Condensed Financial Information of Parent Company (Details) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Fixed Maturities, Cost	$ 34,762	$ 35,061
Equity securities, Cost	1,264	1,285
Preferred Stock, Par Value	$ 1	$ 1
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Common Stock, Par Value	$ 1	$ 1
Common Stock, Shares Issued	371,980,460	371,980,460
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Treasury Stock, Shares	99,519,509	74,707,547
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Fixed Maturities, Cost	935	1,138
Equity securities, Cost	$ 200	$ 205
Preferred Stock, Par Value	$ 1	$ 1
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Common Stock, Par Value	$ 1	$ 1
Common Stock, Shares Issued	371,980,460	371,980,460
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Treasury Stock, Shares	99,519,509	74,707,547