Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019
Provision for income tax	$ 265,000	$ 280,000	$ 749,000	$ 767,000
Percentage of rental income excluded from accounting standard adoption			94.00%
Percentage of total revenue subject to revenue recognition standard			6.00%
Right-of-use assets	481,044,000		$ 481,044,000		$ 434,201,000
Lease liabilities	$ 333,312,000		333,312,000		$ 278,287,000
Federal [Member]
Provision for income tax			$ 0