Equity, Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated net income	$ 16,814,000	$ 83,671,000	$ 90,803,000	$ 328,849,000
Other Comprehensive Income (Loss), Net of Tax:
Change in unrealized (loss) gain on investments	8,400,000	(8,700,000)	17,500,000	(5,800,000)
Change in foreign currency translation adjustment	5,200,000	(7,500,000)	5,300,000	1,700,000
Total other comprehensive (loss) income	13,600,000	(16,200,000)	22,800,000	(4,100,000)
Consolidated comprehensive income	30,400,000	67,500,000	113,600,000	324,700,000
Adjust for comprehensive loss attributable to noncontrolling interest	0	0	0	100,000
Comprehensive income	$ 30,403,000	$ 67,425,000	$ 113,620,000	$ 324,756,000