Other Balance Sheet Accounts (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Other Current Liabilities
Accrued compensation	$ 45.2	$ 60.7
Deferred revenue	26.0	19.5
Environmental contingencies	22.7	23.5
Income taxes payable	20.3	12.2
Pension liabilities	14.8	15.0
Accrued interest	13.3	16.5
Other accrued liabilities	75.0	70.4
Total Other Current Liabilities	217.3	217.8
Other Liabilities, Noncurrent
Liability to unconsolidated affiliate	56.0	32.7
Environmental contingencies	38.5	46.8
Deferred revenue	22.3	14.9
Fair value of currency and interest rate contracts	19.1	22.7
Asset retirement obligation	9.1	10.4
Deferred income taxes	8.0	8.2
Postemployment liability	4.9	5.2
Other noncurrent liabilities	30.8	28.4
Other Liabilities, Noncurrent	$ 188.7	$ 169.3