Borrowings (Schedule of Other Borrowed Funds) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Total short-term borrowings	$ 192,535	$ 202,928	$ 193,930
Total long-term borrowings	67,405	72,728
Total other borrowed funds	259,940	275,656
Securities sold under repurchase agreements - retail [Member]
Debt Instrument [Line Items]
Total short-term borrowings	151,035	144,228
Securities sold under repurchase agreements - commercial [Member]
Debt Instrument [Line Items]
Total long-term borrowings	66,187	71,243
FHLBB and correspondent bank overnight borrowings [Member]
Debt Instrument [Line Items]
Total short-term borrowings	41,500	58,700
Notes Payable [Member]
Debt Instrument [Line Items]
Total long-term borrowings	117	360
Capital lease obligation [Member]
Debt Instrument [Line Items]
Total long-term borrowings	$ 1,101	$ 1,125