Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Statement of Income and Comprehensive Income [Abstract]
Net income	$ 91,464	$ 72,610	$ 180,867	$ 125,201
Other comprehensive income (loss), net of tax:
Net realized and unrealized holding gains (losses) on investments	6,431	(4,272)	29,045	(36,060)
Reclassification for net losses on investments included in earnings	821	4,636	6,619	6,590
Noncredit-related impairment losses on securities not expected to be sold	(10,323)	(729)	(15,303)	(729)
Accretion of securities with noncredit-related impairment losses not expected to be sold	367	73	532	99
Net unrealized losses on derivative instruments	(1,876)	(5,036)	(4,956)	(13,095)
Other comprehensive income (loss)	(4,580)	(5,328)	15,937	(43,195)
Comprehensive income	86,884	67,282	196,804	82,006
Comprehensive loss applicable to noncontrolling interests	(273)	(265)	(546)	(491)
Comprehensive income applicable to controlling interest	$ 87,157	$ 67,547	$ 197,350	$ 82,497