Real Estate Investments (Narrative) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property
Property, Plant and Equipment [Line Items]
Number of real estate properties \| property	819
Gain (loss) on sale of real estate investments	$ 23,690	$ 31,776	$ 15,128
Impairment of real estate investments	2,432	21,080	25,049
Impairment of real estate investments	827	21,080	25,049
One Property Held For Use
Property, Plant and Equipment [Line Items]
Impairment of real estate investments	$ 700
12 Properties Held For Use
Property, Plant and Equipment [Line Items]
Impairment of real estate investments		$ 10,100
38 Properties Held For Use
Property, Plant and Equipment [Line Items]
Impairment of real estate investments			20,500
SunTrust Bank
Property, Plant and Equipment [Line Items]
Number of real estate properties \| property	1	7
Impairment of real estate investments			25,000
Impaired real estate investments held for sale
Property, Plant and Equipment [Line Items]
Number of real estate properties \| property	1	7
Number of additional real estate properties \| property	1
Impairment of real estate investments	$ 100	$ 11,000	$ 4,500
Impairment of real estate investments	$ 0	$ 2,176
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Property, Plant and Equipment [Line Items]
Number of real estate properties \| property	5
Properties sold \| property	25	44	25
Aggregate contract sale price	$ 131,700	$ 161,500	$ 291,500
Gain (loss) on sale of real estate investments			$ 31,800
Number of real estate properties impaired \| property		12	38
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Multi Tenant Property
Property, Plant and Equipment [Line Items]
Number of real estate properties impaired \| property		2
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| SunTrust Bank
Property, Plant and Equipment [Line Items]
Properties sold \| property	22	31	18
Impairment of real estate investments		$ 1,700	$ 17,200
Number of real estate properties impaired \| property		9	36

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Number of Real Estate Properties Impaired

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Number of Real Estate Properties Sold

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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This element represents the amount of gain (loss) on sale of properties during the reporting period net of the applicable income taxes realized.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 974
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The charge against earnings in the period to reduce the carrying amount of real property to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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The number of real estate properties owned as of the balance sheet date.

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Cash received for the sale of real estate that is not part of an investing activity during the current period.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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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.

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No definition available.

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