Significant Accounting Policies (Narrative) (Details)	12 Months Ended
Dec. 31, 2020 segment trust
Property, Plant and Equipment [Line Items]
Number of wholly owned trusts \| trust	23
Cash and cash equivalents general maturity	90 days
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of primary segments \| segment	4
Land and Building
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	39 years
Minimum
Property, Plant and Equipment [Line Items]
Lessor, Operating Lease, Renewal Term	1 year
Minimum \| Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Minimum \| Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Lessor, Operating Lease, Renewal Term	10 years
Maximum \| Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Maximum \| Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	7 years
2013 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation award, vesting period	3 years

Cash and cash equivalents general maturity.

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- Definition

Number Of Wholly Owned Trusts

+ References

No definition available.

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Term of lessor's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

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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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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

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-SubTopic 10
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-Paragraph 2
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No definition available.

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