate Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	2
Post-Modification Recorded Investment | $		$ 0	$ 335
Real Estate Loan [Member] | Commercial Real Estate Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	1
Post-Modification Recorded Investment | $		$ 0	$ 509
Commercial and Industrial Sector [Member] | Commercial Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		12	12
Post-Modification Recorded Investment | $		$ 1,233	$ 14,883
Commercial and Industrial Sector [Member] | Commercial Portfolio Segment [Member] | Combination Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		18	2
Post-Modification Recorded Investment | $		$ 9,592	$ 648
Commercial and Industrial Sector [Member] | Commercial Portfolio Segment [Member] | other concessions [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		4	13
Post-Modification Recorded Investment | $		$ 6,375	$ 1,767
[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, and/or other concessions.

Loans and Leases (Information72

Loans and Leases (Information on Loans and Leases Modified as TDR within the Previous 12 Months (Details)	12 Months Ended
	Dec. 31, 2017USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0

Loans and Leases (Investments i

Loans and Leases (Investments in TDRs, Segregated by Risk Rating Exposure) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 221,404	$ 223,528
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	61,673	58,464
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (1) - (6) Pass [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	8,268	10,210
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (7) Special Mention [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	355	7
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (8) Substandard [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	53,050	45,509
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (9) Doubtful [Member]
Financing Receivable, Modifications [Line Items]
Total recorded investment of TDRs	$ 0	$ 2,738

Transfers of Financial Assets74

Transfers of Financial Assets (Reserve for loan repurchases) (Details) - Reserve for Off-balance Sheet Activities [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 790	$ 1,192	$ 1,059
Provision (benefit) charged to expense	100	(303)	133
Repurchased loans and settlements charged off	(18)	(99)	0
Ending balance	$ 872	$ 790	$ 1,192

Transfers of Financial Assets75

Transfers of Financial Assets (Loans sold) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Servicing Assets at Fair Value [Line Items]
Net gain on sale	$ 9,937	$ 14,635	$ 7,795
Proceeds from loans not originated for sale	14,679	34,170	33,644
Residential Mortgage [Member]
Servicing Assets at Fair Value [Line Items]
Proceeds from sale	335,656	438,925	452,590
Loans sold with servicing rights retained	304,788	399,318	416,277
Net gain on sale	6,211	11,629	7,795
Ancillary Fee Income Generated by Servicing Financial Assets, Amount	2,629	3,532	0
Fair value option adjustment	1,097	(526)	0
Proceeds from loans not originated for sale	7,400	7,600
Commercial Loan [Member]
Servicing Assets at Fair Value [Line Items]
Net gain on sale		2,100
Proceeds from loans not originated for sale	$ 7,200	$ 26,500	700
Consumer Loan [Member]
Servicing Assets at Fair Value [Line Items]
Proceeds from loans not originated for sale			$ 32,900

Transfers of Financial Assets76

Transfers of Financial Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Proceeds from loans not originated for sale	$ 14,679	$ 34,170	$ 33,644
Net gain on sale	9,937	14,635	7,795
Residential Mortgage [Member]
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Retained servicing rights	2,600,000	2,600,000
Bank servicing fees	800	1,100	1,500
Proceeds from loans not originated for sale	7,400	7,600
Net gain on sale	6,211	11,629	7,795
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	$ 7,200	26,500	700
Net gain on sale		$ 2,100
Consumer 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			$ 32,900

Transfers of Financial Assets S

Transfers of Financial Assets Servicing Assets at Amortized Cost Roll Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Beginning balance	$ 24,466	$ 20,698	$ 19,379
Additions	9,249	11,312	8,027
Amortization	(8,576)	(7,544)	(6,708)
Ending balance	$ 25,139	$ 24,466	$ 20,698

Premises and Equipment (Summary

Premises and Equipment (Summary of Premises and Equipment) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Land		$ 11,302		$ 12,595
Buildings and improvements		80,646		83,903
Leasehold improvements		82,067		83,971
Fixtures and equipment		76,665		76,146
Data processing and software		234,667		220,002
Total premises and equipment		485,347		476,617
Less: Accumulated depreciation and amortization		(355,346)		(339,204)
Premises and equipment, net		130,001		$ 137,413
Depreciation and amortization	$ 30,800	$ 33,100	$ 28,400

Premises and Equipment (Disclos

Premises and Equipment (Disclosure of Long Lived Assets Held-for-sale) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Movement in Property, Plant and Equipment [Roll Forward]
Beginning balance	$ 637	$ 637
Additions	2,006	0
Write-downs	(529)	0
Sales	(1,970)	0
Ending balance	$ 144	$ 637

Goodwill and Other Intangible80

Goodwill and Other Intangible Assets (Gross Carrying Value And Accumulated Amortization Of Other Intangible Assets) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 43,000	$ 43,000
Accumulated Amortization	(13,389)	(9,326)
Net Carrying Amount	29,611	33,674
Goodwill	538,373	538,373
Community Banking [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	516,560	516,560
HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	21,813	21,813
Core Deposits [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22,000	22,000
Accumulated Amortization	(8,610)	(6,162)
Net Carrying Amount	13,390	15,838
Customer Relationships [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,000	21,000
Accumulated Amortization	(4,779)	(3,164)
Net Carrying Amount	$ 16,221	$ 17,836

Goodwill and Other Intangible81

Goodwill and Other Intangible Assets (Schedule Of Expected Future Amortization Expense) (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 3,847
2,019	3,847
2,020	3,847
2,021	3,847
2,022	3,847
Thereafter	$ 10,376

Income Taxes (Income Tax Expens

Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal									$ 96,364	$ 73,194	$ 97,575
State and local									11,061	5,429	10,970
Total current									107,425	78,623	108,545
Deferred:
Federal									39,568	12,542	(7,279)
State and local									(48,642)	5,158	(8,234)
Total deferred									(9,074)	17,700	(15,513)
Total:
Total federal									135,932	85,736	90,296
Total state and local									(37,581)	10,587	2,736
Income tax expense	$ 17,029	$ 30,281	$ 29,090	$ 21,951	$ 23,845	$ 24,445	$ 24,599	$ 23,434	$ 98,351	$ 96,323	$ 93,032

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, State and Local tax expense (benefit)		$ (47,500)
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, State and Local tax expense (benefit), net		(37,500)
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Federal tax increase related to DTA valuation allowance		10,000
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional SALT DTA benefits		(1,800)
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, DTA measurement Adjustments		31,500
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Federal tax increase related to DTA valuation and SALT Adj		10,600
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional SALT and DTA benefits gross		(39,300)
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Federal income tax (benefit)		20,900
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional DTA SALT DTA valuation net benefit 2		(28,700)
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Tax benefit, net		(7,800)
Operating loss carryforwards		25,100	$ 0	$ 3,000
Net tax credits		$ 1,600	$ 1,000	$ 2,100
Income tax expense at federal statutory rate, Percent		35.00%	35.00%	35.00%
Increase (decrease) in deferred income taxes		$ 8,200
Deferred tax (benefit) expense		(9,074)	$ 17,700	$ (15,513)
Valuation allowance		38,292	71,474
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration		400
Valuation allowance increase (decrease)		(33,200)
Net operating loss and credit carry forwards		71,813	64,644
Unrecognized deferred tax liability for thrift bad-debt reserves		14,900
Cumulative taxable temporary differences		58,000
Unrecognized tax benefits that would impact effective tax rate		2,800	2,500	3,300
Interest and penalties		200	(200)	$ 1,100
Accrued interest and penalties related to UTBs		1,900	$ 1,700
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance		38,200
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration		644,000
Capital Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance		100
Change in the estimated realizability of SALT DTAs in future years [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)		27,000
Estimated utilization and expiration of capital loss carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)		3,500
estimated utilization of capital loss carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)		2,100
Estimated expiration of capital loss carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)		1,400
Decrease in State and Local net DTAs [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)		2,700
Connecticut [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss and credit carry forwards		1,200,000
Tax credit carryforwards		800
Minimum [Member] | Forecast [Member]
Operating Loss Carryforwards [Line Items]
Decrease in UTBs	$ 600
Maximum [Member] | Forecast [Member]
Operating Loss Carryforwards [Line Items]
Decrease in UTBs	$ 1,800
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		1,100
Shareholders' Equity [Member]
Operating Loss Carryforwards [Line Items]
Increase (decrease) in deferred income taxes		$ 700

