Pension and Other Postretirement Benefits (Summary of Components of Accumulated Other Comprehensive Loss Related to Pensions and Postretirement Benefits) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Deferred tax benefit	$ 11,147	$ (10,812)	$ (101)
Webster Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	70,437	41,267
Prior service cost	0	0
Total pre-tax amounts included in accumulated other comprehensive loss	70,437	41,267
Deferred tax benefit	25,415	14,779
Amounts included in accumulated other comprehensive loss, net of tax	45,022	26,488
Webster SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	2,430	1,419
Prior service cost	0	0
Total pre-tax amounts included in accumulated other comprehensive loss	2,430	1,419
Deferred tax benefit	877	508
Amounts included in accumulated other comprehensive loss, net of tax	1,553	911
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	816	351
Prior service cost	87	159
Total pre-tax amounts included in accumulated other comprehensive loss	903	510
Deferred tax benefit	326	183
Amounts included in accumulated other comprehensive loss, net of tax	$ 577	$ 327