Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 8,871	$ 8,638
Equity securities, cost	2,728	2,523
Land, building and equipment, accumulated depreciation	$ 446	$ 420
Common stock, par value	$ 2	$ 2
common stock, authorized	500,000,000	500,000,000
Common stock, issued	198,300,000	198,300,000
Common stock, shares outstanding	198,300,000	198,300,000
Treasury stock, shares	34,600,000	35,200,000