Other income and operating expenses - Balance Sheet Impact of PPP Activities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets
Restricted cash	$ 47,697	$ 51,728	$ 28,921
PPP loans, at fair value	1,658,779	1,733,864
Other assets
Accrued interest	12,656	10,583
Total Assets	5,372,095	4,977,018
Liabilities
Secured borrowings	1,370,519	1,189,392
Interest payable	19,695	17,305
Deferred PPP loan revenue	10,700
Repair and denial reserve	9,557	5,179
Total Liabilities	4,537,887	$ 4,132,234
PPP Loans
Assets
Restricted cash	178
PPP loans, at fair value	74,931
Other assets
Prepaid expenses	77
PPP fee receivable	18
Accrued interest	510
Total Assets	75,714
Liabilities
Secured borrowings	76,276
Interest payable	104
Deferred PPP loan revenue	10,700
Accrued PPP Related Costs	498
Payable to third parties	2,716
Repair and denial reserve	3,305
Total Liabilities	$ 93,599