Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule of Condensed Financial Information of Registrant, Statements of Operations) (Details) (USD $) In Millions, 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
Other revenues									$ 294	$ 292	$ 288
Total revenues	2,259	2,175	2,198	2,315	2,298	2,363	2,233	2,315	8,947	9,209	8,472
Expenses
Interest									175	157	128
Income tax (expense) benefit									(246)	(333)	(57)
Net income (loss)	190	75	126	223	302	(140)	283	245	614	690	419
Parent Company [Member]
Revenues
Net Investment Income									1	4	3
Net realized investment gains (losses)									(9)	(1)	8
Other revenues									40	96	101
Total revenues									32	99	112
Expenses
Administrative and general									3	5	2
Interest									167	148	116
Total expenses									170	153	118
Gain (loss) from operations before income taxes and equity in net income (loss) of subsidiaries									(138)	(54)	(6)
Income tax (expense) benefit									46	19	2
Gain (loss) before equity in net income (loss) of subsidiaries									(92)	(35)	(4)
Equity in net income (loss) of subsidiaries									706	725	423
Net income (loss)									$ 614	$ 690	$ 419