Webster Financial (WBS) 10-Q 8 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document Documentand Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	WBS
Entity Registrant Name	WEBSTER FINANCIAL CORP
Entity Central Index Key	801337
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		90,781,009

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Assets:
Cash and due from banks	$233,970		$261,544
Interest-bearing deposits	119,297		132,695
Securities available-for-sale, at fair value	2,968,109		2,793,873
Securities held-to-maturity (fair value of $4,022,981 and $3,948,706)	3,923,189		3,872,955
Federal Home Loan Bank and Federal Reserve Bank stock	193,290		193,290
Loans held for sale	45,866		67,952
Loans and leases	14,270,226	[1]	13,900,025	[1]
Allowance for loan and lease losses	-161,970		-159,264
Loans and leases, net	14,108,256		13,740,761
Deferred tax asset, net	61,136		73,873
Premises and equipment, net	123,548		121,933
Goodwill	538,373		529,887
Other intangible assets, net	44,378		2,666
Cash surrender value of life insurance policies	443,225		440,073
Accrued interest receivable and other assets	304,051		301,670
Total assets	23,106,688		22,533,172
Liabilities and shareholders' equity:
Non-interest-bearing	3,450,316		3,598,872
Interest-bearing	14,095,334		12,052,733
Total deposits	17,545,650		15,651,605
Securities sold under agreements to repurchase and other borrowings	1,083,877		1,250,756
Federal Home Loan Bank advances	1,584,357		2,859,431
Long-term debt	226,267		226,237
Accrued expenses and other liabilities	310,962		222,328
Total liabilities	20,751,113		20,210,357
Shareholders’ equity:
Common stock, $.01 par value: Authorized - 200,000,000 shares: Issued - 93,644,633 and 93,623,090 shares	936		936
Paid-in capital	1,128,897		1,127,534
Retained earnings	1,230,816		1,202,251
Treasury stock, at cost (3,147,804 and 3,241,555 shares)	-106,633		-103,294
Accumulated other comprehensive loss	-50,090		-56,261
Total shareholders' equity	2,355,575		2,322,815
Total liabilities and shareholders' equity	23,106,688		22,533,172
Series A Preferred Stock [Member]
Shareholders’ equity:
Preferred stock, $.01 par value; Authorized - 3,000,000 shares: Series A issued and outstanding - 28,939 and Series E issued and outstanding - 5,060 shares	28,939		28,939
Series E Preferred Stock [Member]
Shareholders’ equity:
Preferred stock, $.01 par value; Authorized - 3,000,000 shares: Series A issued and outstanding - 28,939 and Series E issued and outstanding - 5,060 shares	$122,710		$122,710
[1]	Loans and leases include net deferred fees and unamortized premiums of $12.1 million and $10.6 million at March 31, 2015 and December 31, 2014, respectively.

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Securities held-to-maturity ,fair value	$4,022,981	$3,948,706
Preferred stock, par value (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Common stock par value	$0.01	$0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	93,644,633	93,623,090
Treasury stock ,shares	3,147,804	3,241,555
Series A Preferred Stock [Member]
Preferred stock, shares issued	28,939	28,939
Preferred stock, shares outstanding	28,939	28,939
Series E Preferred Stock [Member]
Preferred stock, shares issued	5,060	5,060
Preferred stock, shares outstanding	5,060	5,060

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest Income:
Interest and fees on loans and leases	$130,723	$124,010
Taxable interest and dividends on securities	47,652	48,841
Non-taxable interest on securities	4,027	4,751
Loans held for sale	510	177
Total interest income	182,912	177,779
Interest Expense:
Deposits	11,542	10,644
Securities sold under agreements to repurchase and other borrowings	4,387	5,205
Federal Home Loan Bank advances	4,821	3,847
Long-term debt	2,398	2,782
Total interest expense	23,148	22,478
Net interest income	159,764	155,301
Provision for loan and lease losses	9,750	9,000
Net interest income after provision for loan and lease losses	150,014	146,301
Non-interest Income:
Deposit service fees	32,625	24,712
Loan related fees	5,679	4,482
Wealth and investment services	7,889	8,838
Mortgage banking activities	1,561	775
Increase in cash surrender value of life insurance policies	3,152	3,258
Net gain on sale of investment securities	43	4,336
Impairment loss recognized in earnings	0	-88
Other income	6,941	3,515
Total non-interest income	57,890	49,828
Non-interest Expense:
Compensation and benefits	70,864	66,371
Occupancy	13,596	12,759
Technology and equipment	19,248	15,010
Intangible assets amortization	1,288	1,168
Marketing	4,176	3,180
Professional and outside services	2,453	2,702
Deposit insurance	6,241	5,311
Other expense	16,224	17,962
Total non-interest expense	134,090	124,463
Income before income tax expense	73,814	71,666
Income tax expense	24,092	21,237
Net income	49,722	50,429
Preferred stock dividends	-2,639	-2,639
Net income available to common shareholders	$47,083	$47,790
Net income per common share:
Basic (in dollars per share)	$0.52	$0.53
Diluted (in dollars per share)	$0.52	$0.53

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$49,722	$50,429
Total available-for-sale and transferred securities	6,967	8,122
Total derivative instruments	-1,770	-3,726
Total defined benefit pension and other postretirement benefit plans	974	462
Net current-period other comprehensive income (loss), net of tax	6,171	4,858
Comprehensive income	$55,893	$55,287

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (USD $)	Total	Series A Preferred Stock [Member]	Series E Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]
In Thousands, unless otherwise specified								Series A Preferred Stock [Member]	Series E Preferred Stock [Member]
Beginning Balance at Dec. 31, 2013	$2,209,188			$151,649	$934	$1,125,584	$1,080,488			($100,918)	($48,549)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	50,429						50,429
Other comprehensive income, net of taxes	4,858										4,858
Dividends paid on common stock of $0.20 and $0.15 per share during 3 months ended March 31, 2015 and 2014, respectively	-13,536					10	-13,546
Dividends on Series A and Series E preferred stock $21.25 and $400.00 per share for the 3 months ended March 31, 2014 and 2013, respectively	-2,639	-615	-2,024					-615	-2,024
Stock-based compensation, net of tax impact	3,302					1,083	-638			2,857
Shares acquired related to employee share-based compensation plans	-2,098									-2,098
Common stock repurchased	-10,067									-10,067
Common stock issued	198					198	0			0
Ending Balance at Mar. 31, 2014	2,239,795			151,649	934	1,126,875	1,114,254			-110,226	-43,691
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	49,722						49,722
Other comprehensive income, net of taxes	6,171										6,171
Dividends paid on common stock of $0.20 and $0.15 per share during 3 months ended March 31, 2015 and 2014, respectively	-18,136					25	-18,161
Dividends on Series A and Series E preferred stock $21.25 and $400.00 per share for the 3 months ended March 31, 2014 and 2013, respectively	-2,639	-615	-2,024					-615	-2,024
Stock-based compensation, net of tax impact	3,385					1,471	-357			2,271
Exercise of stock options	261					-133				394
Shares acquired related to employee share-based compensation plans	-3,379									-3,379
Common stock repurchased	-2,625									-2,625
Ending Balance at Mar. 31, 2015	$2,355,575			$151,649	$936	$1,128,897	$1,230,816			($106,633)	($50,090)

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Common Stock, Dividends, Per Share, Declared	$0.20	$0.15
Series A Preferred Stock [Member]
Preferred Stock, Dividends Per Share, Declared	$21.25	$21.25
Series E Preferred Stock [Member]
Preferred Stock, Dividends Per Share, Declared	$400	$400

Condensed_Consolidated_Stateme4

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Activities:
Net income	$49,722	$50,429
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	9,750	9,000
Deferred tax expense	10,138	7,423
Depreciation and amortization	8,099	8,418
Amortization of earning assets and funding premium/discount, net	12,955	11,606
Stock-based compensation	2,282	2,773
Loss (gain) on sale, net of write-down, on foreclosed and repossessed assets	536	-260
(Gain) loss on sale, net of write-down, on premises and equipment	-373	58
Impairment loss recognized in earnings	0	88
Net gain on the sale of investment securities	-43	-4,336
Increase in cash surrender value of life insurance policies	-3,152	-3,258
Gain from life insurance policies	-220	0
Gain, net on sale of loans held for sale	-1,561	-775
Proceeds from sale of loans held for sale	76,895	65,643
Origination of loans held for sale	-86,882	-58,560
Net increase in accrued interest receivable and other assets	-33,912	-16,397
Net increase (decrease) in accrued expenses and other liabilities	14,552	-8,564
Net cash provided by operating activities	58,786	63,288
Investing Activities:
Net decrease (increase) in interest-bearing deposits	13,398	-6,219
Purchases of available for sale securities	-236,668	-9,908
Proceeds from maturities and principal payments of available for sale securities	137,874	96,983
Proceeds from sales of available for sale securities	27,859	21,695
Purchases of held-to-maturity securities	-201,182	-225,839
Proceeds from maturities and principal payments of held-to-maturity securities	143,891	131,364
Net purchase of Federal Home Loan Bank stock	0	-7,255
Net increase in loans	-380,155	-304,401
Proceeds from loans not originated for sale	32,915	0
Proceeds from life insurance policies	3,912	0
Proceeds from the sale of foreclosed and repossessed assets	3,399	2,824
Proceeds from the sale of premises and equipment	650	0
Purchases of premises and equipment	-8,437	-7,970
Acquisition of business, net of cash acquired	1,396,414	0
Net cash provided by (used for) investing activities	933,870	-308,726
Financing Activities:
Net increase in deposits	447,021	185,238
Proceeds from Federal Home Loan Bank advances	2,800,000	1,401,234
Repayments of Federal Home Loan Bank advances	-4,075,070	-1,250,043
Net decrease in securities sold under agreements to repurchase and other borrowings	-166,879	-183,780
Issuance of long-term debt	0	150,000
Debt issuance costs	0	-1,349
Dividends paid to common shareholders	-18,029	-13,493
Dividends paid to preferred shareholders	-2,639	-2,639
Exercise of stock options	261	0
Excess tax benefits from stock-based compensation	1,109	507
Common stock issued	0	198
Common stock repurchased	-2,625	-10,067
Shares acquired related to employee share-based compensation plans	-3,379	-2,098
Net cash (used for) provided by financing activities	-1,020,230	273,708
Net (decrease) increase in cash and due from banks	-27,574	28,270
Cash and due from banks at beginning of period	261,544	223,616
Cash and due from banks at end of period	233,970	251,886
Supplemental disclosure of cash flow information:
Interest paid	25,695	19,419
Income taxes paid	12,009	9,764
Noncash investing and financing activities:
Transfer of loans and leases to foreclosed properties and repossessed assets	2,722	1,661
Deposits assumed in business acquisition	$1,446,899	$0

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Nature of Operations
	Webster Financial Corporation (collectively, with its consolidated subsidiaries, “Webster” or the “Company”) is a bank holding company and financial holding company under the Bank Holding Company Act of 1956, as amended, incorporated under the laws of Delaware in 1986 and headquartered in Waterbury, Connecticut. At March 31, 2015, Webster Financial Corporation's principal asset is all of the outstanding capital stock of Webster Bank, National Association ("Webster Bank").
	Webster, through Webster Bank and various non-banking financial services subsidiaries, delivers financial services to individuals, families, and businesses primarily from New York, N.Y. to Boston, Mass. Webster provides business and consumer banking, mortgage lending, financial planning, trust, and investment services through banking offices, ATMs, telephone banking, mobile banking, and its Internet website (www.websterbank.com). Webster also offers equipment financing, commercial real estate lending, and asset-based lending across the Northeast. Webster Bank offers, through its HSA Bank division, health savings accounts on a nationwide basis.
	Basis of Presentation
	The accounting and reporting policies of the Company that materially affect the Condensed Consolidated Financial Statements conform with U.S. Generally Accepted Accounting Principles ("GAAP"). The accompanying unaudited Condensed Consolidated Financial Statements of the Company have been prepared in conformity with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements and should be read in conjunction with the Company's Consolidated Financial Statements, and notes thereto, for the year ended December 31, 2014, included in the Company's Annual Report on Form 10-K filed with the SEC on February 27, 2015.
	The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts of assets and liabilities as of the date of the financial statements as well as income and expense during the period. Actual results could differ from those estimates. Operating results for the interim period disclosed herein are not necessarily indicative of the results that may be expected for the full year or any future period.
	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 stockholders' equity, net cash provided by operating activities, net cash used for investing activities, and net cash provided by financing activities.
	Acquisition
	On January 13, 2015 (the "acquisition date”), the Company completed its acquisition of the health savings account business of JPMorgan Chase Bank, N.A. The results of the acquisition have been included in the financial statements from the acquisition date. See Note 2 - Acquisition and Note 6 - Goodwill and Other Intangible Assets for further information.
	Modifications to Significant Accounting Policies
	Non-accrual loans. Effective during the first quarter of 2015, residential loans that are more than 90 days past due, fully insured against loss, and in the process of collection, remain accruing loans and are reported as 90 days or more past due and accruing. Previously, these loans were placed on non-accrual when payments were 90 days or more past due. For presentation purposes, previously reported amounts have been reclassified to conform to the current year presentation. The change in accounting policy did not have a material impact on the financial statements.
	Other intangible assets. Other intangible assets with finite useful lives are amortized to non-interest expense over their estimated useful lives. Effective during the first quarter of 2015, core deposit intangibles resulting from the acquisition are amortized on an accelerated basis over their estimated useful lives. Core deposit intangibles existing prior to the acquisition will continue to be amortized on a straight line basis over their remaining estimated useful lives. Intangible assets relating to customer relationships are amortized on a straight line basis over their estimated useful lives.
	Recently Adopted Accounting Standards Updates
	ASU No. 2014-01 - Investments - Equity Method and Joint Ventures (Topic 323) - "Accounting for Investments in Qualified Affordable Housing Projects (a consensus of the FASB Emerging Issues Task Force)." The ASU requires an entity to disclose information about its investments in qualified affordable housing projects and provides an accounting policy election for it to account for such investments using the proportional amortization method. Under that method, the initial cost of an investment is amortized in proportion to its tax credits and other tax benefits as a component of income tax expense or benefit. The decision to apply the proportionate amortization method is to be applied consistently to all such investments.
	The Company adopted this ASU effective January 1, 2015 and retrospectively applied the effects of its accounting policy decision to use the proportional amortization method. Webster believes presenting the investment performance net of taxes as a component of income tax expense or benefit better represents the economics of such investments, and the change has no material effect on its financial statements. See the Income Taxes section of Management's Discussion and Analysis of Financial Condition and Results of Operation for information regarding the financial impact of the adopted ASU.
	ASU No. 2014-04, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40) - "Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure (a consensus of the FASB Emerging Issues Task Force)." The ASU clarifies that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (i) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (ii) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar agreement. In addition, the amendments require disclosure of both the amount of foreclosed residential real estate property held by the creditor and the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure in accordance with local requirements of the applicable jurisdiction. An entity can elect to adopt the amendments using either a modified retrospective method or a prospective transition method. This amendment was adopted during the first quarter of 2015 and did not have a material impact on the Company's financial statements.
	ASU No. 2014-11 - Transfers and Servicing (Topic 860) - “Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures.” The ASU requires two accounting changes: (i) repurchase-to-maturity transactions are to be accounted for as secured borrowings; and (ii) with respect to repurchase financing arrangements, accounting is required for a transfer of a financial asset contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. Additionally, disclosure requirements have been expanded to include a disaggregation of collateral used for secured borrowings, and contractual maturity disclosure has been expanded to interim periods. This amendment was adopted during the first quarter of 2015 and did not have a material impact on the Company's financial statements.
	ASU No. 2014-14, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40) - "Classification of Certain Government-Guaranteed Residential Mortgage Loans upon Foreclosure (a consensus of the FASB Emerging Issues Task Force)." The ASU has been issued to reduce diversity in practice in the classification of foreclosed residential mortgage loans held by creditors that are fully guaranteed under certain government programs, including the Federal Housing Administration guarantees. A residential mortgage loan would be derecognized, and a separate other receivable would be recognized upon foreclosure if the loan has both of the following characteristics: (i) the loan has a government guarantee that is not separable from the loan before foreclosure entitling the creditor to the full unpaid principal balance of the loan; and (ii) at the time of foreclosure, the creditor has the intent to make a claim on the guarantee and the ability to recover the full unpaid principal balance of the loan through the guarantee. Notably, upon foreclosure, the separate other receivable would be measured based on the current amount of the loan balance expected to be recovered under the guarantee. This amendment was adopted during the first quarter of 2015 and did not have a material impact on the Company's financial statements.
	Recently Issued Accounting Standards Updates
	ASU No. 2014-09 - Revenue from Contracts with Customers (Topic 606). The ASU establishes a single comprehensive model for an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled, and will supersede nearly all existing revenue recognition guidance, and clarify and converge revenue recognition principles under US GAAP and IFRS. The update outlines five steps to recognizing revenue: (i) identify the contracts with the customer; (ii) identify the separate performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the separate performance obligations; and (v) recognize revenue when each performance obligation is satisfied. The update requires more comprehensive disclosures, relating to quantitative and qualitative information for amounts, timing, the nature and uncertainty of revenue, and cash flows arising from contracts with customers, which will mainly impact construction and high-tech industries. The most significant potential impact to banking entities relates to less prescriptive derecognition requirements on the sale of owned real estate properties. An entity may elect either a full retrospective or a modified retrospective application. Subsequent to the filing of the Company's Consolidated Financial Statements and Notes thereto, for the year ended December 31, 2014, included in its 2014 Form 10-K, the ASU's effective date was changed from annual and interim periods beginning after December 15, 2016 to annual and interim periods beginning after December 15, 2017. As such, the Company revised its intended adoption date of the accounting standard from the first quarter of 2017 to the first quarter of 2018. The adoption of this amendment is not anticipated to have a material impact on the Company's financial statements.

Acquisition

Acquisition	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Acquisition	Acquisition
	On January 13, 2015 (“the acquisition date”) the Bank, having previously received regulatory approval, completed its acquisition of the health savings account business of JPMorgan Chase Bank, N.A. As a result of the acquisition, the Company became the leading administrator of health savings accounts in the United States. The acquisition significantly augments a source of stable, low cost, long duration deposits.
	The acquisition-date fair value of the consideration transferred consisted of the following:
	(In thousands)	At January 13, 2015
	Cash	$	50,485
	Contingent consideration (1)	(5,000		)
	Total net consideration transferred	$	45,485
	(1) The contingent consideration arrangement entitles the Company to receive a rebate of the purchase price relating to the premium paid for account attrition.
	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed at the acquisition date:
	(In thousands)	At January 13, 2015
	Cash	$	1,446,898
	Intangible assets	43,000
	Total identifiable assets acquired	$	1,489,898
	Deposits	$	1,446,899
	Contingent liability	6,000
	Total liabilities assumed	$	1,452,899
	Net identifiable assets acquired	$	36,999
	Goodwill	8,486
	Net assets acquired	$	45,485
	The fair value of the acquired identifiable intangible assets includes a core deposit intangible and customer relationships.  The Company is in the process of completing its analysis of fair value of the assets acquired and liabilities assumed; thus, the measurements of identifiable intangible assets, goodwill and contingencies are subject to change. Refer to Note 6 - Goodwill and Other Intangible Assets for additional information relating to the initial amounts of goodwill and other intangible assets recognized.
	The contingent liability represents an obligation that existed at the acquisition date. Accordingly, Webster assumed the liability as part of the transaction and has accounted for it at fair value.
	Refer to Note 15 - Fair Value Measurements for additional information on the contingent liability, as well as a discussion of the inputs used to derive the fair value of the contingent consideration recorded.

Investment_Securities

Investment Securities	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities
	Summaries of the amortized cost, carrying value, and fair value of Webster’s investment securities are presented below:
		At March 31, 2015
					Recognized in OCI									Not Recognized in OCI
	(In thousands)	Amortized			Gross			Gross			Carrying			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized			Value			Unrealized			Unrealized
					Gains			Losses						Gains			Losses
	Available-for-sale:
	U.S. Treasury Bills	$	425		$	—		$	—		$	425		$	—		$	—		$	425
	Agency collateralized mortgage obligations (“agency CMO”)	654,911			10,580			(791		)	664,700			—			—			664,700
	Agency mortgage-backed securities (“agency MBS”)	1,012,462			12,093			(7,548		)	1,017,007			—			—			1,017,007
	Agency commercial mortgage-backed securities (“agency CMBS”)	126,439			1,263			—			127,702			—			—			127,702
	Non-agency commercial mortgage-backed securities agency (“non-agency CMBS”)	544,483			18,173			(33		)	562,623			—			—			562,623
	Collateralized loan obligations ("CLO") (1)	441,061			1,979			(339		)	442,701			—			—			442,701
	Single issuer trust preferred securities	42,025			31			(3,774		)	38,282			—			—			38,282
	Corporate debt securities	105,905			4,179			—			110,084			—			—			110,084
	Equity securities - financial institutions	3,500			1,085			—			4,585			—			—			4,585
	Total available-for-sale	$	2,931,211		$	49,383		$	(12,485	)	$	2,968,109		$	—		$	—		$	2,968,109
	Held-to-maturity:
	Agency CMO	$	414,952		$	—		$	—		$	414,952		$	8,648		$	(423	)	$	423,177
	Agency MBS	2,109,728			—			—			2,109,728			64,646			(7,001		)	2,167,373
	Agency CMBS	625,320			—			—			625,320			9,127			(872		)	633,575
	Municipal bonds and notes	404,735			—			—			404,735			13,615			(972		)	417,378
	Non-agency CMBS	363,319			—			—			363,319			13,092			(153		)	376,258
	Private Label MBS	5,135			—			—			5,135			85			—			5,220
	Total held-to-maturity	$	3,923,189		$	—		$	—		$	3,923,189		$	109,213		$	(9,421	)	$	4,022,981
	-1	Amortized cost is net of $3.6 million of other-than-temporary impairments at March 31, 2015.
		At December 31, 2014
					Recognized in OCI									Not Recognized in OCI
	(In thousands)	Amortized			Gross			Gross			Carrying			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized			Value			Unrealized			Unrealized
					Gains			Losses						Gains			Losses
	Available-for-sale:
	U.S. Treasury Bills	$	525		$	—		$	—		$	525		$	—		$	—		$	525
	Agency CMO	543,417			8,636			(1,065		)	550,988			—			—			550,988
	Agency MBS	1,030,724			10,462			(12,668		)	1,028,518			—			—			1,028,518
	Agency CMBS	80,400			—			(134		)	80,266			—			—			80,266
	Non-agency CMBS	534,631			18,885			(123		)	553,393			—			—			553,393
	CLO (1)	426,269			482			(1,017		)	425,734			—			—			425,734
	Single issuer trust preferred securities	41,981			—			(3,736		)	38,245			—			—			38,245
	Corporate debt securities	106,520			3,781			—			110,301			—			—			110,301
	Equity securities - financial institutions	3,500			2,403			—			5,903			—			—			5,903
	Total available-for-sale	$	2,767,967		$	44,649		$	(18,743	)	$	2,793,873		$	—		$	—		$	2,793,873
	Held-to-maturity:
	Agency CMO	$	442,129		$	—		$	—		$	442,129		$	6,584		$	(739	)	$	447,974
	Agency MBS	2,134,319			—			—			2,134,319			57,196			(11,340		)	2,180,175
	Agency CMBS	578,687			—			—			578,687			1,597			(1,143		)	579,141
	Municipal bonds and notes	373,211			—			—			373,211			15,138			(55		)	388,294
	Non-agency CMBS	338,723			—			—			338,723			9,428			(1,015		)	347,136
	Private Label MBS	5,886			—			—			5,886			100			—			5,986
	Total held-to-maturity	$	3,872,955		$	—		$	—		$	3,872,955		$	90,043		$	(14,292	)	$	3,948,706
	-1	Amortized cost is net of $3.7 million of other-than-temporary impairments at December 31, 2014.
	Contractual Maturities
	The amortized cost and fair value of debt securities at March 31, 2015, by contractual maturity, are set forth below:
		Available-for-Sale							Held-to-Maturity
	(In thousands)	Amortized			Fair				Amortized			Fair
		Cost			Value				Cost			Value
	Due in one year or less	$	25,465		$	25,567			$	805		$	808
	Due after one year through five years	120,864			124,974				54,040			56,105
	Due after five through ten years	395,985			397,416				74,404			77,194
	Due after ten years	2,385,397			2,415,567				3,793,940			3,888,874
	Total debt securities	$	2,927,711		$	2,963,524			$	3,923,189		$	4,022,981
	For the maturity schedule above, mortgage-backed securities and collateralized loan obligations, 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 because borrowers have the right to prepay obligations with or without prepayment penalties. At March 31, 2015, the Company had a carrying value of $908.6 million in callable securities in its CMBS, CLO, and municipal bond portfolios. The Company considers these factors in the evaluation of its interest rate risk profile. These maturities do not reflect actual duration which is impacted by prepayment assumptions.
	Securities with a carrying value totaling $2.9 billion at March 31, 2015 and December 31, 2014, were pledged to secure public funds, trust deposits, repurchase agreements and for other purposes, as required or permitted by law. At March 31, 2015 and December 31, 2014, the Company had no investments in obligations of individual states, counties, or municipalities which exceeded 10% of consolidated shareholders’ equity.
Gross Unrealized Losses and Fair Value
The following tables provide information on the gross unrealized losses and fair value of the Company’s investment securities with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment security type and length of time that individual investment securities have been in a continuous unrealized loss position:
	At March 31, 2015
	Less Than Twelve Months							Twelve Months or Longer							Total
(Dollars in thousands)	Fair			Unrealized				Fair			Unrealized				# of	Fair			Unrealized
	Value			Losses				Value			Losses				Holdings	Value			Losses
Available-for-sale:
Agency CMO	$	43,228		$	(264	)		$	31,579		$	(527	)		5	$	74,807		$	(791	)
Agency MBS	187,105			(889		)		404,414			(6,659		)		60	591,519			(7,548		)
Agency CMBS	—			—				—			—				—	—			—
Non-agency CMBS	48,214			(20		)		9,387			(13		)		6	57,601			(33		)
CLO	30,760			(339		)		—			—				2	30,760			(339		)
Single issuer trust preferred securities	—			—				34,057			(3,774		)		7	34,057			(3,774		)
Total available-for-sale in an unrealized loss position	$	309,307		$	(1,512	)		$	479,437		$	(10,973	)		80	$	788,744		$	(12,485	)
Held-to-maturity:
Agency CMO	$	8,856		$	(53	)		$	24,116		$	(370	)		3	$	32,972		$	(423	)
Agency MBS	151,582			(769		)		529,147			(6,232		)		47	680,729			(7,001		)
Agency CMBS	22,325			(872		)		—			—				1	22,325			(872		)
Municipal bonds and notes	46,405			(944		)		3,076			(28		)		37	49,481			(972		)
Non-agency CMBS	5,273			(33		)		30,849			(120		)		3	36,122			(153		)
Total held-to-maturity in an unrealized loss position	$	234,441		$	(2,671	)		$	587,188		$	(6,750	)		91	$	821,629		$	(9,421	)
	At December 31, 2014
	Less Than Twelve Months							Twelve Months or Longer							Total
(Dollars in thousands)	Fair			Unrealized				Fair			Unrealized				# of	Fair			Unrealized
	Value			Losses				Value			Losses				Holdings	Value			Losses
Available-for-sale:
Agency CMO	$	47,217		$	(240	)		$	35,968		$	(825	)		8	$	83,185		$	(1,065	)
Agency MBS	3,691			(18		)		641,355			(12,650		)		64	645,046			(12,668		)
Agency CMBS	80,266			(134		)		—			—				4	80,266			(134		)
Non-agency CMBS	24,932			(117		)		9,396			(6		)		4	34,328			(123		)
CLO	99,221			(1,017		)		—			—				6	99,221			(1,017		)
Single issuer trust preferred securities	4,150			(36		)		34,095			(3,700		)		8	38,245			(3,736		)
Total available-for-sale in an unrealized loss position	$	259,477		$	(1,562	)		$	720,814		$	(17,181	)		94	$	980,291		$	(18,743	)
Held-to-maturity:
Agency CMO	$	52,172		$	(187	)		$	24,942		$	(552	)		6	$	77,114		$	(739	)
Agency MBS	20,791			(86		)		608,568			(11,254		)		44	629,359			(11,340		)
Agency CMBS	324,394			(1,143		)		—			—				17	324,394			(1,143		)
Municipal bonds and notes	5,341			(23		)		3,074			(32		)		15	8,415			(55		)
Non-agency CMBS	13,003			(30		)		65,913			(985		)		7	78,916			(1,015		)
Total held-to-maturity in an unrealized loss position	$	415,701		$	(1,469	)		$	702,497		$	(12,823	)		89	$	1,118,198		$	(14,292	)
Available-for-Sale Impairment Analysis
The following discussion summarizes, by investment security type, the basis for evaluating if the applicable investment securities within the Company’s available-for-sale portfolio were other-than-temporarily impaired at March 31, 2015. 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.
Agency CMO. There were unrealized losses of $0.8 million on the Company’s investment in agency CMO at March 31, 2015 compared to $1.1 million at December 31, 2014. Unrealized losses decreased due to lower market rates which resulted in higher security prices at March 31, 2015 compared to December 31, 2014. The contractual cash flows for these investments are performing as expected, and there has been no change in the underlying credit quality. As such, the Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Agency MBS. There were unrealized losses of $7.5 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at March 31, 2015 compared to $12.7 million at December 31, 2014. Unrealized losses decreased due to lower market rates which resulted in higher security prices at March 31, 2015 compared to December 31, 2014. These investments are issued by a government or a government-sponsored agency and, therefore, are backed by certain government guarantees, either direct or indirect. There has been no change in the credit quality, and the contractual cash flows are performing as expected. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
CLO. There were unrealized losses of $0.3 million on the Company’s investment in Volcker compliant collateralized loan obligations at March 31, 2015 compared to $1.0 million of unrealized losses at December 31, 2014. The unrealized losses decreased due to tighter CLO spreads during the period. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015. The Company continues to recognize the full write-down of CLO positions to market value if they meet the definition of a Covered Fund under the Volcker Rule effective December 10, 2013.
Single issuer trust preferred securities. There were unrealized losses of $3.8 million on the Company's investment in single issuer trust preferred securities at March 31, 2015 compared to $3.7 million at December 31, 2014. Unrealized losses increased due to higher market spreads for the asset class which resulted in lower security prices at March 31, 2015 compared to December 31, 2014. The single issuer portfolio consists of four investments issued by three large capitalization money center financial institutions, which continue to service the debt. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Held-to-Maturity Impairment Analysis
The following discussion summarizes, by investment type, the basis for the conclusion that the applicable investment securities within the Company’s held-to-maturity portfolio were not other-than-temporarily impaired at March 31, 2015. Unless otherwise noted under 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 its amortized cost.
Agency CMO. There were unrealized losses of $0.4 million on the Company’s investment in agency CMO at March 31, 2015 compared to $0.7 million at December 31, 2014. Unrealized losses decreased due to lower market rates which resulted in higher security prices on CMO positions purchased during the quarter. The contractual cash flows for these investments are performing as expected, and there has been no change in the underlying credit quality. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Agency MBS. There were unrealized losses of $7.0 million on the Company’s investment in residential mortgage-backed securities issued by government agencies at March 31, 2015 compared to $11.3 million at December 31, 2014. Unrealized losses decreased due to lower market rates which resulted in higher security prices at March 31, 2015 compared to December 31, 2014. These investments are issued by a government or a government-sponsored agency and, therefore, are backed by certain government guarantees, either direct or indirect. There has been no change in the credit quality, and the contractual cash flows are performing as expected. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Agency CMBS. There were unrealized losses of $0.9 million on the Company’s investment in commercial mortgage-backed securities issued by government agencies at March 31, 2015 compared to $1.1 million at December 31, 2014. Unrealized losses decreased due to lower market rates which resulted in higher security prices at March 31, 2015 compared to December 31, 2014. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Municipal bonds and notes. There were unrealized losses of $1.0 million on the Company’s investment in municipal bonds and notes at March 31, 2015 compared to $0.1 million at December 31, 2014. Unrealized losses increased due to higher market rates which resulted in lower security prices on new purchases since December 31, 2014. The municipal portfolio is primarily comprised of bank qualified bonds, over 99.4% with credit ratings of A or better. In addition, the portfolio is comprised of 89.7% general obligation bonds, 9.8% revenue bonds, and 0.5% other bonds. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Non-agency CMBS. There were unrealized losses of $0.2 million on the Company’s investment in non-agency commercial mortgage-backed securities issued by entities other than government agencies at March 31, 2015 compared to $1.0 million unrealized losses at December 31, 2014. Unrealized losses decreased due to lower market rates which resulted in higher security prices at March 31, 2015 compared to December 31, 2014. Internal and external metrics are considered when evaluating potential other-than temporary impairment. Internal stress tests are performed on individual bonds to monitor potential losses under stress scenarios. The contractual cash flows for these investments are performing as expected. The Company does not consider these securities to be other-than-temporarily impaired at March 31, 2015.
Other-Than-Temporary Impairment ("OTTI")
There were no additions to OTTI for the three months ended March 31, 2015 and additions of $0.1 million for the three months ended March 31, 2014. The cumulative OTTI related to previously impaired securities at the beginning of each period was reduced due to the call of one CLO during the first quarter of 2015 and the sale of four trust preferred securities during the first quarter of 2014. To the extent that changes in interest rates, credit movements, and other factors that influence the fair value of investments occur, the Company may be required to record impairment charges for OTTI in future periods.
The following is a roll forward of the amount of OTTI related to debt securities:
	Three months ended March 31,
(In thousands)	2015				2014
Balance of OTTI, beginning of period	$	3,696			$	16,633
Reduction for securities sold, called	(99		)		(7,056		)
Additions for OTTI not previously recognized	—				88
Balance of OTTI, end of period	$	3,597			$	9,665
Realized Gains and Losses
The following table summarizes proceeds from available-for-sale securities, the gross realized gains and losses from those sales, and the impact of the recognition of other-than-temporary impairments for the periods presented:
	Three months ended March 31,
(In thousands)	2015				2014
Proceeds from sales	$	27,859			$	21,695
Gross realized gains	$	43			$	4,336
OTTI write-down	—				(88		)
Net realized gains from investment securities	$	43			$	4,248

