Income taxes - Provision for income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. federal - Current	$ 948	$ 357	$ 483
Non-U.S. - Current	169	192	135
U.S. state - Current	18	10	12
Total current income tax expense (benefit)	1,135	559	630
U.S. federal - Deferred	(23)	(122)	25
Non-U.S. - Deferred	38	(15)	56
U.S. state - Deferred	0	0	0
Total deferred income tax expense (benefit)	15	(137)	81
Total U.S. federal income taxes	925	235	508
Total Non-U.S. income taxes	207	177	191
Total U.S. state income taxes	18	10	12
Provision for income taxes	$ 1,150	$ 422	$ 711