Other Real Estate Owned (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Real Estate Acquired Through Foreclosure [Roll Forward]
Balance at beginning of year	$ 37,452	$ 33,632	$ 38,400
Additions	43,541	26,644	21,314
Capitalized improvements	75	14	240
Valuation adjustments	(6,724)	(7,464)	(6,724)
Dispositions	(41,773)	(15,374)	(19,598)
Balance at end of year	32,571	37,452	33,632
Valuation adjustments	(6,724)	(7,464)	(6,724)
Write-down due to change in appraised value	702	4,197	2,491
Write-down due to change in management estimates	$ 6,022	$ 3,267	$ 4,233