Income Taxes (Schedule of Effec

Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax expense at federal statutory rate									$ 123,826	$ 106,208	$ 104,217
SALT expense, net of federal									8,189	6,882	7,563
Tax-exempt interest income, net									(10,826)	(8,917)	(7,117)
SALT DTA adjustments, net of federal									(28,724)	0	(5,785)
Increase in cash surrender value of life insurance									(5,120)	(5,166)	(4,557)
Other, net									(3,536)	(2,684)	(1,289)
Income tax expense	$ 17,029	$ 30,281	$ 29,090	$ 21,951	$ 23,845	$ 24,445	$ 24,599	$ 23,434	$ 98,351	$ 96,323	$ 93,032
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax expense at federal statutory rate, Percent									35.00%	35.00%	35.00%
State and local taxes, net of federal benefit, Percent									2.30%	2.30%	2.50%
Tax-exempt interest income, net, Percent									(3.10%)	(2.90%)	(2.40%)
Decrease in valuation allowance applicable to net state deferred tax assets, net of federal effects, Percent									(8.10%)	0.00%	(1.90%)
Increase in cash surrender value of life insurance, Percent									(1.40%)	(1.70%)	(1.50%)
Other, net, Percent									(1.00%)	(1.00%)	(0.50%)
Effective Tax Rate, Percent									27.80%	31.70%	31.20%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount									$ 20,891	$ 0	$ 0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent									5.90%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount									$ (6,349)	$ 0	$ 0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent									(1.80%)	0.00%	0.00%

Income Taxes (Schedule of Defer

Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for loan and lease losses	$ 51,203	$ 77,908
Net operating loss and credit carry forwards	71,813	64,644
Compensation and employee benefit plans	25,023	46,433
Net losses on derivative instruments	3,767	8,624
Net unrealized loss on securities available for sale	9,548	9,898
Other	12,273	17,682
Gross deferred tax assets	173,627	225,189
Valuation allowance	(38,292)	(71,474)
Total deferred tax assets, net of valuation allowance	135,335	153,715
Deferred tax liabilities:
Equipment-financing leases	27,955	41,910
Deferred income on repurchase of debt	1,275	4,251
Intangible assets	6,164	9,952
Mortgage servicing assets	4,445	7,313
Other	2,866	5,898
Gross deferred tax liabilities	42,705	69,324
Deferred tax assets, net	$ 92,630	$ 84,391

Income Taxes (Summary of Positi

Income Taxes (Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 3,847	$ 5,094	$ 4,593
Additions as a result of tax positions taken during the current year	584	613	865
Additions as a result of tax positions taken during prior years	7	0	1,254
Reductions as a result of tax positions taken during prior years	(61)	(625)	(247)
Reductions relating to settlements with taxing authorities	(392)	(693)	(992)
Reductions as a result of lapse of statute of limitation periods	(390)	(542)	(379)
Ending balance	$ 3,595	$ 3,847	$ 5,094

Deposits (Summary Of Deposits)

Deposits (Summary Of Deposits) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Banking and Thrift [Abstract]
Demand	$ 4,191,496	$ 4,021,061
Checking	2,736,952	2,528,274
Health Savings Accounts	5,038,681	4,362,503
Money market	2,209,492	2,047,121
Savings	4,348,700	4,320,090
Time deposits	2,468,408	2,024,808
Total interest-bearing	16,802,233	15,282,796
Total deposits	20,993,729	19,303,857
Time deposits and interest-bearing checking, included in above balances, obtained through brokers	898,157	848,618
Time deposits, included in above balance, that meet or exceed the FDIC limit	561,512	490,721
Demand deposit overdrafts reclassified as loan balances	$ 2,210	$ 1,885

Deposits (Scheduled Maturities

Deposits (Scheduled Maturities Of Time Deposits) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Banking and Thrift [Abstract]
2,018	$ 1,381,899
2,019	693,554
2,020	236,955
2,021	106,042
2,022	49,831
Thereafter	127
Total time deposits	$ 2,468,408	$ 2,024,808

Borrowings Borrowings - (Narrat

Borrowings Borrowings - (Narrative) (Details) - USD ($) $ in Billions	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Total borrowings	$ 2.5	$ 4

Borrowings (Summary Of Securiti

Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	$ 588,269	$ 740,526
Fed funds purchased	55,000	209,000
Securities sold under agreements to repurchase and other borrowings	643,269	949,526
Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	288,269	340,526
Original maturity of greater than one year, non-callable [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	$ 300,000	$ 400,000
Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.66%	1.82%
Securities Sold under Agreements to Repurchase [Member] | Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.17%	0.16%
Securities Sold under Agreements to Repurchase [Member] | Original maturity of greater than one year, non-callable [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	3.10%	3.09%
Federal Funds Purchased [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.37%	0.46%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.64%	1.53%

Borrowings (Summary Of Advances

Borrowings (Summary Of Advances Payable To The Federal Home Loan Bank) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Federal Home Loan Bank, Advances, Maturity, Rolling Year [Abstract]
FHLB advances maturing within 1 year, Total Outstanding	$ 1,150,000	$ 2,130,500
FHLB advances maturing after 1 but within 2 years, Total Outstanding	103,026	200,000
FHLB advances maturing after 2 but within 3 years, Total Outstanding	215,000	128,026
FHLB advances maturing after 3 but within 4 years, Total Outstanding	200,000	175,000
FHLB advances maturing after 4 but within 5 years, Total Outstanding	170	200,000
FHLB advances maturing after 5 years, Total Outstanding	8,909	9,370
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	1,677,105	2,842,896
Premiums on advances	0	12
Federal Home Loan Bank advances	$ 1,677,105	$ 2,842,908
Federal Home Loan Bank, Advances, Weighted Average Interest Rate [Abstract]
FHLB advances maturing within 1 year, Weighted-Average Contractual Coupon Rate (as a percent)	1.48%	0.71%
FHLB advances maturing after 1 but within 2 years, Weighted-Average Contractual Coupon Rate (as a percent)	1.81%	1.36%
FHLB advances maturing after 2 but within 3 years, Weighted-Average Contractual Coupon Rate (as a percent)	1.73%	1.73%
FHLB advances maturing after 3 but within 4 years, Weighted-Average Contractual Coupon Rate (as a percent)	4.13%	1.77%
FHLB advances maturing after 4 but within 5 years, Weighted-Average Contractual Coupon Rate (as a percent)	0.00%	1.81%
FHLB advances maturing after 5 years, Weighted-Average Contractual Coupon Rate (as a percent)	1.96%	2.59%
Federal Home Loan Bank, Advances, Weighted Average Interest Rate (as a percent)	1.85%	0.95%
Aggregate carrying value of assets pledged as collateral	$ 6,402,066	$ 5,967,318
Remaining borrowing capacity	$ 2,600,624	$ 1,192,758

Borrowings (Long-Term Debt) (De

Borrowings (Long-Term Debt) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Notes and subordinated debt	$ 227,320,000	$ 227,320,000
Debt issuance cost on senior fixed-rate notes	(826,000)	(961,000)
Long-term debt	$ 225,767,000	$ 225,514,000
Long term debt, variable interest rate, percentage	4.55%	3.94%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Interest rate spread of LIBOR plus (as a percent)	2.95%
Long-term Debt [Member]
Debt Instrument [Line Items]
Discount on senior fixed-rate notes	$ (727,000)	$ (845,000)
Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate, percentage	4.375%
Notes and subordinated debt	$ 150,000,000	150,000,000
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Notes and subordinated debt	$ 77,320,000	$ 77,320,000

Shareholders' Equity (Class of

Shareholders' Equity (Class of Stock Disclosure) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Jun. 08, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock Held, beginning balance	1,899,502
Common Stock Outstanding, beginning balance	91,752,099
Restricted share activity	124,800
Stock options exercised	(338,176)
Common stock repurchased	(222,000)
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	28,690	3,282,276
Treasury Stock Held, ending balance	1,658,526
Common Stock Outstanding, ending balance	92,021,765
Series E Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance	5,060
Stock Redeemed or Called During Period, Shares	(5,060)
Shares, ending balance	0
Series F Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance	0
Stock Issued During Period, Shares, New Issues	6,000
Shares, ending balance	6,000
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance	93,651,601
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	28,690
Shares, ending balance	93,680,291
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock Held, beginning balance	1,899,502
Restricted share activity	(124,800)
Stock options exercised	(338,176)
Common stock repurchased	(222,000)

