Other income and operating expenses - Income and Expenses Related to Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other income
LSP origination fees	$ 12,415	$ 40,836	$ 5,860
Interest income	403,496	258,636	229,916
Interest and Fee Income	295,622	243,648	218,267
Other operating expenses
Direct operating expenses	24,337	19,815	10,168
R&D reserve	(10,168)	(4,133)	345
Interest expense	213,561	175,481	151,880
Total other operating expenses	58,401	54,369	33,162
Net income	159,974	46,069	$ 75,056
Paycheck Protection Program loans
Other income
Interest and Fee Income	89,615	38,498
Other operating expenses
Total other operating expenses	33,554	15,079
Net income	56,061	23,419
Paycheck Protection Program loans | Other Income
Other income
LSP origination fees		27,768
PPP processing fees		5,162
Other operating expenses
R&D reserve	9,539	3,305
Paycheck Protection Program loans | Servicing income
Other income
LSP fee income	10,414	4,829
Paycheck Protection Program loans | Interest income
Other income
Interest income	79,201	739
Paycheck Protection Program loans | Other operating expenses
Other operating expenses
Direct operating expenses	8,241	9,600
Paycheck Protection Program loans | Interest expense
Other operating expenses
Interest expense	$ 15,774	$ 2,174