Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	$ 59,876	$ 61,503
Loans with a specific valuation allowance, Unpaid principal balance	61,145	63,406
Loans with a specific valuation allowance, Specific valuation allowance	10,236	11,949
Loans with a specific valuation allowance, Average balance	60,689	59,823
Loans without a specific valuation allowance, Recorded balance	132,308	138,177
Loans without a specific valuation allowance, Unpaid principal balance	163,353	169,082
Loans without a specific valuation allowance, Average balance	135,243	139,129
Recorded balance	192,184	199,680
Unpaid principal balance	224,498	232,488
Specific valuation allowance	10,236	11,949
Average balance	195,932	198,952
Residential Real Estate
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	6,083	7,233
Loans with a specific valuation allowance, Unpaid principal balance	6,277	7,394
Loans with a specific valuation allowance, Specific valuation allowance	699	990
Loans with a specific valuation allowance, Average balance	6,658	7,237
Loans without a specific valuation allowance, Recorded balance	15,337	16,837
Loans without a specific valuation allowance, Unpaid principal balance	16,361	18,033
Loans without a specific valuation allowance, Average balance	16,087	18,103
Recorded balance	21,420	24,070
Unpaid principal balance	22,638	25,427
Specific valuation allowance	699	990
Average balance	22,745	25,340
Commercial Real Estate
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	27,047	23,917
Loans with a specific valuation allowance, Unpaid principal balance	27,762	25,331
Loans with a specific valuation allowance, Specific valuation allowance	3,429	3,763
Loans with a specific valuation allowance, Average balance	25,482	26,105
Loans without a specific valuation allowance, Recorded balance	91,677	95,609
Loans without a specific valuation allowance, Unpaid principal balance	115,489	119,017
Loans without a specific valuation allowance, Average balance	93,643	95,808
Recorded balance	118,724	119,526
Unpaid principal balance	143,251	144,348
Specific valuation allowance	3,429	3,763
Average balance	119,125	121,913
Other Commercial
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	22,794	27,015
Loans with a specific valuation allowance, Unpaid principal balance	22,975	27,238
Loans with a specific valuation allowance, Specific valuation allowance	4,731	6,155
Loans with a specific valuation allowance, Average balance	24,904	22,460
Loans without a specific valuation allowance, Recorded balance	14,235	14,489
Loans without a specific valuation allowance, Unpaid principal balance	18,882	19,156
Loans without a specific valuation allowance, Average balance	14,362	14,106
Recorded balance	37,029	41,504
Unpaid principal balance	41,857	46,394
Specific valuation allowance	4,731	6,155
Average balance	39,266	36,566
Home Equity
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	1,104	886
Loans with a specific valuation allowance, Unpaid principal balance	1,190	949
Loans with a specific valuation allowance, Specific valuation allowance	167	265
Loans with a specific valuation allowance, Average balance	995	767
Loans without a specific valuation allowance, Recorded balance	7,818	8,153
Loans without a specific valuation allowance, Unpaid principal balance	9,274	9,631
Loans without a specific valuation allowance, Average balance	7,986	8,844
Recorded balance	8,922	9,039
Unpaid principal balance	10,464	10,580
Specific valuation allowance	167	265
Average balance	8,981	9,611
Other Consumer
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	2,848	2,452
Loans with a specific valuation allowance, Unpaid principal balance	2,941	2,494
Loans with a specific valuation allowance, Specific valuation allowance	1,210	776
Loans with a specific valuation allowance, Average balance	2,650	3,254
Loans without a specific valuation allowance, Recorded balance	3,241	3,089
Loans without a specific valuation allowance, Unpaid principal balance	3,347	3,245
Loans without a specific valuation allowance, Average balance	3,165	2,268
Recorded balance	6,089	5,541
Unpaid principal balance	6,288	5,739
Specific valuation allowance	1,210	776
Average balance	$ 5,815	$ 5,522