Commitments and Contingencies Lease Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Operating Leases, Rent Expense	$ 11.0	$ 7.9	$ 0.6
Operating Leases, Future Minimum Payments Due, Next Twelve Months	8.3
Operating Leases, Future Minimum Payments, Due in Two Years	8.6
Operating Leases, Future Minimum Payments, Due in Three Years	6.5
Operating Leases, Future Minimum Payments, Due in Four Years	5.9
Operating Leases, Future Minimum Payments, Due in Five Years	5.6
Operating Leases, Future Minimum Payments, Due Thereafter	13.2
Operating Leases, Future Minimum Payments Due	$ 48.1
Lessee, Operating Lease, Term of Contract	6 years 3 months