Fair Value Measurement - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Carrying Value
Financial Assets:
Cash and cash equivalents	$ 15,430	$ 11,475
FHLB and FRB stock	1,146	1,392
Loans and leases held for investment, net	67,071	83,627
Financial Liabilities:
Deposits	75,870	81,526
Borrowed funds	14,426	21,267
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	15,430	11,475
FHLB and FRB stock	1,146	1,392
Loans and leases held for investment, net	61,831	79,333
Financial Liabilities:
Deposits	75,894	81,247
Borrowed funds	14,217	21,082
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Cash and cash equivalents	15,430	11,475
FHLB and FRB stock	0	0
Loans and leases held for investment, net	0	0
Financial Liabilities:
Deposits	48,546	59,972
Borrowed funds	0	0
Estimated Fair Value | Significant Other Observable Inputs (Level 2)
Financial Assets:
Cash and cash equivalents	0	0
FHLB and FRB stock	1,146	1,392
Loans and leases held for investment, net	0	0
Financial Liabilities:
Deposits	27,348	21,275
Borrowed funds	14,217	21,082
Estimated Fair Value | Significant Unobservable Inputs (Level 3)
Financial Assets:
Cash and cash equivalents	0	0
FHLB and FRB stock	0	0
Loans and leases held for investment, net	61,831	79,333
Financial Liabilities:
Deposits	0	0
Borrowed funds	$ 0	$ 0