Fair Value Measurements (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets and liabilities measured at fair value
Valuation allowance	$ 6,259,000	$ 13,054,000
OREO Valuation allowance	31,454,000	23,462,000	22,220,000
OREO charge to expense	(16,385,000)	(15,114,000)
Nonrecurring basis | Impaired loans
Assets and liabilities measured at fair value
Valuation allowance	6,300,000	13,000,000
Decrease of specific allocations within the allowance for loan losses	6,800,000	9,900,000
Nonrecurring basis | Impaired loans | Carrying Amount
Assets and liabilities measured at fair value
Total	27,800,000	64,100,000
Nonrecurring basis | Other real estate owned, net
Assets and liabilities measured at fair value
Carrying value of loans fully charged	72,400,000	93,300,000
Outstanding balance	109,700,000	116,800,000
OREO Valuation allowance	31,400,000	23,500,000
OREO participations	5,900,000
OREO charge to expense	16,400,000	15,100,000
Nonrecurring basis | Level 3
Assets and liabilities measured at fair value
Total	93,966,000	144,365,000
Nonrecurring basis | Level 3 | Impaired loans
Assets and liabilities measured at fair value
Total	21,543,000	51,075,000
Nonrecurring basis | Level 3 | Other real estate owned, net
Assets and liabilities measured at fair value
Total	72,423,000	93,290,000
Nonrecurring basis | Total
Assets and liabilities measured at fair value
Total	93,966,000	144,365,000
Nonrecurring basis | Total | Impaired loans
Assets and liabilities measured at fair value
Total	21,543,000	51,075,000
Nonrecurring basis | Total | Other real estate owned, net
Assets and liabilities measured at fair value
Total	$ 72,423,000	$ 93,290,000