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) - USD ($)	Jun. 01, 2015	Dec. 04, 2012	Dec. 31, 2017	Dec. 31, 2016	Dec. 06, 2012	Jun. 08, 2011
Class of Stock [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			28,690			3,282,276
Common stock par value (in usd per share)			$ 0.01	$ 0.01		$ 0.01
Exercise price of warrants or rights (in usd per share)						$ 18.28
Warrants exercised in cashless exchange			44,275
Warrants outstanding (in shares)			8,752
Preferred Stock, Par or Stated Value Per Share			$ 0.01	$ 0.01
Conversion price (in usd per share)	$ 25,400
Common Stock [Member]
Class of Stock [Line Items]
Stock repurchase program, authorized amount					$ 100,000,000
Treasury stock acquired, average cost per share (in usd per share)			$ 52.18
Stock repurchase program, remaining authorized repurchase amount			$ 103,900,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			28,690
Series A [Member]
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percent)	6.40%
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, dividend rate (as a percent)		5.25%
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Preferred stock, liquidation preference per share (in usd per share)		$ 25,000
Depository shares, issued		6,000,000
Depository share, par or stated value per share (in usd per share)		$ 25

Accumulated Other Comprehensi95

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 2,527,012	$ 2,413,960	$ 2,322,815
Other comprehensive income (loss), net of tax	1,110	1,113	(21,845)
Ending Balance	2,701,958	2,527,012	2,413,960
Available For Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	(4,881)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(7,590)	(8,901)	(22,512)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(15,476)	(6,407)	16,421
Amounts reclassified from accumulated other comprehensive (loss) income	0	(168)	(316)
Other comprehensive income (loss), net of tax	(7,590)	(9,069)	(22,828)
Ending Balance	(27,947)	(15,476)	(6,407)
Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	(2,513)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	181	825	(3,136)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(17,068)	(22,980)	(25,530)
Amounts reclassified from accumulated other comprehensive (loss) income	4,384	5,087	5,686
Other comprehensive income (loss), net of tax	4,565	5,912	2,550
Ending Balance	(15,016)	(17,068)	(22,980)
Defined Benefit Pension and Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	(8,254)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	98	(232)	(5,500)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(44,449)	(48,719)	(47,152)
Amounts reclassified from accumulated other comprehensive (loss) income	4,037	4,502	3,933
Other comprehensive income (loss), net of tax	4,135	4,270	(1,567)
Ending Balance	(48,568)	(44,449)	(48,719)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	(15,648)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(7,311)	(8,308)	(31,148)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(76,993)	(78,106)	(56,261)
Amounts reclassified from accumulated other comprehensive (loss) income	8,421	9,421	9,303
Other comprehensive income (loss), net of tax	1,110	1,113	(21,845)
Ending Balance	$ (91,531)	$ (76,993)	$ (78,106)

Accumulated Other Comprehensi96

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Reclassifications from AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Impairment loss on securities recognized in earnings									$ (126)	$ (149)	$ (110)
Income before income tax expense	$ 86,922	$ 94,777	$ 90,669	$ 81,422	$ 81,505	$ 76,262	$ 75,202	$ 70,481	353,790	303,450	297,761
Income tax expense	(17,029)	$ (30,281)	$ (29,090)	$ (21,951)	$ (23,845)	$ (24,445)	$ (24,599)	$ (23,434)	(98,351)	(96,323)	(93,032)
Earnings applicable to common shareholders	$ 67,710								246,831	198,423	195,361
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of investment securities, net									0	414	609
Impairment loss on securities recognized in earnings									0	(149)	(110)
Income before income tax expense									0	265	499
Available For Sale and Transferred Securities [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax									0	168	316
Available For Sale and Transferred Securities [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									0	(97)	(183)
Earnings applicable to common shareholders									0	168	316
Derivative Instruments [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net of tax									(4,384)	(5,087)	(5,686)
Derivative Instruments [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									2,776	2,933	3,279
Earnings applicable to common shareholders									(4,384)	(5,087)	(5,686)
Total interest expense									(7,160)	(8,020)	(8,965)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax									(6,612)	(7,126)	(6,161)	[1]
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax									0	(14)	(73)	[1]
Defined benefit pension and postretirement benefit plans [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax									(6,612)	(7,140)	(6,234)
Tax benefit									2,575	2,638	2,301
Net of tax									$ (4,037)	$ (4,502)	$ (3,933)
[1]	These accumulated other comprehensive income components are included in the computation of net periodic benefit cost (see Note 17 Retirement Benefit Plans for further details).

Accumulated Other Comprehensi97

Accumulated Other Comprehensive Loss, Net of Tax (Schedule of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale and transferred securities:
Net unrealized loss during the period	$ (12,423)	$ (14,113)	$ (35,701)
Reclassification for net gain included in net income	0	(414)	(609)
Net non-credit other-than-temporary impairment	0	149	110
Amortization of unrealized loss on securities transferred to held-to-maturity	0	0	37
Total available-for-sale and transferred securities	(12,423)	(14,378)	(36,163)
Derivative instruments:
Net unrealized gain during the period	291	1,331	(4,945)
Reclassification adjustment for net loss included in net income	7,160	8,020	8,965
Total derivative instruments	7,451	9,351	4,020
Defined benefit pension and other postretirement benefit plans:
Current year actuarial loss	155	(368)	(8,719)
Reclassification adjustment for amortization of net loss included in net income	6,612	7,126	6,161
Reclassification adjustment for prior service cost included in net income	0	14	73
Total defined benefit pension and postretirement benefit plans	6,767	6,772	(2,485)
Available-for-sale and transferred securities:
Net unrealized loss during the period	4,833	5,212	13,166
Reclassification for net gain included in net income	0	152	223
Net non-credit other-than-temporary impairment	0	(55)	(40)
Amortization of unrealized loss on securities transferred to held-to-maturity	0	0	(14)
Total available-for-sale and transferred securities	4,833	5,309	13,335
Derivative instruments:
Net unrealized gain during the period	(110)	(506)	1,809
Reclassification adjustment for net loss included in net income	(2,776)	(2,933)	(3,279)
Total derivative instruments	(2,886)	(3,439)	(1,470)
Defined benefit pension and other postretirement benefit plans:
Current year actuarial loss	(57)	136	3,219
Reclassification adjustment for amortization of net loss included in net income	(2,575)	(2,633)	(2,274)
Reclassification adjustment for prior service cost included in net income	0	(5)	(27)
Total defined benefit pension and postretirement benefit plans	(2,632)	(2,502)	918
Available-for-sale and transferred securities:
Net unrealized loss during the period	(7,590)	(8,901)	(22,535)
Reclassification for net gain included in net income	0	(262)	(386)
Net non-credit other-than-temporary impairment	0	94	70
Amortization of unrealized loss on securities transferred to held-to-maturity	0	0	23
Total available-for-sale and transferred securities	(7,590)	(9,069)	(22,828)
Derivative instruments:
Net unrealized gains (losses) on derivative instruments	181	825	(3,136)
Reclassification adjustment for net loss included in net income	4,384	5,087	5,686
Total derivative instruments	4,565	5,912	2,550
Defined benefit pension and other postretirement benefit plans:
Current year actuarial loss	98	(232)	(5,500)
Reclassification adjustment for amortization of net loss included in net income	4,037	4,493	3,887
Reclassification adjustment for prior service cost included in net income	0	9	46
Total defined benefit pension and postretirement benefit plans	4,135	4,270	(1,567)
Other Comprehensive Income (Loss), Pre-Tax Amount	1,795	1,745	(34,628)
Other Comprehensive Income (Loss), Tax Benefit (Expense)	(685)	(632)	12,783
Other comprehensive income (loss), net of tax	$ 1,110	$ 1,113	$ (21,845)

