Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2443-110228

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The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Amount of insurance proceeds for an event or transaction that is unusual in nature or infrequent in occurrence, or both.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64828382&loc=d3e15138-107781

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Real Estate Properties - Narrative (Details) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended	18 Months Ended
Real Estate Properties - Narrative (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017	Mar. 31, 2018
Loss Contingencies [Line Items]
Gain on insurance recovery	$ 3,227,000		$ 0	$ 3,227,000	$ 0
Loss from Catastrophes
Loss Contingencies [Line Items]
Reduction in carrying value						$ 3,471,000
Insurance proceeds				7,400,000
Rental Income
Loss Contingencies [Line Items]
Gain on insurance recovery	$ 294,000	$ 98,000		$ 588,000			$ 686,000