Revenues - Additional Information (Details) - ASC 2014-09 - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Revenue Recognition [Line Items]
Lease receivables	$ 13.3	$ 13.3		$ 45.5
Receivables from contracts with customers	55.8	55.8		$ 57.1
Revenue recognized that was included in the contract liabilty	$ 1.1	$ 2.5
Future revenues under contract			$ 588.0
Contracts currently being invoiced			513.2
Backlog for sales bookings			$ 74.8
Average remaining contract term of backlog sales bookings		4 years 2 months 12 days