Business Segments (Operating Results And Total Assets Reportable Segments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Segment Reporting Information [Line Items]
Net interest income	$ 137,027	[1]	$ 135,458	[1]	$ 133,065	[1]	$ 131,721	[1]	$ 563,768	[2]	$ 537,271	[2],[3]	$ 495,386	[2],[3]
(Benefit) provision for loan and lease losses	15,000	[1]	25,000	[1]	32,000	[1]	43,000	[1]	22,500	[2]	115,000	[2],[3]	303,000	[2],[3]
Net (loss) interest income after provision for loan and lease losses									541,268	[2]	422,271	[2],[3]	192,386	[2],[3]
Non-interest income	42,721	[1]	45,185	[1]	52,099	[1]	45,265	[1]	177,042	[2]	201,225	[2],[3]	184,395	[2],[3]
Non-interest expense	127,962	[1]	126,921	[1]	127,991	[1]	133,624	[1]	510,976	[2]	538,974	[2],[3]	507,394	[2],[3]
Income (loss) from continuing operations before income taxes	39,081	[1]	27,184	[1]	17,257	[1]	1,000	[1]	207,334	[2]	84,522	[2],[3]	(130,613)	[2],[3]
Income tax (benefit) expense	7,219	[1]	4,561	[1]	378	[1]	200	[1]	57,951	[2]	12,358	[2],[3]	(53,424)	[2],[3]
Income (loss) from continuing operations									149,383	[2]	72,164	[2],[3]	(77,189)	[2],[3]
Income from discontinued operations									1,995	[2]	94	[2],[3]	302	[2],[3]
(Loss) income before noncontrolling interests	31,956	[1]	22,623	[1]	16,879	[1]	800	[1]	151,378	[2]	72,258	[2],[3]	(76,887)	[2],[3]
Less: Net (loss) income attributable to noncontrolling interests	(1)	[1]	(3)	[1]	7	[1]			(1)	[2]	3	[2],[3]	22	[2],[3]
Net income attributable to Webster Financial Corporation	31,957	[1]	22,626	[1]	16,872	[1]	800	[1]	151,379	[2]	72,255	[2],[3]	(76,909)	[2],[3]
Total assets at period end	18,033,881	[2],[3]							18,714,340	[2]	18,033,881	[2],[3]	17,737,070	[2],[3]
Percentage of provision expense attributable to business segments									108.80%
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income									168,930	[2]	145,745	[2],[3]	128,282	[2],[3]
(Benefit) provision for loan and lease losses									(21,213)	[2]	25,618	[2],[3]	137,816	[2],[3]
Net (loss) interest income after provision for loan and lease losses									190,143	[2]	120,127	[2],[3]	(9,534)	[2],[3]
Non-interest income									27,717	[2]	23,523	[2],[3]	24,991	[2],[3]
Non-interest expense									95,092	[2]	94,215	[2],[3]	96,298	[2],[3]
Income (loss) from continuing operations before income taxes									122,768	[2]	49,435	[2],[3]	(80,841)	[2],[3]
Income tax (benefit) expense									34,314	[2]	6,969	[2],[3]	(33,021)	[2],[3]
Income (loss) from continuing operations									88,454	[2]	42,466	[2],[3]	(47,820)	[2],[3]
(Loss) income before noncontrolling interests									88,454	[2]	42,466	[2],[3]	(47,820)	[2],[3]
Net income attributable to Webster Financial Corporation									88,454	[2]	42,466	[2],[3]	(47,820)	[2],[3]
Total assets at period end	4,080,975	[2],[3]							4,310,195	[2]	4,080,975	[2],[3]	4,113,157	[2],[3]
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net interest income									233,441	[2]	211,818	[2],[3]	156,030	[2],[3]
(Benefit) provision for loan and lease losses									14,189	[2]	10,463	[2],[3]	20,264	[2],[3]
Net (loss) interest income after provision for loan and lease losses									219,252	[2]	201,355	[2],[3]	135,766	[2],[3]
Non-interest income									98,763	[2]	107,761	[2],[3]	118,793	[2],[3]
Non-interest expense									304,271	[2]	306,401	[2],[3]	293,660	[2],[3]
