Income Taxes - Total income tax provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current taxes:
Federal	$ 250	$ 196	$ 153
State	10	8	6
Foreign	2	0	0
Deferred taxes:
Federal	(23)	(82)	5
Impact of change in U.S. corporate tax rate	0	0	83
Total Federal deferred taxes	(23)	(82)	88
Provision for income taxes as shown in the Statement of Earnings	$ 239	$ 122	$ 247