Goodwill - Changes in Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of year	$ 180.8	$ 178.6
Translation adjustments	(3.0)	2.2
Balance at end of year	177.8	180.8
Services
Goodwill [Roll Forward]
Balance at beginning of year	72.1	69.9
Translation adjustments	(3.0)	2.2
Balance at end of year	69.1	72.1
Technology
Goodwill [Roll Forward]
Balance at beginning of year	108.7	108.7
Translation adjustments	0.0	0.0
Balance at end of year	$ 108.7	$ 108.7