Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2017
Real Estate Properties [Line Items]
Net operating loss carryforwards		$ 120.0
Australian Properties
Real Estate Properties [Line Items]
Income tax expense (benefit)	$ 1.6

Amount of tax expense (benefit) on gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 3B
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721525-107759

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 50
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

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