Income Taxes - Components of income tax expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of income tax expense (benefit)
Current	$ 841	$ 1,480	$ 919
Deferred	448	(107)	197
Total income tax expense	$ 1,289	$ 1,373	$ 1,116