Retirement Benefit Plans (Summary of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Webster Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 45	$ 40	$ 40
Interest cost on benefit obligations	8,008	8,068	7,365
Expected return on plan assets	(11,873)	(11,495)	(11,114)
Amortization of prior service cost	0	0	0
Recognized net loss	5,724	2,781	6,355
Net periodic benefit cost (benefit)	1,904	(606)	2,646
Webster SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost on benefit obligations	345	364	289
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Recognized net loss	390	135	125
Net periodic benefit cost (benefit)	735	499	414
Postretirement Health Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost on benefit obligations	123	139	109
Expected return on plan assets	0	0	0
Amortization of prior service cost	73	73	73
Recognized net loss	47	5	0
Net periodic benefit cost (benefit)	$ 243	$ 217	$ 182