Regulatory Matters (Information

Regulatory Matters (Information On The Capital Ratios) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,093,116	$ 1,932,171
Common Equity Tier One Capital Required for Capital Adequacy	$ 845,389	$ 826,504
Common Equity Tier One Capital Ratio	11.14%	10.52%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 1,221,118	$ 1,193,840
Total risk-based capital, Actual Amount	$ 2,517,848	$ 2,328,808
Total risk-based capital, Actual Ratio	13.40%	12.68%
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,502,914	$ 1,469,341
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%	8.00%
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,878,643	$ 1,836,677
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%	10.00%
Tier 1 risk-based capital, Actual Amount	$ 2,238,172	$ 2,054,881
Tier 1 risk-based capital, Actual Ratio	11.91%	11.19%
Tier 1 risk-based capital, Capital Requirements, Minimum Amount	$ 1,127,186	$ 1,102,006
Tier 1 risk-based capital, Capital Requirements, Minimum Ratio	6.00%	6.00%
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,502,914	$ 1,469,341
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Ratio	8.00%	8.00%
Tier 1 leverage capital, Actual Amount	$ 2,238,172	$ 2,054,881
Tier 1 leverage capital, Actual Ratio	8.63%	8.13%
Tier 1 leverage capital, Capital Requirements, Minimum Amount	$ 1,036,817	$ 1,010,857
Tier 1 leverage capital, Capital Requirements, Minimum Ratio	4.00%	4.00%
Tier 1 leverage capital, Capital Requirements, Well Capitalized Amount	$ 1,296,021	$ 1,263,571
Tier 1 leverage capital, Capital Requirements, Well Capitalized Ratio	5.00%	5.00%
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 2,114,224	$ 1,945,332
Common Equity Tier One Capital Required for Capital Adequacy	$ 844,693	$ 825,228
Common Equity Tier One Capital Ratio	11.26%	10.61%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 1,220,113	$ 1,191,995
Total risk-based capital, Actual Amount	$ 2,316,580	$ 2,141,939
Total risk-based capital, Actual Ratio	12.34%	11.68%
Total risk-based capital, Capital Requirements, Minimum Amount	$ 1,501,677	$ 1,467,071
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%	8.00%
Total risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,877,097	$ 1,833,839
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%	10.00%
Tier 1 risk-based capital, Actual Amount	$ 2,114,224	$ 1,945,332
Tier 1 risk-based capital, Actual Ratio	11.26%	10.61%
Tier 1 risk-based capital, Capital Requirements, Minimum Amount	$ 1,126,258	$ 1,100,304
Tier 1 risk-based capital, Capital Requirements, Minimum Ratio	6.00%	6.00%
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Amount	$ 1,501,677	$ 1,467,071
Tier 1 risk-based capital, Capital Requirements, Well Capitalized Ratio	8.00%	8.00%
Tier 1 leverage capital, Actual Amount	$ 2,114,224	$ 1,945,332
Tier 1 leverage capital, Actual Ratio	8.14%	7.70%
Tier 1 leverage capital, Capital Requirements, Minimum Amount	$ 1,038,442	$ 1,010,005
Tier 1 leverage capital, Capital Requirements, Minimum Ratio	4.00%	4.00%
Tier 1 leverage capital, Capital Requirements, Well Capitalized Amount	$ 1,298,052	$ 1,262,507
Tier 1 leverage capital, Capital Requirements, Well Capitalized Ratio	5.00%	5.00%
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%

Regulatory Matters Regulatory M

Regulatory Matters Regulatory Matters - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash dividends paid to parent company	$ 120	$ 145
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash held by Bank	$ 82.3	$ 58.6

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								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share Reconciliation [Abstract]
Net income	$ 69,893	$ 64,496	$ 61,579	$ 59,471	$ 57,660	$ 51,817	$ 50,603	$ 47,047	$ 255,439	$ 207,127	$ 204,729
Less: Preferred stock dividends									8,184	8,096	8,711
Net income available to common shareholders, basic		$ 62,426	$ 59,485	$ 57,342	$ 55,501	$ 49,634	$ 48,398	$ 44,921	247,255	199,031	196,018
Net income available to common shareholders, diluted									247,255	199,031	196,018
Less: Earnings applicable to participating securities, basic									424	608	657
Less: Earnings applicable to participating securities, diluted									424	608	657
Earnings applicable to common shareholders	$ 67,710								246,831	198,423	195,361
Earnings applicable to common shareholders, diluted									$ 246,831	$ 198,423	$ 195,361
Shares:
Weighted-average common shares outstanding - basic									91,965	91,367	90,968
Effect of dilutive securities:
Stock options and restricted stock (in shares)									385	461	524
Warrants (in shares)									6	28	41
Weighted Average Number of Shares Outstanding, Diluted									92,356	91,856	91,533
Earnings per common share:
Earnings per common share, Basic (in dollars per share)	$ 0.74	$ 0.68	$ 0.65	$ 0.62	$ 0.61	$ 0.54	$ 0.53	$ 0.49	$ 2.68	$ 2.17	$ 2.15
Earnings per common share, Diluted (in dollars per share)	$ 0.73	$ 0.67	$ 0.64	$ 0.62	$ 0.60	$ 0.54	$ 0.53	$ 0.49	$ 2.67	$ 2.16	$ 2.13

Earnings Per Common Share (Sche

Earnings Per Common Share (Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	0	41	213
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	58	125	92

Derivative Financial Instrum102

Derivative Financial Instruments (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	$ 8,992	$ 35,727
Derivative Asset, Collateral, Obligation to Return Cash, Offset	32,000
Derivative Asset	43	0
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	2,387	25,300
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	35,100
Derivative Liability	142	446
Loan Origination Commitments [Member]
Derivative [Line Items]
Other Commitment	39,000
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Other Commitment	11,300
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	2,770	3,270
Derivative Asset, Fair Value, Amount Offset Against Collateral	91	2,335
Derivative Asset, Collateral, Obligation to Return Cash, Offset	2,679	935
Derivative Asset	0	0
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	0	792
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	792
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	0	0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	6,222	32,457
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,154	21,917
Derivative Asset, Collateral, Obligation to Return Cash, Offset	4,025	10,540
Derivative Asset	43	0
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	2,387	24,508
Derivative Liability, Fair Value, Amount Offset Against Collateral	2,245	23,462
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	600
Derivative Liability	142	446
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	325,000	225,000
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	2,770	3,270
Derivative Liability, Notional Amount	0	100,000
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	0	792
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	2,791,760	1,943,485
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	5,977	32,226
Derivative Liability, Notional Amount	721,048	1,242,937
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	1,968	24,388
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	7,914	10,634
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	258	231
Derivative Liability, Notional Amount	30,328	14,265
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	419	120
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	4,288,183	3,879,713
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	29,745	74,367
Derivative Liability, Notional Amount	3,056,079	2,856,313
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	28,423	44,397
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	1,366,299	1,734,679
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	23,009	38,668
Derivative Liability, Notional Amount	2,146,518	1,451,762
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	25,631	19,001
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Credit Risk Contract [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	93,713	86,037
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	80	139
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Credit Risk Contract [Member] | Credit Default Swap, Selling Protection [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	116,882	87,273
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	111	166
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	0	1,438
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	0	19
Derivative Liability, Notional Amount	2,073	181
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	184	11
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	28,497	103,440
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	421	3,084
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member] | Credit Default Swap, Selling Protection [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	39,230	59,895
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	110	711
Subject to and not subject to Master Netting Agreements [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	4,613,183	4,104,713
Derivative Asset, Fair Value, Gross derivative instruments, before netting	32,515	77,637
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,245	24,252
Derivative Asset, Collateral, Obligation to Return Cash, Offset	6,704	11,475
Derivative Asset	23,566	41,910
Derivative Liability, Notional Amount	3,056,079	2,956,313
Derivative Liability, Fair Value, Gross derivative instruments, before netting	28,423	45,189
Derivative Liability, Fair Value, Amount Offset Against Collateral	2,245	24,254
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	600
Derivative Liability	$ 26,178	$ 20,335

Derivative Financial Instrum103

Derivative Financial Instruments (Schedule of the changes in the fair value of non-hedge accounting derivatives) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Total impact on other non-interest income	$ 114	$ 9,793	$ 5,066
Operating Expense [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Total impact on other non-interest income	2,702	8,668	4,361
Operating Expense [Member] | Not Designated as Hedging Instrument [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Total impact on other non-interest income	242	(361)	(33)
Operating Expense [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Total impact on other non-interest income	(2,062)	1,553	801
Operating Expense [Member] | Not Designated as Hedging Instrument [Member] | Other Contract [Member]
Derivative [Line Items]
Total impact on other non-interest income	$ (768)	$ (67)	$ (63)

Derivative Financial Instrum104

Derivative Financial Instruments (AOCL Cash Flow Derivatives - Narrative) (Details) - Cash Flow Hedging [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Derivative [Line Items]
Cash flow hedge to be reclassified from AOCL as an increase to interest expense	$ (6.2)
Remaining unamortized loss on termination of cash flow hedges	14.9
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Cash flow hedge to be reclassified from AOCL as an increase to interest expense	$ 0.8

Derivative Financial Instrum105

Derivative Financial Instruments (Schedule of offsetting financial assets and liabilities for non-customer derivative positions) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Asset, Gross Amount	$ 8,992	$ 35,727
Derivative Asset, Collateral, Obligation to Return Cash, Offset	32,000
Derivative Asset, Net Amount	43	0
Derivative Liability, Gross Amount	2,387	25,300
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	35,100
Derivative Liability, Net Amount	142	446
Subject to and not subject to Master Netting Agreements [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,245	24,252
Derivative Asset, Collateral, Obligation to Return Cash, Offset	6,704	11,475
Derivative Asset, Net Amount	23,566	41,910
Derivative Liability, Fair Value, Amount Offset Against Collateral	2,245	24,254
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	600
Derivative Liability, Net Amount	26,178	20,335
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Gross Amount	2,770	3,270
Derivative Asset, Fair Value, Amount Offset Against Collateral	91	2,335
Derivative Asset, Collateral, Obligation to Return Cash, Offset	2,679	935
Derivative Asset, Net Amount	0	0
Derivative Liability, Gross Amount	0	792
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	792
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability, Net Amount	0	0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Gross Amount	6,222	32,457
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,154	21,917
Derivative Asset, Collateral, Obligation to Return Cash, Offset	4,025	10,540
Derivative Asset, Net Amount	43	0
Derivative Liability, Gross Amount	2,387	24,508
Derivative Liability, Fair Value, Amount Offset Against Collateral	2,245	23,462
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	600
Derivative Liability, Net Amount	$ 142	$ 446

