Income Taxes - Reconciliation of unrecognized tax benefits (UTB) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Federal, State and Foreign Tax
Gross UTB Balance, beginning balance	$ 927	$ 1,071	$ 1,113
Additions based on tax positions related to the current year	11	115	91
Additions for tax positions of prior years	63	36	22
Reductions for tax positions of prior years	(53)	(138)	(60)
Settlements	(34)	(118)	(57)
Reductions due to lapse of applicable statute of limitations	(114)	(39)	(38)
Gross UTB Balance, ending balance	$ 800	$ 927	$ 1,071