Fair Value Measurements - Financial Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Mortgages Payable | Fair Value
Financial liabilities:
Financial liabilities	$ 1,699,355	$ 1,162,890
Mortgages Payable | Carrying Amount
Financial liabilities:
Financial liabilities	1,701,271	1,127,848
Revolving Credit Facility | Fair Value
Financial liabilities:
Financial liabilities		200,177
Revolving Credit Facility | Carrying Amount
Financial liabilities:
Financial liabilities		200,000
Tranche A-1 and A-2 Loans | Fair Value
Financial liabilities:
Financial liabilities	389,493	300,607
Tranche A-1 and A-2 Loans | Carrying Amount
Financial liabilities:
Financial liabilities	$ 400,000	$ 300,000