Equity-Based Compensation - Equity-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Equity-based compensation expense
Total equity-based compensation expense	$ 5,533	$ 5,778
Income tax effect	(942)	(1,605)
After-tax effect of equity-based compensation expense	4,591	4,173
Cost of product sales and services
Equity-based compensation expense
Total equity-based compensation expense	347	129
Research and development
Equity-based compensation expense
Total equity-based compensation expense	720	756
Selling, general and administrative
Equity-based compensation expense
Total equity-based compensation expense	$ 4,466	$ 4,893