Acquisitions and Dispositions - Property Dispositions (Details) $ in Thousands											3 Months Ended		9 Months Ended
	Dec. 21, 2016 USD ($) property_unit	Nov. 30, 2016 USD ($) property_unit	Nov. 21, 2016 USD ($) property_unit	Oct. 26, 2016 USD ($) property_unit	Oct. 19, 2016 USD ($) property_unit	Jun. 01, 2016 USD ($) property_unit	Apr. 06, 2016 USD ($) property_unit	Mar. 16, 2016 USD ($) property_unit	Mar. 02, 2016 USD ($) property_unit	Oct. 01, 2015 USD ($) property_unit	Jun. 30, 2017 USD ($) property_unit	Jun. 30, 2016 USD ($) property_unit	Jun. 30, 2017 USD ($) property_unit	Jun. 30, 2016 USD ($) property_unit
Business Acquisition [Line Items]
No. of Units | property_unit											9,890		9,890
Gain on Sale											$ 0	$ 0	$ 0	$ (2,788)
Discontinued Operations, Disposed of by Sale
Business Acquisition [Line Items]
No. of Units | property_unit											1,017	1,539	1,017	1,539
Sales Price											$ 130,710	$ 168,552	$ 130,710	$ 168,552
Gain on Sale													35,838	35,098
Non-controlling partner portion of gain													$ 17,125	$ 14,554
Discontinued Operations, Disposed of by Sale | Greenville, NC
Business Acquisition [Line Items]
No. of Units | property_unit					350
Sales Price					$ 68,000
Gain on Sale					18,483
Non-controlling partner portion of gain					$ 9,329
Discontinued Operations, Disposed of by Sale | Panama City, FL
Business Acquisition [Line Items]
No. of Units | property_unit				160
Sales Price				$ 14,720
Gain on Sale				7,393
Non-controlling partner portion of gain				$ 3,478
Discontinued Operations, Disposed of by Sale | Atlanta, GA
Business Acquisition [Line Items]
No. of Units | property_unit			350
Sales Price			$ 36,750
Gain on Sale			8,905
Non-controlling partner portion of gain			$ 4,166
Discontinued Operations, Disposed of by Sale | Hixson, TN
Business Acquisition [Line Items]
No. of Units | property_unit		156
Sales Price		$ 10,775
Gain on Sale		608
Non-controlling partner portion of gain		$ 152
Discontinued Operations, Disposed of by Sale | New York, NY (Location 2)
Business Acquisition [Line Items]
No. of Units | property_unit	1
Sales Price	$ 465
Gain on Sale	449
Non-controlling partner portion of gain	$ 0
Discontinued Operations, Disposed of by Sale | New York, NY
Business Acquisition [Line Items]
No. of Units | property_unit										1
Sales Price										$ 652
Gain on Sale										609
Non-controlling partner portion of gain										$ 0
Discontinued Operations, Disposed of by Sale | Cordova, TN
Business Acquisition [Line Items]
No. of Units | property_unit									464
Sales Price									$ 31,100
Gain on Sale									6,764
Non-controlling partner portion of gain									$ 2,195
Discontinued Operations, Disposed of by Sale | Kennesaw, GA
Business Acquisition [Line Items]
No. of Units | property_unit								450
Sales Price								$ 64,000
Gain on Sale								17,429
Non-controlling partner portion of gain								$ 10,037
Discontinued Operations, Disposed of by Sale | Pooler, GA
Business Acquisition [Line Items]
No. of Units | property_unit							300
Sales Price							$ 38,500
Gain on Sale							5,710
Non-controlling partner portion of gain							$ 1,405
Discontinued Operations, Disposed of by Sale | Collierville, TN
Business Acquisition [Line Items]
No. of Units | property_unit						324
Sales Price						$ 34,300
Gain on Sale						4,586
Non-controlling partner portion of gain						$ 917