Loans_and_Leases

Loans and Leases	3 Months Ended
	Mar. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	Loans and Leases
	Recorded Investment in Loans and Leases. The following tables summarize the recorded investment in loans and leases by portfolio segment:
		At March 31, 2015
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total (2)
											Real Estate (1)			Financing
	Recorded Investment:
	Individually evaluated for impairment	$	140,815		$	50,834		$	49,619		$	73,972		$	631		$	315,871
	Collectively evaluated for impairment	3,464,162			2,526,616			3,862,095			3,597,297			543,005			13,993,175
	Recorded investment in loans and leases	3,604,977			2,577,450			3,911,714			3,671,269			543,636			14,309,046
	Less: Accrued interest	10,705			8,013			11,904			8,198			—			38,820
	Loans and leases	$	3,594,272		$	2,569,437		$	3,899,810		$	3,663,071		$	543,636		$	14,270,226
		At December 31, 2014
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total (2)
											Real Estate (1)			Financing
	Recorded Investment:
	Individually evaluated for impairment	$	142,435		$	50,374		$	36,454		$	103,045		$	632		$	332,940
	Collectively evaluated for impairment	3,377,196			2,507,060			3,723,991			3,460,116			537,119			13,605,482
	Recorded investment in loans and leases	3,519,631			2,557,434			3,760,445			3,563,161			537,751			13,938,422
	Less: Accrued interest	10,456			8,033			11,175			8,733			—			38,397
	Loans and leases	$	3,509,175		$	2,549,401		$	3,749,270		$	3,554,428		$	537,751		$	13,900,025
	-1	Includes certain loans individually evaluated for impairment under the Company's loan policy that were deemed not to be impaired at both March 31, 2015 and December 31, 2014.
	-2	Loans and leases include net deferred fees and unamortized premiums of $12.1 million and $10.6 million at March 31, 2015 and December 31, 2014, respectively.
	At March 31, 2015, the Company had pledged $6.2 billion of eligible loan collateral to support available borrowing capacity at the Federal Home Loan Bank of Boston ("FHLB") and the Federal Reserve Bank of Boston.
	Loans and Leases Portfolio Aging. The following tables summarize the aging of the recorded investment in loans and leases by portfolio class:
		At March 31, 2015
	(In thousands)	30-59 Days			60-89 Days			> 90 Days Past Due			Non-accrual			Total Past Due and Non-accrual			Current			Total Loans
		Past Due and			Past Due and			and Accruing												and Leases
		Accruing			Accruing
	Residential	$	9,631		$	4,514		$	1,895		$	61,371		$	77,411		$	3,527,566		$	3,604,977
	Consumer:
	Home equity	12,001			7,658			—			37,617			57,276			2,408,439			2,465,715
	Other consumer	587			343			—			267			1,197			110,538			111,735
	Commercial:
	Commercial non-mortgage	3,121			950			273			26,974			31,318			3,161,881			3,193,199
	Asset-based	—			—			—			—			—			718,515			718,515
	Commercial real estate:
	Commercial real estate	3,199			805			42			22,183			26,229			3,398,306			3,424,535
	Commercial construction	—			—			—			3,651			3,651			243,083			246,734
	Equipment financing	729			60			—			285			1,074			542,562			543,636
	Total	$	29,268		$	14,330		$	2,210		$	152,348		$	198,156		$	14,110,890		$	14,309,046
		At December 31, 2014
	(In thousands)	30-59 Days			60-89 Days			> 90 Days Past Due			Non-accrual			Total Past Due and Non-accrual			Current			Total Loans
		Past Due and			Past Due and			and Accruing												and Leases
		Accruing			Accruing
	Residential (1), (2)	$	11,521		$	5,931		$	2,039		$	64,117		$	83,608		$	3,436,023		$	3,519,631
	Consumer:
	Home equity (1)	11,516			5,161			—			40,025			56,702			2,424,584			2,481,286
	Other consumer	720			425			—			281			1,426			74,722			76,148
	Commercial:
	Commercial non-mortgage	1,971			156			50			6,449			8,626			3,088,656			3,097,282
	Asset-based	—			—			—			—			—			663,163			663,163
	Commercial real estate:
	Commercial real estate	2,348			397			—			15,038			17,783			3,310,765			3,328,548
	Commercial construction	—			—			—			3,659			3,659			230,954			234,613
	Equipment financing	551			150			—			578			1,279			536,472			537,751
	Total	$	28,627		$	12,220		$	2,089		$	130,147		$	173,083		$	13,765,339		$	13,938,422
	-1	A total of $17.6 million aggregate principal amount of residential and consumer loans was reclassified from non-accrual to accrual status as a result of updated regulatory guidance issued in the first quarter of 2014.
	-2	For the year ended 2014, US Government secured loans of $2.0 million were reclassified from non-accrual to over 90 days and accruing due to a policy change effective in the first quarter of 2015. See Note 1 - Summary of Significant Accounting Policies.
	Interest on non-accrual loans and leases that would have been recorded as additional interest income for the three months ended March 31, 2015 and 2014, had the loans and leases been current in accordance with their original terms, totaled $2.8 million and $3.5 million, respectively.
	Allowance for Loan and Lease Losses. The following tables summarize the ALLL by portfolio segment:
		At or for the three months ended March 31, 2015
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total
											Real Estate			Financing
	Allowance for loan and lease losses:
Balance, beginning of period	$	25,452		$	43,518		$	52,114		$	32,102		$	6,078		$	159,264
Provision (benefit) charged to expense	4,144			2,232			2,754			1,398			(778		)	9,750
Losses charged off	(1,955		)	(4,296		)	(255		)	(3,153		)	(15		)	(9,674		)
Recoveries	108			1,162			1,015			202			143			2,630
Balance, end of period	$	27,749		$	42,616		$	55,628		$	30,549		$	5,428		$	161,970
Individually evaluated for impairment	$	14,350		$	4,255		$	4,939		$	3,668		$	28		$	27,240
Collectively evaluated for impairment	$	13,399		$	38,361		$	50,689		$	26,881		$	5,400		$	134,730
	At or for the three months ended March 31, 2014
(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total
										Real Estate			Financing
Allowance for loan and lease losses:
Balance, beginning of period	$	23,027		$	41,951		$	51,001		$	32,408		$	4,186		$	152,573
Provision (benefit) charged to expense	(542		)	(903		)	7,975			3,287			(817		)	9,000
Losses charged off	(1,158		)	(4,886		)	(3,148		)	(2,405		)	—			(11,597		)
Recoveries	260			1,113			973			479			799			3,624
Balance, end of period	$	21,587		$	37,275		$	56,801		$	33,769		$	4,168		$	153,600
Individually evaluated for impairment	$	10,993		$	4,109		$	989		$	4,013		$	—		$	20,104
Collectively evaluated for impairment	$	10,594		$	33,166		$	55,812		$	29,756		$	4,168		$	133,496
Impaired Loans and Leases. The following tables summarize impaired loans and leases by portfolio class:
	At March 31, 2015
(In thousands)	Unpaid			Total			Recorded			Recorded			Related
	Principal			Recorded			Investment			Investment			Valuation
	Balance			Investment			No Allowance			With Allowance			Allowance
Residential:	$	154,795		$	140,815		$	23,494		$	117,321		$	14,350
Consumer:
Home equity	57,403			50,834			26,827			24,007			4,255
Commercial:
Commercial non-mortgage	54,277			49,619			23,986			25,633			4,939
Commercial real estate:
Commercial real estate	73,371			67,114			34,466			32,648			3,658
Commercial construction	7,172			6,164			5,951			213			10
Equipment financing	629			631			—			631			28
Totals:
Residential	154,795			140,815			23,494			117,321			14,350
Consumer	57,403			50,834			26,827			24,007			4,255
Commercial	54,277			49,619			23,986			25,633			4,939
Commercial real estate	80,543			73,278			40,417			32,861			3,668
Equipment financing	629			631			—			631			28
Total	$	347,647		$	315,177		$	114,724		$	200,453		$	27,240
	At December 31, 2014
(In thousands)	Unpaid			Total			Recorded			Recorded			Related
	Principal			Recorded			Investment			Investment			Valuation
	Balance			Investment			No Allowance			With Allowance			Allowance
Residential:	$	157,152		$	142,435		$	24,388		$	118,047		$	12,094
Consumer:
Home equity	60,424			50,374			26,464			23,910			4,237
Commercial:
Commercial non-mortgage	41,019			36,454			16,064			20,390			2,710
Commercial real estate:
Commercial real estate	99,687			96,160			40,575			55,585			6,222
Commercial construction	7,218			6,177			5,956			221			10
Equipment financing	629			632			—			632			28
Totals:
Residential	157,152			142,435			24,388			118,047			12,094
Consumer	60,424			50,374			26,464			23,910			4,237
Commercial	41,019			36,454			16,064			20,390			2,710
Commercial real estate	106,905			102,337			46,531			55,806			6,232
Equipment financing	629			632			—			632			28
Total	$	366,129		$	332,232		$	113,447		$	218,785		$	25,301
The following table summarizes the average recorded investment and interest income recognized for impaired loans and leases by portfolio class:
	31-Mar-15			Three months ended March 31, 2015							31-Mar-14			Three months ended March 31, 2014
(In thousands)	Average			Accrued			Cash Basis Interest Income				Average			Accrued			Cash Basis Interest Income
	Recorded			Interest							Recorded			Interest
	Investment			Income							Investment			Income
Residential	$	141,625		$	1,059		$	256			$	142,768		$	1,192		$	324
Consumer:
Home equity	50,604			361			282				52,269			370			324
Commercial:
Commercial non-mortgage	43,037			427			—				50,179			628			—
Commercial real estate:
Commercial real estate	81,637			530			—				91,730			801			—
Commercial construction	6,171			33			—				10,393			82			—
Equipment financing	632			11			—				197			3			—
Totals:
Residential	141,625			1,059			256				142,768			1,192			324
Consumer	50,604			361			282				52,269			370			324
Commercial	43,037			427			—				50,179			628			—
Commercial real estate	87,808			563			—				102,123			883			—
Equipment financing	632			11			—				197			3			—
Total	$	323,706		$	2,421		$	538			$	347,536		$	3,076		$	648
Credit Quality Indicators. To measure credit risk for the commercial, commercial real estate, and equipment financing portfolios, the Company employs a dual grade credit risk grading system for estimating the probability of borrower default and the loss given default. The credit risk grade system assigns a rating to each borrower and to the facility, which together form a Composite Credit Risk Profile (“CCRP”). The credit risk grade system categorizes borrowers by common financial profiles that measure the credit strength of borrowers and facilities by common structural characteristics. The CCRP has 10 grades, with each grade corresponding to a progressively greater risk of default. Grades 1 through 6 are considered pass ratings, and 7 through 10 are 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 the borrowers’ current financial positions and outlooks, risk profiles, and the related collateral and structural positions. Loan officers review updated financial information at least annually for all pass rated loans to assess the accuracy of the risk grade. All criticized loans undergo frequent review and enhanced monitoring of the underlying borrower.
A “Special Mention” (7) credit has the potential weakness that, if left uncorrected, may result in deterioration of the repayment prospects for the asset. “Substandard” (8) assets have a well-defined weakness that jeopardizes the full repayment of the debt. An asset rated “Doubtful” (9) 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 “Loss” (10) in accordance with regulatory guidelines are considered uncollectible and charged off.
The recorded investment in commercial loans, commercial real estate loans, and equipment financing leases segregated by risk rating exposure is as follows:
	Commercial								Commercial Real Estate								Equipment Financing
(In thousands)	At March 31,				At December 31,				At March 31,				At December 31,				At March 31,				At December 31,
	2015				2014				2015				2014				2015				2014
(1) - (6) Pass	$	3,677,136			$	3,555,559			$	3,546,467			$	3,416,214			$	524,907			$	516,115
(7) Special Mention	100,320				89,064				29,187				33,580				4,039				4,364
(8) Substandard	134,094				115,653				95,157				112,874				14,690				17,272
(9) Doubtful	164				169				458				493				—				—
(10) Loss	—				—				—				—				—				—
Total	$	3,911,714			$	3,760,445			$	3,671,269			$	3,563,161			$	543,636			$	537,751
For residential and consumer loans, the Company considers factors such as updated FICO scores, employment status, home prices, loan to value, 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 both 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 Case-Shiller data indicates trends for Metropolitan Statistical Areas. The trend data is applied to the loan portfolios taking into account the age of the most recent valuation and geographic area.
Troubled Debt Restructurings ("TDRs"). The following table summarizes information for TDRs:
(Dollars in thousands)	At March 31, 2015				At December 31, 2014
Recorded investment of TDRs:
Accrual status (1)	$	201,175			$	243,231
Non-accrual status (1)	92,788				76,939
Total recorded investment of TDRs	$	293,963			$	320,170
Accruing TDRs performing under modified terms more than one year	66.1		%		67.6		%
Specific reserves for TDRs included in the balance of allowance for loan and lease losses	$	22,539			$	23,785
Additional funds committed to borrowers in TDR status	555				552
-1	A total of $17.6 million residential and consumer loans was reclassified from non-accrual to accrual status as a result of updated regulatory guidance issued in the first quarter of 2014.
In the three months ended March 31, 2015 and 2014, Webster charged off $3.9 million and $6.2 million, respectively, for the portion of TDRs deemed to be uncollectible.
TDRs may be modified by means of extended maturity, below market adjusted interest rates, a combination of rate and maturity, or other means, including covenant modifications, forbearance, loans discharged under Chapter 7 bankruptcy, or other concessions.
The following table provides information on how loans and leases were modified as TDRs:
	Three months ended March 31,
	2015						2014
	Number of		Post-				Number of		Post-
	Loans and		Modification				Loans and		Modification
	Leases		Recorded				Leases		Recorded
(Dollars in thousands)			Investment(1)						Investment(1)
Residential:
Extended Maturity	9		$	1,345			6		$	706
Adjusted Interest Rates	—		—				1		227
Combination Rate and Maturity	10		1,668				8		2,589
Other	3		536				11		2,077
Consumer:
Extended Maturity	4		499				9		470
Adjusted Interest Rates	—		—				1		51
Combination Rate and Maturity	8		444				4		255
Other	21		1,332				27		1,444
Commercial:
Extended Maturity	1		33				2		54
Adjusted Interest Rates	—		—				—		—
Combination Rate and Maturity	2		132				6		241
Other	—		—				1		150
TOTAL TDRs	58		$	5,989			76		$	8,264
(1) Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant.
The Company's loan and lease portfolio at March 31, 2015 included loans with A-Note/B-Note ("A/B Notes") structures that were restructured into A/B Notes as a result of evaluating the cash flow of the borrowers to support repayment. 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.
The following table provides information on loans and leases modified as TDRs within the previous 12 months and for which there was a payment default during the periods presented:
	Three months ended March 31,
	2015					2014
(Dollars in thousands)	Number of	Recorded				Number of	Recorded
	Loans and	Investment				Loans and	Investment
	Leases					Leases
Residential:
1-4 family	3	$	642			6	$	645
Consumer:
Home equity	2	251				3	190
Commercial:
Commercial non-mortgage	2	6,317				1	76
Commercial real estate:
Commercial real estate	1	10,930				—	—
Total	8	$	18,140			10	$	911
The recorded investment in commercial, commercial real estate, and equipment financing TDRs segregated by risk rating exposure is as follows:
(In thousands)	At March 31,				At December 31,
	2015				2014
(1) - (6) Pass	$	32,714			$	40,943
(7) Special Mention	8,242				8,304
(8) Substandard	61,016				77,771
(9) Doubtful	342				343
(10) Loss	—				—
Total	$	102,314			$	127,361

Transfers_of_Financial_Assets_

Transfers of Financial Assets and Mortgage Servicing Assets	3 Months Ended
	Mar. 31, 2015
Transfers and Servicing [Abstract]
Transfers of Financial Assets and Mortgage Servicing Assets	Transfers of Financial Assets and Mortgage Servicing Assets
	Transfers of Financial Assets
	The Company sells financial assets in the normal course of business, the majority of which are residential mortgage loans primarily sold to government-sponsored enterprises through established programs, commercial loans sold through participation agreements, and other individual or portfolio loans and securities. In accordance with the 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. For loans sold through participation agreements, the terms of the loan participation agreement and whether they meet the definition of a participating interest, and thus qualify for derecognition, are also taken into consideration.
	With the exception of servicing rights, the Company’s continuing involvement with financial assets sold is minimal and limited to customary market representations and warranties covering certain characteristics of the mortgage loans sold and the Company's origination process. Under the performance-based guarantees in the sale agreements, 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. The gain or loss on loans sold depends on the carrying amount of the transferred financial assets, the consideration received, and any liabilities incurred in exchange for the transferred assets and is included as mortgage banking activities in the accompanying Condensed Consolidated Statements of Income.
	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 monthly 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 also may impact the reserve. The provision recorded at the time of the loan sale is netted from the gain or loss recorded in mortgage banking activities, while any incremental provision, post loan sale, is recorded in other non-interest expense in the accompanying Condensed Consolidated Statements of Income.
	The following table provides a summary of activity in the reserve for loan repurchases:
		Three months ended March 31,
	(In thousands)	2015			2014
	Beginning balance	$	1,059		$	2,254
	Provision (benefit)	23			(310		)
	Loss on repurchased loans and settlements	—			(43		)
	Ending balance	$	1,082		$	1,901
	The following table provides detail of activity related to loan sales related to mortgage banking activities:
		Three months ended March 31,
	(In thousands)	2015			2014
	Residential mortgage loans:
	Proceeds from the sale of loans held for sale	$	76,895		$	65,643
	Net gain on sale included as mortgage banking activities	1,561			775
	Loans sold with servicing rights retained	69,265			48,552
	Mortgage Servicing Assets
	The Company has retained servicing rights on loans totaling $2.4 billion at both March 31, 2015 and December 31, 2014, resulting in mortgage servicing assets totaling $19.2 million at March 31, 2015 and $19.4 million at December 31, 2014, which are carried at the lower of cost or fair value and are included as a component of other assets in the accompanying Condensed Consolidated Balance Sheets. Changes in fair value are included as a component of other non-interest income in the accompanying Condensed Consolidated Statements of Income.
	The following table presents the changes in fair value for those mortgage servicing assets:
		Three months ended March 31,
	(In thousands)	2015			2014
	Fair value, beginning of period	$	28,690		$	29,150
	Originations of servicing assets	1,463			961
	Changes in fair value:
	Due to payoffs/paydowns	(736		)	(473		)
	Due to market changes	(1,516		)	(484		)
	Fair value, end of period	$	27,901		$	29,154
	See Note 15 - Fair Value Measurements for a further discussion on the fair value of mortgage servicing assets.
	Loan servicing fees, net of mortgage servicing rights amortization, were $0.4 million for both the three months ended March 31, 2015 and 2014 and are included as a component of loan related fees in the accompanying Condensed Consolidated Statements of Income.

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets
	The following table presents the carrying value for goodwill allocated to the segments:
		Operating Segment
	(In thousands)	Community Banking		HSA Bank			Total
	Balance at December 31, 2014	$	516,560	$	13,327		$	529,887
	Goodwill acquired during the period	—		8,486			8,486
	Balance at March 31, 2015	$	516,560	$	21,813		$	538,373
	The $8.5 million of goodwill arising from the acquisition is attributable primarily to expected synergies of the business combination. The full amount of goodwill recorded in the current the period is expected to be deductible for income tax purposes.
	The gross carrying amount and accumulated amortization of core deposit intangibles ("CDI") and other intangible assets allocated to the business segments are as follows:
		At March 31, 2015							At December 31, 2014
	(In thousands)	Gross Carrying		Accumulated			Net Carrying		Gross Carrying		Accumulated			Net Carrying
		Amount		Amortization			Amount		Amount		Amortization			Amount
	Community Banking CDI	$	49,420	$	(47,135	)	$	2,285	$	49,420	$	(46,754	)	$	2,666
	HSA Bank:
	CDI	22,000		(509		)	21,491		—		—			—
	Customer relationships	21,000		(398		)	20,602		—		—			—
	Total HSA Bank	43,000		(907		)	42,093		—		—			—
	Total Intangible Assets	$	92,420	$	(48,042	)	$	44,378	$	49,420	$	(46,754	)	$	2,666
	For the three months ended March 31, 2015, $43.0 million of intangibles were added as a result of the acquisition at fair value, including $22.0 million of core deposit intangible assets with an estimated useful life of 9 years and $21.0 million of customer relationship intangible assets with an estimated useful life of 13 years years.
	Amortization expense on intangible assets for the three months ended March 31, 2015 and 2014 totaled $1.3 million and $1.2 million, respectively. Future estimated annual amortization expense is summarized below:
	(In thousands)
	Years ending December 31:
	Remainder of 2015	$	5,052
	2016	5,652
	2017	4,062
	2018	3,847
	2019	3,847
	Thereafter	21,918

Deposits

Deposits	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Deposits	Deposits
	A summary of deposits by type follows:
	(In thousands)	At March 31,		At December 31,
		2015		2014
	Non-interest-bearing:
	Demand	$	3,450,316	$	3,598,872
	Interest-bearing:
	Checking	2,267,350		2,155,047
	Health savings accounts	3,529,301		1,824,799
	Money market	2,114,300		1,908,522
	Savings	3,978,655		3,892,778
	Time deposits	2,205,728		2,271,587
	Total interest-bearing	14,095,334		12,052,733
	Total deposits	$	17,545,650	$	15,651,605
	Deposits obtained through brokers included in above balances	$	765,500	$	651,725
	Demand deposit overdrafts reclassified as loan balances	1,530		1,655
	At March 31, 2015, the scheduled maturities of time deposits are as follows:
	(In thousands)
	Remainder of 2015	$	964,901
	2016	474,162
	2017	153,773
	2018	176,488
	2019	375,843
	Thereafter	60,561
	Time deposits	$	2,205,728

Securities_Sold_Under_Agreemen

Securities Sold Under Agreements to Repurchase and Other Borrowings	3 Months Ended
	Mar. 31, 2015
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Abstract]
Securities Sold Under Agreements to Repurchase and Other Borrowings	Securities Sold Under Agreements To Repurchase and Other Borrowings
	The following table summarizes securities sold under agreements to repurchase and other borrowings:
	(In thousands)	At March 31,		At December 31,
		2015		2014
	Securities sold under agreements to repurchase:
	Original maturity of one year or less	$	317,877	$	409,756
	Original maturity of greater than one year, non-callable	550,000		550,000
		867,877		959,756
	Other borrowings:
	Federal funds purchased	216,000		291,000
	Securities sold under agreements to repurchase and other borrowings	$	1,083,877	$	1,250,756
	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 with counterparties are limited to primary dealers in government securities and commercial/municipal customers through Webster’s Treasury Sales desk. 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. At March 31, 2015, the Company has a gross repurchase liability of $0.9 billion.

