Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 11,312	$ 11,108
Equity securities, cost	3,927	3,581
Land, building and equipment, accumulated depreciation	$ 285	$ 276
Common stock, par value	$ 2	$ 2
common stock, authorized	500,000	500,000
Common stock, issued	198,300	198,300
Treasury stock, shares	37,400	35,400