Noncontrolling Interest of Unitholders in Operating Partnership - Additional Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) item $ / shares shares	Sep. 30, 2018 $ / shares shares	Dec. 31, 2018 shares
Noncontrolling Interest
Distributions per unit | $ / shares			$ 0.78375	$ 0.763125
Maximum
Noncontrolling Interest
Number of permitted exchange requests in a calendar year | item			2
Limited Partnership
Noncontrolling Interest
Total units	17,820,000		17,820,000		17,876,000
Units converted by limited partners into common shares			1,475	0
Total units			1,475
Common shares value | $			$ 28
Limited Partnership | Minimum
Noncontrolling Interest
Number of units which can be redeemed in single redemption			1,000
Operating Partnership
Noncontrolling Interest
Declared distributions | $	$ 4,655	$ 4,470