Federal_Home_Loan_Bank_Advance

Federal Home Loan Bank Advances	3 Months Ended
	Mar. 31, 2015
Federal Home Loan Banks [Abstract]
Federal Home Loan Bank Advances	Federal Home Loan Bank Advances
	The following table summarizes Federal Home Loan Bank advances:
		At March 31, 2015				At December 31, 2014
	(Dollars in thousands)	Total		Weighted-		Total		Weighted-
		Outstanding		Average Contractual Coupon Rate		Outstanding		Average Contractual Coupon Rate
	FHLB advances maturing:
	Within 1 year	$	995,934	0.33	%	$	2,275,000	0.23	%
	After 1 but within 2 years	100,000		1.48		145,934		1.8
	After 2 but within 3 years	50,500		1.1		500		5.66
	After 3 but within 4 years	150,000		1.46		200,000		1.36
	After 4 but within 5 years	128,026		1.82		78,026		1.95
	After 5 years	159,864		1.29		159,934		1.27
		1,584,324		0.75	%	2,859,394		0.5	%
	Unamortized premiums	33				37
	Federal Home Loan Bank advances	$	1,584,357			$	2,859,431
	At March 31, 2015, Webster Bank had pledged loans with an aggregate carrying value of $5.2 billion as collateral for borrowings and had additional borrowing capacity from the FHLB of approximately $1.9 billion, as well as an unused line of credit of approximately $5.0 million. At December 31, 2014, Webster Bank had pledged loans with an aggregate carrying value of $5.2 billion as collateral for borrowings and had additional borrowing capacity from the FHLB of approximately $0.7 billion, as well as an unused line of credit of approximately $5.0 million. At March 31, 2015 and December 31, 2014, Webster Bank was in compliance with FHLB collateral requirements.

LongTerm_Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt
	The following table summarizes long-term debt:
	(Dollars in thousands)		At March 31,			At December 31,
			2015			2014
	4.38%	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
	Unamortized discount on senior fixed-rate notes		(1,053		)	(1,083		)
	Long-term debt		$	226,267		$	226,237
	-1	The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month LIBOR plus 2.950%, was 3.221% at March 31, 2015 and 3.193% at December 31, 2014

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss
	The following tables summarize the changes in accumulated other comprehensive loss by component:
		Three months ended March 31, 2015
	(In thousands)	Available For Sale and Transferred Securities			Derivative Instruments			Defined Benefit Pension and Other Postretirement Benefit Plans			Total
	Beginning balance	$	16,421		$	(25,530	)	$	(47,152	)	$	(56,261	)
	Other comprehensive income (loss) before reclassifications	6,994			(3,096		)	536			4,434
	Amounts reclassified from accumulated other comprehensive (loss) income	(27		)	1,326			438			1,737
	Net current-period other comprehensive income (loss), net of tax	6,967			(1,770		)	974			6,171
	Ending balance	$	23,388		$	(27,300	)	$	(46,178	)	$	(50,090	)
		Three months ended March 31, 2014
	(In thousands)	Available For Sale and Transferred Securities			Derivative Instruments			Defined Benefit Pension and Other Postretirement Benefit Plans			Total
	Beginning balance	$	(2,617	)	$	(18,206	)	$	(27,726	)	$	(48,549	)
	Other comprehensive income (loss) before reclassifications	10,849			(5,151		)	467			6,165
	Amounts reclassified from accumulated other comprehensive (loss) income	(2,727		)	1,425			(5		)	(1,307		)
	Net current-period other comprehensive income (loss), net of tax	8,122			(3,726		)	462			4,858
	Ending balance	$	5,505		$	(21,932	)	$	(27,264	)	$	(43,691	)
	The following table summarizes the amount reclassified from accumulated other comprehensive loss:
	(In thousands)	Three months ended March 31,						Associated Line Item in the Condensed
	Accumulated Other Comprehensive Loss Components	2015			2014			Consolidated Statements Of Income
	Available-for-sale and transferred securities:
	Unrealized gains (losses) on investment securities	$	43		$	4,336		Net gain on sale of investment securities
	Unrealized gains (losses) on investment securities	—			(88		)	Impairment loss recognized in earnings
	Tax expense	(16		)	(1,521		)	Income tax expense
	Net of tax	$	27		$	2,727
	Derivative instruments:
	Cash flow hedges	$	(2,090	)	$	(2,221	)	Total interest expense
	Tax benefit	764			796			Income tax expense
	Net of tax	$	(1,326	)	$	(1,425	)
	Defined benefit pension and other postretirement benefit plans:
	Amortization of (loss) gain	$	(672	)	$	26		Compensation and benefits
	Prior service costs	(18		)	(18		)	Compensation and benefits
	Tax benefit (expense)	252			(3		)	Income tax expense
	Net of tax	$	(438	)	$	5

Regulatory_Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2015
Regulatory Matters Disclosure [Abstract]
Regulatory Matters	Regulatory Matters
	Regulatory Capital Requirements. Webster is subject to regulatory capital requirements administered by the Federal Reserve, while Webster Bank is subject to regulatory capital requirements administered by the Office of the Comptroller of the Currency ("OCC"). Regulatory authorities can initiate certain mandatory actions if Webster or Webster Bank fail to meet minimum capital requirements, which could have a direct material effect on the Company’s financial statements. Capital adequacy guidelines and, additionally for banks, prompt corrective action regulations involve quantitative measures of assets, liabilities, and certain off-balance sheet items calculated under regulatory accounting practices. These quantitative measures, to ensure capital adequacy, require minimum amounts and ratios.
	Basel III rules enhanced the comprehensive methodology for calculating risk-weighted assets which vary by asset class previously established under Basel I rules. Under Basel III, total risk-based capital is comprised of three categories: Common Equity Tier 1 capital ("CET1 capital"), additional Tier 1 capital, and Tier 2 capital. CET1 capital includes common shareholders' equity, less deductions for goodwill, other intangibles, and certain deferred tax losses. Webster's common shareholders' equity, for purposes of CET1, excludes accumulated other comprehensive 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. Basel III became effective on January 1, 2015 for non-advanced approach banks as defined, and all prior period data is based on Basel I rules.
	The following table provides information on the capital ratios for Webster Financial Corporation and Webster Bank, N.A.:
						Capital Requirements (*)
		Actual (*)				Minimum				Well Capitalized
	(Dollars in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
	At March 31, 2015
	Webster Financial Corporation
	Common equity tier 1	$	1,707,480	10.9	%	$	702,842	4.5	%	$	1,015,217	6.5	%
	Total risk-based capital	2,098,907		13.4		1,249,497		8		1,561,872		10
	Tier 1 capital	1,876,139		12		937,123		6		1,249,497		8
	Tier 1 leverage capital	1,876,139		8.5		883,529		4		1,104,412		5
	Webster Bank, N.A.
	Common equity tier 1	$	1,784,448	11.5	%	$	699,865	4.5	%	$	1,010,916	6.5	%
	Total risk-based capital	1,948,738		12.5		1,244,204		8		1,555,255		10
	Tier 1 capital	1,784,448		11.5		933,153		6		1,244,204		8
	Tier 1 leverage capital	1,784,448		8.1		882,516		4		1,103,145		5
	At December 31, 2014
	Webster Financial Corporation
	Total risk-based capital	$	2,096,772	14.1	%	$	1,192,651	8	%	$	1,490,706	10	%
	Tier 1 capital	1,931,276		13		596,326		4		894,423		6
	Tier 1 leverage capital	1,931,276		9		859,241		4		1,074,051		5
	Webster Bank, N.A.
	Total risk-based capital	$	1,939,229	13	%	$	1,190,242	8	%	$	1,487,803	10	%
	Tier 1 capital	1,774,814		11.9		595,121		4		892,682		6
	Tier 1 leverage capital	1,774,814		8.3		858,197		4		1,072,746		5
	(*) Calculated under the Basel III capital standard at March 31, 2015 and under the Basel I capital standard at December 31, 2014.
	Dividend Restrictions. In the ordinary course of business, Webster 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 totaled $20.0 million during the three months ended March 31, 2015, while none were paid during the three months ended March 31, 2014.

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share
	The calculation of basic and diluted earnings per common share follows:
		Three months ended March 31,
	(Dollars in thousands, except per share data)	2015		2014
	Earnings for basic and diluted earnings per common share:
	Net income available to common shareholders	$	47,083	$	47,790
	Less: Earnings allocated to participating securities	146		173
	Net income allocated to common shareholders	$	46,937	$	47,617
	Shares:
	Weighted-average common shares outstanding - basic	90,251		89,880
	Effect of dilutive securities:
	Stock options and restricted stock	540		503
	Warrants	50		275
	Weighted-average common shares outstanding - diluted	90,841		90,658
	Earnings per common share:
	Basic	$	0.52	$	0.53
	Diluted	0.52		0.53
	Stock Options
	Options to purchase 344 thousand shares for the three months ended March 31, 2015 and 839 thousand shares for the three months ended March 31, 2014 were excluded from the calculation of diluted earnings per share because the options’ exercise prices were greater than the average market price of Webster's common stock for the respective periods presented.
	Restricted Stock
	Non-participating restricted stock awards of 143 thousand shares and 172 thousand shares for the three months ended March 31, 2015 and 2014, respectively, whose issuance is contingent upon the satisfaction of certain performance conditions, were deemed to be anti-dilutive and, therefore, are excluded from the calculation of diluted earnings per share for the respective periods presented.
	Series A Preferred Stock
	The Series A Preferred Stock represents potential issuable common stock at March 31, 2015 and 2014. The weighted-average effect of 1.1 million shares of common stock associated with the Series A Preferred Stock was deemed to be anti-dilutive and, therefore, is excluded from the calculation of diluted earnings per share for the three months ended March 31, 2015 and 2014.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2015
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 along with the use of interest rate derivative financial instruments. Webster enters into interest rate derivative financial instruments to manage exposure that arises from business activities that result in the receipt or payment of both future known and uncertain cash amounts determined by interest rates.
	Webster’s primary objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish these objectives, Webster uses interest rate swaps and interest rate caps as part of its interest rate risk management strategy. Interest rate swaps and 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 an up-front premium.
	The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded as OCI and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. During the three months ended March 31, 2015, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt and forecasted issuances of debt. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the three months ended March 31, 2015 and 2014, the Company recorded no ineffectiveness and immaterial amounts of ineffectiveness in earnings, respectively, attributable to the difference in the effective date of the swap and the effective date of the debt issuance.
	At March 31, 2015, the Company has hedged its exposure to the variability in future cash flows for forecasted transactions over a maximum period of three months, excluding transactions related to the payment of variable interest on existing financial instruments.
	Webster is also exposed to changes in the fair value of certain of its fixed-rate obligations due to changes in benchmark interest rates. Webster, on occasion, uses interest rate swaps to manage its exposure to changes in fair value on these obligations attributable to changes in the benchmark interest rates. Interest rate swaps designated as fair value hedges involve the receipt of fixed-rate amounts from a counterparty in exchange for Webster making variable-rate payments over the life of the agreements without the exchange of the underlying notional amount. 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. Webster did not have interest rate derivative financial instruments designated as ‘fair value’ hedges as of March 31, 2015 and December 31, 2014. During the three months ended March 31, 2015 and 2014, there was nothing and $799 thousand, respectively, related to previous fair value hedges recognized in interest expense.
	Webster has additional interest rate derivatives that do not qualify for hedge accounting and are, therefore, accounted for as free-standing derivatives with changes in fair value recorded in other non-interest income. Webster's derivatives not designated as hedges are not speculative and are used to manage the Company's exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements.
	The Company’s risk management strategy includes the use of interest rate derivatives, specifically futures contracts to modify the re-pricing risk of assets and liabilities. As part of this strategy, the Company uses futures contracts to hedge certain loans at March 31, 2015. Webster holds short-sale Fed funds futures with notional values of $800 million and maturity dates extending three months into the future. This approach is designed to work in conjunction with floating rate assets with interest rate floors, which would not generate a benefit from an increase in short-term interest rates. The value of the contracts will increase with actual or expected increases in the Fed funds rate over the next three months to mitigate this risk of the interest rate floors.
	Other derivative instruments include interest rate swap and cap contracts 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 which is recorded in other non-interest income.
	The Company enters into Risk Participation Agreements ("RPA") as financial guarantees of performance on interest rate swap derivatives. The purchased (asset) or sold (liability) guarantee allows the Company to participate-in (for a fee received) or participate-out (for a fee paid) the risk associated with certain derivative positions executed with the borrower by a lead bank. The RPA guarantee is recorded on the balance sheet at fair value, with changes in fair value recognized in other non-interest income each period.
	Derivative positions
	The notional amounts of Webster’s derivative instruments are shown in the table below:
	(In thousands)	At March 31,				At December 31,
		2015				2014
	Interest rate derivatives	$	8,126,315			$	10,237,325
	RPA	97,273				90,448
	Other	60				60
	Total	$	8,223,648			$	10,327,833
	The table below presents the fair value for Webster’s derivative instruments as well as their classification in the accompanying Condensed Consolidated Balance Sheets. Information about the valuation methods used to measure fair value is provided in Note 15 - Fair Value Measurements.
		At March 31, 2015							At December 31, 2014
	(In thousands)	Other			Other Liabilities				Other			Other Liabilities
		Assets							Assets
	Derivatives designated as hedging instruments:
	Interest rate derivatives	$	3,460		$	6,276			$	4,481		$	4,598
	Derivatives not designated as hedging instruments:
	Interest rate derivatives	69,034			51,496				48,209			31,915
	RPA	236			305				182			258
	Other	—			7				—			7
	Total derivatives not designated as hedging instruments	$	69,270		$	51,808			$	48,391		$	32,180
	Amounts recorded in OCI related to cash flow hedges
	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 $3.2 million will be reclassified from accumulated other comprehensive loss ("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 March 31, 2015, the remaining unamortized loss on the termination of cash flow hedges is $31.6 million. Over the next twelve months, the Company estimates that $8.4 million will be reclassified from AOCL as an increase to interest expense.
	The net losses included in the Condensed Consolidated Statements of Income and Condensed Consolidated Statements of Comprehensive Income, on a pre-tax basis, related to interest rate derivatives designated as hedges of cash flows were as follows:
		Three months ended March 31,
	(In thousands)	2015				2014
	Amount of net loss reclassified from AOCL to interest expense	$	(2,090	)		$	(2,221	)
	Amount of net loss recognized as OCI	(4,887		)		(8,029		)
	Refer to the Net Interest Income section of Management's Discussion and Analysis of Financial Condition and Results of Operation for additional information regarding cash flow hedges impact on borrowing interest expense.
	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 Condensed Consolidated Statements of Income as follows:
		Three months ended March 31,
	(In thousands)	2015				2014
	Derivatives not designated as hedging instruments:
	Interest rate derivatives	$	2,637			$	1,783
	RPA	(76		)		90
	Other	(42		)		(35		)
	Total	$	2,519			$	1,838
	Offsetting Derivatives
	Webster has entered into transactions with counterparties that are subject to a master netting agreement. Hedge accounting positions are recorded on a gross basis in other assets for a gain position and in other liabilities for a loss position, while non-hedge accounting net positions are recorded in other assets for a net gain or in other liabilities for a net loss position in the accompanying Condensed Consolidated Balance Sheets.
	The table below presents the financial assets and liabilities for non-customer derivative positions, including futures contracts, summarized by dealer counterparty or Derivative Clearing Organization ("DCO"):
		At March 31, 2015
		Notional Amount				Hedge Accounting Positions							Non-Hedge Accounting Positions					Total MTM(Loss) Gain			Cash Collateral Posted (Received)			Net Exposure (1)
	(In thousands)					MTM Gain			MTM Loss				MTM Gain		MTM Loss
	Dealer A	$	414,515			$	—		$	(1,930	)		$	450	$	(6,365	)	$	(7,845	)	$	7,600		$	—
	Dealer B	299,587				1,153			—				229		(6,536		)	(5,154		)	4,860			—
	Dealer C	6,068				—			—				—		(590		)	(590		)	—			—
	Dealer D	355,333				577			—				290		(2,881		)	(2,014		)	1,700			—
	Dealer E	446,818				1,730			—				257		(2,569		)	(582		)	330			—
	Dealer F (2)	4,315,805				—			(4,346		)		95		(33,512		)	(37,763		)	56,241			18,478
	Total	$	5,838,126			$	3,460		$	(6,276	)		$	1,321	$	(52,453	)	$	(53,948	)	$	70,731
		At December 31, 2014
		Notional Amount				Hedge Accounting Positions							Non-Hedge Accounting Positions					Total MTM (Loss) Gain			Cash Collateral Posted (Received)			Net Exposure (1)
	(In thousands)					MTM Gain			MTM Loss				MTM Gain		MTM Loss
Dealer A	$	427,430			$	—		$	(739	)		$	1,861	$	(6,576	)	$	(5,454	)	$	5,300		$	—
Dealer B	319,663				1,494			—				978		(6,420		)	(3,948		)	3,610			—
Dealer C	11,538				—			—				—		(834		)	(834		)	—			—
Dealer D	303,663				747			—				1,147		(1,627		)	267			(400		)	—
Dealer E	424,401				2,240			—				867		(1,698		)	1,409			(1,420		)	—
Dealer F (2)	6,631,936				—			(3,858		)		555		(17,629		)	(20,932		)	39,037			18,105
Total	$	8,118,631			$	4,481		$	(4,597	)		$	5,408	$	(34,784	)	$	(29,492	)	$	46,127
(1) Net positive exposure represents over-collateralized loss positions which can be the result of DCO initial margin requirements posted in compliance with the Dodd-Frank Wall Street Reform and Consumer Protection Act.
(2) Dealer F represents Chicago Mercantile Exchange, our designated DCO.
Counterparty Credit Risk
Derivative contracts involve the risk of dealing with both bank customers and institutional derivative counterparties and their ability to meet contractual terms. The Company has International Swap Derivative Association ("ISDA") Master agreements, including a Credit Support Annex ("CSA"), with all derivative counterparties for non-cleared trades. 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 CSA, 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 $70.7 million in net margin collateral posted with financial counterparties at March 31, 2015. 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 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 $69.0 million at March 31, 2015. 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 $18.2 million at March 31, 2015. The credit exposure is mitigated as transactions with customers are generally secured by the same collateral of the underlying transactions being hedged.
Mortgage Banking Derivatives
Forward sales of mortgage loans and MBS 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 MBS. At March 31, 2015, outstanding rate locks totaled approximately $104.4 million and the outstanding commitments to sell residential mortgage loans totaled approximately $116.0 million. Forward sales, which include mandatory forward commitments of approximately $116.0 million at March 31, 2015, 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. The interest rate locked loan commitments and forward sales commitments are recorded at fair value, with changes in fair value recorded as non-interest income in the accompanying Condensed Consolidated Statements of Income. At both March 31, 2015 and December 31, 2014, the fair value of interest rate locked loan commitments and forward sales commitments totaled gains of $0.5 million, and were recorded as a component of other assets in the accompanying Condensed Consolidated Balance Sheets.
Foreign Currency Derivatives
The Company enters into foreign currency forward contracts that are not designated for hedge accounting to minimize fluctuations of currency exchange rates on certain lending arrangements. The carrying amount and fair value of foreign currency forward contracts is immaterial at March 31, 2015 and December 31, 2014.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
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, the fair value estimates may not be realized in an immediate transfer of the respective asset or liability.
	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 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.
	Categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
	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 securities within Level 1 of the valuation hierarchy. Level 1 securities include equity securities in financial institutions and U.S. Treasury Bills.
	If 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. Level 2 securities include agency CMO, agency MBS, agency CMBS, CMBS, CLO, single-issuer trust preferred securities, and corporate debt.
	When a market is illiquid or there is a lack of transparency around the inputs to valuation, the securities are classified as Level 3, and reliance is placed upon internally developed models and management judgment for valuation.
	Derivative Instruments
	Fed funds futures contracts are valued based on unadjusted quoted prices in active markets and are classified within Level 1 of the fair value hierarchy. All other derivative instruments are valued using third-party valuation software, which considers the present value of cash flows discounted using observable forward rate assumptions. The resulting fair values are validated against valuations performed by independent third parties and are classified within Level 2 of the fair value hierarchy. In determining if any fair value adjustments related to credit risk are 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
	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 a 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 Company consolidates the invested assets of the trust along with the total deferred compensation obligations and includes them in other assets and other liabilities, respectively, in the accompanying Condensed Consolidated Balance Sheets. Earnings in the Rabbi Trust, including appreciation or depreciation, are reflected as other non-interest income, and changes in the corresponding liability are reflected as compensation and benefits in the accompanying Condensed Consolidated Statements of Income. The cost basis of the investments held in the Rabbi Trust is $4.1 million as of March 31, 2015.
	Alternative Investments
	The Company generally records alternative investments at cost, subject to impairment testing. The alternative investments that are carried at cost are considered to be measured at fair value on a non-recurring basis when there is impairment. There are certain funds in which the ownership percentage is greater than 3% and are, therefore, recorded at fair value on a recurring basis based upon the net asset value of the respective fund. Alternative investments are non-public entities that cannot be redeemed since the Company’s investment is distributed as the underlying investments are liquidated. As such, these investments are classified within Level 3 of the fair value hierarchy. The Company has $10.4 million in unfunded commitments remaining for its alternative investments as of March 31, 2015. See Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations, Investment Securities Portfolio section for a further discussion on the Company's alternative investments.
	Contingent Consideration
	A contingent asset was transferred as part of the consideration for the Company's acquisition that occurred during the first quarter of 2015. The contingent consideration arrangement entitles the Company to receive a rebate of the purchase price relating to the premium paid for account attrition that occurs during the eighteen-month period beginning on the closing date of the transaction. The valuation is reliant upon a pricing model and techniques that require significant management judgment or estimation. Therefore, the contingent consideration is classified within Level 3 of the fair value hierarchy. The key assumptions in the model are a 2.5% annual growth rate, 13.0% annual account attrition rate plus approximately 6.0% of shock attrition in 2015, 16.5% discount rate and a premium on deposits of 4.5%.
	Contingent Liability
	A contingent liability was assumed as part of the Company's acquisition that occurred during the first quarter of 2015. The contingent liability represents an existing obligation as a result of the acquisition. The obligation is expected to be settled during the first year and half following the transaction. The valuation is based upon unobservable inputs. Therefore, the contingent liability is classified within Level 3 of the fair value hierarchy. The fair value of the contingency represents the estimated price to transfer the liability between market participants at the measurement date under current market conditions.
	A summary of fair value for assets and liabilities measured at fair value on a recurring basis is as follows:
		At March 31, 2015
	(In thousands)	Total			Quoted Prices in			Significant Other			Significant
					Active Markets for			Observable  Inputs			Unobservable  Inputs
					Identical Assets			(Level 2)			(Level 3)
					(Level 1)
	Financial assets held at fair value:
	Available-for-sale investment securities:
	U.S. Treasury Bills	$	425		$	425		$	—		$	—
	Agency CMO	664,700			—			664,700			—
	Agency MBS	1,017,007			—			1,017,007			—
	Agency CMBS	127,702			—			127,702			—
	CMBS	562,623			—			562,623			—
	CLO	442,701			—			442,701			—
	Single issuer trust preferred securities	38,282			—			38,282			—
	Corporate debt	110,084			—			110,084			—
	Equity securities	4,585			4,585			—			—
	Total available-for-sale investment securities	2,968,109			5,010			2,963,099			—
	Derivative instruments	72,730			—			72,730			—
	Mortgage banking derivatives	541			—			541			—
	Investments held in Rabbi Trust	5,684			5,684			—			—
	Alternative investments	441			—			—			441
	Contingent Consideration	5,000			—			—			5,000
	Total financial assets held at fair value	$	3,052,505		$	10,694		$	3,036,370		$	5,441
	Financial liabilities held at fair value:
	Derivative instruments	$	58,084		$	245		$	57,839		$	—
	Contingent liability	6,000			—			—			6,000
	Total financial liabilities held at fair value	$	64,084		$	245		$	57,839		$	6,000
		At December 31, 2014
	(In thousands)	Total			Quoted Prices in			Significant Other			Significant
					Active Markets for			Observable  Inputs			Unobservable  Inputs
					Identical Assets			(Level 2)			(Level 3)
					(Level 1)
	Financial assets held at fair value:
	Available-for-sale investment securities:
	U.S. Treasury Bills	$	525		$	525		$	—		$	—
	Agency CMO	550,988			—			550,988			—
	Agency MBS	1,028,518			—			1,028,518			—
	Agency CMBS	80,266			—			80,266			—
CMBS	553,393			—			553,393			—
CLO	425,734			—			425,734			—
Single issuer trust preferred securities	38,245			—			38,245			—
Corporate debt	110,301			—			110,301			—
Equity securities	5,903			5,903			—			—
Total available-for-sale investment securities	2,793,873			6,428			2,787,445			—
Derivative instruments	52,872			—			52,872			—
Mortgage banking derivatives	18			—			18			—
Investments held in Rabbi Trust	5,901			5,901			—			—
Alternative investments	475			—			—			475
Contingent Consideration	—			—			—			—
Total financial assets held at fair value	$	2,853,139		$	12,329		$	2,840,335		$	475
Financial liabilities held at fair value:
Derivative instruments	$	36,777		$	293		$	36,484		$	—
Contingent liability	—			—			—			—
Total financial liabilities held at fair value	$	36,777		$	293		$	36,484		$	—
The following table presents the changes in Level 3 assets and liabilities that are measured at fair value on a recurring basis:
	Financial Assets
(In thousands)	Alternative Investments			Contingent Consideration			Total				Contingent Liability
Level 3, beginning of period	$	475		$	—		$	475			$	—
Acquisition	—			5,000			5,000				6,000
Unrealized loss included in net income	1			—			1				—
Calls/paydowns	(35		)	—			(35		)		—
Level 3, end of period	$	441		$	5,000		$	5,441			$	6,000
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.
Loans Held for Sale
Loans held for sale 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 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 as Level 2 of the fair value hierarchy. On occasion, the loans held for sale portfolio includes commercial loans in which adjustments are required for changes in loan characteristics. When observable data is unavailable, such loans are classified within Level 3.
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 impaired loans and leases are classified as Level 3 of the fair value hierarchy.
Other Real Estate Owned (OREO) and Repossessed Assets
The total book value of OREO and repossessed assets was $5.3 million at March 31, 2015. 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 and as such OREO and repossessed assets are classified as Level 3 of the fair value hierarchy.
Mortgage Servicing Assets
Mortgage servicing assets are accounted for at cost, subject to impairment testing. When the carrying cost exceeds fair value, a valuation allowance is established to reduce the carrying cost to fair value. 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 and 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 table below presents the valuation methodology and unobservable inputs for Level 3 assets measured at fair value on a non-recurring basis at March 31, 2015:
(Dollars in thousands)
Asset	Fair Value			Valuation Methodology	Unobservable Inputs	Range of Inputs
Impaired loans and leases	$	27,862		Real Estate Appraisals	Discount for appraisal type	3% - 15%
					Discount for costs to sell	0% - 8%
Other real estate owned	$	3,091		Real Estate Appraisals	Discount for appraisal type	0% - 25%
					Discount for costs to sell	8%
Mortgage servicing assets	$	27,901		Discounted cash flow	Constant prepayment rate	9.2% - 28.8%
					Discount rates	1.4% - 2.9%
Fair Value of Financial Instruments
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, 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 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. Webster has 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 investments which include agency CMO, agency MBS, agency CMBS, Municipal, and Private Label MBS securities are classified within Level 2 of the fair value hierarchy.
Loans and Leases
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. The fair value of fixed-maturity certificates of deposit is estimated using the rates currently offered for deposits of similar remaining maturities. Deposit liabilities are classified within Level 2 of the fair value hierarchy.
Securities Sold Under Agreements to Repurchase and Other Borrowings
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 Federal Home Loan Bank ("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.
The estimated fair value of selected financial instruments are as follows:
	At March 31, 2015								At December 31, 2014
(In thousands)	Carrying				Fair Value				Carrying				Fair Value
	Amount								Amount
Financial Assets
Level 2:
Held-to-maturity investment securities	$	3,923,189			$	4,022,981			3,872,955				$	3,948,706
Loans held for sale	45,866				46,733				67,952				68,705
Level 3:
Loans and leases	14,108,256				14,151,073				13,740,761				13,775,850
Mortgage servicing assets (1)	19,243				27,901				19,379				28,690
Alternative investments	15,265				17,706				16,524				18,046
Financial Liabilities
Level 2:
Deposit liabilities, other than time deposits	$	15,339,922			$	15,339,922			$	13,380,018			$	13,380,018
Time deposits	2,205,728				2,224,374				2,271,587				2,288,760
Securities sold under agreements to repurchase and other borrowings	1,083,877				1,105,190				1,250,756				1,271,596
FHLB advances (2)	1,584,357				1,597,986				2,859,431				2,872,515
Long-term debt (3)	226,267				226,379				226,237				227,751
The following adjustments to the carrying amount are not included in the fair value:
-1	Mortgage servicing assets is net of $25 thousand and $23 thousand in reserves at March 31, 2015 and December 31, 2014, respectively.
-2	FHLB advances is net of $33 thousand and $37 thousand in unamortized premiums at March 31, 2015 and December 31, 2014, respectively.
-3	Long-term debt is net of $1.1 million in unamortized discounts at March 31, 2015 and December 31, 2014.
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.

