Regulatory Matters (Information On The Capital Ratios) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preceding period of retained net profits	2 years
Dividends paid by Webster Bank	$ 70,000,000	$ 110,000,000
Trust Preferred Securities Included in Tier One Capital	75,000,000		75,000,000
Webster Financial Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, Actual Amount	1,939,194,000		1,840,736,000
Total risk-based capital, Actual Ratio	14.30%		13.70%
Total risk-based capital, Capital Requirements Amount	1,088,630,000		1,072,749,000
Total risk-based capital, Capital Requirements Ratio	8.00%		8.00%
Total risk-based capital, Well Capitalized Amount	1,360,788,000		1,340,936,000
Total risk-based capital, Well Capitalized Ratio	10.00%		10.00%
Tier 1 capital, Actual Amount	1,775,605,000		1,672,009,000
Tier 1 capital, Actual Ratio	13.10%		12.50%
Tier 1 capital, Capital Requirements Amount	544,315,000		536,375,000
Tier 1 capital, Capital Requirements Ratio	4.00%		4.00%
Tier 1 capital, Well Capitalized Amount	816,473,000		804,562,000
Tier 1 capital, Well Capitalized Ratio	6.00%		6.00%
Tier 1 leverage capital ratio, Actual Amount	1,775,605,000		1,672,009,000
Tier 1 leverage capital ratio, Actual Ratio	9.00%		8.70%
Tier 1 leverage capital ratio, Capital Requirements Amount	792,663,000		767,289,000
Tier 1 leverage capital ratio, Capital Requirements Ratio	4.00%		4.00%
Tier 1 leverage capital ratio, Well Capitalized Amount	990,829,000		959,111,000
Tier 1 leverage capital ratio, Well Capitalized Ratio	5.00%		5.00%
Webster Bank, N.A. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, Actual Amount	1,791,608,000		1,718,564,000
Total risk-based capital, Actual Ratio	13.20%		12.90%
Total risk-based capital, Capital Requirements Amount	1,084,672,000		1,069,652,000
Total risk-based capital, Capital Requirements Ratio	8.00%		8.00%
Total risk-based capital, Well Capitalized Amount	1,355,840,000		1,337,064,000
Total risk-based capital, Well Capitalized Ratio	10.00%		10.00%
Tier 1 capital, Actual Amount	1,629,406,000		1,551,238,000
Tier 1 capital, Actual Ratio	12.00%		11.60%
Tier 1 capital, Capital Requirements Amount	542,336,000		534,826,000
Tier 1 capital, Capital Requirements Ratio	4.00%		4.00%
Tier 1 capital, Well Capitalized Amount	813,504,000		802,239,000
Tier 1 capital, Well Capitalized Ratio	6.00%		6.00%
Tier 1 leverage capital ratio, Actual Amount	1,629,406,000		1,551,238,000
Tier 1 leverage capital ratio, Actual Ratio	8.20%		8.10%
Tier 1 leverage capital ratio, Capital Requirements Amount	791,132,000		766,025,000
Tier 1 leverage capital ratio, Capital Requirements Ratio	4.00%		4.00%
Tier 1 leverage capital ratio, Well Capitalized Amount	$ 988,915,000		$ 957,532,000
Tier 1 leverage capital ratio, Well Capitalized Ratio	5.00%		5.00%