SCHEDULE II - Condensed Statements of Operations - Parent Company Only (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Net investment income (loss)	$ 155,500	$ 163,700	$ 158,300	$ 151,600	$ 160,800	$ 164,400	$ 174,500	$ 173,100	$ 629,148	$ 672,782	$ 596,071
Net realized and unrealized investment gains (losses)	74,600	26,100	78,200	(112,200)	(83,200)	293,200	46,000	145,500	66,692	401,482	591,707
Total revenues	1,414,600	1,485,500	1,345,600	1,105,800	1,287,300	1,774,300	1,325,900	1,473,700	5,351,509	5,861,205	5,418,342
Expenses
Other operating expenses	113,000	103,800	113,700	104,300	133,200	118,200	160,200	128,100	434,846	539,751	430,808
Interest expense	12,300	12,200	12,200	12,300	12,200	12,300	12,800	7,100	48,949	44,413	28,301
Net foreign exchange (gains) losses	(14,700)	(10,600)	(8,700)	(700)	8,300	27,100	(11,000)	(3,600)	(34,675)	20,686	1,464
Net (loss) income	(17,600)	180,100	124,200	(807,000)	57,000	524,900	190,900	79,600	(520,291)	852,552	1,536,854
[ParentCompanyMember]
Revenues
Net investment income (loss)									2,452	1,745	(375)
Net realized and unrealized investment gains (losses)									5,499	(3,884)	18,582
Total revenues									7,951	(2,139)	18,207
Expenses
Other operating expenses									76,690	92,361	103,293
Interest expense on intercompany loans									739	5,609	6,425
Interest expense									0	301	3,919
Net foreign exchange (gains) losses									(9,540)	17,244	4,517
Total expenses									67,889	115,515	118,154
Loss before equity in net (loss) income of subsidiaries									(59,938)	(117,654)	(99,947)
Equity in net (loss) income of subsidiaries									(460,353)	970,206	1,636,801
Net (loss) income									$ (520,291)	$ 852,552	$ 1,536,854