Acquisitions and Dispositions - Property Dispositions (Details) $ in Thousands	3 Months Ended
Dec. 31, 2018 USD ($) property property_Unit	Dec. 31, 2017 USD ($) property
Business Acquisition [Line Items]
No. of Units \| property_Unit	9,696
Property dispositions
Business Acquisition [Line Items]
No. of Units \| property	691
Sales Price	$ 92,850
Gain on Sale	19,514
Non-controlling partner's portion of the gain	$ 8,047
Property dispositions \| North Charleston, SC
Business Acquisition [Line Items]
No. of Units \| property	271
Sales Price	$ 51,650
Gain on Sale	11,921
Non-controlling partner's portion of the gain	$ 5,970
Property dispositions \| Lake St. Louis, MO
Business Acquisition [Line Items]
No. of Units \| property	420
Sales Price	$ 41,200
Gain on Sale	7,593
Non-controlling partner's portion of the gain	$ 2,077
Property dispositions \| Melbourne, FL
Business Acquisition [Line Items]
No. of Units \| property		208
Sales Price		$ 22,250
Gain on Sale		12,519
Non-controlling partner's portion of the gain		$ 2,504

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

Amount after tax of income (loss) from a discontinued operation attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
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-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=65878427&loc=d3e1012-107759

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4569616-111683

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
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-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4568447-111683

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5C
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-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721675-107760

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=65878427&loc=d3e957-107759

+ Details