Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	$ 34,014	$ 34,014	$ 45,688
Loans with a specific valuation allowance, Unpaid principal balance	35,374	35,374	48,477
Specific valuation allowance	7,254	7,254	11,597
Loans with a specific valuation allowance, Average balance	34,166	38,006	53,339
Loans without a specific valuation allowance, Recorded balance	117,718	117,718	115,678
Loans without a specific valuation allowance, Unpaid principal balance	146,826	146,826	145,038
Loans without a specific valuation allowance, Average balance	122,973	120,541	128,645
Recorded balance	151,732	151,732	161,366
Unpaid principal balance	182,200	182,200	193,515
Average balance	157,139	158,547	181,984
Residential Real Estate
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	5,055	5,055	4,110
Loans with a specific valuation allowance, Unpaid principal balance	5,186	5,186	4,276
Specific valuation allowance	793	793	853
Loans with a specific valuation allowance, Average balance	5,081	4,757	5,480
Loans without a specific valuation allowance, Recorded balance	13,144	13,144	15,466
Loans without a specific valuation allowance, Unpaid principal balance	14,440	14,440	16,683
Loans without a specific valuation allowance, Average balance	13,525	14,172	15,580
Recorded balance	18,199	18,199	19,576
Unpaid principal balance	19,626	19,626	20,959
Average balance	18,606	18,929	21,060
Commercial Real Estate
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	15,111	15,111	27,155
Loans with a specific valuation allowance, Unpaid principal balance	15,505	15,505	28,048
Specific valuation allowance	2,546	2,546	2,967
Loans with a specific valuation allowance, Average balance	14,034	18,408	24,519
Loans without a specific valuation allowance, Recorded balance	79,749	79,749	78,109
Loans without a specific valuation allowance, Unpaid principal balance	101,325	101,325	100,266
Loans without a specific valuation allowance, Average balance	82,629	81,122	89,015
Recorded balance	94,860	94,860	105,264
Unpaid principal balance	116,830	116,830	128,314
Average balance	96,663	99,530	113,534
Other Commercial
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	11,862	11,862	11,377
Loans with a specific valuation allowance, Unpaid principal balance	12,184	12,184	12,461
Specific valuation allowance	3,306	3,306	6,836
Loans with a specific valuation allowance, Average balance	13,003	12,461	19,874
Loans without a specific valuation allowance, Recorded balance	16,199	16,199	13,944
Loans without a specific valuation allowance, Unpaid principal balance	21,622	21,622	19,117
Loans without a specific valuation allowance, Average balance	18,345	16,878	14,024
Recorded balance	28,061	28,061	25,321
Unpaid principal balance	33,806	33,806	31,578
Average balance	31,348	29,339	33,898
Home Equity
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	234	234	1,214
Loans with a specific valuation allowance, Unpaid principal balance	253	253	1,336
Specific valuation allowance	111	111	447
Loans with a specific valuation allowance, Average balance	319	617	1,039
Loans without a specific valuation allowance, Recorded balance	6,346	6,346	5,687
Loans without a specific valuation allowance, Unpaid principal balance	7,100	7,100	6,403
Loans without a specific valuation allowance, Average balance	6,220	6,042	7,163
Recorded balance	6,580	6,580	6,901
Unpaid principal balance	7,353	7,353	7,739
Average balance	6,539	6,659	8,202
Other Consumer
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	1,752	1,752	1,832
Loans with a specific valuation allowance, Unpaid principal balance	2,246	2,246	2,356
Specific valuation allowance	498	498	494
Loans with a specific valuation allowance, Average balance	1,729	1,763	2,427
Loans without a specific valuation allowance, Recorded balance	2,280	2,280	2,472
Loans without a specific valuation allowance, Unpaid principal balance	2,339	2,339	2,569
Loans without a specific valuation allowance, Average balance	2,254	2,327	2,863
Recorded balance	4,032	4,032	4,304
Unpaid principal balance	4,585	4,585	4,925
Average balance	$ 3,983	$ 4,090	$ 5,290