Summary of Significant Accounting Policies (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) class item	Dec. 31, 2018 USD ($)
Amount in money market mutual funds	$ 0	$ 600
Number of days loans must be delinquent to be placed on nonaccrual status	90 days
Number of separate classes of servicing rights used for risk management purposes | class	2
Number of repurchase agreements accounted for as components of linked transactions | item	0
Unrecognized accrued taxes, interest and penalties	$ 0	0
The number of consecutive months contractual payments that must be received on a loan in non-accrual status before resuming recognition of interest income | item	3
Borrowings under credit facilities | Maximum
Maturity period	2 years
Restricted cash
Cash collateral receivable	$ 21,500	$ 11,600