Income Taxes (Details) - Effective Tax Rate - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. income before income taxes									$ 3,095	$ 3,211	$ 3,039
Foreign income (loss) before income taxes									142	(73)	(78)
Income before income taxes	$ 1,616	$ 986	$ (85)	$ 720	$ 1,074	$ 432	$ 665	$ 967	$ 3,237	$ 3,138	$ 2,961
Statutory tax rate (percent)									21.00%	21.00%	21.00%
Expected federal income tax expense									$ 680	$ 659	$ 622
Tax effect of nontaxable investment income									(147)	(149)	(150)
Tax effect of other, net									7	6	(34)
Total income tax expense included in the consolidated statement of income	306	$ 159	$ (45)	$ 120	201	$ 36	$ 108	$ 171	$ 540	$ 516	$ 438
Effective tax rate (percent)									17.00%	16.00%	15.00%
Income taxes paid									$ 578	$ 428	$ 408
Current income tax payable	$ 131				$ 126				$ 131	$ 126