Subsequent Events (Details) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) buildings $ / shares	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) buildings	Jun. 30, 2016 USD ($)	Dec. 31, 2016 buildings
Subsequent Event [Line Items]
Repayments of Unsecured Debt				$ 545,924	$ 75,668
Loss on debt extinguishment		$ (9,561)	$ (2,430)	$ (9,536)	(2,430)
Discontinued Operation, Number of Real Estate Properties Sold | buildings				73		0
Proceeds from land and depreciated property sales, net				$ 1,977,127	$ 174,882
Subsequent Event [Member]
Subsequent Event [Line Items]
Repayments of Unsecured Debt	$ 128,700
Debt Instrument, Interest Rate, Stated Percentage	6.75%
Loss on debt extinguishment	$ 16,600
Discontinued Operation, Number of Real Estate Properties Sold | buildings	4
Proceeds from land and depreciated property sales, net	$ 155,100
Subsequent Event [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Common stock dividends declared per share | $ / shares	$ 0.19
Record date	Aug. 16, 2017
Dividends Payable, Date to be Paid	Aug. 31, 2017