Fair Value Measures - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Carrying Value
Financial Assets:
Cash and cash equivalents	$ 15,806	$ 2,032
FHLB and FRB stock	1,136	1,267
Loans and leases held for investment, net	82,684	68,608
Financial Liabilities:
Deposits	88,497	58,721
Borrowed funds	16,412	21,332
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	15,806	2,032
FHLB and FRB stock	1,136	1,267
Loans and leases held for investment, net	79,144	65,673
Financial Liabilities:
Deposits	88,245	58,479
Borrowed funds	16,161	21,231
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Cash and cash equivalents	15,806	2,032
FHLB and FRB stock	0	0
Loans and leases held for investment, net	0	0
Financial Liabilities:
Deposits	70,309	46,211
Borrowed funds		0
Estimated Fair Value | Significant Other Observable Inputs (Level 2)
Financial Assets:
Cash and cash equivalents		0
FHLB and FRB stock	1,136	1,267
Loans and leases held for investment, net		0
Financial Liabilities:
Deposits	17,936	12,268
Borrowed funds	16,161	21,231
Estimated Fair Value | Significant Unobservable Inputs (Level 3)
Financial Assets:
Cash and cash equivalents		0
FHLB and FRB stock		0
Loans and leases held for investment, net	79,144	65,673
Financial Liabilities:
Deposits		0
Borrowed funds		$ 0