Derivative Financial Instrum106

Derivative Financial Instruments (Counterparty Credit Risk) (Narrative) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Derivative [Line Items]
Derivative, Collateral, Obligation to Return Cash	$ 406
Net margin collateral posted	(3,100)
Initial margin	32,000
Variation margin collateral received	35,100
Maximum exposure	23,000
Market Approach Valuation Technique [Member]
Derivative [Line Items]
Maximum exposure	$ 28,200

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,806,789	$ 5,399,762
Rabbi Trust [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	2,200
Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	18,000
Total credit-related financial instruments with off-balance sheet risk	9,100
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	$ 6,100

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring Basis) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 43	$ 0
Originated loans held for sale	20,888	60,260
Derivative liability	142	446
Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	18,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets held at fair value	2,703,701	3,139,609
Derivative liability	28,423	45,189
Fair Value, Measurements, Recurring [Member] | US Treasury Bill Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,247	734
Fair Value, Measurements, Recurring [Member] | Agency collateralized mortgage obligations (agency CMO) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	306,333	419,706
Fair Value, Measurements, Recurring [Member] | Agency mortgage-backed securities (agency MBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,107,841	954,349
Fair Value, Measurements, Recurring [Member] | Agency commercial mortgage-backed securities (agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	588,026	573,272
Fair Value, Measurements, Recurring [Member] | Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	361,067	477,365
Fair Value, Measurements, Recurring [Member] | Collateralized loan obligations (CLO) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	209,851	427,390
Fair Value, Measurements, Recurring [Member] | Trust Preferred Securities Single Issuers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	7,050	28,633
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	56,622	109,642
Fair Value, Measurements, Recurring [Member] | Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	4,801	5,119
Fair Value, Measurements, Recurring [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	7,460	5,502
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Originated loans held for sale	20,888	60,260
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	32,515	77,637
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets held at fair value	6,306	6,103
Derivative liability	587	120
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Bill Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,247	734
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Agency commercial mortgage-backed securities (agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	4,801	5,119
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Loan Origination Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Originated loans held for sale	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	258	250
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets held at fair value	2,689,935	3,128,004
Derivative liability	27,836	45,069
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency collateralized mortgage obligations (agency CMO) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	306,333	419,706
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency mortgage-backed securities (agency MBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,107,841	954,349
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency commercial mortgage-backed securities (agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	588,026	573,272
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	361,067	477,365
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Collateralized loan obligations (CLO) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	209,851	427,390
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Trust Preferred Securities Single Issuers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	7,050	28,633
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	56,622	109,642
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Loan Origination Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Originated loans held for sale	20,888	60,260
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	32,257	77,387
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets held at fair value	7,460	5,502
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Agency commercial mortgage-backed securities (agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	7,460	5,502
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		0
Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	2,638,037	2,991,091
Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,247	734
Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 2,636,790	$ 2,990,357

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements (Schedule Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) - Equity Method Investments [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3, beginning of period, Financial Assets	$ 5,502
Unrealized gain included in net income	613
Purchases/capital funding	1,399
Payments	(54)
Level 3, end of period, Financial Assets	$ 7,460

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Valuation Methodology And Unobservable Inputs) (Detail) - Fair Value, Measurements, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Nonperforming Financial Instruments [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Collateral dependent impaired loans and leases	$ 12,556
Nonperforming Financial Instruments [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	0.00%
Nonperforming Financial Instruments [Member] | Minimum [Member] | Market Approach Valuation Technique - Discount for cost to sell [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	0.00%
Nonperforming Financial Instruments [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	15.00%
Nonperforming Financial Instruments [Member] | Maximum [Member] | Market Approach Valuation Technique - Discount for cost to sell [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	8.00%
Other Real Estate Owned [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Other Assets, Fair Value Disclosure	$ 1,077
Other Real Estate Owned [Member] | Market Approach Valuation Technique - Discount for cost to sell [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	8.00%
Other Real Estate Owned [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	0.00%
Other Real Estate Owned [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates	20.00%

Fair Value Measurements (Summar

Fair Value Measurements (Summary Of Estimated Fair Values Of Significant Financial Instruments) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
LHFS, at fair value option	$ 20,888	$ 60,260
Mortgage servicing assets, Carrying Amount	25,139	24,466	$ 20,698	$ 19,379
Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments	18,000
Reported Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
LHFS, at fair value option	0	7,317
Loans and leases, net	17,323,864	16,832,268
Securities sold under agreements to repurchase and other borrowings	643,269	949,526
FHLB advances	1,677,105	2,842,908
Long-term debt	225,767	225,514
Reported Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Deposits other than time deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	18,525,321	17,279,049
Reported Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Time Deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,468,408	2,024,808
Reported Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage servicing assets, Carrying Amount	25,139	24,466
Reported Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Securities held-to-maturity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	4,487,392	4,160,658
Reported Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments	10,562	11,034
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
LHFS, at fair value option	0	7,444
Securities sold under agreements to repurchase and other borrowings	644,084	955,660
FHLB advances	1,678,070	2,825,101
Long-term debt	234,359	225,514
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Deposits other than time deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	18,525,321	17,279,049
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Time Deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	2,455,245	2,024,395
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Securities held-to-maturity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	4,456,350	4,125,125
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases, net	17,211,619	16,678,106
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage servicing assets	45,309	52,075
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments	$ 12,940	$ 13,189

Retirement Benefit Plans (Narra

Retirement Benefit Plans (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Jul. 01, 2015
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 78
Defined Benefit Plan, Accumulated Benefit Obligation	245,500	$ 227,200
Net actuarial loss	$ 5,100
Assumed healthcare cost trend (as a percent)	7.50%
Healthcare-cost trend rate in 2024 (as a percent)	4.60%
Employer matching contribution, percent of match	100.00%
Employer matching contribution, percent of employees' gross pay	2.00%
Employer matching contribution, additional percent of match	50.00%
Employer additional matching contribution, percent of employees' gross pay	6.00%
Compensation expense	$ 12,000	11,100	$ 10,900
Multiemployer Plans, Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan						$ (800)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	$ 20,000
Expected long-term return on assets (as a percent)	6.50%	7.00%	7.00%
Funded status of plan	$ (13,093)	$ (18,586)
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	122	124
Funded status of plan	(13,096)	(11,806)
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 219	185
Assumed healthcare cost trend (as a percent)	7.50%			8.25%	8.00%
Increase in net periodic postretirement benefit cost if trend increased by 1%	$ 5
Increase in accumulated benefit obligation if trend increased by 1%	148
Decrease in net periodic postretirement benefit cost if trend rate decreased by 1%	5
Decrease in accumulated benefit obligation if trend rate decreased 1%	134
Funded status of plan	$ (3,094)	$ (3,852)
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' gross pay	3.00%

Retirement Benefit Plans (Chang

Retirement Benefit Plans (Changes in Plan Assets and Funded Status of Pension Plans and Other Postretirement Benefit Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets:
Beginning balance	$ 192,734
Employer contributions	78
Ending balance	216,225	$ 192,734
Pension Plan [Member]
Change in benefit obligation:
Beginning balance	211,508	203,645
Service cost	50	45	$ 45
Interest cost	7,314	8,441	8,008
Actuarial loss (gain)	18,396	6,108
Benefits paid and administrative expenses	(7,950)	(6,731)
Ending balance (1)	229,318	211,508	203,645
Change in plan assets:
Beginning balance	192,922	161,369
Actual return on plan assets	31,253	18,284
Employer contributions	0	20,000
Benefits paid and administrative expenses	(7,950)	(6,731)
Ending balance	216,225	192,922	161,369
Funded status of the plan at year end (2)	(13,093)	(18,586)
SERP [Member]
Change in benefit obligation:
Beginning balance	11,806	10,518
Service cost	0	0	0
Interest cost	375	389	345
Actuarial loss (gain)	1,037	1,023
Benefits paid and administrative expenses	(122)	(124)
Ending balance (1)	13,096	11,806	10,518
Change in plan assets:
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	122	124
Benefits paid and administrative expenses	(122)	(124)
Ending balance	0	0	0
Funded status of the plan at year end (2)	(13,096)	(11,806)
Other Benefits [Member]
Change in benefit obligation:
Beginning balance	3,852	3,853
Service cost	0	0	0
Interest cost	92	125	123
Actuarial loss (gain)	(631)	59
Benefits paid and administrative expenses	(219)	(185)
Ending balance (1)	3,094	3,852	3,853
Change in plan assets:
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	219	185
Benefits paid and administrative expenses	(219)	(185)
Ending balance	0	0	$ 0
Funded status of the plan at year end (2)	$ (3,094)	$ (3,852)

