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