Borrowings (Schedule of Other Borrowed Funds) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Securities Sold under Agreements to Repurchase	[1]	$ 215,041	$ 187,855
FHLBB advances less than 90 days		25,000
Total short-term borrowings		452,852	445,921	$ 398,932
Total long-term borrowings		5,911	31,018
Total other borrowed funds		458,763	476,939
Short-term Debt [Member]
Debt Instrument [Line Items]
Securities Sold under Agreements to Repurchase		184,989	157,758
FHLBB advances less than 90 days		230,000	245,000
FHLBB and correspondent bank overnight borrowings		12,800	43,100
Capital lease obligation		63	63
Long-term Debt [Member]
Debt Instrument [Line Items]
Securities Sold under Agreements to Repurchase		5,052	30,097
Capital lease obligation		859	921
Commercial and Industrial Sector [Member] | Short-term Debt [Member]
Debt Instrument [Line Items]
Securities Sold under Agreements to Repurchase		$ 25,000	$ 0

[1] (1) Total repurchase agreements are presented within other borrowed funds on the consolidated statements of condition.