Fair Value Option and Fair Value Measurements (Details 3) (USD $)	3 Months Ended		6 Months Ended						6 Months Ended				6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2012 Nonrecurring basis Impaired loans	Dec. 31, 2011 Nonrecurring basis Impaired loans	Jun. 30, 2012 Nonrecurring basis Impaired loans Carrying Amount	Dec. 31, 2011 Nonrecurring basis Impaired loans Carrying Amount	Jun. 30, 2012 Nonrecurring basis Other real estate owned	Dec. 31, 2011 Nonrecurring basis Other real estate owned	Jun. 30, 2012 Nonrecurring basis Level 3	Dec. 31, 2011 Nonrecurring basis Level 3	Jun. 30, 2012 Nonrecurring basis Level 3 Impaired loans	Dec. 31, 2011 Nonrecurring basis Level 3 Impaired loans	Jun. 30, 2012 Nonrecurring basis Level 3 Other real estate owned	Dec. 31, 2011 Nonrecurring basis Level 3 Other real estate owned	Jun. 30, 2012 Nonrecurring basis Total	Dec. 31, 2011 Nonrecurring basis Total	Jun. 30, 2012 Nonrecurring basis Total Impaired loans	Dec. 31, 2011 Nonrecurring basis Total Impaired loans	Jun. 30, 2012 Nonrecurring basis Total Other real estate owned	Dec. 31, 2011 Nonrecurring basis Total Other real estate owned
Assets and liabilities measured at fair value
Total											$ 45,700,000	$ 64,100,000			$ 129,063,000	$ 144,365,000	$ 39,392,000	$ 51,075,000	$ 89,671,000	$ 93,290,000	$ 129,063,000	$ 144,365,000	$ 39,392,000	$ 51,075,000	$ 89,671,000	$ 93,290,000
Valuation allowance	6,347,000		6,347,000			13,054,000			6,300,000	13,000,000
Increase/decrease of specific allocations within the allowance for loan losses									6,700,000					9,900,000
Carrying value of loans fully charged									89,700,000	93,300,000
Outstanding balance													117,100,000	116,800,000
OREO Valuation allowance	27,469,000	21,504,000	27,469,000	21,504,000	23,994,000	23,462,000	21,883,000	22,220,000					27,500,000	23,500,000
OREO charge to expense	$ (5,127,000)	$ (4,109,000)	$ (7,627,000)	$ (6,434,000)									$ 7,600,000	$ 15,100,000