Leases - Supplemental Income Statement Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating lease cost:
Operating lease cost	$ 6.3	$ 9.9	$ 23.3	$ 33.9
Short-term lease cost	10.2	15.8	31.7	34.7
Variable lease cost	1.1	2.0	3.7	16.6
Sublease income	0.0	(1.0)	0.0	(1.9)
Total operating lease cost	17.6	26.7	58.7	83.3
Finance lease cost:
Amortization of right-of-use assets	0.8	3.4	5.2	12.0
Interest on lease liabilities	0.2	0.3	0.5	1.2
Total finance lease cost	$ 1.0	$ 3.7	$ 5.7	$ 13.2