Retirement Benefit Plans (Summa

Retirement Benefit Plans (Summary of Components of Accumulated Other Comprehensive Loss Related to Pensions and Postretirement Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Deferred tax benefit		$ (2,632)	$ (2,502)	$ 918
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)		59,433	65,857
Prior service cost		0	0
Total pre-tax amounts included in AOCL		59,433	65,857
Deferred tax benefit	$ 23,727	13,407
Amounts included in accumulated AOCL, net of tax		46,026	42,130
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)		3,299	3,009
Prior service cost		0	0
Total pre-tax amounts included in AOCL		3,299	3,009
Deferred tax benefit	1,084	744
Amounts included in accumulated AOCL, net of tax		2,555	1,925
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)		(16)	616
Prior service cost		0	0
Total pre-tax amounts included in AOCL		(16)	616
Deferred tax benefit	$ 222	(3)
Amounts included in accumulated AOCL, net of tax		$ (13)	$ 394

Retirement Benefit Plans (Expec

Retirement Benefit Plans (Expected Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	$ 9,009
2,019	8,630
2,020	9,065
2,021	9,792
2,022	10,425
2023-2027	55,206
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	11,371
2,019	130
2,020	132
2,021	132
2,022	131
2023-2027	651
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	354
2,019	342
2,020	328
2,021	311
2,022	292
2023-2027	$ 1,125

Retirement Benefit Plans (Su116

Retirement Benefit Plans (Summary of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 50	$ 45	$ 45
Interest cost on benefit obligations	7,314	8,441	8,008
Expected return on plan assets	(12,296)	(11,461)	(11,873)
Amortization of prior service cost	0	0	0
Recognized net loss	5,864	6,665	5,724
Net periodic benefit cost (benefit)	932	3,690	1,904
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost on benefit obligations	375	389	345
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Recognized net loss	748	426	390
Net periodic benefit cost (benefit)	1,123	815	735
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost on benefit obligations	92	125	123
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	14	73
Recognized net loss	0	35	47
Net periodic benefit cost (benefit)	$ 92	$ 174	$ 243

Retirement Benefit Plans (Ch117

Retirement Benefit Plans (Changes in Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (gain) loss	$ (155)	$ 368	$ 8,719
Amounts reclassified from AOCL	(6,612)	(7,126)	(6,161)
Total (gain) loss recognized in OCI	(6,767)	(6,772)	2,485
Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (gain) loss	(561)	(715)	8,525
Amounts reclassified from AOCL	(5,864)	(6,665)	(5,724)
Amortization of prior service cost	0	0	0
Total (gain) loss recognized in OCI	(6,425)	(7,380)	2,801
SERP [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (gain) loss	1,037	1,023	372
Amounts reclassified from AOCL	(748)	(426)	(390)
Amortization of prior service cost	0	0	0
Total (gain) loss recognized in OCI	289	597	(18)
Other Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (gain) loss	(631)	60	(178)
Amounts reclassified from AOCL	0	(35)	(47)
Amortization of prior service cost	0	(14)	(73)
Total (gain) loss recognized in OCI	$ (631)	$ 11	$ (298)

Retirement Benefit Plans (Su118

Retirement Benefit Plans (Summary of Fair Value of Plan Assets by Level) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 216,225	$ 192,734
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38,963	32,227
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	177,262	159,714
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	793	$ 934
Exchange traded funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37,848	31,526
Exchange traded funds [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37,848	31,526
Exchange traded funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Exchange traded funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,115	701
Cash and cash equivalents [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,115	701
Cash and cash equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and cash equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	107,430	96,429
Fixed Income Funds [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed Income Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	107,430	96,429
Fixed Income Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69,832	63,285
Equity Funds [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69,832	63,285
Equity Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Insurance Company Investment Contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	793
Insurance Company Investment Contract [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Insurance Company Investment Contract [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Insurance Company Investment Contract [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 793

Retirement Benefit Plans (Ch119

Retirement Benefit Plans (Changes in Fair Value of Level 3 Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	$ 192,734
Employer contributions	78
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(705)	$ 0
Ending balance	216,225	192,734
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	793	934
Employer contributions		0
Unrealized gains relating to instruments still held at the reporting date	0	(10)
Benefit payments, administrative expenses	(166)	(131)
Ending balance	$ 0	$ 793

Retirement Benefit Plans (Defin

Retirement Benefit Plans (Defined Benefit, Information about Plan Assets) (Details)	Dec. 31, 2017	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Target Allocation (as a percent)	100.00%
Percentage of Pension Plan assets	100.00%	100.00%
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation (as a percent)	55.00%
Percentage of Pension Plan assets	50.00%	51.00%
Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation (as a percent)	45.00%
Percentage of Pension Plan assets	50.00%	49.00%

Retirement Benefit Plans (Weigh

Retirement Benefit Plans (Weighted Average Assumptions used to Determine Benefit Obligations) (Details)	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.50%	4.01%
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.30%	3.63%
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.00%	3.27%

Retirement Benefit Plans (We122

Retirement Benefit Plans (Weighted Average Assumptions used to Determine Net Periodic Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Assumed healthcare cost trend (as a percent)	7.50%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	4.01%	4.20%	3.85%
Expected long-term return on assets (as a percent)	6.50%	7.00%	7.00%
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.63%	3.75%	3.50%
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.27%	3.35%	3.15%
Assumed healthcare cost trend (as a percent)	7.50%			8.25%	8.00%

Retirement Benefit Plans (Contr

Retirement Benefit Plans (Contributions and Funding Status of the Fund) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Contributions by Webster Bank	$ 614	$ 690	$ 340
Funded Status of the Plan at December 31,	At least 80 percent	At least 80 percent

Share-Based Plans (Narrative) (

Share-Based Plans (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized	13,400,000
Number of common shares available for grant	2,600,000
Vesting period (in years)	1 year
Stock options granted	124,800
Aggregate intrinsic value	$ 25.2
Total intrinsic value of options exercised	$ 11.1	$ 6.4	$ 4.3
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	168,369
Unrecognized stock compensation expense	$ 13.5
Unrecognized stock compensation expense, recognition period (in years)	1 year 10 months 24 days
Fair value of restricted stock awards	$ 12.7	$ 11.6	$ 11.6
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common shares available for grant	100,000
Time Based Restricted Stock Awards [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Time Based Restricted Stock Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	89,581
Vesting period (in years)	3 years
Award vesting percentage	50.00%
Performance Shares [Member] | Minimum [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	0.00%
Performance Shares [Member] | Maximum [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	150.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted	0
Number of options outstanding (in shares)	673,039	1,072,974
Employee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life (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)	639,151
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	33,888

Share-Based Plans (Summary of S

Share-Based Plans (Summary of Stock-based Compensation Expense Recognized) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 12,276	$ 11,438	$ 10,935
Income tax benefit (1)	11,849	4,132	3,903
Tax Benefit from Share-based Payment Awards	7,100
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	0	43	379
Restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 12,276	$ 11,395	$ 10,556

