Income Taxes - Provision for Federal & Foreign Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Operations	$ 1,292	$ 698	$ 975
One-time charge due to tax legislation	0	0	(6)
Deferred
Operations	21	235	(194)
One-time charge due to tax legislation	0	0	(37)
Total federal income tax expense	1,313	933	738
Foreign income tax expense (benefit):
Current	50	91	67
Deferred	(16)	(13)	(13)
Total foreign income tax expense	34	78	54
Total income tax expense	$ 1,347	$ 1,011	$ 792