Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 89,403	$ 52,591
Other comprehensive income (loss), net of tax:
Net realized and unrealized holding gains (losses) on investments	22,614	(31,788)
Reclassification for net losses on investments included in earnings	5,798	1,954
Noncredit-related impairment losses on securities not expected to be sold	(4,980)
Accretion of securities with noncredit-related impairment losses not expected to be sold	165	26
Net unrealized losses on derivative instruments	(3,080)	(8,059)
Other comprehensive income (loss)	20,517	(37,867)
Comprehensive income	109,920	14,724
Comprehensive loss applicable to noncontrolling interests	(273)	(226)
Comprehensive income applicable to controlling interest	$ 110,193	$ 14,950