Pension_and_Other_Postretireme

Pension and Other Postretirement Benefits	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefit Plans
	The following table summarizes the components of net periodic benefit cost (benefit) for the Company's benefit plans:
		Three months ended March 31,
		Webster Pension						Webster SERP				Other Benefits
	(In thousands)	2015			2014			2015		2014		2015		2014
	Service cost	$	10		$	10		$	—	$	—	$	—	$	—
	Interest cost on benefit obligations	1,989			2,003			86		92		31		34
	Expected return on plan assets	(2,963		)	(2,875		)	—		—		—		—
	Amortization of prior service cost	—			—			—		—		18		18
	Recognized net loss	1,427			687			80		23		12		—
	Net periodic benefit cost (benefit)	$	463		$	(175	)	$	166	$	115	$	61	$	52
	The Webster Bank Pension Plan and the supplemental pension plans were frozen effective December 31, 2007. No additional benefits have been accrued since that time. Additional contributions to the Webster Bank Pension Plan will be made as deemed appropriate by management in conjunction with information provided by the Plan’s actuaries.
	Multiple-employer plan
	Webster Bank is a sponsor of a multiple-employer plan administered by Pentegra (the “Fund”) for the benefit of former employees of a bank acquired by Webster. The Fund does not segregate the assets or liabilities of its participating employers in the ongoing administration of this plan. According to the Fund’s administrators, as of July 1, 2014, the date of the latest actuarial valuation, Webster’s portion of the plan was overfunded by $0.3 million.
	The following table sets forth contributions and funding status of the Fund:
	(In thousands)	Contributions by Webster  Bank							Funded Status of Plan
		Three Months Ended March 31,
	EIN/Pension Plan Number	2015			2014				As of July 1, 2014
	13-5645888/333	$	91		$	337			At least 80 percent
	Multi-employer accounting is applied to the Fund. As a multiple-employer plan, there are no collective bargained contracts affecting the Fund's contribution or benefit provisions. All shortfall amortization bases are being amortized over seven years, as required by the Pension Protection Act. All benefit accruals were frozen as of September 1, 2004.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans
	Webster maintains stock-based compensation plans (collectively, the "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-based 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 following table provides a summary of stock-based compensation expense recognized in the accompanying Condensed Consolidated Statements of Income:
		Three months ended March 31,
	(In thousands)	2015				2014
	Stock options	$	164			$	552
	Restricted stock	2,118				2,221
	Stock-based compensation	$	2,282			$	2,773
	The following table provides a summary of unrecognized stock-based compensation expense:
		At March 31, 2015
	(Dollars in thousands)	Unrecognized Compensation Expense			Weighted-Average Period To Be Recognized
	Stock options	$	259		0.9 years
	Restricted stock	$	17,878		2.2 years
	The following table provides a summary of the activity under the Plans for the three months ended March 31, 2015:
		Restricted Stock Awards Outstanding														Stock Options Outstanding
		Time-Based										Performance-Based
		Number of		Weighted-Average				Number of		Weighted-Average		Number of		Weighted-Average		Number of		Weighted-Average
		Shares		Grant Date				Units		Grant Date		Shares		Grant Date		Shares		Exercise Price
				Fair Value						Fair Value				Fair Value
	Outstanding, at January 1, 2015	243,015		$	27.03			2,279		$	29.34	130,193		$	28.61	1,900,144		$	24.95
	Granted	191,824		32.91				12,531		34.45		138,591		36.15		—		—
	Exercised options	—		—				—		—		—		—		(13,033	)	20.1
	Vested restricted stock awards (1)	(52,837	)	26.9				(3,323	)	30.95		(50,159	)	29.94		—		—
	Forfeited	(683	)	29.75				—		—		—		—		(25,044	)	40.3
	Outstanding, at March 31, 2015	381,319		$	30.85			11,487		$	34.45	218,625		$	33.09	1,862,067		$	24.78
	Options exercisable, at March 31, 2015															1,753,892		$	24.89
	Options expected to vest, at March 31, 2015															102,314		$	23
	(1) Vested for purposes of recording compensation expense.
	Time-based restricted stock awards vest over the applicable service period ranging from one to five years. The Plans limit the number of time-based awards that may be granted to an eligible individual in a calendar year to 100,000 shares. Compensation expense is recorded over the vesting period based on a fair value, which is measured using the Company's common stock closing price at the date of grant.
	Performance-based restricted stock awards vest after a three year performance period, with share quantity dependent on that performance. Awards granted in 2015 and 2014 vest in a range from zero to 150%, while previous awards vest in a range from zero to 200%, of the target number of shares under the grant. The performance-based shares granted in 2015 vest, based 50% upon Webster's ranking for total shareholder return versus Webster's compensation peer group companies and 50% upon Webster's average of return on equity for each year during the three year vesting period. The compensation peer group companies are utilized because they represent the mix of size and type of financial institutions that best compare with Webster. The Company records compensation expense over the vesting period, based on a fair value calculated using the Monte-Carlo simulation model, which allows for the incorporation of the performance condition for the 50% of the performance-based shares tied to total shareholder return versus the compensation peer group, and based on a fair value of the market price on the date of grant for the remaining 50% of the performance-based shares tied to Webster's return on equity. Compensation expense is subject to adjustment based on management's assessment of Webster's return on equity performance relative to the target number of shares condition.
	Stock option awards have an exercise price equal to the market price of Webster's stock on the date of grant and vest over periods ranging from three to four years. 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 were 1,702,165 non-qualified stock options and 159,902 incentive stock options outstanding at March 31, 2015.

Segment_Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting
	Beginning in 2015, Webster’s operations are divided into four reportable segments that represent its core businesses – Commercial Banking, Community Banking, HSA Bank, and Private Banking. Community Banking includes the operating segments of Webster's Personal Banking and Business Banking. With the acquisition of a health savings account business, the reported revenue of the HSA Bank segment is now in excess of 10% of the combined revenue of all operating segments. As a result, the HSA Bank and Private Banking segments are now disclosed separately. These segments reflect how executive management responsibilities are assigned by the chief operating decision maker for each of the core businesses, the products and services provided, and the type of customer served and reflect how discrete financial information is currently evaluated. The Company’s Treasury unit and consumer liquidating portfolio are included in the Corporate and Reconciling category along with the amounts required to reconcile profitability metrics to GAAP reported amounts. The 2014 segment results have been adjusted for comparability to the 2015 segment presentation.
	Webster’s business 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, the 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 continually being 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 the full profitability and GAAP measures are reconciled in the Corporate and Reconciling category.
	The Company uses a matched maturity funding concept, called funds transfer pricing (“FTP”), to allocate interest income and interest expense to each business while also transferring the primary interest rate risk exposures to the Corporate and Reconciling category. The allocation process considers the specific interest rate risk and liquidity risk of financial instruments and other assets and liabilities in each line of business. The “matched maturity funding concept” considers the origination date and the earlier of the maturity date or the repricing date of a financial instrument to assign an FTP rate for loans and deposits originated each day. Loans are assigned an FTP rate for funds “used” and deposits are assigned an FTP rate for funds “provided.” This process is executed by the Company’s Financial Planning and Analysis division and is overseen by the Company’s Asset/Liability Committee.
	Webster attributes 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 business 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 business segment using a full-absorption costing process. Costs, including corporate overhead, are analyzed, pooled by process, and assigned to the appropriate business segment. Income tax expense is allocated to each business segment based on the consolidated effective income tax rate for the period shown.
	The following tables present the results for Webster’s business segments and incorporate the allocation of the provision for loan and lease losses and income tax expense to each of Webster’s business segments for the periods presented:
		Three months ended March 31, 2015
	(In thousands)	Commercial		Community Banking		HSA Bank		Private Banking			Corporate and			Consolidated
		Banking									Reconciling			Total
	Net interest income (loss)	$	61,578	$	84,239	$	16,465	$	2,395		$	(4,913	)	$	159,764
	Provision for loan and lease losses	3,374		6,421		—		(57		)	12			9,750
	Net interest income (loss) after provision for loan and lease losses	58,204		77,818		16,465		2,452			(4,925		)	150,014
	Non-interest income	9,525		25,540		15,151		2,326			5,348			57,890
	Non-interest expense	26,469		81,690		18,958		4,879			2,094			134,090
	Income (loss) before income tax expense	41,260		21,668		12,658		(101		)	(1,671		)	73,814
	Income tax expense (benefit)	13,467		7,073		4,131		(33		)	(546		)	24,092
	Net income (loss)	$	27,793	$	14,595	$	8,527	$	(68	)	$	(1,125	)	$	49,722
		Three months ended March 31, 2014
	(In thousands)	Commercial		Community Banking		HSA Bank		Private Banking			Corporate and			Consolidated
		Banking									Reconciling			Total
	Net interest income	$	56,152	$	87,341	$	9,206	$	2,161		$	441		$	155,301
	Provision (benefit) for loan and lease losses	10,445		645		—		446			(2,536		)	9,000
	Net interest income after provision for loan and lease losses	45,707		86,696		9,206		1,715			2,977			146,301
	Non-interest income	7,951		24,436		6,889		2,621			7,931			49,828
	Non-interest expense	26,019		81,518		10,147		4,556			2,223			124,463
	Income (loss) before income tax expense	27,639		29,614		5,948		(220		)	8,685			71,666
	Income tax expense (benefit)	8,190		8,775		1,754		(66		)	2,584			21,237
	Net income (loss)	$	19,449	$	20,839	$	4,194	$	(154	)	$	6,101		$	50,429
		Total Assets
	(In thousands)	Commercial		Community Banking		HSA Bank		Private Banking			Corporate and			Consolidated
		Banking									Reconciling			Total
	At March 31, 2015	$	6,830,310	$	7,817,188	$	90,818	$	412,229		$	7,956,143		$	23,106,688
	At December 31, 2014	$	6,550,868	$	8,198,115	$	25,148	$	400,425		$	7,358,616		$	22,533,172

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Lease Commitments. At March 31, 2015, Webster was obligated under various non-cancelable operating leases for properties used as banking and other office facilities. The leases contain renewal options and escalation clauses, which provide for increased rental expense or equipment replaced with new leased equipment as the leases expire. Rental expense under leases was $5.3 million and $5.0 million for the three months ended March 31, 2015 and 2014, respectively, and is recorded as a component of occupancy expense in the accompanying Condensed Consolidated Statements of Income. Rental income from sub-leases on certain of these properties is also recorded 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 Condensed Consolidated Statements of Income. Rental income was $0.2 million for the three months ended March 31, 2015 and 2014. There has been no significant change in future minimum lease payments payable since December 31, 2014. See Webster's 2014 Form 10-K for additional information regarding these commitments.
	Credit-Related Financial Instruments. The Company is a party to credit-related financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit, standby letters of credit, and commercial letters of credit. Such commitments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the balance sheet. The Company’s exposure to credit loss is represented by the contractual amount of these commitments as it is for on-balance sheet instruments.
	The following table summarizes outstanding contract amounts for off-balance sheet instruments that represent credit risk:
	(In thousands)	At March 31,			At December 31,
		2015			2014
	Unused commitments to extend credit	$	4,431,835		$	4,376,733
	Standby letters of credit	144,606			142,964
	Commercial letters of credit	34,782			27,787
	Total financial instruments with off-balance sheet risk	$	4,611,223		$	4,547,484
	Unused Commitments to Extend Credit. The Company makes commitments under various terms to lend funds to customers. These commitments include revolving credit arrangements, term loan commitments, and short-term borrowing agreements. Many of these loans have fixed expiration dates or other termination clauses where a fee may be required. Since commitments are expected to expire without being funded, the total commitment amounts do not necessarily represent future liquidity requirements.
	Standby Letters of Credit. Standby letters of credit commit 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. Historically, a large percentage of standby letters of credit expire without being funded. The contractual amount of standby letters of credit represents the maximum potential amount of future payments the Company could be required to make and represents the Company's maximum credit risk.
	Commercial Letters of Credit. Commercial letters of credit are issued to facilitate domestic or foreign trade transactions for customers. As a general rule, drafts will be drawn when the goods underlying the transaction are in transit.
	The reserve for unfunded credit commitments is reported as a component of accrued expenses and other liabilities in the accompanying Condensed Consolidated Balance Sheets. The following table provides activity details for the Company’s reserve for unfunded credit commitments:
		Three months ended March 31,
	(In thousands)	2015			2014
	Balance, beginning of period	$	5,151		$	4,384
	Provision (benefit)	(2,831		)	327
	Balance, end of period	$	2,320		$	4,711
	Litigation Reserves. 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 as of March 31, 2015 any reasonably possible losses, in addition to amounts accrued, are not material to Webster’s consolidated financial condition. However, in light of the uncertainties involved in such actions and proceedings, there is no assurance that the ultimate resolution of these matters will not significantly exceed the reserves currently accrued by Webster or that the Company’s litigation reserves will not need to be adjusted in future periods. Such an outcome could be material to the Company’s operating results in a particular period, depending on, among other factors, the size of the loss or liability imposed and the level of the Company’s income for that period.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation
	The accounting and reporting policies of the Company that materially affect the Condensed Consolidated Financial Statements conform with U.S. Generally Accepted Accounting Principles ("GAAP"). The accompanying unaudited Condensed Consolidated Financial Statements of the Company have been prepared in conformity with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements and should be read in conjunction with the Company's Consolidated Financial Statements, and notes thereto, for the year ended December 31, 2014, included in the Company's Annual Report on Form 10-K filed with the SEC on February 27, 2015.
	The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts of assets and liabilities as of the date of the financial statements as well as income and expense during the period. Actual results could differ from those estimates. Operating results for the interim period disclosed herein are not necessarily indicative of the results that may be expected for the full year or any future period.
	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 stockholders' equity, net cash provided by operating activities, net cash used for investing activities, and net cash provided by financing activities.
Business Combinations Policy [Policy Text Block]	Acquisition
	On January 13, 2015 (the "acquisition date”), the Company completed its acquisition of the health savings account business of JPMorgan Chase Bank, N.A. The results of the acquisition have been included in the financial statements from the acquisition date. See Note 2 - Acquisition and Note 6 - Goodwill and Other Intangible Assets for further information.
Loans and Leases Receivable, Nonperforming Loan and Lease, Policy [Policy Text Block]	Non-accrual loans. Effective during the first quarter of 2015, residential loans that are more than 90 days past due, fully insured against loss, and in the process of collection, remain accruing loans and are reported as 90 days or more past due and accruing. Previously, these loans were placed on non-accrual when payments were 90 days or more past due. For presentation purposes, previously reported amounts have been reclassified to conform to the current year presentation. The change in accounting policy did not have a material impact on the financial statements.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	Other intangible assets. Other intangible assets with finite useful lives are amortized to non-interest expense over their estimated useful lives. Effective during the first quarter of 2015, core deposit intangibles resulting from the acquisition are amortized on an accelerated basis over their estimated useful lives. Core deposit intangibles existing prior to the acquisition will continue to be amortized on a straight line basis over their remaining estimated useful lives. Intangible assets relating to customer relationships are amortized on a straight line basis over their estimated useful lives.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Adopted Accounting Standards Updates
	ASU No. 2014-01 - Investments - Equity Method and Joint Ventures (Topic 323) - "Accounting for Investments in Qualified Affordable Housing Projects (a consensus of the FASB Emerging Issues Task Force)." The ASU requires an entity to disclose information about its investments in qualified affordable housing projects and provides an accounting policy election for it to account for such investments using the proportional amortization method. Under that method, the initial cost of an investment is amortized in proportion to its tax credits and other tax benefits as a component of income tax expense or benefit. The decision to apply the proportionate amortization method is to be applied consistently to all such investments.
	The Company adopted this ASU effective January 1, 2015 and retrospectively applied the effects of its accounting policy decision to use the proportional amortization method. Webster believes presenting the investment performance net of taxes as a component of income tax expense or benefit better represents the economics of such investments, and the change has no material effect on its financial statements. See the Income Taxes section of Management's Discussion and Analysis of Financial Condition and Results of Operation for information regarding the financial impact of the adopted ASU.
	ASU No. 2014-04, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40) - "Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure (a consensus of the FASB Emerging Issues Task Force)." The ASU clarifies that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (i) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (ii) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar agreement. In addition, the amendments require disclosure of both the amount of foreclosed residential real estate property held by the creditor and the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure in accordance with local requirements of the applicable jurisdiction. An entity can elect to adopt the amendments using either a modified retrospective method or a prospective transition method. This amendment was adopted during the first quarter of 2015 and did not have a material impact on the Company's financial statements.
	ASU No. 2014-11 - Transfers and Servicing (Topic 860) - “Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures.” The ASU requires two accounting changes: (i) repurchase-to-maturity transactions are to be accounted for as secured borrowings; and (ii) with respect to repurchase financing arrangements, accounting is required for a transfer of a financial asset contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. Additionally, disclosure requirements have been expanded to include a disaggregation of collateral used for secured borrowings, and contractual maturity disclosure has been expanded to interim periods. This amendment was adopted during the first quarter of 2015 and did not have a material impact on the Company's financial statements.
	ASU No. 2014-14, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40) - "Classification of Certain Government-Guaranteed Residential Mortgage Loans upon Foreclosure (a consensus of the FASB Emerging Issues Task Force)." The ASU has been issued to reduce diversity in practice in the classification of foreclosed residential mortgage loans held by creditors that are fully guaranteed under certain government programs, including the Federal Housing Administration guarantees. A residential mortgage loan would be derecognized, and a separate other receivable would be recognized upon foreclosure if the loan has both of the following characteristics: (i) the loan has a government guarantee that is not separable from the loan before foreclosure entitling the creditor to the full unpaid principal balance of the loan; and (ii) at the time of foreclosure, the creditor has the intent to make a claim on the guarantee and the ability to recover the full unpaid principal balance of the loan through the guarantee. Notably, upon foreclosure, the separate other receivable would be measured based on the current amount of the loan balance expected to be recovered under the guarantee. This amendment was adopted during the first quarter of 2015 and did not have a material impact on the Company's financial statements.

Acquisition_Tables

Acquisition (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Schedule of Business Acquisitions	The acquisition-date fair value of the consideration transferred consisted of the following:
	(In thousands)	At January 13, 2015
	Cash	$	50,485
	Contingent consideration (1)	(5,000		)
	Total net consideration transferred	$	45,485
	(1) The contingent consideration arrangement entitles the Company to receive a rebate of the purchase price relating to the premium paid for account attrition.
	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed at the acquisition date:
	(In thousands)	At January 13, 2015
	Cash	$	1,446,898
	Intangible assets	43,000
	Total identifiable assets acquired	$	1,489,898
	Deposits	$	1,446,899
	Contingent liability	6,000
	Total liabilities assumed	$	1,452,899
	Net identifiable assets acquired	$	36,999
	Goodwill	8,486
	Net assets acquired	$	45,485

Investment_Securities_Tables

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Summary of Investment Securities	Summaries of the amortized cost, carrying value, and fair value of Webster’s investment securities are presented below:
		At March 31, 2015
					Recognized in OCI									Not Recognized in OCI
	(In thousands)	Amortized			Gross			Gross			Carrying			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized			Value			Unrealized			Unrealized
					Gains			Losses						Gains			Losses
	Available-for-sale:
	U.S. Treasury Bills	$	425		$	—		$	—		$	425		$	—		$	—		$	425
	Agency collateralized mortgage obligations (“agency CMO”)	654,911			10,580			(791		)	664,700			—			—			664,700
	Agency mortgage-backed securities (“agency MBS”)	1,012,462			12,093			(7,548		)	1,017,007			—			—			1,017,007
	Agency commercial mortgage-backed securities (“agency CMBS”)	126,439			1,263			—			127,702			—			—			127,702
	Non-agency commercial mortgage-backed securities agency (“non-agency CMBS”)	544,483			18,173			(33		)	562,623			—			—			562,623
	Collateralized loan obligations ("CLO") (1)	441,061			1,979			(339		)	442,701			—			—			442,701
	Single issuer trust preferred securities	42,025			31			(3,774		)	38,282			—			—			38,282
	Corporate debt securities	105,905			4,179			—			110,084			—			—			110,084
	Equity securities - financial institutions	3,500			1,085			—			4,585			—			—			4,585
	Total available-for-sale	$	2,931,211		$	49,383		$	(12,485	)	$	2,968,109		$	—		$	—		$	2,968,109
	Held-to-maturity:
	Agency CMO	$	414,952		$	—		$	—		$	414,952		$	8,648		$	(423	)	$	423,177
	Agency MBS	2,109,728			—			—			2,109,728			64,646			(7,001		)	2,167,373
	Agency CMBS	625,320			—			—			625,320			9,127			(872		)	633,575
	Municipal bonds and notes	404,735			—			—			404,735			13,615			(972		)	417,378
	Non-agency CMBS	363,319			—			—			363,319			13,092			(153		)	376,258
	Private Label MBS	5,135			—			—			5,135			85			—			5,220
	Total held-to-maturity	$	3,923,189		$	—		$	—		$	3,923,189		$	109,213		$	(9,421	)	$	4,022,981
	-1	Amortized cost is net of $3.6 million of other-than-temporary impairments at March 31, 2015.
		At December 31, 2014
					Recognized in OCI									Not Recognized in OCI
	(In thousands)	Amortized			Gross			Gross			Carrying			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized			Value			Unrealized			Unrealized
					Gains			Losses						Gains			Losses
	Available-for-sale:
	U.S. Treasury Bills	$	525		$	—		$	—		$	525		$	—		$	—		$	525
	Agency CMO	543,417			8,636			(1,065		)	550,988			—			—			550,988
	Agency MBS	1,030,724			10,462			(12,668		)	1,028,518			—			—			1,028,518
	Agency CMBS	80,400			—			(134		)	80,266			—			—			80,266
	Non-agency CMBS	534,631			18,885			(123		)	553,393			—			—			553,393
	CLO (1)	426,269			482			(1,017		)	425,734			—			—			425,734
	Single issuer trust preferred securities	41,981			—			(3,736		)	38,245			—			—			38,245
	Corporate debt securities	106,520			3,781			—			110,301			—			—			110,301
	Equity securities - financial institutions	3,500			2,403			—			5,903			—			—			5,903
	Total available-for-sale	$	2,767,967		$	44,649		$	(18,743	)	$	2,793,873		$	—		$	—		$	2,793,873
	Held-to-maturity:
	Agency CMO	$	442,129		$	—		$	—		$	442,129		$	6,584		$	(739	)	$	447,974
	Agency MBS	2,134,319			—			—			2,134,319			57,196			(11,340		)	2,180,175
	Agency CMBS	578,687			—			—			578,687			1,597			(1,143		)	579,141
	Municipal bonds and notes	373,211			—			—			373,211			15,138			(55		)	388,294
	Non-agency CMBS	338,723			—			—			338,723			9,428			(1,015		)	347,136
	Private Label MBS	5,886			—			—			5,886			100			—			5,986
	Total held-to-maturity	$	3,872,955		$	—		$	—		$	3,872,955		$	90,043		$	(14,292	)	$	3,948,706
	-1	Amortized cost is net of $3.7 million of other-than-temporary impairments at December 31, 2014.
Summary of Debt Securities by Contractual Maturity	The amortized cost and fair value of debt securities at March 31, 2015, by contractual maturity, are set forth below:
		Available-for-Sale							Held-to-Maturity
	(In thousands)	Amortized			Fair				Amortized			Fair
		Cost			Value				Cost			Value
	Due in one year or less	$	25,465		$	25,567			$	805		$	808
	Due after one year through five years	120,864			124,974				54,040			56,105
	Due after five through ten years	395,985			397,416				74,404			77,194
	Due after ten years	2,385,397			2,415,567				3,793,940			3,888,874
	Total debt securities	$	2,927,711		$	2,963,524			$	3,923,189		$	4,022,981
Summary of Gross Unrealized Losses not Considered OTTI	The following tables provide information on the gross unrealized losses and fair value of the Company’s investment securities with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment security type and length of time that individual investment securities have been in a continuous unrealized loss position:
		At March 31, 2015
		Less Than Twelve Months							Twelve Months or Longer							Total
	(Dollars in thousands)	Fair			Unrealized				Fair			Unrealized				# of	Fair			Unrealized
		Value			Losses				Value			Losses				Holdings	Value			Losses
	Available-for-sale:
	Agency CMO	$	43,228		$	(264	)		$	31,579		$	(527	)		5	$	74,807		$	(791	)
	Agency MBS	187,105			(889		)		404,414			(6,659		)		60	591,519			(7,548		)
	Agency CMBS	—			—				—			—				—	—			—
	Non-agency CMBS	48,214			(20		)		9,387			(13		)		6	57,601			(33		)
	CLO	30,760			(339		)		—			—				2	30,760			(339		)
	Single issuer trust preferred securities	—			—				34,057			(3,774		)		7	34,057			(3,774		)
	Total available-for-sale in an unrealized loss position	$	309,307		$	(1,512	)		$	479,437		$	(10,973	)		80	$	788,744		$	(12,485	)
	Held-to-maturity:
	Agency CMO	$	8,856		$	(53	)		$	24,116		$	(370	)		3	$	32,972		$	(423	)
	Agency MBS	151,582			(769		)		529,147			(6,232		)		47	680,729			(7,001		)
	Agency CMBS	22,325			(872		)		—			—				1	22,325			(872		)
	Municipal bonds and notes	46,405			(944		)		3,076			(28		)		37	49,481			(972		)
	Non-agency CMBS	5,273			(33		)		30,849			(120		)		3	36,122			(153		)
	Total held-to-maturity in an unrealized loss position	$	234,441		$	(2,671	)		$	587,188		$	(6,750	)		91	$	821,629		$	(9,421	)
		At December 31, 2014
		Less Than Twelve Months							Twelve Months or Longer							Total
	(Dollars in thousands)	Fair			Unrealized				Fair			Unrealized				# of	Fair			Unrealized
		Value			Losses				Value			Losses				Holdings	Value			Losses
	Available-for-sale:
	Agency CMO	$	47,217		$	(240	)		$	35,968		$	(825	)		8	$	83,185		$	(1,065	)
	Agency MBS	3,691			(18		)		641,355			(12,650		)		64	645,046			(12,668		)
	Agency CMBS	80,266			(134		)		—			—				4	80,266			(134		)
	Non-agency CMBS	24,932			(117		)		9,396			(6		)		4	34,328			(123		)
	CLO	99,221			(1,017		)		—			—				6	99,221			(1,017		)
	Single issuer trust preferred securities	4,150			(36		)		34,095			(3,700		)		8	38,245			(3,736		)
	Total available-for-sale in an unrealized loss position	$	259,477		$	(1,562	)		$	720,814		$	(17,181	)		94	$	980,291		$	(18,743	)
	Held-to-maturity:
	Agency CMO	$	52,172		$	(187	)		$	24,942		$	(552	)		6	$	77,114		$	(739	)
	Agency MBS	20,791			(86		)		608,568			(11,254		)		44	629,359			(11,340		)
	Agency CMBS	324,394			(1,143		)		—			—				17	324,394			(1,143		)
	Municipal bonds and notes	5,341			(23		)		3,074			(32		)		15	8,415			(55		)
	Non-agency CMBS	13,003			(30		)		65,913			(985		)		7	78,916			(1,015		)
	Total held-to-maturity in an unrealized loss position	$	415,701		$	(1,469	)		$	702,497		$	(12,823	)		89	$	1,118,198		$	(14,292	)
Other than Temporary Impairment, Credit Losses Recognized in Earnings	The following is a roll forward of the amount of OTTI related to debt securities:
		Three months ended March 31,
	(In thousands)	2015				2014
	Balance of OTTI, beginning of period	$	3,696			$	16,633
	Reduction for securities sold, called	(99		)		(7,056		)
	Additions for OTTI not previously recognized	—				88
	Balance of OTTI, end of period	$	3,597			$	9,665
Summary of Sale Proceeds of Available for Sale Securities	The following table summarizes proceeds from available-for-sale securities, the gross realized gains and losses from those sales, and the impact of the recognition of other-than-temporary impairments for the periods presented:
		Three months ended March 31,
	(In thousands)	2015				2014
	Proceeds from sales	$	27,859			$	21,695
	Gross realized gains	$	43			$	4,336
	OTTI write-down	—				(88		)
	Net realized gains from investment securities	$	43			$	4,248

