Schedule of Geographic Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 521,290	$ 384,758	$ 373,598
Percentage of Total	100.00%	100.00%	100.00%
UNITED STATES
Segment Reporting Information [Line Items]
Revenue	$ 220,583	$ 154,756	$ 154,825
Percentage of Total	42.30%	40.20%	41.40%
GERMANY
Segment Reporting Information [Line Items]
Revenue	$ 68,003	$ 55,940	$ 54,743
Percentage of Total	13.00%	14.50%	14.70%
Rest Of Europe
Segment Reporting Information [Line Items]
Revenue	$ 81,001	$ 51,705	$ 48,277
Percentage of Total	15.50%	13.40%	12.90%
CHINA
Segment Reporting Information [Line Items]
Revenue	$ 56,128	$ 44,225	$ 38,491
Percentage of Total	10.80%	11.50%	10.30%
Rest of Asia-Pacific
Segment Reporting Information [Line Items]
Revenue	$ 84,727	$ 60,104	$ 62,467
Percentage of Total	16.30%	15.60%	16.70%
Other Countries
Segment Reporting Information [Line Items]
Revenue	$ 10,848	$ 18,028	$ 14,795
Percentage of Total	2.10%	4.80%	4.00%