Income Taxes - Effective tax rates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income tax reconciliation
Tax expense (benefit) at the U.S. Federal statutory income tax rate	$ 192	$ (206)	$ 57
State and local taxes, net of Federal benefit	31	(2)	23
Non-deductible FDIC assessment fees	13	15	5
Non-deductible goodwill impairment	0	165	77
Items affecting prior periods	0	3	7
Uncertain tax positions	6	(8)	5
Low income housing and other tax credit investments	(15)	(14)	(13)
Other	(3)	5	(4)
Provision (benefit) for income taxes	$ 224	$ (42)	$ 157
Effective income tax reconciliation
Tax expense (benefit) at the U.S. federal statutory income tax rate (in percent)	21.00%	(21.00%)	21.00%
State and local taxes, net of federal benefit (in percent)	3.40%	(0.20%)	8.50%
Non-deductible FDIC assessment fees (in percent)	1.40%	1.50%	1.90%
Non-deductible goodwill impairment (in percent)	0.00%	16.80%	28.50%
Items affecting prior periods (in percent)	0.00%	0.30%	2.60%
Uncertain tax positions (in percent)	0.70%	(0.80%)	1.90%
Low income housing and other tax credit investments (in percent)	(1.70%)	(1.40%)	(4.80%)
Other (in percent)	(0.20%)	0.50%	(1.50%)
Effective tax rate (in percent)	24.60%	(4.30%)	58.10%