Leases - Components of Total Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Finance lease expense:
Amortization of right-of-use asset	$ 0.0	$ 0.7
Operating lease expense:
Long-term operating lease expense	6.4	6.3
Short-term lease expense	5.5	6.9
Variable lease expense	2.8	1.6
Total lease expense	$ 14.7	$ 15.5