Loans and the Allowance for Credit Losses (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Summary of impaired loans
Unpaid Principal Balance	$ 72,100		$ 73,404
Recorded Investment	63,146		63,653
Related Allowance	1,244		1,743
Average Recorded Investment	63,401	83,940
Interest Income Recognized	488	415
Impaired loans with no related allowance recorded [Member]
Summary of impaired loans
Unpaid Principal Balance	67,064		67,679
Recorded Investment	58,110		58,044
Related Allowance
Average Recorded Investment	58,078	71,305
Interest Income Recognized	460	306
Impaired loans with no related allowance recorded [Member] | Commercial real estate land and construction [Member]
Summary of impaired loans
Unpaid Principal Balance	9,653		9,278
Recorded Investment	6,257		5,577
Related Allowance
Average Recorded Investment	5,917	11,981
Interest Income Recognized	60	92
Impaired loans with no related allowance recorded [Member] | Commercial real estate improved property [Member]
Summary of impaired loans
Unpaid Principal Balance	26,406		27,515
Recorded Investment	23,875		24,455
Related Allowance
Average Recorded Investment	24,165	33,370
Interest Income Recognized	131	120
Impaired loans with no related allowance recorded [Member] | Commercial and industrial [Member]
Summary of impaired loans
Unpaid Principal Balance	4,839		4,546
Recorded Investment	4,231		4,019
Related Allowance
Average Recorded Investment	4,125	8,327
Interest Income Recognized	33	18
Impaired loans with no related allowance recorded [Member] | Residential real estate [Member]
Summary of impaired loans
Unpaid Principal Balance	22,210		22,146
Recorded Investment	20,245		20,269
Related Allowance
Average Recorded Investment	20,257	16,153
Interest Income Recognized	194	74
Impaired loans with no related allowance recorded [Member] | Home equity [Member]
Summary of impaired loans
Unpaid Principal Balance	2,225		2,437
Recorded Investment	2,040		2,207
Related Allowance
Average Recorded Investment	2,124	1,200
Interest Income Recognized	15	2
Impaired loans with no related allowance recorded [Member] | Consumer [Member]
Summary of impaired loans
Unpaid Principal Balance	1,731		1,757
Recorded Investment	1,462		1,517
Related Allowance
Average Recorded Investment	1,490	274
Interest Income Recognized	27
Impaired loans with an allowance recorded [Member]
Summary of impaired loans
Unpaid Principal Balance	5,036		5,725
Recorded Investment	5,036		5,609
Related Allowance	1,244		1,743
Average Recorded Investment	5,323	12,635
Interest Income Recognized	28	109
Impaired loans with an allowance recorded [Member] | Commercial real estate land and construction [Member]
Summary of impaired loans
Unpaid Principal Balance	1,544		1,627
Recorded Investment	1,544		1,627
Related Allowance	850		832
Average Recorded Investment	1,586	4,197
Interest Income Recognized	13
Impaired loans with an allowance recorded [Member] | Commercial real estate improved property [Member]
Summary of impaired loans
Unpaid Principal Balance	3,492		4,098
Recorded Investment	3,492		3,982
Related Allowance	394		911
Average Recorded Investment	3,737	8,438
Interest Income Recognized	15	109
Impaired loans with an allowance recorded [Member] | Commercial and industrial [Member]
Summary of impaired loans
Average Recorded Investment
Interest Income Recognized