Allowance for Credit Losses - Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Commercial	Jun. 30, 2011 Commercial	Jun. 30, 2012 Commercial	Jun. 30, 2011 Commercial	Dec. 31, 2011 Commercial	Jun. 30, 2012 Real Estate Portfolio Segment	Jun. 30, 2011 Real Estate Portfolio Segment	Jun. 30, 2012 Real Estate Portfolio Segment	Jun. 30, 2011 Real Estate Portfolio Segment	Dec. 31, 2011 Real Estate Portfolio Segment	Jun. 30, 2012 Consumer	Jun. 30, 2011 Consumer	Jun. 30, 2012 Consumer	Jun. 30, 2011 Consumer	Dec. 31, 2011 Consumer	Jun. 30, 2012 Unallocated	Jun. 30, 2011 Unallocated	Jun. 30, 2012 Unallocated	Jun. 30, 2011 Unallocated	Dec. 31, 2011 Unallocated
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance	$ 10,285	$ 11,019	$ 11,396	$ 11,014	$ 2,714	$ 2,960	$ 2,266	$ 2,437		$ 5,140	$ 6,536	$ 7,155	$ 5,836		$ 2,142	$ 998	$ 1,836	$ 2,503		$ 289	$ 525	$ 139	$ 238
Provision charged to operations	100	250	500	350	(124)	(40)	361	466		653	(513)	111	185		(513)	23	(206)	(1,368)		84	780	234	1,067
Losses charged to allowance	(512)	(420)	(2,181)	(741)	(16)	(70)	(122)	(226)		(319)	(221)	(1,792)	(247)		(177)	(129)	(267)	(268)		0	0	0	0
Recoveries	267	186	425	412	225	160	294	333		0	3	0	31		42	23	131	48		0	0	0	0
Allowance for credit losses, ending balance	10,140	11,035	10,140	11,396	2,799	3,010	2,799	3,010		5,474	5,805	5,474	5,805		1,494	915	1,494	915		373	1,305	373	1,305
Ending balance: individually evaluated for impairment	2,195		2,195	4,368	536		536		231	1,600		1,600		3,764	59		59		373	0		0		0
Ending balance: collectively evaluated for impairment	$ 7,945		$ 7,945	$ 7,028	$ 2,263		$ 2,263		$ 2,035	$ 3,874		$ 3,874		$ 3,391	$ 1,435		$ 1,435		$ 1,463	$ 373		$ 373		$ 139