Deposits - Weighted Average Interest Rates for Each Type of Deposit (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deposits:
Interest-bearing checking and money market accounts	$ 13,209	$ 12,610
Savings accounts	8,892	6,416
Certificates of deposit	8,424	10,331
Non-interest-bearing accounts	4,534	3,080
Total deposits	$ 35,059	$ 32,437
Percent of Total
Interest-bearing checking and money market accounts	37.68%	38.87%
Savings accounts	25.36%	19.78%
Certificates of deposit	24.03%	31.85%
Non-interest-bearing accounts	12.93%	9.50%
Total deposits	100.00%	100.00%
Weighted Average Interest Rate
Interest-bearing checking and money market accounts, weighted average interest rate	0.20%	0.28%
Savings accounts, weighted average interest rate	0.35%	0.41%
Certificates of deposit, weighted average interest rate	0.52%	0.83%
Total deposits, weighted average interest rate	0.29%	0.45%