Consolidated Balance Sheet (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Fixed maturities, available for sale at amortized cost	$ 22,083	$ 20,562
Equity securities, at cost	$ 778	$ 744
Common Stock, par value	$ 0	$ 0
Common Stock, shares authorized	200,000,000	200,000,000
Common Stock, shares outstanding	88,979,303	97,846,402