Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	$ 2,932	$ 2,477	$ 5,555	$ 4,970
Income tax benefit	889	736	1,704	1,469
Cost of sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	19	15	34	29
Research and development expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee and director stock-based compensation expense	144	137	263	273
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	1,975	1,731	3,719	3,576
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	$ 794	$ 594	$ 1,539	$ 1,092