Real Estate Investments - Preferred Equity Investments and Real Estate Under Development (Details) $ in Thousands	1 Months Ended					12 Months Ended
	Nov. 30, 2019 USD ($)	Oct. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Apr. 30, 2019 USD ($)	Feb. 28, 2019 USD ($)	Dec. 31, 2019 USD ($) investment unit project	Dec. 31, 2018 USD ($) investment
Schedule of Equity Method Investments [Line Items]
Co-investment						$ 1,335,339	$ 1,300,140
Ownership interests, number of consolidated projects | project						5
Ownership Interests, number of unconsolidated projects | investment						2
Number of units to be developed | unit						1,960
Real Estate Predevelopment Projects
Schedule of Equity Method Investments [Line Items]
Actual cost of active development projects						$ 1,000,000
Minimum
Schedule of Equity Method Investments [Line Items]
Annualized preferred return rate						10.15%	10.25%
Maximum
Schedule of Equity Method Investments [Line Items]
Annualized preferred return rate						11.30%	12.00%
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Commitment to fund preferred equity investment in the project						$ 141,700	$ 45,100
Number of investments with a commitment to fund | investment						5	2
Equity method investment, funded amount						$ 125,400	$ 41,100
Total Preferred Interest Investments
Schedule of Equity Method Investments [Line Items]
Co-investment						$ 444,900	$ 372,800
Joint Venture that Holds Property San Jose, CA
Schedule of Equity Method Investments [Line Items]
Full redemption of a preferred equity investment					$ 10,900
Early redemption fee					$ 100
Joint Venture that Holds Property in Santa Ana, California
Schedule of Equity Method Investments [Line Items]
Full redemption of a preferred equity investment				$ 16,300
Early redemption fee				$ 700
Redmond, WA
Schedule of Equity Method Investments [Line Items]
Full redemption of a preferred equity investment			$ 14,800
Early redemption fee			300
Seattle, WA
Schedule of Equity Method Investments [Line Items]
Full redemption of a preferred equity investment			16,300
Early redemption fee			$ 1,400
San Jose, CA
Schedule of Equity Method Investments [Line Items]
Full redemption of a preferred equity investment		$ 15,800
Early redemption fee		$ 200
Bellevue, WA
Schedule of Equity Method Investments [Line Items]
Full redemption of a preferred equity investment	$ 16,000
Early redemption fee	$ 900