Equity-Based Compensation - Equity-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity-based compensation expense
Total equity-based compensation expense	$ 23,664	$ 22,543	$ 17,237
Income tax effect	(6,884)	(6,232)	(4,885)
After-tax effect of equity-based compensation expense	16,780	16,311	12,352
Cost of product sales and services
Equity-based compensation expense
Total equity-based compensation expense	1,278	520	371
Research and development
Equity-based compensation expense
Total equity-based compensation expense	3,225	3,476	2,992
Selling, general and administrative
Equity-based compensation expense
Total equity-based compensation expense	$ 19,161	$ 18,547	$ 13,874