Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fixed-maturity securities held as available-for-sale, amortized cost	$ 3,852	$ 4,438
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	283,625,689	283,717,973
Accumulated other comprehensive income (loss), taxes	$ 7	$ 16
Treasury stock, shares	192,936,029	192,233,526
Non Variable Interest Entity [Member]
Fixed-maturity securities held as available-for-sale, amortized cost	$ 3,562	$ 3,728
Investments pledged as collateral, amortized cost	32	147
Short-term investments held as available-for-sale, amortized cost	411	589
Other investments, fair value	0	4
Medium-term notes, financial instruments carried at fair value	123	115
Variable Interest Entity Primary Beneficiary [Member]
Investments held-to-maturity, fair value	901	916
Variable interest entity notes, financial instruments carried at fair value	$ 709	$ 1,069