Leases - Components of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 6.7	$ 13.7
Short-term lease cost	0.9	1.6
Variable lease cost	1.7	3.5
Total lease cost	$ 9.3	$ 18.8