Related Party Transactions (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) unit	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($) investment	Dec. 31, 2016 USD ($)	Nov. 30, 2016 USD ($)
Related Party Transaction [Line Items]
Management and other fees from affiliates		$ 2,900	$ 3,200	$ 5,900	$ 6,500
Development and redevelopment fees		600	$ 1,100	1,400	2,400
Co-investments		1,081,084		1,081,084			$ 1,161,275
Payments to acquire preferred equity investments				144,599	$ 96,698
Short-term loans outstanding and due from various joint ventures		4,400		4,400			4,700
Notes receivable		54,660		54,660			40,970
Secured Note Receivable, 9.5% Interest Rate, Due October 2019 [Member]
Related Party Transaction [Line Items]
Notes receivable		6,596		6,596			6,593
Limited Liability Company [Member]
Related Party Transaction [Line Items]
Payments to acquire preferred equity investments						$ 20,000
Number of preferred equity method investments acquired during period (in investments) | investment						3
Preferred stock, stated interest percentage (as a percent)						9.50%
Marcus and Millichamp Company TMMC Affiliate [Member] | Secured Note Receivable, 9.5% Interest Rate, Due October 2019 [Member]
Related Party Transaction [Line Items]
Notes receivable		$ 6,600		$ 6,600			$ 6,600	$ 6,600
Membership Interest In Sage At Cupertino [Member]
Related Party Transaction [Line Items]
Co-investments	$ 90,000
Number of units acquired (in units) | unit	230
Equity method investment, ownership percentage acquired (as a percent)	40.50%
Contract price	$ 15,300
Mortgage encumbrance	$ 52,000