Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 31, 2017
Document and Entity Information [Abstract]
Document Period End Date	Jun. 30, 2017
Document Type	10-Q
Amendment Flag	false
Entity Registrant Name	WEBSTER FINANCIAL CORPORATION
Entity Common Stock, Shares Outstanding		92,075,458
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Trading Symbol	WBS
Entity Central Index Key	0000801337
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer