Revenue Recognition (Extended Warranties and Post-Contract Support) (Details) - Extended warranties and post contract support - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Post-contract support contract, term	12 months
Deferred revenue	$ 40.2	$ 40.7
Deferred revenue recognized	12.7
Estimation of future revenues	$ 26.7
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Extended product warranty, term	1 year
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Extended product warranty, term	5 years