Schedule III - Real Estate and Accumulated Depreciation - Reconciliation of Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance, beginning of year	$ 656,900	$ 556,546	$ 465,584
Depreciation expense	130,069	119,490	106,343
Disposals	(39,665)	(19,136)	(15,381)
Balance, end of year	$ 747,304	$ 656,900	$ 556,546