Securitizations and Variable Interest Entities - Summary of Select Information Related to VIEs (Details) - USD ($) $ in Thousands		Jun. 30, 2021	Dec. 31, 2020
Assets
Restricted cash	[1]	$ 123,896	$ 103,522
Securities available for sale at fair value		277,505	142,226
Loans held for sale at fair value		180,061	121,902
Retail and certificate loans held for investment at fair value	[1]	391,362	636,686
Other loans held for investment at fair value		2,299,045	0
Other assets	[1]	278,403	187,399
Total assets		4,370,101	1,863,293
Liabilities
Retail notes, certificates and secured borrowings at fair value	[1]	391,384	636,774
Payable on Structured Program borrowings	[1]	110,871	152,808
Other liabilities	[1]	285,871	244,551
Total liabilities		3,607,742	1,139,122
Consolidated VIEs
Assets
Restricted cash		16,472	15,983
Securities available for sale at fair value		0	0
Loans held for sale at fair value		69,105	98,190
Retail and certificate loans held for investment at fair value		23,810	52,620
Other loans held for investment at fair value		34,275	50,102
Other assets		764	1,270
Total assets		144,426	218,165
Liabilities
Retail notes, certificates and secured borrowings at fair value		23,810	52,620
Payable on Structured Program borrowings		110,871	152,808
Other liabilities		386	729
Total liabilities		135,067	206,157
Total net assets		9,359	12,008
Unconsolidated VIEs
Assets
Restricted cash		0	0
Securities available for sale at fair value		95,474	142,026
Loans held for sale at fair value		0	0
Retail and certificate loans held for investment at fair value		0	0
Other loans held for investment at fair value		0	0
Other assets		23,008	32,865
Total assets		118,482	174,891
Liabilities
Retail notes, certificates and secured borrowings at fair value		0	0
Payable on Structured Program borrowings		0	0
Other liabilities		0	0
Total liabilities		0	0
Total net assets		118,482	174,891
Total
Assets
Restricted cash		16,472	15,983
Securities available for sale at fair value		95,474	142,026
Loans held for sale at fair value		69,105	98,190
Retail and certificate loans held for investment at fair value		23,810	52,620
Other loans held for investment at fair value		34,275	50,102
Other assets		23,772	34,135
Total assets		262,908	393,056
Liabilities
Retail notes, certificates and secured borrowings at fair value		23,810	52,620
Payable on Structured Program borrowings		110,871	152,808
Other liabilities		386	729
Total liabilities		135,067	206,157
Total net assets		$ 127,841	$ 186,899

[1] Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below.