Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net Income	$ 21,048	$ 30,598	$ 71,487	$ 364,775
Accumulated other comprehensive income [Roll Forward]
Beginning balance, accumulated other comprehensive income	30,751	67,102	60,712	61,115
Change in unrealized gains on investments and MBS available-for-sale	(1,321)	16,235	(48,878)	28,547
Realized net gains reclassified from other comprehensive income	0	(3,129)	0	(5,773)
Less deferred income tax benefit (provision)	489	(4,945)	18,085	(8,626)
Net other comprehensive (loss) income	(832)	8,161	(30,793)	14,148
Ending balance, accumulated other comprehensive income	29,919	75,263	29,919	75,263
Comprehensive Income	$ 20,216	$ 38,759	$ 40,694	$ 378,923