Fair Value Measurement - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financial assets:
Loans Held-for-sale, Fair Value Disclosure	$ 1,700	$ 1,000
Level 1
Financial assets:
Cash and cash equivalents	3,716	4,164
Restricted cash for securitization investors	399	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	21,176	17,582
Restricted cash for securitization investors	0	0
Net loans held for investment	0	0
Loans Held-for-sale, Fair Value Disclosure	5	5,091
Interest receivable	1,853	1,460
Other investments	1,623	1,344
Financial liabilities:
Deposits with defined maturities	34,380	18,062
Securitized debt obligations	15,878	15,122
Senior and subordinated notes	30,302	27,842
Federal funds purchased and securities loaned or sold under agreements to repurchase	528	820
Other borrowings	7,500
Interest payable	433	281
Level 3
Financial assets:
Cash and cash equivalents	0	0
Restricted cash for securitization investors	0	0
Net loans held for investment	296,142	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	24,892	21,746
Restricted cash for securitization investors	399	308
Net loans held for investment	291,734	265,910
Loans Held-for-sale, Fair Value Disclosure	5	4,862
Interest receivable	1,853	1,460
Other investments	1,623	1,344
Financial liabilities:
Deposits with defined maturities	34,758	17,923
Securitized debt obligations	15,926	14,994
Senior and subordinated notes	30,615	27,219
Federal funds purchased and securities loaned or sold under agreements to repurchase	528	820
Other borrowings	7,500
Interest payable	433	281
Estimated Fair Value
Financial assets:
Cash and cash equivalents	24,892	21,746
Restricted cash for securitization investors	399	308
Net loans held for investment	296,142	270,508
Loans Held-for-sale, Fair Value Disclosure	5	5,091
Interest receivable	1,853	1,460
Other investments	1,623	1,344
Financial liabilities:
Deposits with defined maturities	34,380	18,062
Securitized debt obligations	15,878	15,122
Senior and subordinated notes	30,302	27,842
Federal funds purchased and securities loaned or sold under agreements to repurchase	528	820
Other borrowings	7,500
Interest payable	$ 433	$ 281