Real Estate Investments - Preferred Equity Investments and Real Estate Under Development (Details) $ in Thousands	1 Months Ended							12 Months Ended
	Nov. 30, 2016 USD ($)	Aug. 31, 2016 USD ($)	May 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Aug. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) unit joint_venture project	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Equity Method Investments [Line Items]
Co-investment					$ 20,400		$ 13,700	$ 1,161,275	$ 1,036,047
Payments to acquire additional investments							1,300
Payments to acquire equity method investments							1,300	183,989	127,879	$ 246,006
Gain on disposal of equity method investment					$ 1,500			$ 13,046	0	$ 6,558
Number of development projects | project								2
Ownership interests, number of active development projects | project								6
Real Estate Under Development Activities [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interests, number of active development projects | joint_venture								4
Real Estate predevelopment projects [Member]
Schedule of Equity Method Investments [Line Items]
Number of units to be developed | unit								2,223
Estimated cost active development projects								$ 1,300,000
Active development projects estimated costs to be expended								704,000
Remaining estimated cost to be contributed by Company								528,000
Total preferred interest investments [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment								222,053	$ 106,312
Preferred interest in a related party limited liability company that owns Madison Park at Anaheim with a preferred return of 9% [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment							$ 13,700
Cumulative dividend rate (in hundredths)							9.00%
Greentree Apartments [Member] | Limited Liability Company [Member]
Schedule of Equity Method Investments [Line Items]
Cumulative dividend rate (in hundredths)						9.50%
Payments to acquire equity method investments						$ 10,000
Sterling Cove [Member] | Limited Liability Company [Member]
Schedule of Equity Method Investments [Line Items]
Cumulative dividend rate (in hundredths)						9.50%
Payments to acquire equity method investments						$ 5,000
Alta Vista Apartments [Member] | Limited Liability Company [Member]
Schedule of Equity Method Investments [Line Items]
Cumulative dividend rate (in hundredths)					9.50%
Payments to acquire equity method investments					$ 5,000
Equity Method Investments [Member] | Limited Liability Company Located In Glendale, CA [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment				$ 47,100				47,100
Cumulative dividend rate (in hundredths)				12.00%
Equity Method Investments [Member] | Limited Liability Company Located In Seattle, WA [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment			$ 23,700
Compounded preferred return rate, initial (as a percent)			10.00%
Compounded preferred return rate, initial measurement period			30 months
Compounded preferred return rate, subsequent (as a percent)			8.00%
Equity Method Investments [Member] | Limited Liability Company Located In Santa Ana, CA [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment		$ 11,600						$ 11,600
Cumulative dividend rate (in hundredths)		12.00%
Equity Method Investments [Member] | Limited Liability Company Located In San Jose, CA [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment	$ 23,000
Compounded preferred return rate, initial (as a percent)	11.00%
Compounded preferred return rate, subsequent (as a percent)	9.00%
Equity Method Investments [Member] | Limited Liability Company Located In Redmond, WA [Member]
Schedule of Equity Method Investments [Line Items]
Co-investment	$ 10,700
Compounded preferred return rate, initial (as a percent)	11.00%
Compounded preferred return rate, initial measurement period	30 months
Compounded preferred return rate, subsequent (as a percent)	9.50%