Restricted Cash, Other Assets and Accrued and Other Liabilities - Summary of Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 84,011	$ 126,065	$ 114,127	$ 110,146
Borrower escrow deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	50,605	74,496
Real estate escrow reserves
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	19,354	18,020
Capital expenditure reserves
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	6,499	8,882
Working capital and other reserves
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	3,882	4,198
Margin pledged as collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	2,633	19,536
Tenant lockboxes
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 1,038	$ 933