Loans_and_Leases_Loans_and_Lea

Loans and Leases Loans and Leases (Tables)	3 Months Ended
	Mar. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Schedule of Participating Mortgage Loans	The following tables summarize the recorded investment in loans and leases by portfolio segment:
		At March 31, 2015
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total (2)
											Real Estate (1)			Financing
	Recorded Investment:
	Individually evaluated for impairment	$	140,815		$	50,834		$	49,619		$	73,972		$	631		$	315,871
	Collectively evaluated for impairment	3,464,162			2,526,616			3,862,095			3,597,297			543,005			13,993,175
	Recorded investment in loans and leases	3,604,977			2,577,450			3,911,714			3,671,269			543,636			14,309,046
	Less: Accrued interest	10,705			8,013			11,904			8,198			—			38,820
	Loans and leases	$	3,594,272		$	2,569,437		$	3,899,810		$	3,663,071		$	543,636		$	14,270,226
		At December 31, 2014
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total (2)
											Real Estate (1)			Financing
	Recorded Investment:
	Individually evaluated for impairment	$	142,435		$	50,374		$	36,454		$	103,045		$	632		$	332,940
	Collectively evaluated for impairment	3,377,196			2,507,060			3,723,991			3,460,116			537,119			13,605,482
	Recorded investment in loans and leases	3,519,631			2,557,434			3,760,445			3,563,161			537,751			13,938,422
	Less: Accrued interest	10,456			8,033			11,175			8,733			—			38,397
	Loans and leases	$	3,509,175		$	2,549,401		$	3,749,270		$	3,554,428		$	537,751		$	13,900,025
	-1	Includes certain loans individually evaluated for impairment under the Company's loan policy that were deemed not to be impaired at both March 31, 2015 and December 31, 2014.
	-2	Loans and leases include net deferred fees and unamortized premiums of $12.1 million and $10.6 million at March 31, 2015 and December 31, 2014, respectively.
Past Due Financing Receivables	The following tables summarize the aging of the recorded investment in loans and leases by portfolio class:
		At March 31, 2015
	(In thousands)	30-59 Days			60-89 Days			> 90 Days Past Due			Non-accrual			Total Past Due and Non-accrual			Current			Total Loans
		Past Due and			Past Due and			and Accruing												and Leases
		Accruing			Accruing
	Residential	$	9,631		$	4,514		$	1,895		$	61,371		$	77,411		$	3,527,566		$	3,604,977
	Consumer:
	Home equity	12,001			7,658			—			37,617			57,276			2,408,439			2,465,715
	Other consumer	587			343			—			267			1,197			110,538			111,735
	Commercial:
	Commercial non-mortgage	3,121			950			273			26,974			31,318			3,161,881			3,193,199
	Asset-based	—			—			—			—			—			718,515			718,515
	Commercial real estate:
	Commercial real estate	3,199			805			42			22,183			26,229			3,398,306			3,424,535
	Commercial construction	—			—			—			3,651			3,651			243,083			246,734
	Equipment financing	729			60			—			285			1,074			542,562			543,636
	Total	$	29,268		$	14,330		$	2,210		$	152,348		$	198,156		$	14,110,890		$	14,309,046
		At December 31, 2014
	(In thousands)	30-59 Days			60-89 Days			> 90 Days Past Due			Non-accrual			Total Past Due and Non-accrual			Current			Total Loans
		Past Due and			Past Due and			and Accruing												and Leases
		Accruing			Accruing
	Residential (1), (2)	$	11,521		$	5,931		$	2,039		$	64,117		$	83,608		$	3,436,023		$	3,519,631
	Consumer:
	Home equity (1)	11,516			5,161			—			40,025			56,702			2,424,584			2,481,286
	Other consumer	720			425			—			281			1,426			74,722			76,148
	Commercial:
	Commercial non-mortgage	1,971			156			50			6,449			8,626			3,088,656			3,097,282
	Asset-based	—			—			—			—			—			663,163			663,163
	Commercial real estate:
	Commercial real estate	2,348			397			—			15,038			17,783			3,310,765			3,328,548
	Commercial construction	—			—			—			3,659			3,659			230,954			234,613
	Equipment financing	551			150			—			578			1,279			536,472			537,751
	Total	$	28,627		$	12,220		$	2,089		$	130,147		$	173,083		$	13,765,339		$	13,938,422
	-1	A total of $17.6 million aggregate principal amount of residential and consumer loans was reclassified from non-accrual to accrual status as a result of updated regulatory guidance issued in the first quarter of 2014.
	-2	For the year ended 2014, US Government secured loans of $2.0 million were reclassified from non-accrual to over 90 days and accruing due to a policy change effective in the first quarter of 2015. See Note 1 - Summary of Significant Accounting Policies.
Activity In Allowance For Losses	The following tables summarize the ALLL by portfolio segment:
		At or for the three months ended March 31, 2015
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total
											Real Estate			Financing
	Allowance for loan and lease losses:
	Balance, beginning of period	$	25,452		$	43,518		$	52,114		$	32,102		$	6,078		$	159,264
	Provision (benefit) charged to expense	4,144			2,232			2,754			1,398			(778		)	9,750
	Losses charged off	(1,955		)	(4,296		)	(255		)	(3,153		)	(15		)	(9,674		)
	Recoveries	108			1,162			1,015			202			143			2,630
	Balance, end of period	$	27,749		$	42,616		$	55,628		$	30,549		$	5,428		$	161,970
	Individually evaluated for impairment	$	14,350		$	4,255		$	4,939		$	3,668		$	28		$	27,240
	Collectively evaluated for impairment	$	13,399		$	38,361		$	50,689		$	26,881		$	5,400		$	134,730
		At or for the three months ended March 31, 2014
	(In thousands)	Residential			Consumer			Commercial			Commercial			Equipment			Total
											Real Estate			Financing
	Allowance for loan and lease losses:
	Balance, beginning of period	$	23,027		$	41,951		$	51,001		$	32,408		$	4,186		$	152,573
	Provision (benefit) charged to expense	(542		)	(903		)	7,975			3,287			(817		)	9,000
	Losses charged off	(1,158		)	(4,886		)	(3,148		)	(2,405		)	—			(11,597		)
	Recoveries	260			1,113			973			479			799			3,624
	Balance, end of period	$	21,587		$	37,275		$	56,801		$	33,769		$	4,168		$	153,600
	Individually evaluated for impairment	$	10,993		$	4,109		$	989		$	4,013		$	—		$	20,104
	Collectively evaluated for impairment	$	10,594		$	33,166		$	55,812		$	29,756		$	4,168		$	133,496
Impaired Loans	The following tables summarize impaired loans and leases by portfolio class:
		At March 31, 2015
	(In thousands)	Unpaid			Total			Recorded			Recorded			Related
		Principal			Recorded			Investment			Investment			Valuation
		Balance			Investment			No Allowance			With Allowance			Allowance
	Residential:	$	154,795		$	140,815		$	23,494		$	117,321		$	14,350
	Consumer:
	Home equity	57,403			50,834			26,827			24,007			4,255
	Commercial:
	Commercial non-mortgage	54,277			49,619			23,986			25,633			4,939
	Commercial real estate:
	Commercial real estate	73,371			67,114			34,466			32,648			3,658
	Commercial construction	7,172			6,164			5,951			213			10
	Equipment financing	629			631			—			631			28
	Totals:
	Residential	154,795			140,815			23,494			117,321			14,350
	Consumer	57,403			50,834			26,827			24,007			4,255
	Commercial	54,277			49,619			23,986			25,633			4,939
	Commercial real estate	80,543			73,278			40,417			32,861			3,668
	Equipment financing	629			631			—			631			28
	Total	$	347,647		$	315,177		$	114,724		$	200,453		$	27,240
		At December 31, 2014
	(In thousands)	Unpaid			Total			Recorded			Recorded			Related
		Principal			Recorded			Investment			Investment			Valuation
		Balance			Investment			No Allowance			With Allowance			Allowance
	Residential:	$	157,152		$	142,435		$	24,388		$	118,047		$	12,094
	Consumer:
	Home equity	60,424			50,374			26,464			23,910			4,237
	Commercial:
	Commercial non-mortgage	41,019			36,454			16,064			20,390			2,710
	Commercial real estate:
	Commercial real estate	99,687			96,160			40,575			55,585			6,222
	Commercial construction	7,218			6,177			5,956			221			10
	Equipment financing	629			632			—			632			28
	Totals:
	Residential	157,152			142,435			24,388			118,047			12,094
	Consumer	60,424			50,374			26,464			23,910			4,237
	Commercial	41,019			36,454			16,064			20,390			2,710
	Commercial real estate	106,905			102,337			46,531			55,806			6,232
	Equipment financing	629			632			—			632			28
	Total	$	366,129		$	332,232		$	113,447		$	218,785		$	25,301
	The following table summarizes the average recorded investment and interest income recognized for impaired loans and leases by portfolio class:
		31-Mar-15			Three months ended March 31, 2015							31-Mar-14			Three months ended March 31, 2014
	(In thousands)	Average			Accrued			Cash Basis Interest Income				Average			Accrued			Cash Basis Interest Income
		Recorded			Interest							Recorded			Interest
		Investment			Income							Investment			Income
	Residential	$	141,625		$	1,059		$	256			$	142,768		$	1,192		$	324
	Consumer:
	Home equity	50,604			361			282				52,269			370			324
	Commercial:
	Commercial non-mortgage	43,037			427			—				50,179			628			—
	Commercial real estate:
	Commercial real estate	81,637			530			—				91,730			801			—
	Commercial construction	6,171			33			—				10,393			82			—
	Equipment financing	632			11			—				197			3			—
	Totals:
	Residential	141,625			1,059			256				142,768			1,192			324
	Consumer	50,604			361			282				52,269			370			324
	Commercial	43,037			427			—				50,179			628			—
	Commercial real estate	87,808			563			—				102,123			883			—
	Equipment financing	632			11			—				197			3			—
	Total	$	323,706		$	2,421		$	538			$	347,536		$	3,076		$	648
Financing Receivable Credit Quality Indicators	The recorded investment in commercial loans, commercial real estate loans, and equipment financing leases segregated by risk rating exposure is as follows:
		Commercial								Commercial Real Estate								Equipment Financing
	(In thousands)	At March 31,				At December 31,				At March 31,				At December 31,				At March 31,				At December 31,
		2015				2014				2015				2014				2015				2014
	(1) - (6) Pass	$	3,677,136			$	3,555,559			$	3,546,467			$	3,416,214			$	524,907			$	516,115
	(7) Special Mention	100,320				89,064				29,187				33,580				4,039				4,364
	(8) Substandard	134,094				115,653				95,157				112,874				14,690				17,272
	(9) Doubtful	164				169				458				493				—				—
	(10) Loss	—				—				—				—				—				—
	Total	$	3,911,714			$	3,760,445			$	3,671,269			$	3,563,161			$	543,636			$	537,751
	The recorded investment in commercial, commercial real estate, and equipment financing TDRs segregated by risk rating exposure is as follows:
	(In thousands)	At March 31,				At December 31,
		2015				2014
	(1) - (6) Pass	$	32,714			$	40,943
	(7) Special Mention	8,242				8,304
	(8) Substandard	61,016				77,771
	(9) Doubtful	342				343
	(10) Loss	—				—
	Total	$	102,314			$	127,361
Troubled Debt Restructurings on Financing Receivables	The following table provides information on loans and leases modified as TDRs within the previous 12 months and for which there was a payment default during the periods presented:
		Three months ended March 31,
		2015					2014
	(Dollars in thousands)	Number of	Recorded				Number of	Recorded
		Loans and	Investment				Loans and	Investment
		Leases					Leases
	Residential:
	1-4 family	3	$	642			6	$	645
	Consumer:
	Home equity	2	251				3	190
	Commercial:
	Commercial non-mortgage	2	6,317				1	76
	Commercial real estate:
	Commercial real estate	1	10,930				—	—
	Total	8	$	18,140			10	$	911
	The following table provides information on how loans and leases were modified as TDRs:
		Three months ended March 31,
		2015						2014
		Number of		Post-				Number of		Post-
		Loans and		Modification				Loans and		Modification
		Leases		Recorded				Leases		Recorded
	(Dollars in thousands)			Investment(1)						Investment(1)
	Residential:
	Extended Maturity	9		$	1,345			6		$	706
	Adjusted Interest Rates	—		—				1		227
	Combination Rate and Maturity	10		1,668				8		2,589
	Other	3		536				11		2,077
	Consumer:
	Extended Maturity	4		499				9		470
	Adjusted Interest Rates	—		—				1		51
	Combination Rate and Maturity	8		444				4		255
	Other	21		1,332				27		1,444
	Commercial:
	Extended Maturity	1		33				2		54
	Adjusted Interest Rates	—		—				—		—
	Combination Rate and Maturity	2		132				6		241
	Other	—		—				1		150
	TOTAL TDRs	58		$	5,989			76		$	8,264
	(1) Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant.
	Troubled Debt Restructurings ("TDRs"). The following table summarizes information for TDRs:
	(Dollars in thousands)	At March 31, 2015				At December 31, 2014
	Recorded investment of TDRs:
	Accrual status (1)	$	201,175			$	243,231
	Non-accrual status (1)	92,788				76,939
	Total recorded investment of TDRs	$	293,963			$	320,170
	Accruing TDRs performing under modified terms more than one year	66.1		%		67.6		%
	Specific reserves for TDRs included in the balance of allowance for loan and lease losses	$	22,539			$	23,785
	Additional funds committed to borrowers in TDR status	555				552
	-1	A total of $17.6 million residential and consumer loans was reclassified from non-accrual to accrual status as a result of updated regulatory guidance issued in the first quarter of 2014.

Transfers_of_Financial_Assets_1

Transfers of Financial Assets and Mortgage Servicing Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Transfers and Servicing [Abstract]
Schedule Of Reserve For Loan Repurchases Table	The following table provides a summary of activity in the reserve for loan repurchases:
		Three months ended March 31,
	(In thousands)	2015			2014
	Beginning balance	$	1,059		$	2,254
	Provision (benefit)	23			(310		)
	Loss on repurchased loans and settlements	—			(43		)
	Ending balance	$	1,082		$	1,901
Schedule of Loan Sale Activity	The following table provides detail of activity related to loan sales related to mortgage banking activities:
		Three months ended March 31,
	(In thousands)	2015			2014
	Residential mortgage loans:
	Proceeds from the sale of loans held for sale	$	76,895		$	65,643
	Net gain on sale included as mortgage banking activities	1,561			775
	Loans sold with servicing rights retained	69,265			48,552
Schedule of Servicing Assets at Fair Value	The following table presents the changes in fair value for those mortgage servicing assets:
		Three months ended March 31,
	(In thousands)	2015			2014
	Fair value, beginning of period	$	28,690		$	29,150
	Originations of servicing assets	1,463			961
	Changes in fair value:
	Due to payoffs/paydowns	(736		)	(473		)
	Due to market changes	(1,516		)	(484		)
	Fair value, end of period	$	27,901		$	29,154

Goodwill_and_Other_Intangible_1

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill And Other Intangible Assets, Net Of Accumulated Amortization	The following table presents the carrying value for goodwill allocated to the segments:
		Operating Segment
	(In thousands)	Community Banking		HSA Bank			Total
	Balance at December 31, 2014	$	516,560	$	13,327		$	529,887
	Goodwill acquired during the period	—		8,486			8,486
	Balance at March 31, 2015	$	516,560	$	21,813		$	538,373
Schedule of Finite-Lived Intangible Assets	The gross carrying amount and accumulated amortization of core deposit intangibles ("CDI") and other intangible assets allocated to the business segments are as follows:
		At March 31, 2015							At December 31, 2014
	(In thousands)	Gross Carrying		Accumulated			Net Carrying		Gross Carrying		Accumulated			Net Carrying
		Amount		Amortization			Amount		Amount		Amortization			Amount
	Community Banking CDI	$	49,420	$	(47,135	)	$	2,285	$	49,420	$	(46,754	)	$	2,666
	HSA Bank:
	CDI	22,000		(509		)	21,491		—		—			—
	Customer relationships	21,000		(398		)	20,602		—		—			—
	Total HSA Bank	43,000		(907		)	42,093		—		—			—
	Total Intangible Assets	$	92,420	$	(48,042	)	$	44,378	$	49,420	$	(46,754	)	$	2,666
Schedule Of Expected Amortization Expense, Next Four Years	Future estimated annual amortization expense is summarized below:
	(In thousands)
	Years ending December 31:
	Remainder of 2015	$	5,052
	2016	5,652
	2017	4,062
	2018	3,847
	2019	3,847
	Thereafter	21,918

Deposits_Tables

Deposits (Tables)	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Summary Of Deposits	A summary of deposits by type follows:
	(In thousands)	At March 31,		At December 31,
		2015		2014
	Non-interest-bearing:
	Demand	$	3,450,316	$	3,598,872
	Interest-bearing:
	Checking	2,267,350		2,155,047
	Health savings accounts	3,529,301		1,824,799
	Money market	2,114,300		1,908,522
	Savings	3,978,655		3,892,778
	Time deposits	2,205,728		2,271,587
	Total interest-bearing	14,095,334		12,052,733
	Total deposits	$	17,545,650	$	15,651,605
	Deposits obtained through brokers included in above balances	$	765,500	$	651,725
	Demand deposit overdrafts reclassified as loan balances	1,530		1,655
Scheduled Maturities Of Time Deposits	At March 31, 2015, the scheduled maturities of time deposits are as follows:
	(In thousands)
	Remainder of 2015	$	964,901
	2016	474,162
	2017	153,773
	2018	176,488
	2019	375,843
	Thereafter	60,561
	Time deposits	$	2,205,728

Securities_Sold_Under_Agreemen1

Securities Sold Under Agreements to Repurchase and Other Borrowings (Tables)	3 Months Ended
	Mar. 31, 2015
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Abstract]
Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings	The following table summarizes securities sold under agreements to repurchase and other borrowings:
	(In thousands)	At March 31,		At December 31,
		2015		2014
	Securities sold under agreements to repurchase:
	Original maturity of one year or less	$	317,877	$	409,756
	Original maturity of greater than one year, non-callable	550,000		550,000
		867,877		959,756
	Other borrowings:
	Federal funds purchased	216,000		291,000
	Securities sold under agreements to repurchase and other borrowings	$	1,083,877	$	1,250,756

Federal_Home_Loan_Bank_Advance1

Federal Home Loan Bank Advances (Tables)	3 Months Ended
	Mar. 31, 2015
Federal Home Loan Banks [Abstract]
Summary Of Advances Payable To The Federal Home Loan Bank	The following table summarizes Federal Home Loan Bank advances:
		At March 31, 2015				At December 31, 2014
	(Dollars in thousands)	Total		Weighted-		Total		Weighted-
		Outstanding		Average Contractual Coupon Rate		Outstanding		Average Contractual Coupon Rate
	FHLB advances maturing:
	Within 1 year	$	995,934	0.33	%	$	2,275,000	0.23	%
	After 1 but within 2 years	100,000		1.48		145,934		1.8
	After 2 but within 3 years	50,500		1.1		500		5.66
	After 3 but within 4 years	150,000		1.46		200,000		1.36
	After 4 but within 5 years	128,026		1.82		78,026		1.95
	After 5 years	159,864		1.29		159,934		1.27
		1,584,324		0.75	%	2,859,394		0.5	%
	Unamortized premiums	33				37
	Federal Home Loan Bank advances	$	1,584,357			$	2,859,431

LongTerm_Debt_Tables

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	The following table summarizes long-term debt:
	(Dollars in thousands)		At March 31,			At December 31,
			2015			2014
	4.38%	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
	Unamortized discount on senior fixed-rate notes		(1,053		)	(1,083		)
	Long-term debt		$	226,267		$	226,237
	-1	The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month LIBOR plus 2.950%, was 3.221% at March 31, 2015 and 3.193% at December 31, 2014

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Schedule of Other Comprehensive Income (Loss)	The following tables summarize the changes in accumulated other comprehensive loss by component:
		Three months ended March 31, 2015
	(In thousands)	Available For Sale and Transferred Securities			Derivative Instruments			Defined Benefit Pension and Other Postretirement Benefit Plans			Total
	Beginning balance	$	16,421		$	(25,530	)	$	(47,152	)	$	(56,261	)
	Other comprehensive income (loss) before reclassifications	6,994			(3,096		)	536			4,434
	Amounts reclassified from accumulated other comprehensive (loss) income	(27		)	1,326			438			1,737
	Net current-period other comprehensive income (loss), net of tax	6,967			(1,770		)	974			6,171
	Ending balance	$	23,388		$	(27,300	)	$	(46,178	)	$	(50,090	)
		Three months ended March 31, 2014
	(In thousands)	Available For Sale and Transferred Securities			Derivative Instruments			Defined Benefit Pension and Other Postretirement Benefit Plans			Total
	Beginning balance	$	(2,617	)	$	(18,206	)	$	(27,726	)	$	(48,549	)
	Other comprehensive income (loss) before reclassifications	10,849			(5,151		)	467			6,165
	Amounts reclassified from accumulated other comprehensive (loss) income	(2,727		)	1,425			(5		)	(1,307		)
	Net current-period other comprehensive income (loss), net of tax	8,122			(3,726		)	462			4,858
	Ending balance	$	5,505		$	(21,932	)	$	(27,264	)	$	(43,691	)
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the amount reclassified from accumulated other comprehensive loss:
	(In thousands)	Three months ended March 31,						Associated Line Item in the Condensed
	Accumulated Other Comprehensive Loss Components	2015			2014			Consolidated Statements Of Income
	Available-for-sale and transferred securities:
	Unrealized gains (losses) on investment securities	$	43		$	4,336		Net gain on sale of investment securities
	Unrealized gains (losses) on investment securities	—			(88		)	Impairment loss recognized in earnings
	Tax expense	(16		)	(1,521		)	Income tax expense
	Net of tax	$	27		$	2,727
	Derivative instruments:
	Cash flow hedges	$	(2,090	)	$	(2,221	)	Total interest expense
	Tax benefit	764			796			Income tax expense
	Net of tax	$	(1,326	)	$	(1,425	)
	Defined benefit pension and other postretirement benefit plans:
	Amortization of (loss) gain	$	(672	)	$	26		Compensation and benefits
	Prior service costs	(18		)	(18		)	Compensation and benefits
	Tax benefit (expense)	252			(3		)	Income tax expense
	Net of tax	$	(438	)	$	5

Regulatory_Matters_Tables

Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2015
Regulatory Matters Disclosure [Abstract]
Information On The Capital Ratios	The following table provides information on the capital ratios for Webster Financial Corporation and Webster Bank, N.A.:
						Capital Requirements (*)
		Actual (*)				Minimum				Well Capitalized
	(Dollars in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
	At March 31, 2015
	Webster Financial Corporation
	Common equity tier 1	$	1,707,480	10.9	%	$	702,842	4.5	%	$	1,015,217	6.5	%
	Total risk-based capital	2,098,907		13.4		1,249,497		8		1,561,872		10
	Tier 1 capital	1,876,139		12		937,123		6		1,249,497		8
	Tier 1 leverage capital	1,876,139		8.5		883,529		4		1,104,412		5
	Webster Bank, N.A.
	Common equity tier 1	$	1,784,448	11.5	%	$	699,865	4.5	%	$	1,010,916	6.5	%
	Total risk-based capital	1,948,738		12.5		1,244,204		8		1,555,255		10
	Tier 1 capital	1,784,448		11.5		933,153		6		1,244,204		8
	Tier 1 leverage capital	1,784,448		8.1		882,516		4		1,103,145		5
	At December 31, 2014
	Webster Financial Corporation
	Total risk-based capital	$	2,096,772	14.1	%	$	1,192,651	8	%	$	1,490,706	10	%
	Tier 1 capital	1,931,276		13		596,326		4		894,423		6
	Tier 1 leverage capital	1,931,276		9		859,241		4		1,074,051		5
	Webster Bank, N.A.
	Total risk-based capital	$	1,939,229	13	%	$	1,190,242	8	%	$	1,487,803	10	%
	Tier 1 capital	1,774,814		11.9		595,121		4		892,682		6
	Tier 1 leverage capital	1,774,814		8.3		858,197		4		1,072,746		5
	(*) Calculated under the Basel III capital standard at March 31, 2015 and under the Basel I capital standard at December 31, 2014.

