Amount of assets held-for-sale that are not part of a disposal group.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 15
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=77912953&loc=d3e400-110220

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- Definition

This element represents the amount of gain (loss) on sale of properties during the reporting period net of the applicable income taxes realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 974
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-15.(a)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=6875705&loc=d3e641549-123027

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- References

No definition available.

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- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

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- Definition

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

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- Definition

The cash inflow from the sale of formerly productive land held for sale, anything permanently fixed to it, including buildings, structures on it, and so forth.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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Dispositions of Property (Details) - USD ($) $ in Thousands									1 Months Ended	3 Months Ended	12 Months Ended
Dispositions of Property (Details) - USD ($) $ in Thousands	Oct. 20, 2017	Jan. 06, 2017	Dec. 16, 2016	Apr. 05, 2016	Dec. 09, 2015	May 13, 2015	Mar. 31, 2015	Feb. 23, 2015	Jun. 30, 2016	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Gain (loss) on sale of property
Assets Held-for-sale, Not Part of Disposal Group												$ 3,871
Gain (loss) on sale of property											$ (18,481)	$ (2,938)	$ 23,662
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations \| Office Property in Baltimore Maryland
Gain (loss) on sale of property
Assets Held-for-sale, Not Part of Disposal Group										$ 31,600				$ 31,900
Loss contingency on property held										20,700				$ 20,500
Provision for loss on property held										300
Disposal group disposed of by sale, not classified as discontinued operations \| Office Property in Baltimore Maryland
Gain (loss) on sale of property
Gain (loss) on sale of property	$ (20,800)
Net Proceeds	$ 31,600
Office Property In Milpitas, California \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property		$ 2,300
Office Property In Maryland Heights Missouri \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property				$ 4,200
Office Property In Federal Way Washington \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Gain (loss) on sale of property
Assets Held-for-sale, Not Part of Disposal Group									$ 9,300	8,800
Provision for loss on property held									$ 4,800	500
Gain (loss) on sale of property										$ 5,300
Office Property In Federal Way Washington \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property			$ (7,100)
Net Proceeds			$ 7,300
Office Property in Plano, Texas \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property								$ 1,500
Office Property in Eden Prairie, Minnesota \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property							$ 9,000
Office Property in Charlotte, North Carolina \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property						$ 900
Office Property in San Jose, California \| Disposal group disposed of by sale, not classified as discontinued operations
Gain (loss) on sale of property
Gain (loss) on sale of property					$ 12,300