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Acquisitions (Schedule of Acquired Intangible Assets) (Details) - USD ($) $ in Thousands				12 Months Ended
	Aug. 21, 2018	Feb. 22, 2017	Oct. 11, 2016	Dec. 31, 2018
SolarBOS
Business Acquisition [Line Items]
Fair Value	$ 1,450
SolarBOS | Trademarks
Business Acquisition [Line Items]
Fair Value	$ 300
Estimated Useful Life	3 years
SolarBOS | Technology
Business Acquisition [Line Items]
Fair Value	$ 450
Estimated Useful Life	9 years
SolarBOS | Customer relationships
Business Acquisition [Line Items]
Fair Value	$ 700
Estimated Useful Life	9 years
Package Concierge
Business Acquisition [Line Items]
Fair Value		$ 3,600
Package Concierge | Trademarks
Business Acquisition [Line Items]
Fair Value		600
Package Concierge | Technology
Business Acquisition [Line Items]
Fair Value		$ 1,300
Estimated Useful Life		10 years
Package Concierge | Customer relationships
Business Acquisition [Line Items]
Fair Value		$ 1,700
Estimated Useful Life		7 years
Nexus
Business Acquisition [Line Items]
Fair Value			$ 6,200
Estimated Useful Life				3 months
Nexus | Trademarks
Business Acquisition [Line Items]
Fair Value			3,200
Nexus | Technology
Business Acquisition [Line Items]
Fair Value			1,300
Estimated Useful Life				15 years
Nexus | Customer relationships
Business Acquisition [Line Items]
Fair Value			800
Estimated Useful Life				11 years
Nexus | Backlog
Business Acquisition [Line Items]
Fair Value			$ 900

X

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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- Definition

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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- Definition

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
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