Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Related Party Transactions - Investment in AIC (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Related Party Transaction [Line Items]
Equity in earnings (losses) of investees	$ (206)	$ 0	$ 115
AIC
Related Party Transaction [Line Items]
Unrealized gain on available for sale securities		35
AIC
Related Party Transaction [Line Items]
Equity in earnings (losses) of investees		$ 115
AIC \| Managed Equity REITs
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	14.30%
AIC \| Five Star
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	14.30%
AIC \| TA
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	14.30%
EQC \| AIC \| RMR LLC, the Managed REITs, Five Star, TA
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	14.30%