Leases - Supplemental Income Statement Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Operating leases
Operating lease cost:
Operating lease cost	$ 9.9	$ 33.9
Short-term lease cost	15.8	34.7
Variable lease cost	2.0	16.6
Sublease income	(1.0)	(1.9)
Total operating lease cost	26.7	83.3
Finance leases
Finance lease cost:
Amortization of right-of-use assets	3.4	12.0
Interest on lease liabilities	0.3	1.2
Total finance lease cost	$ 3.7	$ 13.2