Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fixed-maturity securities held as available-for-sale, amortized cost	$ 4,774	$ 5,450
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	283,967,973	283,989,999
Accumulated other comprehensive income (loss), taxes	$ 10	$ 0
Accumulated other comprehensive income (loss), taxes	$ 6	$ 37
Treasury stock, shares	160,858,509	148,789,168
Non Variable Interest Entity [Member]
Fixed-maturity securities held as available-for-sale, amortized cost	$ 4,203	$ 4,713
Investments pledged as collateral, amortized cost	169	234
Short-term investments held as available-for-sale, amortized cost	452	552
Other investments, fair value	4	5
Medium-term notes, financial instruments carried at fair value	127	101
Variable Interest Entity Primary Beneficiary [Member]
Investments held-to-maturity, fair value	897	876
Variable interest entity notes, financial instruments carried at fair value	$ 1,140	$ 1,351