Schedule II (Condensed Balance Sheets) (Details) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Cash and cash equivalents	$ 633	$ 1,130	$ 803	$ 2,280
Total assets	26,873	32,279	25,701
Total liabilities	25,150	29,433
Preferred stock, par value $1 per share; authorized shares-10,000,000; issued and outstanding shares-none
Common stock, par value $1 per share; authorized shares-400,000,000; issued shares-274,896,162 and 274,719,578	275	275
Additional paid-in capital	3,072	3,064
Retained earnings	805	2,124
Accumulated other comprehensive loss, net of deferred tax of $134 and $222	(176)	(406)
Treasury stock, at cost-81,752,966 and 74,973,978 shares	(2,276)	(2,225)
Total shareholders' equity	1,700	2,832
Total liabilities and shareholders' equity	26,873	32,279
Short-term investments held as available-for-sale, amortized cost	9,025	12,822
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	274,896,162	274,719,578
Accumulated other comprehensive loss, net of deferred tax	105	229
Treasury stock, at cost-81,752,966 and 74,973,978 shares	(81,752,966)	(74,973,978)
Parent Company [Member]
Fixed-maturity securities held as available-for-sale, at fair value (amortized cost $1,989 and $2,988)	1,809	2,436
Investments held-to-maturity, at amortized cost (fair value $0 and $55)		59
Fixed-maturity securities at fair value	96	18
Investments pledged as collateral, at fair value (amortized cost $642 and $548)	543	552
Short-term investments held as available-for-sale, at fair value (amortized cost $648 and $992)	643	985
Other investments	83	183
Total	3,174	4,233
Cash and cash equivalents	132	83	149	1,123
Accrued investment income	20	23
Investment in wholly-owned subsidiaries	3,410	4,640
Affiliate loan receivable		128
Derivative assets	2	4
Current income taxes	31	156
Deferred income taxes, net	114	134
Receivable for investments sold	14	8
Other assets	70	41
Total assets	6,967	9,450
Investment agreements	1,523	1,940
Medium-term notes	50	45
Securities sold under agreements to repurchase	669	1,502
Short-term debt		65
Long-term debt	900	905
Affiliate loans payable	1,688	1,776
Derivative liabilities	356	241
Other liabilities	81	111
Total liabilities	5,267	6,585
Preferred stock, par value $1 per share; authorized shares-10,000,000; issued and outstanding shares-none
Common stock, par value $1 per share; authorized shares-400,000,000; issued shares-274,896,162 and 274,719,578	275	275
Additional paid-in capital	3,072	3,064
Retained earnings	805	2,209
Accumulated other comprehensive loss, net of deferred tax of $134 and $222	(176)	(458)
Treasury stock, at cost-81,752,966 and 74,973,978 shares	(2,276)	(2,225)
Total shareholders' equity	1,700	2,865
Total liabilities and shareholders' equity	6,967	9,450
Fixed-maturity securities held as available-for-sale, amortized cost	1,989	2,988
Investments held-to-maturity, fair value	0	55
Investments pledged as collateral, amortized cost	623	548
Short-term investments held as available-for-sale, amortized cost	648	992
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	274,896,162	274,719,578
Accumulated other comprehensive loss, net of deferred tax	$ 134	$ 222
Treasury stock, at cost-81,752,966 and 74,973,978 shares	81,752,966	74,973,978