Subsequent Events (Details) - USD ($) $ in Thousands				3 Months Ended		6 Months Ended
	Jul. 12, 2019	Jul. 08, 2019	Jul. 03, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Subsequent Event [Line Items]
Gains on disposition of property				$ 6,703	$ 16,972	$ 6,703	$ 16,972
2019 Dispositions [Member]
Subsequent Event [Line Items]
Purchase price of real estate				32,500
Gains on disposition of property				$ 6,700
2019 Dispositions [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Purchase price of real estate		$ 4,700	$ 7,300
Gains on disposition of property		$ 2,600
Raleigh NC Land Acquisition (7/2019) [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Acquisition purchase price	$ 6,600