Background and Basis of Presentation - Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Senior notes | 2021 Senior Notes (5.25% fixed rate)
Fair Value of Financial Instruments
Fixed rate of interest (as a percent)	5.25%
Secured debt | German loan agreement (2.45% fixed rate)
Fair Value of Financial Instruments
Fixed rate of interest (as a percent)	2.45%
Secured debt | German loan agreement (1.45% fixed rate)
Fair Value of Financial Instruments
Fixed rate of interest (as a percent)	1.45%
Carrying Value
Fair Value of Financial Instruments
Total debt	$ 249.5	$ 242.6
Carrying Value | Senior notes | 2021 Senior Notes (5.25% fixed rate)
Fair Value of Financial Instruments
Total debt	175.0	175.0
Carrying Value | Secured debt | Global Revolving Credit Facilities (variable rates)
Fair Value of Financial Instruments
Total debt	65.3	57.9
Carrying Value | Secured debt | German loan agreement (2.45% fixed rate)
Fair Value of Financial Instruments
Total debt	4.4	4.8
Carrying Value | Secured debt | German loan agreement (1.45% fixed rate)
Fair Value of Financial Instruments
Total debt	4.8	4.9
Level 2 | Fair Value
Fair Value of Financial Instruments
Total debt	246.2	238.4
Level 2 | Fair Value | Senior notes | 2021 Senior Notes (5.25% fixed rate)
Fair Value of Financial Instruments
Total debt	171.5	170.5
Level 2 | Fair Value | Secured debt | Global Revolving Credit Facilities (variable rates)
Fair Value of Financial Instruments
Total debt	65.3	57.9
Level 2 | Fair Value | Secured debt | German loan agreement (2.45% fixed rate)
Fair Value of Financial Instruments
Total debt	4.6	5.1
Level 2 | Fair Value | Secured debt | German loan agreement (1.45% fixed rate)
Fair Value of Financial Instruments
Total debt	$ 4.8	$ 4.9