Commitments and Contingencies Long-term Operating lease commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating lease commitments [Abstract]
Operating Leases, Rent Expense	$ 9.1	$ 8.0	$ 8.2
Operating Leases, Future Minimum Payments Due, Next Twelve Months	8.7
Operating Leases, Future Minimum Payments, Due in Two Years	7.2
Operating Leases, Future Minimum Payments, Due in Three Years	7.1
Operating Leases, Future Minimum Payments, Due in Four Years	6.9
Operating Leases, Future Minimum Payments, Due in Five Years	7.0
Operating Leases, Future Minimum Payments, Due Thereafter	$ 11.2