Loans - Schedule of Loan Portfolio (Details) - USD ($) $ in Thousands		Mar. 31, 2022	Dec. 31, 2021
Loans and Leases Receivable Disclosure [Line Items]
Total loans at fair value		$ 7,002,885	$ 5,952,972
Total loans	[1]	7,222,001	6,068,884
Commercial and consumer banking
Loans and Leases Receivable Disclosure [Line Items]
Total loans		79,728	0
Credit card loans and commercial loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans		219,116	115,912
Securitized student loans | Student loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans at fair value		513,378	574,328
Securitized personal loans | Personal loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans at fair value		177,179	234,576
Student loans | Student loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans at fair value		3,224,061	2,876,509
Home loans | Home loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans at fair value		146,658	212,709
Personal loans | Personal loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans at fair value		2,941,609	2,054,850
Credit card | Credit card loans
Loans and Leases Receivable Disclosure [Line Items]
Total loans		139,388	115,912
Commercial real estate | Commercial and consumer banking
Loans and Leases Receivable Disclosure [Line Items]
Total loans		67,627	0
Commercial and industrial | Commercial and consumer banking
Loans and Leases Receivable Disclosure [Line Items]
Total loans		8,760	0
Residential real estate and other consumer | Commercial and consumer banking
Loans and Leases Receivable Disclosure [Line Items]
Total loans		$ 3,341	$ 0

[1] Financial statement line items include amounts in consolidated variable interest entities (“VIEs”). See Note 5.(2)As of March 31, 2022 and December 31, 2021, includes loans held for sale measured at fair value of $7,002,885 and $5,952,972, respectively.