Fair Value Measurements, Level 3 Unobservable Inputs (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of assets and liabilities measured at fair value using significant unobservable inputs (Level 3) [Roll Forward]
Beginning balance, at fair value	$ 2,933	$ 4,480
OTTI impairment losses	(164)	(96)
Sales and principal payments	(501)	(1,509)
Change in unrealized loss	505	58
Ending balance, at fair value	$ 2,773	$ 2,933