Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-Based Compensation
Total stock-based compensation	$ 9.4	$ 8.0	$ 9.4
Estimated forfeiture rate (as a percent)	6.20%	5.80%	5.10%
Cost of revenues
Stock-Based Compensation
Total stock-based compensation	$ 1.4	$ 1.2	$ 1.2
Selling, general and administrative
Stock-Based Compensation
Total stock-based compensation	6.6	5.6	5.6
Research and development
Stock-Based Compensation
Total stock-based compensation	1.4	1.2	2.6
Stock options
Stock-Based Compensation
Total stock-based compensation	$ 7.5	$ 7.1	$ 6.7
Risk-free interest rates, minimum (as a percent)	1.23%	1.58%	1.78%
Risk-free interest rates, maximum (as a percent)	2.21%	1.91%	2.10%
Volatility, minimum (as a percent)	33.57%	35.10%	53.07%
Volatility, maximum (as a percent)	41.60%	52.23%	56.24%
Stock options | Minimum
Stock-Based Compensation
Vesting period	3 years
Expected life	5 years 9 months	6 years	6 years
Expected dividend yield (as a percent)	0.00%
Stock options | Maximum
Stock-Based Compensation
Vesting period	5 years
Expected life	7 years 7 days	6 years 3 months	6 years 3 months
Expected dividend yield (as a percent)	0.78%
Restricted stock awards
Stock-Based Compensation
Total stock-based compensation	$ 1.6	$ 0.9	$ 2.7
Restricted stock units
Stock-Based Compensation
Total stock-based compensation	$ 0.3