Stock-Based Compensation Plans (Narrative) (Details) (USD $)	12 Months Ended															12 Months Ended			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Stock Options [Member] years	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2009 Stock Options [Member]	Dec. 31, 2011 Non-vested Stock Options [Member] years	Dec. 31, 2011 Restricted Stock [Member]	Dec. 31, 2010 Restricted Stock [Member]	Dec. 31, 2009 Restricted Stock [Member]	Dec. 31, 2011 Non-Vested Restricted Stock Awards [Member] years	Dec. 31, 2010 Non-Vested Restricted Stock Awards [Member]	Dec. 31, 2009 Non-Vested Restricted Stock Awards [Member]	Dec. 31, 2011 Non-Qualified Stock Options [Member]	Dec. 31, 2011 Incentive Stock Options [Member]	Dec. 31, 2011 Performance-Based Restricted Stock Awards [Member]	Dec. 31, 2008 Performance-Based Restricted Stock Awards [Member]	Dec. 31, 2010 Performance-Based Restricted Stock Awards [Member]	Dec. 31, 2011 Long-Term Cash Awards [Member]	Dec. 31, 2010 Long-Term Cash Awards [Member]	Dec. 31, 2009 Long-Term Cash Awards [Member]	Dec. 31, 2011 Individual [Member]	Dec. 31, 2011 Senior Management [Member]	Dec. 31, 2010 Senior Management [Member]	Dec. 31, 2009 Senior Management [Member]	Dec. 31, 2011 Directors [Member]	Dec. 31, 2010 Directors [Member]	Dec. 31, 2009 Directors [Member]	Dec. 31, 2011 Directors [Member] Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of common shares available for grant	10,900,000
Common shares available for future grants	3,900,000
Stock-based compensation expense	$ 6,000,000	$ 6,700,000	$ 8,900,000	$ 800,000	$ 1,400,000	$ 2,600,000		$ 5,200,000	$ 5,300,000	$ 6,300,000									$ 3,000,000	$ 4,100,000	$ 1,500,000
Recognized income tax benefit	2,100,000	800,000	2,200,000
Vesting period of options, minimum, in years				three																	3
Vesting period of options, maximum, in years				four																	5
Maximum contractual life of options, in years				10
Number of options outstanding	2,513,327	2,743,181												2,337,991	175,336
Unrecognized compensation cost							505,900				7,400,000
Weighted-average vesting period, in years							2.2				1.9
Intrinsic value of options exercised	102,400	85,400	1,100
Weighted-average remaining contractual term of options expected to vest, in years	7.43
Aggregate intrinsic value of options outstanding	7,900,000
Aggregate intrinsic value of options exercisable	6,400,000
Aggregate intrinsic value of options, vested and expected to vest	1,300,000
Restricted stock shares granted during period																104,310	113,412					100,000	153,527	7,953	181,463
Vesting range, minimum																0.00%
Vesting range maximum																200.00%
Vesting period								three																			one	one	3
Options granted, shares	36,128																				357,043					25,137	18,036	14,234
Weighted average grant date fair value of options											$ 22.29	$ 19.47	$ 12.08					$ 15.93
Weighted-average fair value of shares vested	4,800,000	4,900,000	6,800,000
Terms of long-term cash incentive awards																					The value of these cash awards is converted to "phantom shares" by dividing the award value by the average price of Webster common stock for the 10 day period prior to the grant date
Liabilities	$ 4,400,000	$ 5,500,000