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Goodwill and Related Intangible Assets (Schedule of Acquired Intangible Assets) (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 | Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items] |  |
Gross Carrying Amount, Finite-lived intangible assets | $ 116,778 | $ 116,339
Total acquired intangible assets, Gross Carrying Amount | 161,937 | 161,446
Accumulated Amortization, Finite-lived intangible assets | 57,878 | 55,678
Total acquired intangible assets, Accumulated Amortization | 57,878 | 55,678
Trademarks |  |
Finite-Lived Intangible Assets [Line Items] |  |
Gross Carrying Amount, Finite-lived intangible assets | 5,848 | 5,876
Accumulated Amortization, Finite-lived intangible assets | 3,166 | 3,062
Unpatented technology |  |
Finite-Lived Intangible Assets [Line Items] |  |
Gross Carrying Amount, Finite-lived intangible assets | 28,107 | 28,107
Accumulated Amortization, Finite-lived intangible assets | 12,490 | 12,033
Customer relationships |  |
Finite-Lived Intangible Assets [Line Items] |  |
Gross Carrying Amount, Finite-lived intangible assets | 81,174 | 80,707
Accumulated Amortization, Finite-lived intangible assets | 41,215 | 39,652
Non-compete agreements |  |
Finite-Lived Intangible Assets [Line Items] |  |
Gross Carrying Amount, Finite-lived intangible assets | 1,649 | 1,649
Accumulated Amortization, Finite-lived intangible assets | $ 1,007 | 931
Backlog |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 3 months |
Trademarks |  |
Finite-Lived Intangible Assets [Line Items] |  |
Gross Carrying Amount, Indefinite-lived intangible assets | $ 45,159 | 45,107
Accumulated Amortization, Indefinite-lived intangible assets | $ 0 | $ 0
Minimum | Trademarks |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 5 years |
Minimum | Unpatented technology |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 5 years |
Minimum | Customer relationships |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 5 years |
Minimum | Non-compete agreements |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 4 years |
Maximum | Trademarks |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 15 years |
Maximum | Unpatented technology |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 20 years |
Maximum | Customer relationships |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 17 years |
Maximum | Non-compete agreements |  |
Finite-Lived Intangible Assets [Line Items] |  |
Estimated Life | 10 years |

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