Share-Based Plans (Summary of R

Share-Based Plans (Summary of Restricted Stock and Stock Option Activity) (Detail)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted, Number of Shares	124,800
Options exercised, Number of Shares	338,176
Restricted Stock [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)	253,361
Restricted Stock, Granted (in shares)	168,369
Restricted stock, Vested restricted stock awards (in shares)	194,986
Restricted stock, Forfeited (in shares)	18,944
Restricted stock, Outstanding at end of period (in shares)	207,800
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 32.24
Restricted stock, Granted (in dollars per share) | $ / shares	54.76
Restricted stock, Vested restricted stock awards (in dollars per share) | $ / shares	37.16
Restricted stock, Forfeited (in dollars per share) | $ / shares	35.58
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 43.16
Time Based Restricted Stock Unit 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)	2,158
Restricted Stock, Granted (in shares)	8,129
Restricted stock, Vested restricted stock awards (in shares)	10,287
Restricted stock, Forfeited (in shares)	0
Restricted stock, Outstanding at end of period (in shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 32.89
Restricted stock, Granted (in dollars per share) | $ / shares	56.07
Restricted stock, Vested restricted stock awards (in dollars per share) | $ / shares	51.21
Restricted stock, Forfeited (in dollars per share) | $ / shares	0
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 0
Performance 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)	116,184
Restricted Stock, Granted (in shares)	89,581
Restricted stock, Vested restricted stock awards (in shares)	117,695
Restricted stock, Forfeited (in shares)	9,154
Restricted stock, Outstanding at end of period (in shares)	78,916
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted stock, at beginning of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 33.62
Restricted stock, Granted (in dollars per share) | $ / shares	56.18
Restricted stock, Vested restricted stock awards (in dollars per share) | $ / shares	42.09
Restricted stock, Forfeited (in dollars per share) | $ / shares	43.10
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share) | $ / shares	$ 45.35
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	1,072,974
Options granted, Number of Shares	0
Options exercised, Number of Shares	399,935
Options forfeited, Number of Shares	0
Options outstanding, at end of period, Number of Shares	673,039
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Options, at beginning of period, Weighted-average Exercise Price (in dollars per share) | $ / shares	$ 21.24
Options granted, Weighted-Average Exercise Price (in dollars per share) | $ / shares	0
Options exercised, Weighted-Average Exercise Price (in dollars per share) | $ / shares	25.42
Options forfeited, Weighted-Average Exercise Price (in dollars per share) | $ / shares	0
Options, at end of period, Weighted-average Exercise Price (in dollars per share) | $ / shares	$ 18.75

Share-Based Plans (Options Outs

Share-Based Plans (Options Outstanding and Options Exercisable) (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	673,039
Options Outstanding, Weighted-Average Remaining Contractual Life (years)	3 years 4 months 24 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 18.75
Options Exercisable, Number of Shares | shares	673,039
Options Exercisable, Weighted-Average Remaining Contractual Life (years)	3 years 4 months 15 days
Options Exercisable, Weighted-Average Remaining Contractual Life (years)	$ 18.75
$5.14 - 12.85 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum (in dollars per share)	5.14
Range of exercise prices, Maximum (in dollars per share)	$ 12.85
Options Outstanding, Number of Shares | shares	222,947
Options Outstanding, Weighted-Average Remaining Contractual Life (years)	1 year 2 months 12 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 9.43
Options Exercisable, Number of Shares | shares	222,947
Options Exercisable, Weighted-Average Remaining Contractual Life (years)	1 year 2 months
Options Exercisable, Weighted-Average Remaining Contractual Life (years)	$ 9.43
22.04 - 25.15 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum (in dollars per share)	22.04
Range of exercise prices, Maximum (in dollars per share)	$ 25.15
Options Outstanding, Number of Shares | shares	450,092
Options Outstanding, Weighted-Average Remaining Contractual Life (years)	4 years 6 months
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 23.37
Options Exercisable, Number of Shares | shares	450,092
Options Exercisable, Weighted-Average Remaining Contractual Life (years)	4 years 6 months 2 days
Options Exercisable, Weighted-Average Remaining Contractual Life (years)	$ 23.37

Segment Reporting Segment Repor

Segment Reporting Segment Reporting Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | Segment	3
Loans and leases	$ 17,523,858	$ 17,026,588	$ 15,671,735
Consumer Portfolio Segment [Member]
Segment Reporting Information [Line Items]
Loans and leases	$ 2,590,225	2,684,500	$ 2,702,560
Consumer Portfolio Segment [Member] | Home Equity Liquidating Portfolio [Member]
Segment Reporting Information [Line Items]
Loans and leases		$ 65,000

Segment Reporting - Operating R

Segment Reporting - Operating Results and Total Assets Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net interest income (loss)	$ 204,932	$ 200,904	$ 197,787	$ 192,664	$ 185,259	$ 180,197	$ 176,905	$ 176,152	$ 796,287	$ 718,513	$ 664,625
Provision for loan and lease losses	13,000	10,150	7,250	10,500	12,500	14,250	14,000	15,600	40,900	56,350	49,300
Net interest income (loss) after provision for loan and lease losses									755,387	662,163	615,325
Non-interest income	66,039								259,478	264,478	237,777
Non-interest expense	171,049	161,823	164,419	163,784	161,871	156,097	152,778	152,445	661,075	623,191	555,341
Income before income tax expense	86,922	94,777	90,669	81,422	81,505	76,262	75,202	70,481	353,790	303,450	297,761
Income tax expense (benefit)	17,029	30,281	29,090	21,951	23,845	24,445	24,599	23,434	98,351	96,323	93,032
Net income	69,893	$ 64,496	$ 61,579	$ 59,471	57,660	$ 51,817	$ 50,603	$ 47,047	255,439	207,127	204,729
Total Assets	26,487,645				26,072,529				26,487,645	26,072,529
Operating Segments [Member] | Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)									322,393	287,596	266,085
Provision for loan and lease losses									38,518	37,455	30,546
Net interest income (loss) after provision for loan and lease losses									283,875	250,141	235,539
Non-interest income									55,194	57,253	46,967
Non-interest expense									154,037	138,379	129,499
Income before income tax expense									185,032	169,015	153,007
Income tax expense (benefit)									51,438	53,649	47,804
Net income									133,594	115,366	105,203
Total Assets	9,350,028				9,069,445				9,350,028	9,069,445
Operating Segments [Member] | Community Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)									383,700	367,137	356,881
Provision for loan and lease losses									2,382	18,895	18,754
Net interest income (loss) after provision for loan and lease losses									381,318	348,242	338,127
Non-interest income									107,368	110,197	108,647
Non-interest expense									373,081	369,132	335,834
Income before income tax expense									115,605	89,307	110,940
Income tax expense (benefit)									32,137	28,348	34,605
Net income									83,468	60,959	76,335
Total Assets	8,909,671				8,721,046				8,909,671	8,721,046
Operating Segments [Member] | HSA Bank [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)									104,704	81,451	73,433
Provision for loan and lease losses									0	0	0
Net interest income (loss) after provision for loan and lease losses									104,704	81,451	73,433
Non-interest income									77,378	71,710	62,475
Non-interest expense									113,143	97,152	81,449
Income before income tax expense									68,939	56,009	54,459
Income tax expense (benefit)									19,165	17,779	17,016
Net income									49,774	38,230	37,443
Total Assets	76,308				83,987				76,308	83,987
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)									(14,510)	(17,671)	(31,774)
Provision for loan and lease losses									0	0	0
Net interest income (loss) after provision for loan and lease losses									(14,510)	(17,671)	(31,774)
Non-interest income									19,538	25,318	19,688
Non-interest expense									20,814	18,528	8,559
Income before income tax expense									(15,786)	(10,881)	(20,645)
Income tax expense (benefit)									(4,389)	(3,453)	(6,393)
Net income									(11,397)	(7,428)	$ (14,252)
Total Assets	$ 8,151,638				$ 8,198,051				$ 8,151,638	$ 8,198,051

Commitments and Contingencie130

Commitments and Contingencies (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rental expense under leases	$ 31.1	$ 30.4	$ 21.5
Rental income	$ 0.7	$ 0.8	$ 0.8

Commitments and Contingencie131

Commitments and Contingencies (Schedule of Future Minimum Rental Payments and Receipts for Leases) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Rental Payments, 2017	$ 29,181
Rental Payments, 2018	28,035
Rental Payments, 2019	26,254
Rental Payments, 2020	24,552
Rental Payments, 2021	20,885
Rental Payments, Thereafter	77,541
Rental Payments, Total	206,448
Rental Receipts, 2017	717
Rental Receipts, 2018	592
Rental Receipts, 2019	488
Rental Receipts, 2020	395
Rental Receipts, 2021	353
Rental Receipts, Thereafter	1,438
Rental Receipts, Total	$ 3,983

Commitments and Contingencie132

Commitments and Contingencies (Outstanding Financial Instruments Contract Amounts Represent Credit Risk) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,806,789	$ 5,399,762
Standby letters of credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	195,902	128,985
Letter of Credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	43,200	46,497
Commitments to extend credit [Member]
Loss Contingencies [Line Items]
Total credit-related financial instruments with off-balance sheet risk	$ 5,567,687	$ 5,224,280

Commitments and Contingencie133

Commitments and Contingencies (Schedule for Unfunded Commitments) (Details) - Allowance for Credit Loss [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 2,287	$ 2,119	$ 5,151
Provision (benefit)	75	168	(3,032)
Ending balance	$ 2,362	$ 2,287	$ 2,119

