Fair Value Measurement - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financial assets:
Loans Held-for-sale, Fair Value Disclosure	$ 767	$ 1,000
Level 1
Financial assets:
Cash and cash equivalents	4,825	4,164
Restricted cash for securitization investors	697	308
Net loans held for investment	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Interest receivable	0	0
Other investments	0	0
Financial liabilities:
Deposits with defined maturities	0	0
Securitized debt obligations	0	0
Senior and subordinated notes	0	0
Federal funds purchased and securities loaned or sold under agreements to repurchase	0	0
Other borrowings	0
Interest payable	0	0
Level 2
Financial assets:
Cash and cash equivalents	16,728	17,582
Restricted cash for securitization investors	0	0
Net loans held for investment	0	0
Loans Held-for-sale, Fair Value Disclosure	110	5,091
Interest receivable	1,611	1,460
Other investments	1,735	1,344
Financial liabilities:
Deposits with defined maturities	22,026	18,062
Securitized debt obligations	17,446	15,122
Senior and subordinated notes	30,152	27,842
Federal funds purchased and securities loaned or sold under agreements to repurchase	440	820
Other borrowings	10,501
Interest payable	333	281
Level 3
Financial assets:
Cash and cash equivalents	0	0
Restricted cash for securitization investors	0	0
Net loans held for investment	287,254	270,508
Loans Held-for-sale, Fair Value Disclosure	0	0
Interest receivable	0	0
Other investments	0	0
Financial liabilities:
Deposits with defined maturities	0	0
Securitized debt obligations	0	0
Senior and subordinated notes	0	0
Federal funds purchased and securities loaned or sold under agreements to repurchase	0	0
Other borrowings	0
Interest payable	0	0
Carrying Value
Financial assets:
Cash and cash equivalents	21,553	21,746
Restricted cash for securitization investors	697	308
Net loans held for investment	284,893	265,910
Loans Held-for-sale, Fair Value Disclosure	108	4,862
Interest receivable	1,611	1,460
Other investments	1,735	1,344
Financial liabilities:
Deposits with defined maturities	22,225	17,923
Securitized debt obligations	17,466	14,994
Senior and subordinated notes	30,489	27,219
Federal funds purchased and securities loaned or sold under agreements to repurchase	440	820
Other borrowings	10,500
Interest payable	333	281
Estimated Fair Value
Financial assets:
Cash and cash equivalents	21,553	21,746
Restricted cash for securitization investors	697	308
Net loans held for investment	287,254	270,508
Loans Held-for-sale, Fair Value Disclosure	110	5,091
Interest receivable	1,611	1,460
Other investments	1,735	1,344
Financial liabilities:
Deposits with defined maturities	22,026	18,062
Securitized debt obligations	17,446	15,122
Senior and subordinated notes	30,152	27,842
Federal funds purchased and securities loaned or sold under agreements to repurchase	440	820
Other borrowings	10,501
Interest payable	$ 333	$ 281