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share Basic And Diluted	The calculation of basic and diluted earnings per common share follows:
		Three months ended March 31,
	(Dollars in thousands, except per share data)	2015		2014
	Earnings for basic and diluted earnings per common share:
	Net income available to common shareholders	$	47,083	$	47,790
	Less: Earnings allocated to participating securities	146		173
	Net income allocated to common shareholders	$	46,937	$	47,617
	Shares:
	Weighted-average common shares outstanding - basic	90,251		89,880
	Effect of dilutive securities:
	Stock options and restricted stock	540		503
	Warrants	50		275
	Weighted-average common shares outstanding - diluted	90,841		90,658
	Earnings per common share:
	Basic	$	0.52	$	0.53
	Diluted	0.52		0.53

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	The notional amounts of Webster’s derivative instruments are shown in the table below:
	(In thousands)	At March 31,				At December 31,
		2015				2014
	Interest rate derivatives	$	8,126,315			$	10,237,325
	RPA	97,273				90,448
	Other	60				60
	Total	$	8,223,648			$	10,327,833
Fair Value Of Derivative Financial Instruments Designated As Cash Flow Hedges	Information about the valuation methods used to measure fair value is provided in Note 15 - Fair Value Measurements.
		At March 31, 2015							At December 31, 2014
	(In thousands)	Other			Other Liabilities				Other			Other Liabilities
		Assets							Assets
	Derivatives designated as hedging instruments:
	Interest rate derivatives	$	3,460		$	6,276			$	4,481		$	4,598
	Derivatives not designated as hedging instruments:
	Interest rate derivatives	69,034			51,496				48,209			31,915
	RPA	236			305				182			258
	Other	—			7				—			7
	Total derivatives not designated as hedging instruments	$	69,270		$	51,808			$	48,391		$	32,180
Cash Flow Hedges Included in AOCI	The net losses included in the Condensed Consolidated Statements of Income and Condensed Consolidated Statements of Comprehensive Income, on a pre-tax basis, related to interest rate derivatives designated as hedges of cash flows were as follows:
		Three months ended March 31,
	(In thousands)	2015				2014
	Amount of net loss reclassified from AOCL to interest expense	$	(2,090	)		$	(2,221	)
	Amount of net loss recognized as OCI	(4,887		)		(8,029		)
Other Derivatives 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 Condensed Consolidated Statements of Income as follows:
		Three months ended March 31,
	(In thousands)	2015				2014
	Derivatives not designated as hedging instruments:
	Interest rate derivatives	$	2,637			$	1,783
	RPA	(76		)		90
	Other	(42		)		(35		)
	Total	$	2,519			$	1,838
Offsetting Assets and Liabilities	The table below presents the financial assets and liabilities for non-customer derivative positions, including futures contracts, summarized by dealer counterparty or Derivative Clearing Organization ("DCO"):
		At March 31, 2015
		Notional Amount				Hedge Accounting Positions							Non-Hedge Accounting Positions					Total MTM(Loss) Gain			Cash Collateral Posted (Received)			Net Exposure (1)
	(In thousands)					MTM Gain			MTM Loss				MTM Gain		MTM Loss
	Dealer A	$	414,515			$	—		$	(1,930	)		$	450	$	(6,365	)	$	(7,845	)	$	7,600		$	—
	Dealer B	299,587				1,153			—				229		(6,536		)	(5,154		)	4,860			—
	Dealer C	6,068				—			—				—		(590		)	(590		)	—			—
	Dealer D	355,333				577			—				290		(2,881		)	(2,014		)	1,700			—
	Dealer E	446,818				1,730			—				257		(2,569		)	(582		)	330			—
	Dealer F (2)	4,315,805				—			(4,346		)		95		(33,512		)	(37,763		)	56,241			18,478
	Total	$	5,838,126			$	3,460		$	(6,276	)		$	1,321	$	(52,453	)	$	(53,948	)	$	70,731
		At December 31, 2014
		Notional Amount				Hedge Accounting Positions							Non-Hedge Accounting Positions					Total MTM (Loss) Gain			Cash Collateral Posted (Received)			Net Exposure (1)
	(In thousands)					MTM Gain			MTM Loss				MTM Gain		MTM Loss
	Dealer A	$	427,430			$	—		$	(739	)		$	1,861	$	(6,576	)	$	(5,454	)	$	5,300		$	—
	Dealer B	319,663				1,494			—				978		(6,420		)	(3,948		)	3,610			—
	Dealer C	11,538				—			—				—		(834		)	(834		)	—			—
	Dealer D	303,663				747			—				1,147		(1,627		)	267			(400		)	—
	Dealer E	424,401				2,240			—				867		(1,698		)	1,409			(1,420		)	—
	Dealer F (2)	6,631,936				—			(3,858		)		555		(17,629		)	(20,932		)	39,037			18,105
	Total	$	8,118,631			$	4,481		$	(4,597	)		$	5,408	$	(34,784	)	$	(29,492	)	$	46,127
	(1) Net positive exposure represents over-collateralized loss positions which can be the result of DCO initial margin requirements posted in compliance with the Dodd-Frank Wall Street Reform and Consumer Protection Act.
	(2) Dealer F represents Chicago Mercantile Exchange, our designated DCO.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Of Assets And Liabilities Measured On Recurring Basis	A summary of fair value for assets and liabilities measured at fair value on a recurring basis is as follows:
		At March 31, 2015
	(In thousands)	Total			Quoted Prices in			Significant Other			Significant
					Active Markets for			Observable  Inputs			Unobservable  Inputs
					Identical Assets			(Level 2)			(Level 3)
					(Level 1)
	Financial assets held at fair value:
	Available-for-sale investment securities:
	U.S. Treasury Bills	$	425		$	425		$	—		$	—
	Agency CMO	664,700			—			664,700			—
	Agency MBS	1,017,007			—			1,017,007			—
	Agency CMBS	127,702			—			127,702			—
	CMBS	562,623			—			562,623			—
	CLO	442,701			—			442,701			—
	Single issuer trust preferred securities	38,282			—			38,282			—
	Corporate debt	110,084			—			110,084			—
	Equity securities	4,585			4,585			—			—
	Total available-for-sale investment securities	2,968,109			5,010			2,963,099			—
	Derivative instruments	72,730			—			72,730			—
	Mortgage banking derivatives	541			—			541			—
	Investments held in Rabbi Trust	5,684			5,684			—			—
	Alternative investments	441			—			—			441
	Contingent Consideration	5,000			—			—			5,000
	Total financial assets held at fair value	$	3,052,505		$	10,694		$	3,036,370		$	5,441
	Financial liabilities held at fair value:
	Derivative instruments	$	58,084		$	245		$	57,839		$	—
	Contingent liability	6,000			—			—			6,000
	Total financial liabilities held at fair value	$	64,084		$	245		$	57,839		$	6,000
		At December 31, 2014
	(In thousands)	Total			Quoted Prices in			Significant Other			Significant
					Active Markets for			Observable  Inputs			Unobservable  Inputs
					Identical Assets			(Level 2)			(Level 3)
					(Level 1)
	Financial assets held at fair value:
	Available-for-sale investment securities:
	U.S. Treasury Bills	$	525		$	525		$	—		$	—
	Agency CMO	550,988			—			550,988			—
	Agency MBS	1,028,518			—			1,028,518			—
	Agency CMBS	80,266			—			80,266			—
	CMBS	553,393			—			553,393			—
	CLO	425,734			—			425,734			—
	Single issuer trust preferred securities	38,245			—			38,245			—
	Corporate debt	110,301			—			110,301			—
	Equity securities	5,903			5,903			—			—
	Total available-for-sale investment securities	2,793,873			6,428			2,787,445			—
	Derivative instruments	52,872			—			52,872			—
	Mortgage banking derivatives	18			—			18			—
	Investments held in Rabbi Trust	5,901			5,901			—			—
	Alternative investments	475			—			—			475
	Contingent Consideration	—			—			—			—
	Total financial assets held at fair value	$	2,853,139		$	12,329		$	2,840,335		$	475
	Financial liabilities held at fair value:
	Derivative instruments	$	36,777		$	293		$	36,484		$	—
	Contingent liability	—			—			—			—
	Total financial liabilities held at fair value	$	36,777		$	293		$	36,484		$	—
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:
		Financial Assets
	(In thousands)	Alternative Investments			Contingent Consideration			Total				Contingent Liability
	Level 3, beginning of period	$	475		$	—		$	475			$	—
	Acquisition	—			5,000			5,000				6,000
	Unrealized loss included in net income	1			—			1				—
	Calls/paydowns	(35		)	—			(35		)		—
	Level 3, end of period	$	441		$	5,000		$	5,441			$	6,000
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 at March 31, 2015:
	(Dollars in thousands)
	Asset	Fair Value			Valuation Methodology	Unobservable Inputs	Range of Inputs
	Impaired loans and leases	$	27,862		Real Estate Appraisals	Discount for appraisal type	3% - 15%
						Discount for costs to sell	0% - 8%
	Other real estate owned	$	3,091		Real Estate Appraisals	Discount for appraisal type	0% - 25%
						Discount for costs to sell	8%
	Mortgage servicing assets	$	27,901		Discounted cash flow	Constant prepayment rate	9.2% - 28.8%
						Discount rates	1.4% - 2.9%
Summary Of Estimated Fair Values Of Significant Financial Instruments	The estimated fair value of selected financial instruments are as follows:
		At March 31, 2015								At December 31, 2014
	(In thousands)	Carrying				Fair Value				Carrying				Fair Value
		Amount								Amount
	Financial Assets
	Level 2:
	Held-to-maturity investment securities	$	3,923,189			$	4,022,981			3,872,955				$	3,948,706
	Loans held for sale	45,866				46,733				67,952				68,705
	Level 3:
	Loans and leases	14,108,256				14,151,073				13,740,761				13,775,850
	Mortgage servicing assets (1)	19,243				27,901				19,379				28,690
	Alternative investments	15,265				17,706				16,524				18,046
	Financial Liabilities
	Level 2:
	Deposit liabilities, other than time deposits	$	15,339,922			$	15,339,922			$	13,380,018			$	13,380,018
	Time deposits	2,205,728				2,224,374				2,271,587				2,288,760
	Securities sold under agreements to repurchase and other borrowings	1,083,877				1,105,190				1,250,756				1,271,596
	FHLB advances (2)	1,584,357				1,597,986				2,859,431				2,872,515
	Long-term debt (3)	226,267				226,379				226,237				227,751
	The following adjustments to the carrying amount are not included in the fair value:
	-1	Mortgage servicing assets is net of $25 thousand and $23 thousand in reserves at March 31, 2015 and December 31, 2014, respectively.
	-2	FHLB advances is net of $33 thousand and $37 thousand in unamortized premiums at March 31, 2015 and December 31, 2014, respectively.
	-3	Long-term debt is net of $1.1 million in unamortized discounts at March 31, 2015 and December 31, 2014.

Pension_and_Other_Postretireme1

Pension and Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Summary of Net Periodic Benefit Cost	The following table summarizes the components of net periodic benefit cost (benefit) for the Company's benefit plans:
		Three months ended March 31,
		Webster Pension						Webster SERP				Other Benefits
	(In thousands)	2015			2014			2015		2014		2015		2014
	Service cost	$	10		$	10		$	—	$	—	$	—	$	—
	Interest cost on benefit obligations	1,989			2,003			86		92		31		34
	Expected return on plan assets	(2,963		)	(2,875		)	—		—		—		—
	Amortization of prior service cost	—			—			—		—		18		18
	Recognized net loss	1,427			687			80		23		12		—
	Net periodic benefit cost (benefit)	$	463		$	(175	)	$	166	$	115	$	61	$	52
Schedule of Multiemployer Plans	The following table sets forth contributions and funding status of the Fund:
	(In thousands)	Contributions by Webster  Bank							Funded Status of Plan
		Three Months Ended March 31,
	EIN/Pension Plan Number	2015			2014				As of July 1, 2014
	13-5645888/333	$	91		$	337			At least 80 percent

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Allocation of Share-based Compensation Costs by Plan	The following table provides a summary of stock-based compensation expense recognized in the accompanying Condensed Consolidated Statements of Income:
		Three months ended March 31,
	(In thousands)	2015				2014
	Stock options	$	164			$	552
	Restricted stock	2,118				2,221
	Stock-based compensation	$	2,282			$	2,773
Schedule of Unrecognized Share-based Compensation Expense	The following table provides a summary of unrecognized stock-based compensation expense:
		At March 31, 2015
	(Dollars in thousands)	Unrecognized Compensation Expense			Weighted-Average Period To Be Recognized
	Stock options	$	259		0.9 years
	Restricted stock	$	17,878		2.2 years
Schedule of Share-based Compensation, Activity	The following table provides a summary of the activity under the Plans for the three months ended March 31, 2015:
		Restricted Stock Awards Outstanding														Stock Options Outstanding
		Time-Based										Performance-Based
		Number of		Weighted-Average				Number of		Weighted-Average		Number of		Weighted-Average		Number of		Weighted-Average
		Shares		Grant Date				Units		Grant Date		Shares		Grant Date		Shares		Exercise Price
				Fair Value						Fair Value				Fair Value
	Outstanding, at January 1, 2015	243,015		$	27.03			2,279		$	29.34	130,193		$	28.61	1,900,144		$	24.95
	Granted	191,824		32.91				12,531		34.45		138,591		36.15		—		—
	Exercised options	—		—				—		—		—		—		(13,033	)	20.1
	Vested restricted stock awards (1)	(52,837	)	26.9				(3,323	)	30.95		(50,159	)	29.94		—		—
	Forfeited	(683	)	29.75				—		—		—		—		(25,044	)	40.3
	Outstanding, at March 31, 2015	381,319		$	30.85			11,487		$	34.45	218,625		$	33.09	1,862,067		$	24.78
	Options exercisable, at March 31, 2015															1,753,892		$	24.89
	Options expected to vest, at March 31, 2015															102,314		$	23
	(1) Vested for purposes of recording compensation expense.

Segment_Reporting_Tables

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Operating Results And Total Assets Reportable Segments	The following tables present the results for Webster’s business segments and incorporate the allocation of the provision for loan and lease losses and income tax expense to each of Webster’s business segments for the periods presented:
		Three months ended March 31, 2015
	(In thousands)	Commercial		Community Banking		HSA Bank		Private Banking			Corporate and			Consolidated
		Banking									Reconciling			Total
	Net interest income (loss)	$	61,578	$	84,239	$	16,465	$	2,395		$	(4,913	)	$	159,764
	Provision for loan and lease losses	3,374		6,421		—		(57		)	12			9,750
	Net interest income (loss) after provision for loan and lease losses	58,204		77,818		16,465		2,452			(4,925		)	150,014
	Non-interest income	9,525		25,540		15,151		2,326			5,348			57,890
	Non-interest expense	26,469		81,690		18,958		4,879			2,094			134,090
	Income (loss) before income tax expense	41,260		21,668		12,658		(101		)	(1,671		)	73,814
	Income tax expense (benefit)	13,467		7,073		4,131		(33		)	(546		)	24,092
	Net income (loss)	$	27,793	$	14,595	$	8,527	$	(68	)	$	(1,125	)	$	49,722
		Three months ended March 31, 2014
	(In thousands)	Commercial		Community Banking		HSA Bank		Private Banking			Corporate and			Consolidated
		Banking									Reconciling			Total
	Net interest income	$	56,152	$	87,341	$	9,206	$	2,161		$	441		$	155,301
	Provision (benefit) for loan and lease losses	10,445		645		—		446			(2,536		)	9,000
	Net interest income after provision for loan and lease losses	45,707		86,696		9,206		1,715			2,977			146,301
	Non-interest income	7,951		24,436		6,889		2,621			7,931			49,828
	Non-interest expense	26,019		81,518		10,147		4,556			2,223			124,463
	Income (loss) before income tax expense	27,639		29,614		5,948		(220		)	8,685			71,666
	Income tax expense (benefit)	8,190		8,775		1,754		(66		)	2,584			21,237
	Net income (loss)	$	19,449	$	20,839	$	4,194	$	(154	)	$	6,101		$	50,429
		Total Assets
	(In thousands)	Commercial		Community Banking		HSA Bank		Private Banking			Corporate and			Consolidated
		Banking									Reconciling			Total
	At March 31, 2015	$	6,830,310	$	7,817,188	$	90,818	$	412,229		$	7,956,143		$	23,106,688
	At December 31, 2014	$	6,550,868	$	8,198,115	$	25,148	$	400,425		$	7,358,616		$	22,533,172

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Outstanding Financial Instruments Contract Amounts Represent Credit Risk	The following table summarizes outstanding contract amounts for off-balance sheet instruments that represent credit risk:
	(In thousands)	At March 31,			At December 31,
		2015			2014
	Unused commitments to extend credit	$	4,431,835		$	4,376,733
	Standby letters of credit	144,606			142,964
	Commercial letters of credit	34,782			27,787
	Total financial instruments with off-balance sheet risk	$	4,611,223		$	4,547,484
Reserve For Unfunded Credit Commitments	The following table provides activity details for the Company’s reserve for unfunded credit commitments:
		Three months ended March 31,
	(In thousands)	2015			2014
	Balance, beginning of period	$	5,151		$	4,384
	Provision (benefit)	(2,831		)	327
	Balance, end of period	$	2,320		$	4,711

Acquisition_Acquisitiondate_Fa

Acquisition (Acquisition-date Fair Value of Consideration) (Details) (USD $)	0 Months Ended
In Thousands, unless otherwise specified	Jan. 13, 2015	Jan. 13, 2015
Business Combinations [Abstract]
Effective date of acquisition	13-Jan-15
Cash	$50,485
Contingent consideration (1)		-5,000
Total net consideration transferred	$45,485

Acquisition_Estimated_Fair_Val

Acquisition (Estimated Fair Values of Assets and Liabilities) (Details) (USD $)	0 Months Ended	3 Months Ended
In Thousands, unless otherwise specified	Jan. 13, 2015	Mar. 31, 2015	Jan. 13, 2015
Business Combinations [Abstract]
Cash			$1,446,898
Intangible assets			43,000
Total identifiable assets acquired			1,489,898
Deposits			1,446,899
Contingent liability			6,000
Total liabilities assumed			1,452,899
Net identifiable assets acquired			36,999
Goodwill	8,486	8,486
Net assets acquired			$45,485

Investment_Securities_Summary_

Investment Securities (Summary Of Investment Securities) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Available for sale - Amortized cost	$2,931,211		$2,767,967
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	49,383		44,649
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-12,485		-18,743
Fair Value	2,968,109		2,793,873
Held to Maturity, Amortized Cost - Total debt securities	3,923,189		3,872,955
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	109,213		90,043
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	-9,421		-14,292
Held to Maturity, Fair Value - Total debt securities	4,022,981		3,948,706
Other than temporary impairment	3,597		3,696		9,665	16,633
U.S. Treasury Bills [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	425		525
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	0		0
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	0		0
Fair Value	425		525
Agency collateralized mortgage obligations (CMOs) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	654,911		543,417
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	10,580		8,636
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-791		-1,065
Fair Value	664,700		550,988
Held to Maturity, Amortized Cost - Total debt securities	414,952		442,129
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	8,648		6,584
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	-423		-739
Held to Maturity, Fair Value - Total debt securities	423,177		447,974
Agency mortgage-backed securities (MBS) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	1,012,462		1,030,724
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	12,093		10,462
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-7,548		-12,668
Fair Value	1,017,007		1,028,518
Held to Maturity, Amortized Cost - Total debt securities	2,109,728		2,134,319
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	64,646		57,196
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	-7,001		-11,340
Held to Maturity, Fair Value - Total debt securities	2,167,373		2,180,175
Agency commercial mortgage-backed securities (ACMBS) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	126,439		80,400
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	1,263		0
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	0		-134
Fair Value	127,702		80,266
Held to Maturity, Amortized Cost - Total debt securities	625,320		578,687
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	9,127		1,597
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	-872		-1,143
Held to Maturity, Fair Value - Total debt securities	633,575		579,141
Non-agency Commercial mortgage-backed securities (CMBS) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	544,483		534,631
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	18,173		18,885
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-33		-123
Fair Value	562,623		553,393
Held to Maturity, Amortized Cost - Total debt securities	363,319		338,723
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	13,092		9,428
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	-153		-1,015
Held to Maturity, Fair Value - Total debt securities	376,258		347,136
Collateralized loan obligations (CLOs) [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	441,061	[1]	426,269	[2]
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	1,979	[1]	482	[2]
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-339	[2]	-1,017	[2]
Fair Value	442,701	[1]	425,734	[2]
Other than temporary impairment	3,600				3,700
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	42,025		41,981
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	31		0
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-3,774		-3,736
Fair Value	38,282		38,245
Corporate debt securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	105,905		106,520
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	4,179		3,781
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	0		0
Fair Value	110,084		110,301
Equity securities [Member]
Schedule of Investments [Line Items]
Available for sale - Amortized cost	3,500		3,500
Available-for-sale Securities, Accumulated Gross Unrealized Gains Before Tax	1,085		2,403
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	0		0
Fair Value	4,585		5,903
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost - Total debt securities	404,735		373,211
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	13,615		15,138
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	-972		-55
Held to Maturity, Fair Value - Total debt securities	417,378		388,294
Private Label MBS [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost - Total debt securities	5,135		5,886
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Gains	85		100
Held-to-maturity - Not Recognized in OCI - Gross Unrealized Losses	0		0
Held to Maturity, Fair Value - Total debt securities	$5,220		$5,986
[1]	Amortized cost is net of $3.6 million of other-than-temporary impairments at March 31, 2015.
[2]	Amortized cost is net of $3.7 million of other-than-temporary impairments at December 31, 2014.

Investment_Securities_Summary_1

Investment Securities (Summary Of Debt Securities By Contractual Maturity) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available for Sale, Amortized Cost - Due in one year or less	$25,465
Available for Sale, Amortized Cost - Due after one year through five years	120,864
Available for Sale, Amortized Cost - Due after five through ten years	395,985
Available for Sale, Amortized Cost - Due after ten years	2,385,397
Available for Sale, Amortized Cost - Total debt securities	2,927,711
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available for Sale, Fair Value - Due in one year or less	25,567
Available for Sale, Fair Value - Due after one year through five years	124,974
Available for Sale, Fair Value - Due after five through ten years	397,416
Available for Sale, Fair Value - Due after ten years	2,415,567
Available for Sale, Fair Value - Total debt securities	2,963,524
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Held to Maturity, Amortized Cost - Due in one year or less	805
Held to Maturity, Amortized Cost - Due after one year through five years	54,040
Held to Maturity, Amortized Cost - Due after five through ten years	74,404
Held to Maturity, Amortized Cost - Due after ten years	3,793,940
Held to Maturity, Amortized Cost - Total debt securities	3,923,189	3,872,955
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Held to Maturity, Fair Value - Due in one year or less	808
Held-to-maturity, Fair Value, Due after one year through five years	56,105
Held to Maturity, Fair Value - Due after five through ten years	77,194
Held to Maturity, Fair Value - Due after ten years	3,888,874
Held to Maturity, Fair Value - Total debt securities	$4,022,981	$3,948,706

Investment_Securities_Narrativ

Investment Securities (Narrative) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	$2,968,109,000			$2,793,873,000
Pledged securities as required or permitted by law	2,900,000,000
Percentage Of Investments In Government Obligations	10.00%
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-12,485,000			-18,743,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	-9,421,000			-14,292,000
Recognized other-than-temporary impairment	0		-88,000
Callable at the option of the counterparty [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	908,600,000
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Investments in obligations of individual states, counties or municipalities	0
Agency collateralized mortgage obligations (CMOs) [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	664,700,000			550,988,000
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-791,000			-1,065,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	-423,000			-739,000
Agency MBS [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	1,017,007,000			1,028,518,000
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-7,548,000			-12,668,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	-7,001,000			-11,340,000
Collateralized loan obligations (CLOs) [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	442,701,000	[1]		425,734,000	[2]
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-339,000	[2]		-1,017,000	[2]
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	38,282,000			38,245,000
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-3,774,000			-3,736,000
Agency commercial mortgage-backed securities (ACMBS) [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	127,702,000			80,266,000
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	0			-134,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	-872,000			-1,143,000
Non-agency Commercial mortgage-backed securities (CMBS) [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	562,623,000			553,393,000
Available-for-sale - Accumulated Gross Unrealized Losses Before Tax	-33,000			-123,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	-153,000			-1,015,000
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	-972,000			-55,000
Percentage of bank qualified bonds with credit rating range of AAA to A	99.40%
Percentage of municipal bond Portfolio comprised of General Obligation bonds	89.70%
Percentage of municipal bond portfolio comprised of Revenue bonds	9.80%
Percentage of municipal bond portfolio comprised of other bonds	0.50%
Private Label MBS [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	$0			$0
[1]	Amortized cost is net of $3.6 million of other-than-temporary impairments at March 31, 2015.
[2]	Amortized cost is net of $3.7 million of other-than-temporary impairments at December 31, 2014.

Investment_Securities_Summary_2

Investment Securities (Summary Of Gross Unrealized Losses Not Considered OTTI) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified	holding	holding
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$309,307	$259,477
Available for sale, Unrealized Losses - Less Than Twelve Months	-1,512	-1,562
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	479,437	720,814
Available for sale, Unrealized Losses - Twelve Months or Longer	-10,973	-17,181
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	80	94
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	788,744	980,291
Available for sale, Unrealized Losses - Total	-12,485	-18,743
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	234,441	415,701
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	-2,671	-1,469
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	587,188	702,497
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	-6,750	-12,823
Held-to-maturity, Number of Holdings - Total	91	89
Held-to-maturity, Fair Value - Total	821,629	1,118,198
Held-to-maturity, Unrealized Losses - Total	-9,421	-14,292
Agency CMOs [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	43,228	47,217
Available for sale, Unrealized Losses - Less Than Twelve Months	-264	-240
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	31,579	35,968
Available for sale, Unrealized Losses - Twelve Months or Longer	-527	-825
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	5	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	74,807	83,185
Available for sale, Unrealized Losses - Total	-791	-1,065
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	8,856	52,172
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	-53	-187
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	24,116	24,942
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	-370	-552
Held-to-maturity, Number of Holdings - Total	3	6
Held-to-maturity, Fair Value - Total	32,972	77,114
Held-to-maturity, Unrealized Losses - Total	-423	-739
Agency MBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	187,105	3,691
Available for sale, Unrealized Losses - Less Than Twelve Months	-889	-18
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	404,414	641,355
Available for sale, Unrealized Losses - Twelve Months or Longer	-6,659	-12,650
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	60	64
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	591,519	645,046
Available for sale, Unrealized Losses - Total	-7,548	-12,668
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	151,582	20,791
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	-769	-86
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	529,147	608,568
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	-6,232	-11,254
Held-to-maturity, Number of Holdings - Total	47	44
Held-to-maturity, Fair Value - Total	680,729	629,359
Held-to-maturity, Unrealized Losses - Total	-7,001	-11,340
Agency CMBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		80,266
Available for sale, Unrealized Losses - Less Than Twelve Months		-134
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		80,266
Available for sale, Unrealized Losses - Total		-134
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	22,325	324,394
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	-872	-1,143
Held-to-maturity, Number of Holdings - Total	1	17
Held-to-maturity, Fair Value - Total	22,325	324,394
Held-to-maturity, Unrealized Losses - Total	-872	-1,143
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	46,405	5,341
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	-944	-23
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	3,076	3,074
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	-28	-32
Held-to-maturity, Number of Holdings - Total	37	15
Held-to-maturity, Fair Value - Total	49,481	8,415
Held-to-maturity, Unrealized Losses - Total	-972	-55
Non-agency CMBS [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	48,214	24,932
Available for sale, Unrealized Losses - Less Than Twelve Months	-20	-117
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	9,387	9,396
Available for sale, Unrealized Losses - Twelve Months or Longer	-13	-6
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	6	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	57,601	34,328
Available for sale, Unrealized Losses - Total	-33	-123
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	5,273	13,003
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	-33	-30
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	30,849	65,913
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	-120	-985
Held-to-maturity, Number of Holdings - Total	3	7
Held-to-maturity, Fair Value - Total	36,122	78,916
Held-to-maturity, Unrealized Losses - Total	-153	-1,015
Collateralized loan obligations (CLOs) [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	30,760	99,221
Available for sale, Unrealized Losses - Less Than Twelve Months	-339	-1,017
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	2	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	30,760	99,221
Available for sale, Unrealized Losses - Total	-339	-1,017
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		4,150
Available for sale, Unrealized Losses - Less Than Twelve Months		-36
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	34,057	34,095
Available for sale, Unrealized Losses - Twelve Months or Longer	-3,774	-3,700
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	7	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	34,057	38,245
Available for sale, Unrealized Losses - Total	($3,774)	($3,736)

Investment_Securities_Other_Th

Investment Securities (Other Than Temporary Impairment Credit Losses Recognized In Earnings) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of OTTI, beginning of period	$3,696	$16,633
Reduction for securities sold, called	-99	-7,056
Additions for OTTI not previously recognized	0	88
Balance of OTTI, end of period	$3,597	$9,665

Investment_Securities_Summary_3

Investment Securities (Summary Of Sale Proceeds Of Available For Sale Securities) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales of available-for-sale securities	$27,859	$21,695
Gains	43	4,336
OTTI Charges	0	-88
Net	$43	$4,248

Loans_And_Leases_Recorded_Inve

Loans And Leases (Recorded Investment In Loans And Leases) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Individually evaluated for impairment	$315,871,000	[1]	$332,940,000	[1]
Collectively evaluated for impairment	13,993,175,000	[1]	13,605,482,000	[1]
Total Loans and Leases	14,309,046,000	[1]	13,938,422,000	[1]
Less: Accrued interest	38,820,000	[1]	38,397,000	[1]
Loans and leases	14,270,226,000	[1]	13,900,025,000	[1]
Unamortized premiums	12,100,000		10,600,000
Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Individually evaluated for impairment	140,815,000		142,435,000
Collectively evaluated for impairment	3,464,162,000		3,377,196,000
Total Loans and Leases	3,604,977,000		3,519,631,000
Less: Accrued interest	10,705,000		10,456,000
Loans and leases	3,594,272,000		3,509,175,000
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Individually evaluated for impairment	50,834,000		50,374,000
Collectively evaluated for impairment	2,526,616,000		2,507,060,000
Total Loans and Leases	2,577,450,000		2,557,434,000
Less: Accrued interest	8,013,000		8,033,000
Loans and leases	2,569,437,000		2,549,401,000
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Individually evaluated for impairment	49,619,000		36,454,000
Collectively evaluated for impairment	3,862,095,000		3,723,991,000
Total Loans and Leases	3,911,714,000		3,760,445,000
Less: Accrued interest	11,904,000		11,175,000
Loans and leases	3,899,810,000		3,749,270,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Individually evaluated for impairment	73,972,000	[2]	103,045,000	[2]
Collectively evaluated for impairment	3,597,297,000	[2]	3,460,116,000	[2]
Total Loans and Leases	3,671,269,000	[2]	3,563,161,000	[2]
Less: Accrued interest	8,198,000	[2]	8,733,000	[2]
Loans and leases	3,663,071,000	[2]	3,554,428,000	[2]
Equipment financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Individually evaluated for impairment	631,000		632,000
Collectively evaluated for impairment	543,005,000		537,119,000
Total Loans and Leases	543,636,000		537,751,000
Less: Accrued interest	0		0
Loans and leases	$543,636,000		$537,751,000
[1]	Loans and leases include net deferred fees and unamortized premiums of $12.1 million and $10.6 million at March 31, 2015 and December 31, 2014, respectively.
[2]	Includes certain loans individually evaluated for impairment under the Company's loan policy that were deemed not to be impaired at both March 31, 2015 and December 31, 2014.

