Pension and Other Postretirement Benefits (Changes in Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain)	$ 30,683	$ (26,949)	$ 3,832
Amounts reclassified from accumulated other comprehensive income	(37)	(3,169)	(4,042)
Total loss (gain) recognized in other comprehensive income (loss)	30,573	(30,191)	(283)
Webster Pension [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain)	31,951	(23,238)	6,416
Amounts reclassified from accumulated other comprehensive income	(2,781)	(6,355)	(6,103)
Amortization of prior service cost	0	0	0
Total loss (gain) recognized in other comprehensive income (loss)	29,170	(29,593)	313
Webster SERP [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain)	1,145	(160)	353
Amounts reclassified from accumulated other comprehensive income	(134)	(125)	(71)
Amortization of prior service cost	0	0	0
Total loss (gain) recognized in other comprehensive income (loss)	1,011	(285)	282
Other Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain)	470	(239)	(698)
Amounts reclassified from accumulated other comprehensive income	(5)	0	(107)
Amortization of prior service cost	(73)	(73)	(73)
Total loss (gain) recognized in other comprehensive income (loss)	$ 392	$ (312)	$ (878)