Earnings Per Common Share (Earnings Per Share Basic And Diluted) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income from continuing operations available to common shareholders		$ 42,231		$ 108,999
Less: dividends declared or accrued Common shareholders			(21,906)	(9,607)
Net income attributable to Webster Financial Corporation	44,993	42,231	125,171	110,995
Net income allocated to common shareholders	44,378	41,400	123,326	108,502
Net income from discontinued operations available to common shareholders	0	0	0	1,995
Weighted average common shares outstanding - basic	87,394	87,046	87,301	86,978
Stock options and restricted stock (in shares)	260	362	281	383
Weighted average common shares outstanding - diluted	91,884	91,205	91,754	91,954
Earnings from continuing operations per common share, Basic (in dollars per share)	$ 0.51	$ 0.48	$ 1.41	$ 1.22
Earnings from continuing operations per common share, Diluted (in dollars per share)	$ 0.48	$ 0.45	$ 1.34	$ 1.15
Earnings from discontinued operations per common share, Basic (in dollars per share)	$ 0	$ 0	$ 0	$ 0.02
Earnings from discontinued operations per common share, Diluted (in dollars per share)	$ 0	$ 0	$ 0	$ 0.02
Earnings per common share, Basic (in dollars per share)	$ 0.51	$ 0.48	$ 1.41	$ 1.24
Earnings per common share, Diluted (in dollars per share)	$ 0.48	$ 0.45	$ 1.34	$ 1.17
Earnings Per Share, Basic [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income from continuing operations available to common shareholders	44,378	41,400	123,326	106,507
Less: dividends declared or accrued Common shareholders	(8,737)	(4,348)	(21,820)	(9,564)
Less: dividends declared or accrued Participating shares	(37)	(23)	(102)	(50)
Net income attributable to Webster Financial Corporation	35,604	37,029	101,404	96,893
Add dividends paid to common shareholders	8,737	4,348	21,820	9,564
Less: income allocated to participating securities	(149)	(198)	(470)	(499)
Earnings Per Share, Diluted [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income allocated to common shareholders	$ 44,192	$ 41,179	$ 122,754	$ 105,958
Warrants - Series A1 And A2 [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Warrants (in shares)	4,114	3,797	4,060	4,593
Warrants - Other [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Warrants (in shares)	116	0	112	0