Loans_And_Leases_Narrative_Det

Loans And Leases (Narrative) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
	grade
Loans and Leases Receivable Disclosure [Abstract]
Eligible loan collateral	$6,200,000,000
Interest on non-accrual loans that would have been recorded as additional interest income	2,800,000	3,500,000
Number of grades	10
Write-down of TDR's	($3,900,000)	($6,200,000)

Loans_And_Leases_Summary_Of_Lo

Loans And Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	$29,268		$28,627
60-89 Days Past Due and Accruing	14,330		12,220
90 Days Past Due and Accruing	2,210		2,089
Non-accrual	152,348		130,147
Total Past Due and Non-accrual	198,156		173,083
Current	14,110,890		13,765,339
Total Loans and Leases	14,309,046	[1]	13,938,422	[1]
Total recorded investment of TDRs	293,963		320,170
Residential TDR CH 7 Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total recorded investment of TDRs	17,600
Residential, Prime, Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	9,631		11,521	[2],[3]
60-89 Days Past Due and Accruing	4,514		5,931	[2],[3]
90 Days Past Due and Accruing	1,895		2,039	[2],[3]
Non-accrual	61,371		64,117	[2],[3]
Total Past Due and Non-accrual	77,411		83,608	[2],[3]
Current	3,527,566		3,436,023	[2],[3]
Total Loans and Leases	3,604,977		3,519,631	[2],[3]
Home equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	12,001		11,516	[2]
60-89 Days Past Due and Accruing	7,658		5,161	[2]
90 Days Past Due and Accruing	0		0	[2]
Non-accrual	37,617		40,025	[2]
Total Past Due and Non-accrual	57,276		56,702	[2]
Current	2,408,439		2,424,584	[2]
Total Loans and Leases	2,465,715		2,481,286	[2]
Other consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	587		720
60-89 Days Past Due and Accruing	343		425
90 Days Past Due and Accruing	0		0
Non-accrual	267		281
Total Past Due and Non-accrual	1,197		1,426
Current	110,538		74,722
Total Loans and Leases	111,735		76,148
Commercial non-mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	3,121		1,971
60-89 Days Past Due and Accruing	950		156
90 Days Past Due and Accruing	273		50
Non-accrual	26,974		6,449
Total Past Due and Non-accrual	31,318		8,626
Current	3,161,881		3,088,656
Total Loans and Leases	3,193,199		3,097,282
Asset-based [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	0		0
60-89 Days Past Due and Accruing	0		0
90 Days Past Due and Accruing	0		0
Non-accrual	0		0
Total Past Due and Non-accrual	0		0
Current	718,515		663,163
Total Loans and Leases	718,515		663,163
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	3,199		2,348
60-89 Days Past Due and Accruing	805		397
90 Days Past Due and Accruing	42		0
Non-accrual	22,183		15,038
Total Past Due and Non-accrual	26,229		17,783
Current	3,398,306		3,310,765
Total Loans and Leases	3,424,535		3,328,548
Commercial construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	0		0
60-89 Days Past Due and Accruing	0		0
90 Days Past Due and Accruing	0		0
Non-accrual	3,651		3,659
Total Past Due and Non-accrual	3,651		3,659
Current	243,083		230,954
Total Loans and Leases	246,734		234,613
Finance Leases Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due and Accruing	729		551
60-89 Days Past Due and Accruing	60		150
90 Days Past Due and Accruing	0		0
Non-accrual	285		578
Total Past Due and Non-accrual	1,074		1,279
Current	542,562		536,472
Total Loans and Leases	$543,636		$537,751
[1]	Loans and leases include net deferred fees and unamortized premiums of $12.1 million and $10.6 million at March 31, 2015 and December 31, 2014, respectively.
[2]	A total of $17.6 million aggregate principal amount of residential and consumer loans was reclassified from non-accrual to accrual status as a result of updated regulatory guidance issued in the first quarter of 2014.
[3]	For the year ended 2014, US Government secured loans of $2.0 million were reclassified from non-accrual to over 90 days and accruing due to a policy change effective in the first quarter of 2015. See Note 1 - Summary of Significant Accounting Policies.

Loans_And_Leases_Allowance_For

Loans And Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$159,264	$152,573
Provision (benefit) charged to expense	9,750	9,000
Losses charged off	-9,674	-11,597
Recoveries	2,630	3,624
Balance, end of period	161,970	153,600
Individually evaluated for impairment	27,240	20,104
Collectively evaluated for impairment	134,730	133,496
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	25,452	23,027
Provision (benefit) charged to expense	4,144	-542
Losses charged off	-1,955	-1,158
Recoveries	108	260
Balance, end of period	27,749	21,587
Individually evaluated for impairment	14,350	10,993
Collectively evaluated for impairment	13,399	10,594
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	43,518	41,951
Provision (benefit) charged to expense	2,232	-903
Losses charged off	-4,296	-4,886
Recoveries	1,162	1,113
Balance, end of period	42,616	37,275
Individually evaluated for impairment	4,255	4,109
Collectively evaluated for impairment	38,361	33,166
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	52,114	51,001
Provision (benefit) charged to expense	2,754	7,975
Losses charged off	-255	-3,148
Recoveries	1,015	973
Balance, end of period	55,628	56,801
Individually evaluated for impairment	4,939	989
Collectively evaluated for impairment	50,689	55,812
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	32,102	32,408
Provision (benefit) charged to expense	1,398	3,287
Losses charged off	-3,153	-2,405
Recoveries	202	479
Balance, end of period	30,549	33,769
Individually evaluated for impairment	3,668	4,013
Collectively evaluated for impairment	26,881	29,756
Equipment financing [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	6,078	4,186
Provision (benefit) charged to expense	-778	-817
Losses charged off	-15	0
Recoveries	143	799
Balance, end of period	5,428	4,168
Individually evaluated for impairment	28	0
Collectively evaluated for impairment	$5,400	$4,168

Loans_And_Leases_Impaired_Loan

Loans And Leases (Impaired Loans And Leases By Class) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$347,647	$366,129
Total Recorded Investment	315,177	332,232
Recorded Investment No Allowance	114,724	113,447
Recorded Investment With Allowance	200,453	218,785
Related Valuation Allowance	27,240	25,301
Residential [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	154,795	157,152
Total Recorded Investment	140,815	142,435
Recorded Investment No Allowance	23,494	24,388
Recorded Investment With Allowance	117,321	118,047
Related Valuation Allowance	14,350	12,094
Residential, Prime, Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	154,795	157,152
Total Recorded Investment	140,815	142,435
Recorded Investment No Allowance	23,494	24,388
Recorded Investment With Allowance	117,321	118,047
Related Valuation Allowance	14,350	12,094
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	57,403	60,424
Total Recorded Investment	50,834	50,374
Recorded Investment No Allowance	26,827	26,464
Recorded Investment With Allowance	24,007	23,910
Related Valuation Allowance	4,255	4,237
Home equity [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	57,403	60,424
Total Recorded Investment	50,834	50,374
Recorded Investment No Allowance	26,827	26,464
Recorded Investment With Allowance	24,007	23,910
Related Valuation Allowance	4,255	4,237
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	54,277	41,019
Total Recorded Investment	49,619	36,454
Recorded Investment No Allowance	23,986	16,064
Recorded Investment With Allowance	25,633	20,390
Related Valuation Allowance	4,939	2,710
Commercial non-mortgage [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	54,277	41,019
Total Recorded Investment	49,619	36,454
Recorded Investment No Allowance	23,986	16,064
Recorded Investment With Allowance	25,633	20,390
Related Valuation Allowance	4,939	2,710
Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	80,543	106,905
Total Recorded Investment	73,278	102,337
Recorded Investment No Allowance	40,417	46,531
Recorded Investment With Allowance	32,861	55,806
Related Valuation Allowance	3,668	6,232
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	73,371	99,687
Total Recorded Investment	67,114	96,160
Recorded Investment No Allowance	34,466	40,575
Recorded Investment With Allowance	32,648	55,585
Related Valuation Allowance	3,658	6,222
Commercial construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	7,172	7,218
Total Recorded Investment	6,164	6,177
Recorded Investment No Allowance	5,951	5,956
Recorded Investment With Allowance	213	221
Related Valuation Allowance	10	10
Equipment financing [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	629	629
Total Recorded Investment	631	632
Recorded Investment No Allowance	0	0
Recorded Investment With Allowance	631	632
Related Valuation Allowance	28	28
Finance Leases Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	629	629
Total Recorded Investment	631	632
Recorded Investment No Allowance	0	0
Recorded Investment With Allowance	631	632
Related Valuation Allowance	$28	$28

Loans_And_Leases_Interest_Inco

Loans And Leases (Interest Income From Impaired Loans And Leases, By Class) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$323,706	$347,536
Accrued Interest Income	2,421	3,076
Cash Basis Interest Income	538	648
Residential [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	141,625	142,768
Accrued Interest Income	1,059	1,192
Cash Basis Interest Income	256	324
Residential, Prime, Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	141,625	142,768
Accrued Interest Income	1,059	1,192
Cash Basis Interest Income	256	324
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	50,604	52,269
Accrued Interest Income	361	370
Cash Basis Interest Income	282	324
Home equity [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	50,604	52,269
Accrued Interest Income	361	370
Cash Basis Interest Income	282	324
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	43,037	50,179
Accrued Interest Income	427	628
Cash Basis Interest Income	0	0
Commercial non-mortgage [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	43,037	50,179
Accrued Interest Income	427	628
Cash Basis Interest Income	0	0
Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	87,808	102,123
Accrued Interest Income	563	883
Cash Basis Interest Income	0	0
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	81,637	91,730
Accrued Interest Income	530	801
Cash Basis Interest Income	0	0
Commercial construction [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	6,171	10,393
Accrued Interest Income	33	82
Cash Basis Interest Income	0	0
Equipment financing [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	632	197
Accrued Interest Income	11	3
Cash Basis Interest Income	0	0
Finance Leases Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	632	197
Accrued Interest Income	11	3
Cash Basis Interest Income	$0	$0

Loans_And_Leases_Commercial_Co

Loans And Leases (Commercial, Commercial Real Estate Loans And Equipment Financing Loans Segregated By Risk Rating Exposure) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Impaired [Line Items]
Recorded investment	$14,309,046	[1]	$13,938,422	[1]
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	3,911,714		3,760,445
Commercial Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	3,677,136		3,555,559
Commercial Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	100,320		89,064
Commercial Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	134,094		115,653
Commercial Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	164		169
Commercial Portfolio Segment [Member] | (10) Loss [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	0		0
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	3,671,269	[2]	3,563,161	[2]
Commercial Real Estate [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	3,546,467		3,416,214
Commercial Real Estate [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	29,187		33,580
Commercial Real Estate [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	95,157		112,874
Commercial Real Estate [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	458		493
Commercial Real Estate [Member] | (10) Loss [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	0		0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	543,636		537,751
Finance Leases Portfolio Segment [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	524,907		516,115
Finance Leases Portfolio Segment [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	4,039		4,364
Finance Leases Portfolio Segment [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	14,690		17,272
Finance Leases Portfolio Segment [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	0		0
Finance Leases Portfolio Segment [Member] | (10) Loss [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	$0		$0
[1]	Loans and leases include net deferred fees and unamortized premiums of $12.1 million and $10.6 million at March 31, 2015 and December 31, 2014, respectively.
[2]	Includes certain loans individually evaluated for impairment under the Company's loan policy that were deemed not to be impaired at both March 31, 2015 and December 31, 2014.

Loans_And_Leases_Summary_Of_Th

Loans And Leases (Summary Of The Recorded Investment Of Company's TDRs) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	$293,963		$320,170
TDR Loans Performing under modified terms For More Than One Year percentage	66.10%		67.60%
Allowance For Loan And Lease Losses Related To TDR's	22,539		23,785
Additional funds committed to borrowers in TDR status	555		552
Accruing TDR [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	201,175	[1]	243,231	[1]
Non Accrual TDR [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	92,788	[1]	76,939	[1]
Residential TDR CH 7 Accruing [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	$17,600
[1]	A total of $17.6 million residential and consumer loans was reclassified from non-accrual to accrual status as a result of updated regulatory guidance issued in the first quarter of 2014.

Loans_and_Leases_Information_o

Loans and Leases (Information on How Loans and Leases were Modified as a TDR) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
	Contract		Contract
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	$293,963				$320,170
Financing Receivable, Modifications, Number of Contracts	58		76
Financing Receivable, Modifications, Post-Modification Recorded Investment	5,989	[1]	8,264	[1]
Residential TDR CH 7 Accruing [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	17,600
Extended Maturity [Member] | Residential, Prime, Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	9		6
Financing Receivable, Modifications, Post-Modification Recorded Investment	1,345	[1]	706	[1]
Extended Maturity [Member] | Home equity [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	4		9
Financing Receivable, Modifications, Post-Modification Recorded Investment	499	[1]	470	[1]
Extended Maturity [Member] | Commercial non-mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	1		2
Financing Receivable, Modifications, Post-Modification Recorded Investment	33	[1]	54	[1]
Adjusted Interest Rate [Member] | Residential, Prime, Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	0		1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	[1]	227	[1]
Adjusted Interest Rate [Member] | Home equity [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	0		1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	[1]	51	[1]
Adjusted Interest Rate [Member] | Commercial non-mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	[1]	0	[1]
Rate and Maturity [Member] | Residential, Prime, Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	10		8
Financing Receivable, Modifications, Post-Modification Recorded Investment	1,668	[1]	2,589	[1]
Rate and Maturity [Member] | Home equity [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	8		4
Financing Receivable, Modifications, Post-Modification Recorded Investment	444	[1]	255	[1]
Rate and Maturity [Member] | Commercial non-mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	2		6
Financing Receivable, Modifications, Post-Modification Recorded Investment	132	[1]	241	[1]
Other [Member] | Residential, Prime, Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	3		11
Financing Receivable, Modifications, Post-Modification Recorded Investment	536	[1]	2,077	[1]
Other [Member] | Home equity [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	21		27
Financing Receivable, Modifications, Post-Modification Recorded Investment	1,332	[1]	1,444	[1]
Other [Member] | Commercial non-mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts	0		1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$0	[1]	$150	[1]
[1]	Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant.

Loans_and_Leases_Information_o1

Loans and Leases (Information on Loans and Leases Modified as TDR within the Previous 12 Months (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	loan	loan
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases	8	10
Recorded Investment	$18,140	$911
Residential, Prime, Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases	3	6
Recorded Investment	642	645
Home equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases	2	3
Recorded Investment	251	190
Commercial non-mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases	2	1
Recorded Investment	6,317	76
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases	1	0
Recorded Investment	$10,930	$0

Loans_and_Leases_Investments_i

Loans and Leases (Investments in TDRs, Segregated by Risk Rating Exposure) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	$293,963	$320,170
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	102,314	127,361
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (1) - (6) Pass [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	32,714	40,943
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (7) Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	8,242	8,304
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (8) Substandard [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	61,016	77,771
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (9) Doubtful [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	342	343
Commerial, Commercial Real Estate, Equipment Financing TDR's [Member] | (10) Loss [Member]
Financing Receivable, Impaired [Line Items]
Total recorded investment of TDRs	$0	$0

Transfers_of_Financial_Assets_2

Transfers of Financial Assets and Mortgage Servicing Assets (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Number of days required to repurchase mortgage loans	90 days
Residential Mortgage [Member]
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]
Retained servicing rights	$2,400,000,000		$2,400,000,000
Mortgage servicing assets	19,243,000		19,379,000
Bank servicing fees	$400,000	$400,000

Transfers_of_Financial_Assets_3

Transfers of Financial Assets and Mortgage Servicing Assets (Reserve for loan repurchases) (Details) (Loan Purchase Commitments [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Loan Purchase Commitments [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of period	$1,059	$2,254
Provision (benefit)	23	-310
Loss on repurchased loans and settlements	0	-43
Balance, end of period	$1,082	$1,901

Transfers_of_Financial_Assets_4

Transfers of Financial Assets and Mortgage Servicing Assets (Loans sold) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gain on sale included as mortgage banking activities	$1,561	$775
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans on Real Estate, Cost of Mortgages Sold	69,265	48,552
Proceeds from the sale of loans held for sale	76,895	65,643
Net gain on sale included as mortgage banking activities	$1,561	$775

Transfers_of_Financial_Assets_5

Transfers of Financial Assets and Mortgage Servicing Assets (Schedule of Servicing Assets at Fair Value) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Transfers and Servicing [Abstract]
Servicing Asset at Amortized Cost, Fair Value	$27,901	$29,154	$28,690	$29,150
Servicing Asset at Fair Value, Additions	1,463	961
Servicing Asset at Fair Value, Disposals	-736	-473
Servicing Asset at Fair Value, Changes in Fair Value Resulting from Changes in Valuation Inputs or Changes in Assumptions	($1,516)	($484)

Recovered_Sheet1

Goodwill And Other Intangible Assets (Goodwill And Other Intangible Assets, Net Of Accumulated Amortization) (Detail) (USD $)	0 Months Ended	3 Months Ended
In Thousands, unless otherwise specified	Jan. 13, 2015	Mar. 31, 2015
Goodwill [Line Items]
31-Dec-14		$529,887
Goodwill acquired during the period	8,486	8,486
31-Mar-15		538,373
Community Banking [Member]
Goodwill [Line Items]
31-Dec-14		516,560
Goodwill acquired during the period		0
31-Mar-15		516,560
HSA Bank [Member]
Goodwill [Line Items]
31-Dec-14		13,327
Goodwill acquired during the period		8,486
31-Mar-15		$21,813

Recovered_Sheet2

Goodwill And Other Intangible Assets (Gross Carrying Value And Accumulated Amortization Of Other Intangible Assets) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$92,420	$49,420
Accumulated Amortization	-48,042	-46,754
Net Carrying Amount	44,378	2,666
HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	43,000	0
Accumulated Amortization	-907	0
Net Carrying Amount	42,093	0
Core Deposits [Member] | Community Banking [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	49,420	49,420
Accumulated Amortization	-47,135	-46,754
Net Carrying Amount	2,285	2,666
Core Deposits [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22,000	0
Accumulated Amortization	-509	0
Net Carrying Amount	21,491	0
Useful life	9 years
Customer-Related Intangible Assets [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,000	0
Accumulated Amortization	-398	0
Net Carrying Amount	$20,602	$0
Customer Relationships [Member] | HSA Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	13 years

Goodwill_And_Other_Intangible_2

Goodwill And Other Intangible Assets (Schedule Of Expected Amortization Expense, Next Four Years) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets amortization	$1,288	$1,168
Remainder of 2015	5,052
2016	5,652
2017	4,062
2018	3,847
2019	3,847
Thereafter	$21,918

Deposits_Summary_Of_Deposits_D

Deposits (Summary Of Deposits) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
Demand	$3,450,316	$3,598,872
Checking	2,267,350	2,155,047
Health savings accounts	3,529,301	1,824,799
Money market	2,114,300	1,908,522
Savings	3,978,655	3,892,778
Time deposits	2,205,728	2,271,587
Total interest-bearing	14,095,334	12,052,733
Total deposits	17,545,650	15,651,605
Deposits obtained through brokers included in above balances	765,500	651,725
Demand deposit overdrafts reclassified as loan balances	$1,530	$1,655

Deposits_Scheduled_Maturities_

Deposits (Scheduled Maturities Of Time Deposits) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
Remainder of 2015	$964,901
2016	474,162
2017	153,773
2018	176,488
2019	375,843
Thereafter	60,561
Time Deposits	$2,205,728	$2,271,587

Securities_Sold_Under_Agreemen2

Securities Sold Under Agreements To Repurchase And Other Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase:	$867,877,000	$959,756,000
Federal funds purchased	216,000,000	291,000,000
Securities sold under agreements to repurchase and other borrowings	1,083,877,000	1,250,756,000
Gross repurchase agreement liability	900,000,000
Original Maturity Of One Year Or Less [Member]
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase:	317,877,000	409,756,000
Original maturity of greater than one year, non-callable [Member]
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase:	$550,000,000	$550,000,000

Federal_Home_Loan_Bank_Advance2

Federal Home Loan Bank Advances (Summary Of Advances Payable To The Federal Home Loan Bank) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Total Outstanding
Within 1 year	$995,934	$2,275,000
After 1 but within 2 years	100,000	145,934
After 2 but within 3 years	50,500	500
After 3 but within 4 years	150,000	200,000
After 4 but within 5 years	128,026	78,026
After 5 years	159,864	159,934
Federal Home Loan Bank advances	1,584,324	2,859,394
Unamortized premiums	33	37
Federal Home Loan Bank advances	$1,584,357	$2,859,431
Weighted- Average Contractual Coupon Rate
Within 1 year	0.33%	0.23%
After 1 but within 2 years	1.48%	1.80%
After 2 but within 3 years	1.10%	5.66%
After 3 but within 4 years	1.46%	1.36%
After 4 but within 5 years	1.82%	1.95%
After 5 years	1.29%	1.27%
Weighted- Average Contractual Coupon Rate	0.75%	0.50%

Federal_Home_Loan_Bank_Advance3

Federal Home Loan Bank Advances (Narrative) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Collateral pledged	$5,200,000,000	$5,200,000,000
Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Unused funds	1,900,000,000	700,000,000
Line of Credit [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Unused funds	$5,000,000	$5,000,000

LongTerm_Debt_Schedule_Of_Long

Long-Term Debt (Schedule Of Long-Term Debt) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Feb. 11, 2014
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Junior Subordinated Notes	$77,320	[1]	$77,320	[1]
Total notes and subordinated debt	227,320		227,320
Unamortized discount, net	-1,053		-1,083
Long-term debt	226,267		226,237
Variable interest rate	3.22%		3.19%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Interest rate spread of LIBOR plus	2.95%		2.95%
4.375% Maturing 2024 [Member]
Debt Instrument [Line Items]
Senior Notes	$150,000		$150,000
Senior fixed-rate notes [Member] | 4.375% Maturing 2024 [Member]
Debt Instrument [Line Items]
Stated interest rate					4.38%
[1]	The interest rate on Webster Statutory Trust I floating-rate notes, which varies quarterly based on 3-month LIBOR plus 2.950%, was 3.221% at March 31, 2015 and 3.193% at

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss (Schedule of Other Comprehensive Income (Loss)) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	($56,261)	($48,549)
Other comprehensive income (loss) before reclassifications	4,434	6,165
Amounts reclassified from accumulated other comprehensive (loss) income	1,737	-1,307
Net current-period other comprehensive income (loss), net of tax	6,171	4,858
Ending balance	-50,090	-43,691
Available For Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	16,421	-2,617
Other comprehensive income (loss) before reclassifications	6,994	10,849
Amounts reclassified from accumulated other comprehensive (loss) income	-27	-2,727
Net current-period other comprehensive income (loss), net of tax	6,967	8,122
Ending balance	23,388	5,505
Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	-25,530	-18,206
Other comprehensive income (loss) before reclassifications	-3,096	-5,151
Amounts reclassified from accumulated other comprehensive (loss) income	1,326	1,425
Net current-period other comprehensive income (loss), net of tax	-1,770	-3,726
Ending balance	-27,300	-21,932
Defined Benefit Pension and Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	-47,152	-27,726
Other comprehensive income (loss) before reclassifications	536	467
Amounts reclassified from accumulated other comprehensive (loss) income	438	-5
Net current-period other comprehensive income (loss), net of tax	974	462
Ending balance	($46,178)	($27,264)

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Loss (Schedule of Accumulated Other Comprehensive Loss) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Impairment loss recognized in earnings	$0	($88)
Income tax expense	-24,092	-21,237
Interest expense	-23,148	-22,478
Compensation and benefits	-70,864	-66,371
Net income	49,722	50,429
Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Impairment loss recognized in earnings	0	-88
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of investment securities	43	4,336
Income tax expense	-16	-1,521
Net income	-27	-2,727
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	764	796
Interest expense	2,090	2,221
Net income	-1,326	-1,425
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits	-672	26
Net income	-438	5
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits	-18	-18
Defined benefit pension and postretirement benefit plans [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$252	($3)

Regulatory_Matters_Information

Regulatory Matters (Information On The Capital Ratios) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1, Actual Amount	$1,707,480,000	[1]
Common equity tier 1, Actual Ratio	10.90%	[1]
Common equity tier 1, Capital Requirements, Minimum Amount	702,842,000	[1]
Common equity tier 1, Capital Requirements, Minimum Ratio	4.50%	[1]
Common equity tier 1, Capital Requirements, Well Capitalized Amount	1,015,217,000	[1]
Common equity tier 1, Capital Requirements, Well Capitalized Ratio	6.50%	[1]
Total risk-based capital, Actual Amount	2,098,907,000	[1]		2,096,772,000	[1]
Total risk-based capital, Actual Ratio	13.40%	[1]		14.10%	[1]
Total risk-based capital, Capital Requirements, Minimum Amount	1,249,497,000	[1]		1,192,651,000	[1]
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%	[1]		8.00%	[1]
Total risk-based capital, Capital Requirements, Well Capitalized Amount	1,561,872,000	[1]		1,490,706,000	[1]
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%	[1]		10.00%	[1]
Tier 1 capital, Actual Amount	1,876,139,000	[1]		1,931,276,000	[1]
Tier 1 capital, Actual Ratio	12.00%	[1]		13.00%	[1]
Tier 1 capital, Capital Requirements, Minimum Amount	937,123,000	[1]		596,326,000	[1]
Tier 1 capital, Capital Requirements, Minimum Ratio	6.00%	[1]		4.00%	[1]
Tier 1 capital, Capital Requirements, Well Capitalized Amount	1,249,497,000	[1]		894,423,000	[1]
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	8.00%	[1]		6.00%	[1]
Tier 1 leverage capital ratio, Actual Amount	1,876,139,000	[1]		1,931,276,000	[1]
Tier 1 leverage capital ratio, Actual Ratio	8.50%	[1]		9.00%	[1]
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	883,529,000	[1]		859,241,000	[1]
Tier 1 leverage capital ratio, Capital Requirements, Minimum Ratio	4.00%	[1]		4.00%	[1]
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Amount	1,104,412,000	[1]		1,074,051,000	[1]
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	5.00%	[1]		5.00%	[1]
Cash Dividends Paid to Parent Company	20,000,000		0
Webster Bank N.A. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1, Actual Amount	1,784,448,000	[1]
Common equity tier 1, Actual Ratio	11.50%	[1]
Common equity tier 1, Capital Requirements, Minimum Amount	699,865,000	[1]
Common equity tier 1, Capital Requirements, Minimum Ratio	4.50%	[1]
Common equity tier 1, Capital Requirements, Well Capitalized Amount	1,010,916,000	[1]
Common equity tier 1, Capital Requirements, Well Capitalized Ratio	6.50%	[1]
Total risk-based capital, Actual Amount	1,948,738,000	[1]		1,939,229,000	[1]
Total risk-based capital, Actual Ratio	12.50%	[1]		13.00%	[1]
Total risk-based capital, Capital Requirements, Minimum Amount	1,244,204,000	[1]		1,190,242,000	[1]
Total risk-based capital, Capital Requirements, Minimum Ratio	8.00%	[1]		8.00%	[1]
Total risk-based capital, Capital Requirements, Well Capitalized Amount	1,555,255,000	[1]		1,487,803,000	[1]
Total risk-based capital, Capital Requirements, Well Capitalized Ratio	10.00%	[1]		10.00%	[1]
Tier 1 capital, Actual Amount	1,784,448,000	[1]		1,774,814,000	[1]
Tier 1 capital, Actual Ratio	11.50%	[1]		11.90%	[1]
Tier 1 capital, Capital Requirements, Minimum Amount	933,153,000	[1]		595,121,000	[1]
Tier 1 capital, Capital Requirements, Minimum Ratio	6.00%	[1]		4.00%	[1]
Tier 1 capital, Capital Requirements, Well Capitalized Amount	1,244,204,000	[1]		892,682,000	[1]
Tier 1 capital, Capital Requirements, Well Capitalized Ratio	8.00%	[1]		6.00%	[1]
Tier 1 leverage capital ratio, Actual Amount	1,784,448,000	[1]		1,774,814,000	[1]
Tier 1 leverage capital ratio, Actual Ratio	8.10%	[1]		8.30%	[1]
Tier 1 leverage capital ratio, Capital Requirements, Minimum Amount	882,516,000	[1]		858,197,000	[1]
Tier 1 leverage capital ratio, Capital Requirements, Minimum Ratio	4.00%	[1]		4.00%	[1]
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Amount	$1,103,145,000	[1]		$1,072,746,000	[1]
Tier 1 leverage capital ratio, Capital Requirements, Well Capitalized Ratio	5.00%	[1]		5.00%	[1]
[1]	Calculated under the Basel III capital standard at March 31, 2015 and under the Basel I capital standard at December 31, 2014.

