Condensed Consolidated Balance Sheets - (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Fixed maturities securities at amortized cost	$ 37,940	$ 38,085
Equity securities at cost	812	844
Allowance for uncollectible reinsurance	29	29
Allowance for uncollectible insurance receivables	41	42
Accumulated depreciation on property and equipment	214	216
Due to related parties	31	23
Due from related parties	$ 0	$ 8
Common stock, par value (in usd per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	273,040,243	273,040,243
Common stock, shares outstanding (in shares)	271,527,510	271,456,978
Treasury stock, shares (in shares)	1,512,733	1,583,265