Significant Accounting Policies - Additional Information (Details) $ in Thousands		6 Months Ended
	Jan. 01, 2019 USD ($) property lease	Jun. 30, 2019 USD ($) extension	Jun. 30, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of ground leases | lease	6
Number of properties subject to ground leases | property	5
Maximum optional ground lease extension term	70 years
Operating lease right-of-use assets		$ 33,268
Operating lease liabilities		$ 41,300
Weighted average discount rate		5.40%
Number of options to extend, more than | extension		1
Adjustment for uncollectable accounts		$ 9	$ 112
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of contract	20 years
Renewal term		1 year
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of contract	65 years
Renewal term		15 years
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 32,200
Operating lease liabilities	$ 41,400
Weighted average discount rate	5.40%
Adjustment for uncollectable accounts	$ 200