Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 8,961	$ 8,871
Equity securities, cost	2,748	2,728
Short-term investments, amortized cost	25	0
Land, building and equipment, accumulated depreciation	$ 452	$ 446
Common stock, par value	$ 2	$ 2
Common stock, authorized	500	500
Common stock, issued	198.3	198.3
Common stock, outstanding	198.3	198.3
Treasury stock, shares	34.0	34.6