SCHEDULE II - Condensed Statements of Operations - Parent Company Only (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues
Net investment income	$ 135,700	$ 135,300	$ 153,500	$ 146,900	$ 155,500	$ 163,700	$ 158,300	$ 151,600	$ 571,338	$ 629,148	$ 672,782
Net realized and unrealized investment gains (losses)	5,100	257,400	38,100	192,700	74,600	26,100	78,200	(112,200)	493,409	66,692	401,482
Total revenues	1,312,700	1,632,500	1,285,100	1,332,200	1,414,600	1,485,500	1,345,600	1,105,800	5,562,606	5,351,509	5,861,205
Expenses
Other operating expenses	112,300	94,700	106,200	98,200	113,000	103,800	113,700	104,300	411,374	434,846	539,751
Interest expense	12,200	12,200	12,200	12,200	12,300	12,200	12,200	12,300	48,895	48,949	44,413
Net foreign exchange losses (gains)	3,400	2,000	(7,700)	2,600	(14,700)	(10,600)	(8,700)	(700)	175	(34,675)	20,686
Net income (loss)	111,500	486,700	176,100	360,100	(17,600)	180,100	124,200	(807,000)	1,134,514	(520,291)	852,552
Total other comprehensive income (loss), net of tax									23,241	(16,700)	(80,871)
Comprehensive income (loss)									1,157,755	(536,991)	771,681
[ParentCompanyMember]
Revenues
Net investment income									1,152	2,452	1,745
Net realized and unrealized investment gains (losses)									2,208	5,499	(3,884)
Total revenues									3,360	7,951	(2,139)
Expenses
Other operating expenses									82,137	76,690	92,361
Interest expense on intercompany loans									730	739	5,609
Interest expense									0	0	301
Net foreign exchange losses (gains)									1,085	(9,540)	17,244
Total expenses									83,952	67,889	115,515
Loss before equity in net income (loss) of subsidiaries									(80,592)	(59,938)	(117,654)
Equity in net income (loss) of subsidiaries									1,215,106	(460,353)	970,206
Net income (loss)									1,134,514	(520,291)	852,552
Total other comprehensive income (loss), net of tax									23,241	(16,700)	(80,871)
Comprehensive income (loss)									$ 1,157,755	$ (536,991)	$ 771,681