Basis of Presentation - Narrative (Details)	6 Months Ended
	Jun. 30, 2018 USD ($) ground_lease	Dec. 31, 2017 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of ground leases | ground_lease	24
Investments in unconsolidated real estate ventures	$ 97,556,000	$ 75,907,000
Cash distributions in unconsolidated real estate ventures	43,737,000	5,816,000
Reclassification
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Investments in unconsolidated real estate ventures		$ (5,816)
Cash distributions in unconsolidated real estate ventures	$ 5,816