Earnings_Per_Common_Share_Earn

Earnings Per Common Share (Earnings Per Share Basic And Diluted) (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income available to common shareholders	$47,083	$47,790
Less: Earnings allocated to participating securities	-146	-173
Net income allocated to common shareholders	$46,937	$47,617
Weighted average common shares outstanding - basic (in shares)	90,251	89,880
Stock options and restricted stock (in shares)	540	503
Weighted-average common shares outstanding - diluted (in shares)	90,841	90,658
Earnings per common share, Basic (in dollars per share)	$0.52	$0.53
Earnings per common share, Diluted (in dollars per share)	$0.52	$0.53
Warrants - other [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Warrants (in shares)	50	275

Earnings_Per_Common_Share_Narr

Earnings Per Common Share (Narrative) (Detail)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Series A Preferred Stock [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,100	1,100
Stock Options [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	344	839
Restricted Stock [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	143	172

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Risk Management Objective of Using Derivatives (Narrative) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Derivative [Line Items]
Net increase to other non-interest income	$2,519	$1,838
Notional amount	8,223,648		10,327,833
Future [Member]
Derivative [Line Items]
Notional amount	800,000
Designated as Hedging Instrument [Member] | Interest Expense [Member] | Fair Value Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net increase to other non-interest income	$0	($799)

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Notional Amounts of Derivative Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Notional amount	$8,223,648	$10,327,833
Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	8,126,315	10,237,325
Credit Risk Contract [Member]
Derivative [Line Items]
Notional amount	97,273	90,448
Other Contract [Member]
Derivative [Line Items]
Notional amount	$60	$60

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Schedule fair value of derivative instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Other Assets	$69,270	$48,391
Other Liabilities	51,808	32,180
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Other Assets	3,460	4,481
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivative [Line Items]
Other Liabilities	6,276	4,598
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Other Assets	69,034	48,209
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivative [Line Items]
Other Liabilities	51,496	31,915
Credit Risk Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Other Assets	236	182
Credit Risk Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivative [Line Items]
Other Liabilities	305	258
Other Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Other Assets	0	0
Other Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivative [Line Items]
Other Liabilities	$7	$7

Derivative_Financial_Instrumen5

Derivative Financial Instruments - Schedule of the increase/(reduction) to Statements of Income and AOCI related to cash flow hedges (Detail) (Designated as Hedging Instrument [Member], Cash Flow Hedging [Member], Interest Rate Swap [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Amount of net loss reclassified from AOCL to interest expense	($2,090)	($2,221)
Amount of net loss recognized as OCI	($4,887)	($8,029)

Derivative_Financial_Instrumen6

Derivative Financial Instruments - Schedule of the changes in the fair value of non-hedge accounting derivatives (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative [Line Items]
Derivatives not designated as hedging instruments	$2,519	$1,838
Not Designated as Hedging Instrument [Member] | Operating Expense [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivatives not designated as hedging instruments	2,637	1,783
Not Designated as Hedging Instrument [Member] | Operating Expense [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivatives not designated as hedging instruments	-76	90
Not Designated as Hedging Instrument [Member] | Operating Expense [Member] | Other Contract [Member]
Derivative [Line Items]
Derivatives not designated as hedging instruments	($42)	($35)

Derivative_Financial_Instrumen7

Derivative Financial Instruments - Schedule of financial assets and liabilities for non-customer derivative positions (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Offsetting Assets and Liabilities [Line Items]
Notional Amount	$8,223,648		$10,327,833
Cash Collateral Posted (Received)	70,731
Dealer A [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	414,515		427,430
Total MTM(Loss) Gain	-7,845		-5,454
Cash Collateral Posted (Received)	7,600		5,300
Net Exposure	0	[1]	0	[1]
Dealer B [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	299,587		319,663
Total MTM(Loss) Gain	-5,154		-3,948
Cash Collateral Posted (Received)	4,860		3,610
Net Exposure	0	[1]	0	[1]
Dealer C [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	6,068		11,538
Total MTM(Loss) Gain	-590		-834
Cash Collateral Posted (Received)	0		0
Net Exposure	0	[1]	0	[1]
Dealer D [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	355,333		303,663
Total MTM(Loss) Gain	-2,014		267
Cash Collateral Posted (Received)	1,700		-400
Net Exposure	0	[1]	0	[1]
Dealer E [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	446,818		424,401
Total MTM(Loss) Gain	-582		1,409
Cash Collateral Posted (Received)	330		-1,420
Net Exposure	0	[1]	0	[1]
Dealer F [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	4,315,805	[2]	6,631,936	[2]
Total MTM(Loss) Gain	-37,763	[2]	-20,932	[2]
Cash Collateral Posted (Received)	56,241	[2]	39,037	[2]
Net Exposure	18,478	[1],[2]	18,105	[2]
Dealers Total [Member]
Offsetting Assets and Liabilities [Line Items]
Notional Amount	5,838,126		8,118,631
MTM Gain			4,481
MTM Loss			-4,597
Total MTM(Loss) Gain	-53,948		-29,492
Cash Collateral Posted (Received)	70,731		46,127
Designated as Hedging Instrument [Member] | Dealer A [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	0		0
MTM Loss	-1,930		-739
Designated as Hedging Instrument [Member] | Dealer B [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	1,153		1,494
MTM Loss	0		0
Designated as Hedging Instrument [Member] | Dealer C [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	0		0
MTM Loss	0		0
Designated as Hedging Instrument [Member] | Dealer D [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	577		747
MTM Loss	0		0
Designated as Hedging Instrument [Member] | Dealer E [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	1,730		2,240
MTM Loss	0		0
Designated as Hedging Instrument [Member] | Dealer F [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	0	[2]	0	[2]
MTM Loss	-4,346	[2]	-3,858	[2]
Designated as Hedging Instrument [Member] | Dealers Total [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	3,460
MTM Loss	-6,276
Non-Hedge Accounting [Member] | Dealer A [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	450		1,861
MTM Loss	-6,365		-6,576
Non-Hedge Accounting [Member] | Dealer B [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	229		978
MTM Loss	-6,536		-6,420
Non-Hedge Accounting [Member] | Dealer C [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	0		0
MTM Loss	-590		-834
Non-Hedge Accounting [Member] | Dealer D [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	290		1,147
MTM Loss	-2,881		-1,627
Non-Hedge Accounting [Member] | Dealer E [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	257		867
MTM Loss	-2,569		-1,698
Non-Hedge Accounting [Member] | Dealer F [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	95	[2]	555	[2]
MTM Loss	-33,512	[2]	-17,629	[2]
Non-Hedge Accounting [Member] | Dealers Total [Member]
Offsetting Assets and Liabilities [Line Items]
MTM Gain	1,321		5,408
MTM Loss	($52,453)		($34,784)
[1]	Net positive exposure represents over-collateralized loss positions which can be the result of DCO initial margin requirements posted in compliance with the Dodd-Frank Wall Street Reform and Consumer Protection Act.
[2]	Dealer F represents Chicago Mercantile Exchange, our designated DCO.

Derivative_Financial_Instrumen8

Derivative Financial Instruments - AOCI Related to Cash Flow Hedges (Narrative) (Details) (Cash Flow Hedging [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Derivative [Line Items]
Estimated amount to be reclassified form AOCI	$8.40
Unamortized loss on termination of cash flow hedges	31.6
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Estimated amount to be reclassified form AOCI	$3.20

Derivative_Financial_Instrumen9

Derivative Financial Instruments - Counterparty Credit Risk (Narrative) (Details) (USD $)	Mar. 31, 2015
Derivative [Line Items]
Cash Collateral Posted	($70,731,000)
Maximum exposure	69,000,000
Market Approach Valuation Technique [Member]
Derivative [Line Items]
Maximum exposure	$18,200,000

Recovered_Sheet3

Derivative Financial Instruments - Mortgage Banking Derivatives (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Outstanding rate locks	$104,400,000
Outstanding commitments to sell residential mortgage loans	116,000,000
Mandatory forward commitments	116,000,000
Other Assets [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Fair value of interest rate locked loan and forward sale commitments	$500,000	$500,000

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate	2.50%
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, Low End	13.00%
shock attrition rate	6.00%
Fair Value Inputs, Discount Rate	16.50%
Fair Value Inputs, Control Premium	4.50%
Rabbi Trust [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments (cost basis)	4,100,000
Private Equity Funds, Domestic [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unfunded commitment for investments	10,400,000
Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments (cost basis)	441,000	475,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book value of other real estate owned (OREO) and repossessed assets	5,300,000

Fair_Value_Measurements_Fair_V

Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring Basis) (Detail) (USD $)	Mar. 31, 2015	Jan. 13, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Liability Fair Value	$6,000		$0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Asset	5,000		0
Total financial assets held at fair value	3,052,505		2,853,139
Derivative instruments	58,084		36,777
Total financial liabilities held at fair value	64,084		36,777
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	5,684		5,901
Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	441		475
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	72,730		52,872
Fair Value, Measurements, Recurring [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	541		18
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	425		525
Fair Value, Measurements, Recurring [Member] | Agency CMOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	664,700		550,988
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,017,007		1,028,518
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	127,702		80,266
Fair Value, Measurements, Recurring [Member] | Non-agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	562,623		553,393
Fair Value, Measurements, Recurring [Member] | Collateralized loan obligations (CLOs) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	442,701		425,734
Fair Value, Measurements, Recurring [Member] | Single issuer trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	38,282		38,245
Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	110,084		110,301
Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	4,585		5,903
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Asset	0		0
Total financial assets held at fair value	10,694		12,329
Derivative instruments	245		293
Total financial liabilities held at fair value	245		293
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	5,684		5,901
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0		0
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			0
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | U.S. Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	425		525
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | 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] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | 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] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	4,585		5,903
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Asset	0		0
Total financial assets held at fair value	3,036,370		2,840,335
Derivative instruments	57,839		36,484
Total financial liabilities held at fair value	57,839		36,484
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0		0
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 assets	72,730		52,872
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	541		18
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency CMOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	664,700		550,988
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency MBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,017,007		1,028,518
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	127,702		80,266
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Non-agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	562,623		553,393
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Collateralized loan obligations (CLOs) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	442,701		425,734
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Single issuer trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	38,282		38,245
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	110,084		110,301
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Input (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Asset	5,000
Total financial assets held at fair value	5,441		475
Contingent Liability Fair Value		6,000
Total financial liabilities held at fair value	6,000
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Input (Level 3) [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	441		475
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Input (Level 3) [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Input (Level 3) [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Input (Level 3) [Member] | 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 Input (Level 3) [Member] | 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] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	2,968,109		2,793,873
Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	5,010		6,428
Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$2,963,099		$2,787,445

Fair_Value_Measurements_Schedu

Fair Value Measurements (Schedule Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of period, Financial Assets	$475
Level 3, beginning of period, Contingent Liability	0
Acquisition, Financial Assets	5,000
Acquisition, Contingent Liability	6,000
Unrealized loss included in net income, Financial Assets	1
Calls/paydowns, Financial Assets	-35
Level 3, end of period, Financial Assets	5,441
Level 3, end of period, Contingent Liability	6,000
Contingent Asset [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of period, Financial Assets	0
Acquisition, Financial Assets	5,000
Level 3, end of period, Financial Assets	5,000
Equity Method Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of period, Financial Assets	475
Acquisition, Financial Assets	0
Unrealized loss included in net income, Financial Assets	1
Calls/paydowns, Financial Assets	-35
Level 3, end of period, Financial Assets	$441

Fair_Value_Measurements_Schedu1

Fair Value Measurements (Schedule Of Valuation Methodology And Unobservable Inputs) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Measurements [Line Items]
Debt Instrument, Unamortized Discount	1,053	$1,083
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Other real estate owned	3,091
Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Mortgage servicing assets	27,901
Nonperforming Financing Receivable [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Impaired loans and leases	27,862
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	8.00%
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member] | Minimum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	0.00%
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member] | Maximum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	25.00%
Market Approach Valuation Technique [Member] | Nonperforming Financing Receivable [Member] | Minimum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	3.00%
Market Approach Valuation Technique [Member] | Nonperforming Financing Receivable [Member] | Maximum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	15.00%
Market Approach Valuation Technique - Discount for cost to sell [Member] | Nonperforming Financing Receivable [Member] | Minimum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	0.00%
Market Approach Valuation Technique - Discount for cost to sell [Member] | Nonperforming Financing Receivable [Member] | Maximum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	8.00%
Income Approach Valuation Technique [Member] | Mortgage Servicing Rights [Member] | Minimum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	1.40%
Income Approach Valuation Technique [Member] | Mortgage Servicing Rights [Member] | Maximum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	2.90%
Income Approach Valuation Technique [Member] | Interest Rate Risk [Member] | Mortgage Servicing Rights [Member] | Minimum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	9.20%
Income Approach Valuation Technique [Member] | Interest Rate Risk [Member] | Mortgage Servicing Rights [Member] | Maximum [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements [Line Items]
Range of Inputs	28.80%

Fair_Value_Measurements_Summar

Fair Value Measurements (Summary Of Estimated Fair Values Of Significant Financial Instruments) (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
In Thousands, unless otherwise specified
Fair Value Measurements [Line Items]
Mortgage servicing assets reserves	$25		$23
Unamortized premiums	33		37
Unamortized discount, net	-1,053		-1,083
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Fair Value Measurements [Line Items]
Loans held for sale	45,866		67,952
Loans and leases, net	14,108,256		13,740,761
Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	1,083,877		1,250,756
Federal Home Loan Bank advances	1,584,357	[1]	2,859,431	[1]
Long-term debt	226,267	[2]	226,237	[2]
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Residential, Prime, Financing Receivable [Member]
Fair Value Measurements [Line Items]
Mortgage servicing assets	19,243	[3]			19,379	[3]
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Private Equity Funds, Domestic [Member]
Fair Value Measurements [Line Items]
Other assets	15,265		16,524
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Measurements [Line Items]
Loans held for sale	46,733		68,705
Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	1,105,190		1,271,596
Federal Home Loan Bank advances	1,597,986	[1]	2,872,515	[1]
Long-term debt	226,379	[2]	227,751	[2]
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Input (Level 3) [Member]
Fair Value Measurements [Line Items]
Loans and leases, net	14,151,073		13,775,850
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Input (Level 3) [Member] | Residential, Prime, Financing Receivable [Member]
Fair Value Measurements [Line Items]
Mortgage servicing assets	27,901	[3]	28,690	[3]
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Input (Level 3) [Member] | Private Equity Funds, Domestic [Member]
Fair Value Measurements [Line Items]
Other assets	17,706		18,046
Held-to-maturity Securities [Member] | Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Fair Value Measurements [Line Items]
Securities held-to-maturity	3,923,189		3,872,955
Held-to-maturity Securities [Member] | Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Measurements [Line Items]
Securities held-to-maturity	4,022,981		3,948,706
Time Deposits [Member] | Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Fair Value Measurements [Line Items]
Deposits, Fair Value Disclosure	2,205,728		2,271,587
Time Deposits [Member] | Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Measurements [Line Items]
Deposits, Fair Value Disclosure	2,224,374		2,288,760
DepositsOtherThanTimeDeposits [Member] | Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Fair Value Measurements [Line Items]
Deposits, Fair Value Disclosure	15,339,922		13,380,018
DepositsOtherThanTimeDeposits [Member] | Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Measurements [Line Items]
Deposits, Fair Value Disclosure	$15,339,922		$13,380,018
[1]	FHLB advances is net of $33 thousand and $37 thousand in unamortized premiums at March 31, 2015 and December 31, 2014, respectively.
[2]	ong-term debt is net of $1.1 million in unamortized discounts at March 31, 2015 and December 31, 2014.
[3]	ortgage servicing assets is net of $25 thousand and $23 thousand in reserves at March 31, 2015 and December 31, 2014, respectively.

Pension_and_Other_Postretireme2

Pension and Other Postretirement Benefits (Summary of Net Periodic Benefit Costs) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Webster Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$10	$10
Interest cost on projected benefit obligations	1,989	2,003
Expected return on plan assets	-2,963	-2,875
Amortization of prior service cost	0	0
Recognized net loss	1,427	687
Net periodic benefit cost (income)	463	-175
Webster SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost on projected benefit obligations	86	92
Expected return on plan assets	0	0
Amortization of prior service cost	0	0
Recognized net loss	80	23
Net periodic benefit cost (income)	166	115
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost on projected benefit obligations	31	34
Expected return on plan assets	0	0
Amortization of prior service cost	18	18
Recognized net loss	12	0
Net periodic benefit cost (income)	$61	$52

Recovered_Sheet4

Pension And Other Postretirement Benefits (Narrative) (Detail) (Multiemployer Plans, Pension [Member], USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Overfunded amount	$0.30

Pension_and_Other_Postretireme3

Pension and Other Postretirement Benefits (Summary of contributions and funding status) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Contributions	$91	$337
Funded Status of Plan	At least 80 percent

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans (Summary of Stock-based compensation expense recognized) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$2,282	$2,773
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	164	552
Restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$2,118	$2,221

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans (Summary of Unrecognized Compensation Expense) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense, Stock options	$259
Weighted-Average Period To Be Recognized	11 months 1 day
Restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense, Restricted stock	$17,878
Weighted-Average Period To Be Recognized	2 years 1 month 31 days

StockBased_Compensation_Plans_3

Stock-Based Compensation Plans (Summary of Restricted Stock and Stock Option Activity) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, at beginning of period, Number of Shares	1,900,144
Options granted, Number of Shares	0
Exercised options, Number of Shares	-13,033
Options forfeited or expired, Number of Shares	-25,044
Options outstanding, at end of period, Number of Shares	1,862,067
Options exercisable, at end of period, Number of Shares	1,753,892
Options expected to vest, at end of period, Number of Shares	102,314
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)	$24.95
Options granted, Weighted-Average Exercise Price (in dollars per share)	$0
Options exercised, Weighted-Average Exercise Price (in dollars per share)	$20.10
Options forfeited, Weighted-Average Exercise Price (in dollars per share)	$40.30
Options, at end of period, Weighted-average Exercise Price (in dollars per share)	$24.78
Options exercisable, at end of period, Weighted-Average Exercise Price (in dollars per share)	$24.89
Options expected to vest, at end of period, Weighted-Average Exercise Price (in dollars per share)	$23
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	2,279
Restricted stock, Granted	12,531
Restricted stock, Vested restricted stock awards	-3,323	[1]
Restricted stock, Forfeited	0
Restricted stock, Outstanding at end of period	11,487
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)	$29.34
Restricted stock, Granted	$34.45
Restricted stock, Vested restricted stock awards	$30.95	[1]
Restricted stock, Forfeited	$0
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share)	$34.45
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	130,193
Restricted stock, Granted	138,591
Restricted stock, Vested restricted stock awards	-50,159	[1]
Restricted stock, Forfeited	0
Restricted stock, Outstanding at end of period	218,625
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)	$28.61
Restricted stock, Granted	$36.15
Restricted stock, Vested restricted stock awards	$29.94	[1]
Restricted stock, Forfeited	$0
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share)	$33.09
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	243,015
Restricted stock, Granted	191,824
Restricted stock, Vested restricted stock awards	-52,837	[1]
Restricted stock, Forfeited	-683
Restricted stock, Outstanding at end of period	381,319
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)	$27.03
Restricted stock, Granted	$32.91
Restricted stock, Vested restricted stock awards	$26.90	[1]
Restricted stock, Forfeited	$29.75
Restricted stock, at end of period, Weighted-average Grant Date Fair Value (in dollars per share)	$30.85
[1]	Vested for purposes of recording compensation expense.

StockBased_Compensation_Plans_4

Stock-Based Compensation Plans (Narrative) (Detail)	3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding	1,862,067	1,900,144
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	100,000
Time Based Restricted Stock Awards [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Time Based Restricted Stock Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Performance Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Vesting percentage	50.00%
Performance Based Restricted Stock Awards [Member] | Minimum [Member] | Vesting Period 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	0.00%
Performance Based Restricted Stock Awards [Member] | Minimum [Member] | Vesting Period 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	0.00%	0.00%
Performance Based Restricted Stock Awards [Member] | Maximum [Member] | Vesting Period 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			200.00%
Performance Based Restricted Stock Awards [Member] | Maximum [Member] | Vesting Period 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	150.00%	150.00%
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term	10 years
Stock options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Stock options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Non-Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding	1,702,165
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding	159,902

Segment_Reporting_Operating_Re

Segment Reporting - Operating Results and Total Assets Reportable Segments (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	Segment
Segment Reporting Information [Line Items]
Number of Reportable Segments	4
Net interest income (loss)	$159,764	$155,301
Provision for loan and lease losses	9,750	9,000
Net interest income after provision for loan and lease losses	150,014	146,301
Non-interest income	57,890	49,828
Non-interest expense	134,090	124,463
Income before income tax expense	73,814	71,666
Income tax expense (benefit)	24,092	21,237
Net income	49,722	50,429
Total Assets	23,106,688		22,533,172
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	61,578	56,152
Provision for loan and lease losses	3,374	10,445
Net interest income after provision for loan and lease losses	58,204	45,707
Non-interest income	9,525	7,951
Non-interest expense	26,469	26,019
Income before income tax expense	41,260	27,639
Income tax expense (benefit)	13,467	8,190
Net income	27,793	19,449
Total Assets	6,830,310		6,550,868
Community Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	84,239	87,341
Provision for loan and lease losses	6,421	645
Net interest income after provision for loan and lease losses	77,818	86,696
Non-interest income	25,540	24,436
Non-interest expense	81,690	81,518
Income before income tax expense	21,668	29,614
Income tax expense (benefit)	7,073	8,775
Net income	14,595	20,839
Total Assets	7,817,188		8,198,115
HSA Bank [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	16,465	9,206
Provision for loan and lease losses	0	0
Net interest income after provision for loan and lease losses	16,465	9,206
Non-interest income	15,151	6,889
Non-interest expense	18,958	10,147
Income before income tax expense	12,658	5,948
Income tax expense (benefit)	4,131	1,754
Net income	8,527	4,194
Total Assets	90,818		25,148
Private Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	2,395	2,161
Provision for loan and lease losses	-57	446
Net interest income after provision for loan and lease losses	2,452	1,715
Non-interest income	2,326	2,621
Non-interest expense	4,879	4,556
Income before income tax expense	-101	-220
Income tax expense (benefit)	-33	-66
Net income	-68	-154
Total Assets	412,229		400,425
Corporate and Reconciling [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	-4,913	441
Provision for loan and lease losses	12	-2,536
Net interest income after provision for loan and lease losses	-4,925	2,977
Non-interest income	5,348	7,931
Non-interest expense	2,094	2,223
Income before income tax expense	-1,671	8,685
Income tax expense (benefit)	-546	2,584
Net income	-1,125	6,101
Total Assets	$7,956,143		$7,358,616

Commitments_and_Contingencies_1

Commitments and Contingencies - Narrative (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$5.30	$5
Rental Income, Nonoperating	$0.20	$0.20

Commitments_and_Contingencies_2

Commitments and Contingencies - Outstanding Financial Instruments Contract Amounts Represent Credit Risk (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Loss Contingencies [Line Items]
Total financial instruments with off-balance sheet risk	$4,611,223	$4,547,484
Standby letters of credit [Member]
Loss Contingencies [Line Items]
Total financial instruments with off-balance sheet risk	144,606	142,964
Commercial letters of credit [Member]
Loss Contingencies [Line Items]
Total financial instruments with off-balance sheet risk	34,782	27,787
Unused commitments to extend credit [Member]
Loss Contingencies [Line Items]
Total financial instruments with off-balance sheet risk	$4,431,835	$4,376,733

Commitments_and_Contingencies_3

Commitments and Contingencies - Schedule for Unfunded Commitments (Details) (Reserve for Off-balance Sheet Activities [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Reserve for Off-balance Sheet Activities [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of period	$5,151	$4,384
Provision (benefit)	-2,831	327
Balance, end of period	$2,320	$4,711