Summary of Significant Accounting Policies - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property operating expense			$ 157,252			$ 170,506	$ 157,252	$ 146,529
Bad debt, net			159			60	159	(21)
Gains on sales of properties	$ 10,800	$ 27,700	39,524	$ 16,100	$ 23,400	41,665	39,524	41,044
Impairments			(5,385)				(5,385)	(121)
INCOME FROM CONTINUING OPERATIONS			23,092			$ 67,451	$ 20,943	85,571
Loss from discontinued operations			0					0
Impairments of real estate assets			0					0
Gain on sales of properties			0					0
LOSS FROM DISCONTINUED OPERATIONS			0					0
As Previously Reported
Property, Plant and Equipment [Line Items]
Property operating expense			157,233					146,458
Bad debt, net			169					(21)
Gains on sales of properties			39,519					41,038
Impairments			(5,385)					0
INCOME FROM CONTINUING OPERATIONS			23,096					85,756
Loss from discontinued operations			(9)					(71)
Impairments of real estate assets			0					(121)
Gain on sales of properties			5					7
LOSS FROM DISCONTINUED OPERATIONS			$ (4)					$ (185)