Income (loss) from continuing operations before income taxes									13,744	[2]	2,715	[2],[3]	(39,101)	[2],[3]
Income tax (benefit) expense									3,842	[2]	417	[2],[3]	(16,028)	[2],[3]
Income (loss) from continuing operations									9,902	[2]	2,298	[2],[3]	(23,073)	[2],[3]
(Loss) income before noncontrolling interests									9,902	[2]	2,298	[2],[3]	(23,073)	[2],[3]
Net income attributable to Webster Financial Corporation									9,902	[2]	2,298	[2],[3]	(23,073)	[2],[3]
Total assets at period end	1,516,197	[2],[3]							1,546,457	[2]	1,516,197	[2],[3]	1,553,087	[2],[3]
Consumer Finance [Member]
Segment Reporting Information [Line Items]
Net interest income									107,271	[2]	101,958	[2],[3]	102,837	[2],[3]
(Benefit) provision for loan and lease losses									31,104	[2]	68,214	[2],[3]	141,924	[2],[3]
Net (loss) interest income after provision for loan and lease losses									76,167	[2]	33,744	[2],[3]	(39,087)	[2],[3]
Non-interest income									9,449	[2]	11,218	[2],[3]	12,854	[2],[3]
Non-interest expense									63,788	[2]	65,153	[2],[3]	62,902	[2],[3]
Income (loss) from continuing operations before income taxes									21,828	[2]	(20,191)	[2],[3]	(89,135)	[2],[3]
Income tax (benefit) expense									6,101	[2]	(3,100)	[2],[3]	(36,538)	[2],[3]
Income (loss) from continuing operations									15,727	[2]	(17,091)	[2],[3]	(52,597)	[2],[3]
(Loss) income before noncontrolling interests									15,727	[2]	(17,091)	[2],[3]	(52,597)	[2],[3]
Less: Net (loss) income attributable to noncontrolling interests									(1)	[2]	3	[2],[3]	22	[2],[3]
Net income attributable to Webster Financial Corporation									15,728	[2]	(17,094)	[2],[3]	(52,619)	[2],[3]
Total assets at period end	5,912,862	[2],[3]							5,869,028	[2]	5,912,862	[2],[3]	6,047,472	[2],[3]
Other Segments [Member]
Segment Reporting Information [Line Items]
Net interest income									25,437	[2]	18,545	[2],[3]	12,762	[2],[3]
(Benefit) provision for loan and lease losses									398	[2]	(902)	[2],[3]	(507)	[2],[3]
Net (loss) interest income after provision for loan and lease losses									25,039	[2]	19,447	[2],[3]	13,269	[2],[3]
Non-interest income									24,199	[2]	20,862	[2],[3]	19,055	[2],[3]
Non-interest expense									40,898	[2]	36,601	[2],[3]	35,986	[2],[3]
Income (loss) from continuing operations before income taxes									8,340	[2]	3,708	[2],[3]	(3,662)	[2],[3]
Income tax (benefit) expense									2,331	[2]	569	[2],[3]	(1,501)	[2],[3]
Income (loss) from continuing operations									6,009	[2]	3,139	[2],[3]	(2,161)	[2],[3]
(Loss) income before noncontrolling interests									6,009	[2]	3,139	[2],[3]	(2,161)	[2],[3]
Net income attributable to Webster Financial Corporation									6,009	[2]	3,139	[2],[3]	(2,161)	[2],[3]
Total assets at period end	203,707	[2],[3]							245,554	[2]	203,707	[2],[3]	215,573	[2],[3]
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net interest income									535,079	[2]	478,066	[2],[3]	399,911	[2],[3]
(Benefit) provision for loan and lease losses									24,478	[2]	103,393	[2],[3]	299,497	[2],[3]
Net (loss) interest income after provision for loan and lease losses									510,601	[2]	374,673	[2],[3]	100,414	[2],[3]
Non-interest income									160,128	[2]	163,364	[2],[3]	175,693	[2],[3]
Non-interest expense									504,049	[2]	502,370	[2],[3]	488,846	[2],[3]
