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Acquisitions (Schedule of Acquired Intangible Assets) (Details) - USD ($) $ in Thousands |  |  |  | 12 Months Ended
--- | --- | --- | --- | ---
Feb. 22, 2017 | Oct. 11, 2016 | Jun. 09, 2015 | Dec. 31, 2017
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 |  |
Rough Brothers Incorporated |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair Value |  |  | $ 56,392 |
Rough Brothers Incorporated | Trademarks |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair Value |  |  | 13,550 |
Rough Brothers Incorporated | Technology |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair Value |  |  | 3,550 |
Rough Brothers Incorporated | Customer relationships |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair Value |  |  | 32,892 |
Rough Brothers Incorporated | Non-compete agreements |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair Value |  |  | 1,300 |
Rough Brothers Incorporated | Backlog |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair Value |  |  | $ 5,100 |
Rough Brothers Incorporated | Maximum | Technology |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated Useful Life |  |  | 15 years |
Rough Brothers Incorporated | Maximum | Customer relationships |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated Useful Life |  |  | 17 years |
Rough Brothers Incorporated | Minimum | Technology |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated Useful Life |  |  | 7 years |
Rough Brothers Incorporated | Minimum | Customer relationships |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated Useful Life |  |  | 11 years |
Rough Brothers Incorporated | Minimum | Non-compete agreements |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated Useful Life |  |  | 5 years |
Rough Brothers Incorporated | Minimum | Backlog |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated Useful Life |  |  | 6 months |

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