Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Net Income	$ 27,761	$ 320,886	$ 50,439	$ 334,177
Accumulated other comprehensive income [Roll Forward]
Beginning balance, accumulated other comprehensive income	56,076	65,571	60,712	61,115
Change in unrealized gains on investments and MBS available-for-sale	(40,198)	7,714	(47,557)	12,312
Realized net gains reclassified from other comprehensive income	0	(2,502)	0	(2,644)
Less deferred income tax benefit (provision)	14,873	(3,681)	17,596	(3,681)
Net other comprehensive (loss) income	(25,325)	1,531	(29,961)	5,987
Ending balance, accumulated other comprehensive income	30,751	67,102	30,751	67,102
Comprehensive Income	$ 2,436	$ 322,417	$ 20,478	$ 340,164