4. Credit Losses Recognized in Earnings (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Credit Losses Recognized In Earnings Details
Balance, beginning of period	$ (19,223)	$ (16,871)	$ (18,614)	$ (17,335)
Add: Credit losses on securities not previously impaired	0	(277)	(374)	(527)
Add: Credit losses on securities previously impaired	(549)	(100)	(784)	(344)
Less: Credit losses on securities impaired due to intent to sell	0	0	0	0
Less: Credit losses on securities sold	88	0	88	958
Less: Increases in cash flows expected on previously impaired securities	0	0	0	0
Balance, end of period	$ (19,684)	$ (17,248)	$ (19,684)	$ (17,248)