Stock-Based Compensation - Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock-Based Compensation
Total stock-based compensation	$ 2.6	$ 2.4	$ 5.3	$ 4.9
Cost of revenue
Stock-Based Compensation
Total stock-based compensation	0.4	0.3	0.8	0.7
Selling, general and administrative
Stock-Based Compensation
Total stock-based compensation	1.8	1.8	3.7	3.5
Research and development
Stock-Based Compensation
Total stock-based compensation	0.4	0.3	0.8	0.7
Mestrelab Research, S.L
Stock-Based Compensation
Total stock-based compensation	0.4		0.8
Stock options
Stock-Based Compensation
Total stock-based compensation	0.7	1.0	1.4	2.0
Restricted stock awards
Stock-Based Compensation
Total stock-based compensation	0.1	0.2	0.2	0.4
Restricted stock units
Stock-Based Compensation
Total stock-based compensation	$ 1.8	$ 1.2	$ 3.7	$ 2.5