Revenue from Contracts with Customers - Costs of Obtaining Contracts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Revenue from Contracts with Customers
Capitalized contract cost, Beginning of period	$ 43.7	$ 29.6	$ 40.7	$ 26.3
Deferral	4.4	5.0	10.1	9.8
Amortization	(2.9)	(1.8)	(5.6)	(3.3)
Capitalized contract cost, End of period	45.2	32.8	45.2	32.8
Current costs of obtaining contracts with customers					$ 12.0	$ 10.0
Non-current costs of obtaining contracts with customers					33.2	30.7
Total costs of obtaining contracts with customers	$ 45.2	$ 32.8	$ 45.2	$ 32.8	$ 45.2	$ 40.7