Other assets - Qualified Affordable Housing Project Investments (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Other Assets [Abstract]
Qualified affordable housing project investments	$ 1,255			$ 1,255		$ 1,153
Qualified affordable housing project investments, commitment	595			595		$ 543
Qualified affordable housing project commitment - remainder of 2022	92			92
Qualified affordable housing project commitment - 2023	210			210
Qualified affordable housing project commitment - 2024	144			144
Qualified affordable housing project commitment - 2025	90			90
Qualified affordable housing project commitment - 2026	21			21
Qualified affordable housing project commitment - 2027 and thereafter	38			38
Tax credits and other tax benefits	38	$ 38	$ 38	114	$ 114
Amortization expense included in the provision for income taxes	$ 32	$ 33	$ 32	$ 97	$ 96