Fair Value - Summary of Assets Carried at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and preferred equity held for investment, net	$ 2,103,414	$ 2,576,332
Real estate, net	1,133,318	1,484,796
Assets held for sale	203,466	189,470
Fair value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and preferred equity held for investment, net	0	104,797
Loans held for sale	0	5,016
Real estate, net	0	423,540
Assets held for sale	142,559	117,880
Investments in unconsolidated ventures - PE Investments	0	124,860
Deferred leasing costs and intangible assets, net	0	41,862
Fair value, measurements, nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and preferred equity held for investment, net	0	0
Loans held for sale	0	0
Real estate, net	0	0
Assets held for sale	0	0
Investments in unconsolidated ventures - PE Investments	0	0
Deferred leasing costs and intangible assets, net	0	0
Fair value, measurements, nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and preferred equity held for investment, net	0	0
Loans held for sale	0	0
Real estate, net	0	0
Assets held for sale	0	0
Investments in unconsolidated ventures - PE Investments	0	0
Deferred leasing costs and intangible assets, net	0	0
Fair value, measurements, nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and preferred equity held for investment, net	0	104,797
Loans held for sale	0	5,016
Real estate, net	0	423,540
Assets held for sale	142,559	117,880
Investments in unconsolidated ventures - PE Investments	0	124,860
Deferred leasing costs and intangible assets, net	$ 0	$ 41,862