Commitments and Contingencies Minimum Lease Payments Under ASC 842 (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Operating Lease, Liability, Current	$ 20.1	$ 0.0
Operating Lease, Liability, Noncurrent	49.4	0.0
Operating Leases, Future Minimum Payments Due, Next Twelve Months	19.5	17.4
Operating Leases, Future Minimum Payments, Due in Two Years	20.3	13.8
Operating Leases, Future Minimum Payments, Due in Three Years	18.1	9.1
Operating Leases, Future Minimum Payments, Due in Four Years	14.1	7.4
Operating Leases, Future Minimum Payments, Due in Five Years	8.9	4.5
Operating Leases, Future Minimum Payments, Due Thereafter	0.5	$ 0.0
Operating Lease, Expense	(11.9)
Operating Lease, Liability	$ 69.5