Fair Value of Assets and Liabilities Financial Instruments (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2016	Dec. 31, 2015
Fair Value of Assets and Liabilities
Property held for sale	$ 1,501,190	$ 1,440,253
Common shares owned in RMR Inc.	1,214,225
Historical cost	$ 26,888
Unrealized gain on investment in available for sale securities	10,717
Recurring
Fair Value of Assets and Liabilities
Investment in RMR Inc.	37,605
Recurring \| Level 1 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	37,605
Discontinued Operations, Held-for-sale \| Nonrecurring
Fair Value of Assets and Liabilities
Property held for sale and classified as discontinued operations (2)	12,260
Discontinued Operations, Held-for-sale \| Nonrecurring \| Level 3 inputs
Fair Value of Assets and Liabilities
Property held for sale and classified as discontinued operations (2)	12,260
Discontinued operations
Fair Value of Assets and Liabilities
Property held for sale and classified as discontinued operations (2)	$ 12,260

Common shares owned accounted for as available for sale securities.

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- Definition

Amount classified as real estate properties attributable to disposal group held for sale or disposed of.

+ References

No definition available.

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- Definition

Represents the historical cost during the period

+ References

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- Definition

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- Definition

Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19190-110258

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- Definition

Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669646-108580

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- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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