Parent Company Information (Com

Parent Company Information (Components of Condensed Balance Sheets The Parent Company) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 231,158	$ 190,663	$ 199,693	$ 213,914
Securities available-for-sale, at fair value	2,638,037	2,991,091
Other assets	286,677	294,462
Total assets	26,487,645	26,072,529
Liabilities and shareholders’ equity:
Total liabilities	23,785,687	23,545,517
Total liabilities and shareholders' equity	26,487,645	26,072,529
Parent Company [Member]
Assets:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	181,085	152,947	$ 279,644	$ 272,492
Intercompany debt securities	150,000	150,000
Investment in subsidiaries	2,585,955	2,425,398
Alternative investments	2,939	4,275
Other assets	13,252	24,659
Total assets	2,933,231	2,757,279
Liabilities and shareholders’ equity:
Senior notes	148,447	148,194
Junior subordinated debt	77,320	77,320
Accrued interest payable	2,616	2,589
Due to subsidiaries	575	365
Other liabilities	2,315	1,799
Total liabilities	231,273	230,267
Shareholders’ equity	2,701,958	2,527,012
Total liabilities and shareholders' equity	$ 2,933,231	$ 2,757,279

Parent Company Information (135

Parent Company Information (Components of Condensed Income Statement The Parent Company) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Income:
Loss on sale of investment securities									$ 0	$ 414	$ 609
Other non-interest income		$ 65,846	$ 64,551	$ 63,042	$ 70,617	$ 66,412	$ 65,075	$ 62,374
Operating Expense:
Compensation and benefits									359,926	332,127	297,517
Other non-interest expense									87,205	83,910	70,584
Income tax benefit	$ (17,029)	$ (30,281)	$ (29,090)	$ (21,951)	$ (23,845)	$ (24,445)	$ (24,599)	$ (23,434)	(98,351)	(96,323)	(93,032)
Parent Company [Member]
Operating Income:
Dividend income from bank subsidiary									120,000	145,000	110,000
Interest on securities and deposits									4,477	1,911	546
Loss on sale of investment securities									0	(2,410)	0
Alternative investments income									1,504	176	2,274
Other non-interest income									204	7,485	152
Total operating income									126,185	152,162	112,972
Operating Expense:
Interest expense on borrowings									10,380	9,981	9,665
Compensation and benefits									12,425	11,461	10,965
Other non-interest expense									10,583	6,278	6,005
Total operating expense									33,388	27,720	26,635
Income before income tax benefit and equity in undistributed earnings of subsidiaries and associated companies									92,797	124,442	86,337
Income tax benefit									3,004	3,086	2,929
Equity in undistributed earnings of subsidiaries and associated companies									159,638	79,599	115,463
Net income									$ 255,439	$ 207,127	$ 204,729

Parent Company Information (136

Parent Company Information (Components of Condensed Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available for sale securities	$ (7,590)	$ (9,069)	$ (22,828)
Net unrealized gains (losses) on derivative instruments	181	825	(3,136)
Other comprehensive loss of subsidiaries and associated companies	256,549	208,240	182,884
Other comprehensive income (loss), net of tax	1,110	1,113	(21,845)
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income	255,439	207,127	204,729
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available for sale securities	0	584	(2,109)
Net unrealized gains (losses) on derivative instruments	1,216	1,223	1,223
Other comprehensive loss of subsidiaries and associated companies	(106)	(694)	(20,959)
Other comprehensive income (loss), net of tax	1,110	1,113	(21,845)
Comprehensive income	$ 256,549	$ 208,240	$ 182,884

Parent Company Information (137

Parent Company Information (Components of Condensed Cash Flow The Parent Company) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	$ 12,276	$ 11,438	$ 10,935
Gain on redemption of other assets	0	(7,331)	0
Net cash provided by operating activities	444,966	398,145	302,792
Investing activities:
Purchases of available-for-sale securities	(660,106)	(980,870)	(903,240)
Proceeds from sales of available-for-sale securities	0	259,283	123,270
Purchases of intercompany debt securities	873	(381)	458
Net cash provided by (used for) investing activities	(527,220)	(1,635,006)	(774,184)
Financing activities:
Proceeds from Issuance of Redeemable Preferred Stock	145,056	0	0
Payments for Repurchase of Redeemable Preferred Stock	(122,710)	0	0
Cash dividends paid to common shareholders	(94,630)	(89,522)	(80,964)
Cash dividends paid to preferred shareholders	(8,096)	(8,096)	(8,711)
Exercise of stock options	8,259	11,762	3,060
Excess tax benefits from stock-based compensation	0	3,204	2,338
Common stock repurchased/shares acquired related to employee share-based plans	(11,585)	(11,206)	(12,564)
Common stock warrants repurchased	0	(163)	(23)
Net cash (used for) provided by financing activities	122,749	1,227,831	457,171
Net decrease in cash and due from banks	40,495	(9,030)	(14,221)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	190,663	199,693	213,914
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	231,158	190,663	199,693
Parent Company [Member]
Operating activities:
Net income	255,439	207,127	204,729
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries and associated companies	(159,638)	(79,599)	(115,463)
Stock-based compensation	12,276	11,438	10,935
Gain on redemption of other assets	0	(7,331)	0
Other, net	7,880	(3,736)	9,066
Net cash provided by operating activities	115,957	127,899	109,267
Investing activities:
Proceeds from sales of available-for-sale securities	0	1,089	0
Purchases of intercompany debt securities	0	(150,000)	0
Proceeds from Sale of Other Assets, Investing Activities	7,581	0	0
Net cash provided by (used for) investing activities	7,581	(148,911)	0
Financing activities:
Proceeds from Issuance of Redeemable Preferred Stock	145,056	0	0
Payments for Repurchase of Redeemable Preferred Stock	(122,710)	0	0
Cash dividends paid to common shareholders	(94,630)	(89,522)	(80,964)
Cash dividends paid to preferred shareholders	(8,096)	(8,096)	(8,711)
Exercise of stock options	8,259	11,762	3,060
Excess tax benefits from stock-based compensation	0	3,204	2,338
Common stock repurchased/shares acquired related to employee share-based plans	(23,279)	(22,870)	(17,815)
Common stock warrants repurchased	0	(163)	(23)
Net cash (used for) provided by financing activities	(95,400)	(105,685)	(102,115)
Net decrease in cash and due from banks	28,138	(126,697)	7,152
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	152,947	279,644	272,492
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	$ 181,085	$ 152,947	$ 279,644

Selected Quarterly Consolida138

Selected Quarterly Consolidated Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
Interest income	$ 236,115	$ 231,021	$ 226,789	$ 219,680	$ 211,432	$ 205,715	$ 202,431	$ 202,335	$ 913,605	$ 821,913	$ 760,040
Interest expense	31,183	30,117	29,002	27,016	26,173	25,518	25,526	26,183	117,318	103,400	95,415
Net interest income	204,932	200,904	197,787	192,664	185,259	180,197	176,905	176,152	796,287	718,513	664,625
Provision for loan and lease losses	13,000	10,150	7,250	10,500	12,500	14,250	14,000	15,600	40,900	56,350	49,300
Non-interest income		65,846	64,551	63,042	70,617	66,412	65,075	62,374
Non-interest expense	171,049	161,823	164,419	163,784	161,871	156,097	152,778	152,445	661,075	623,191	555,341
Income before income tax expense	86,922	94,777	90,669	81,422	81,505	76,262	75,202	70,481	353,790	303,450	297,761
Income tax expense	17,029	30,281	29,090	21,951	23,845	24,445	24,599	23,434	98,351	96,323	93,032
Net income	$ 69,893	64,496	61,579	59,471	57,660	51,817	50,603	47,047	255,439	207,127	204,729
Earnings applicable to common shareholders		$ 62,426	$ 59,485	$ 57,342	$ 55,501	$ 49,634	$ 48,398	$ 44,921	$ 247,255	$ 199,031	$ 196,018
Earnings per common share:
Earnings per common share, Basic (in dollars per share)	$ 0.74	$ 0.68	$ 0.65	$ 0.62	$ 0.61	$ 0.54	$ 0.53	$ 0.49	$ 2.68	$ 2.17	$ 2.15
Earnings per common share, Diluted (in dollars per share)	$ 0.73	$ 0.67	$ 0.64	$ 0.62	$ 0.60	$ 0.54	$ 0.53	$ 0.49	$ 2.67	$ 2.16	$ 2.13
Noninterest Income	$ 66,039								$ 259,478	$ 264,478	$ 237,777
Gain on sale of investment securities, net									0	414	609
Impairment loss on securities recognized in earnings									$ 126	$ 149	$ 110