Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	$ 3,921	$ 2,668	$ 9,476	$ 7,638
Income tax benefit	603	812	2,307	2,281
Cost of sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	19	14	53	43
Research and development expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	149	136	412	409
Selling, general and administrative expenses | Employees
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	1,843	1,748	5,562	5,324
Selling, general and administrative expenses | Outside directors
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	$ 1,910	$ 770	$ 3,449	$ 1,862