Goodwill and Intangible Assets (Summary of Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 48,643	$ 48,211
Accumulated Amortization	(35,669)	(31,701)
Net Carrying Amount	12,974	16,510
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	28,252	28,018
Accumulated Amortization	(22,290)	(19,736)
Net Carrying Amount	$ 5,962	$ 8,282
Weighted Average Amortization Period	5 years 3 months 18 days	5 years 3 months 18 days
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 15,856	$ 16,009
Accumulated Amortization	(9,966)	(8,857)
Net Carrying Amount	$ 5,890	$ 7,152
Weighted Average Amortization Period	8 years	8 years 18 days
Trade names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,299	$ 1,295
Accumulated Amortization	(1,290)	(1,277)
Net Carrying Amount	$ 9	$ 18
Weighted Average Amortization Period	2 years 1 month	2 years 1 month 12 days
Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,449	$ 1,446
Accumulated Amortization	(1,427)	(1,220)
Net Carrying Amount	$ 22	$ 226
Weighted Average Amortization Period	2 years 3 months 12 days	2 years 3 months 12 days
Patents [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,525	$ 1,180
Accumulated Amortization	(461)	(376)
Net Carrying Amount	$ 1,064	$ 804
Weighted Average Amortization Period	13 years	12 years 4 months 18 days
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 262	$ 263
Accumulated Amortization	(235)	(235)
Net Carrying Amount	$ 27	$ 28
Weighted Average Amortization Period	2 years 8 months 12 days	2 years 8 months 18 days