Significant Accounting Policies - Other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Warranty Costs
Warranty period	1 year
Advertising Expense
Advertising expenses	$ 0.8	$ 0.9	$ 0.6
Concentration of Credit Risk
Allowance for doubtful accounts	$ 0.3	0.2
Maturity period of irrevocable letters of credit, minimum	0 days
Maturity period of irrevocable letters of credit, maximum	90 days
Cash, Cash Equivalents, and Short-Term Investments
Maturity period of short-term investments, maximum	3 months
Cash equivalents	$ 1.5	$ 18.0
Cash and cash equivalents maintained outside the U.S. by subsidiaries (as a percent)	54.00%	50.00%
Goodwill and Indefinite-Lived Intangibles
Number of trading days considered to calculate market capitalization	10 days