Securities Sold Under Agreements to Repurchase and Other Short-Term Debt (Information Regarding Other Borrowed Funds) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Short-term Debt [Line Items]
Amount outstanding at year end	$ 250,314	$ 287,520
FHLBB Short Term Borrowings [Member]
Short-term Debt [Line Items]
Amount outstanding at year end	0	0	0
Maximum amount outstanding during the year	72,500	97,000	0
Average amount outstanding during the year	17,259	38,290	359
Weighted average-rate during the year	0.30%	0.28%	0.28%
Weighted average rate at year-end	0.00%	0.00%	0.00%
Demand Note Due U.S. Treasury [Member]
Short-term Debt [Line Items]
Amount outstanding at year end	0	0	0
Maximum amount outstanding during the year	0	0	3,013
Average amount outstanding during the year	0	0	1,794
Weighted average-rate during the year	0.00%	0.00%	0.00%
Weighted average rate at year-end	0.00%	0.00%	0.00%
Securities Sold under Agreement to Repurchase - Short-Term [Member]
Short-term Debt [Line Items]
Amount outstanding at year end	250,314	287,520	262,527
Maximum amount outstanding during the year	284,297	303,420	266,897
Average amount outstanding during the year	$ 212,644	$ 230,281	$ 217,823
Weighted average-rate during the year	0.41%	0.73%	0.95%
Weighted average rate at year-end	0.18%	0.47%	0.91%