Income (loss) from continuing operations before income taxes									166,680	[2]	35,667	[2],[3]	(212,739)	[2],[3]
Income tax (benefit) expense									46,588	[2]	4,855	[2],[3]	(87,088)	[2],[3]
Income (loss) from continuing operations									120,092	[2]	30,812	[2],[3]	(125,651)	[2],[3]
(Loss) income before noncontrolling interests									120,092	[2]	30,812	[2],[3]	(125,651)	[2],[3]
Less: Net (loss) income attributable to noncontrolling interests									(1)	[2]	3	[2],[3]	22	[2],[3]
Net income attributable to Webster Financial Corporation									120,093	[2]	30,809	[2],[3]	(125,673)	[2],[3]
Total assets at period end	11,713,741	[2],[3]							11,971,234	[2]	11,713,741	[2],[3]	11,929,289	[2],[3]
Corporate And Reconciling [Member]
Segment Reporting Information [Line Items]
Net interest income									28,689	[2]	59,205	[2],[3]	95,475	[2],[3]
(Benefit) provision for loan and lease losses									(1,978)	[2]	11,607	[2],[3]	3,503	[2],[3]
Net (loss) interest income after provision for loan and lease losses									30,667	[2]	47,598	[2],[3]	91,972	[2],[3]
Non-interest income									16,914	[2]	37,861	[2],[3]	8,702	[2],[3]
Non-interest expense									6,927	[2]	36,604	[2],[3]	18,548	[2],[3]
Income (loss) from continuing operations before income taxes									40,654	[2]	48,855	[2],[3]	82,126	[2],[3]
Income tax (benefit) expense									11,363	[2]	7,503	[2],[3]	33,664	[2],[3]
Income (loss) from continuing operations									29,291	[2]	41,352	[2],[3]	48,462	[2],[3]
Income from discontinued operations									1,995	[2]	94	[2],[3]	302	[2],[3]
(Loss) income before noncontrolling interests									31,286	[2]	41,446	[2],[3]	48,764	[2],[3]
Net income attributable to Webster Financial Corporation									31,286	[2]	41,446	[2],[3]	48,764	[2],[3]
Total assets at period end	6,320,140	[2],[3]							6,743,106	[2]	6,320,140	[2],[3]	5,807,781	[2],[3]
Parent Company [Member]
Segment Reporting Information [Line Items]
(Benefit) provision for loan and lease losses									(136)		136	[4]
Income (loss) from continuing operations before income taxes									(29,443)		(6,970)	[4]	(13,628)	[4]
Income tax (benefit) expense									(18,481)		(8,061)	[4]	(1,388)	[4]
Income from discontinued operations									1,995		94	[4]	302	[4]
Total assets at period end	$ 2,175,531	[4]							$ 2,223,633		$ 2,175,531	[4]

[1] Certain previously reported information has been corrected to reflect the deferrment of certain commercial loan fees. For more information refer to Note 1.

[2] Reclassified to conform to the 2011 presentation. The consumer liquidating portfolio was not established as a separate operating unit until April 2010, as part of the presentation for 2010, the consumer liquidating portfolio for the three months ended March 31, 2010 has not been reclassified to conform to the 2011 presentation. As part of the presentation for 2009, the consumer liquidating portfolio for the year ended December 31, 2009 has not been reclassified to conform to the 2011 presentation, and total assets at December 31, 2009 has not been reclassified to conform to the 2011 and 2010 presentations.

[3] Certain previously reported information has been corrected to reflect the deferment of certain commercial loan fees. For more information refer to Note 1

[4] Certain previously reported information has been corrected to reflect the deferment of certain commercial loan fees.