Other income and operating expenses - Income and Expenses Related to Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other income
LSP origination fees	$ 1,613	$ 2,495
Interest income	73,371	69,551
Interest and Fee Income	60,617	66,436
Other operating expenses
Direct operating expenses	8,145	3,025
R&D reserve	(2,069)	136
Interest expense	50,761	46,930
Total other operating expenses	15,484	13,744
Net income (loss)	28,947	$ (51,516)
Paycheck Protection Program loans
Other income
Interest and Fee Income	13,633
Other operating expenses
Total other operating expenses	10,062
Net income (loss)	3,571
Paycheck Protection Program loans | Other Income
Other operating expenses
R&D reserve	1,656
Paycheck Protection Program loans | Servicing income
Other income
LSP fee income	6,741
Paycheck Protection Program loans | Interest income
Other income
Interest income	6,892
Paycheck Protection Program loans | Other operating expenses
Other operating expenses
Direct operating expenses	4,545
Paycheck Protection Program loans | Interest expense
Other operating expenses
Interest expense	$ 3,861