Leases - Components of Lease Expense (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Finance lease cost:
Amortization of right-of-use assets	$ 0.2
Interest on lease liabilities	0.1
Operating lease cost:
Fixed lease cost - operating leases	15.2
Total lease cost	15.5
Sublease income	$ 18.0