Commitments and Contingencies - Summary of Commitments (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Commitments and Contingencies
Investment Commitment	$ 208,201
2018 Funding	25,144
Commitments funded	92,653
Remaining commitment	115,548
Real estate properties
Commitments and Contingencies
Investment Commitment	92,971
2018 Funding	17,847
Commitments funded	42,846
Remaining commitment	50,125
Accrued incentives and earn-out liabilities
Commitments and Contingencies
Investment Commitment	23,000
Remaining commitment	23,000
Lease incentives and rent abatements
Commitments and Contingencies
Investment Commitment	7,380
2018 Funding	2,546
Commitments funded	4,791
Remaining commitment	2,589
Mortgage loans
Commitments and Contingencies
Investment Commitment	58,700
2018 Funding	4,254
Commitments funded	21,505
Remaining commitment	37,195
Joint venture investments
Commitments and Contingencies
Investment Commitment	25,650
2018 Funding	497
Commitments funded	23,511
Remaining commitment	2,139
Notes receivable
Commitments and Contingencies
Investment Commitment	500
Remaining commitment	$ 500