Real Estate - Schedule of Development in Process Activities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property
Property, Plant and Equipment [Line Items]
Number of properties under development | property	3	3	5
Real estate under development, beginning balance	$ 253,402	$ 120,297	$ 173,702
Transfers In	117,344	0
Capitalized Costs	25,580	45,867
Transfers Out	$ 9,819	$ 99,272
Core Portfolio
Property, Plant and Equipment [Line Items]
Number of properties under development | property	0	1	2
Real estate under development, beginning balance	$ 60,863	$ 7,759	$ 21,897
Transfers In	57,342	0
Capitalized Costs	5,581	6,320
Transfers Out	$ 9,819	$ 20,458
Fund Portfolio | Fund II
Property, Plant and Equipment [Line Items]
Number of properties under development | property	0	0	0
Real estate under development, beginning balance	$ 10,703	$ 7,462	$ 4,908
Transfers In	0	0
Capitalized Costs	3,241	2,554
Transfers Out	$ 0	$ 0
Fund Portfolio | Fund III
Property, Plant and Equipment [Line Items]
Number of properties under development | property	1	1	2
Real estate under development, beginning balance	$ 36,240	$ 21,242	$ 63,939
Transfers In	12,313	0
Capitalized Costs	2,685	36,117
Transfers Out	$ 0	$ 78,814
Fund Portfolio | Fund IV
Property, Plant and Equipment [Line Items]
Number of properties under development | property	2	1	1
Real estate under development, beginning balance	$ 145,596	$ 83,834	$ 82,958
Transfers In	47,689	0
Capitalized Costs	14,073	876
Transfers Out	$ 0	$ 0