Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Estimate of Fair Value, Fair Value Disclosure [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	$ (2,199.3)	$ (2,273.4)
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	0.0	0.0
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	(2,199.3)	(2,273.4)
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	(2,103.3)	(2,110.1)
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	0.0	0.0
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	(2,103.3)	(2,110.1)
Fair Value, Measurements, Recurring [Member]
Assets measured at fair value
Assets measured at fair value	69.7	85.7
Liabilities measured at fair value
Liabilities measured at fair value	(5.4)	(5.7)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Assets measured at fair value	44.5	38.0
Liabilities measured at fair value
Liabilities measured at fair value	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Assets measured at fair value	25.2	47.7
Liabilities measured at fair value
Liabilities measured at fair value	(5.4)	(5.7)
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Assets measured at fair value
Cash and cash equivalents	44.5	38.0
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Cash and cash equivalents	44.5	38.0
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Cash and cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member]
Assets measured at fair value
Foreign exchange contracts	0.1	0.2
Commodity hedge contracts - current	20.1	35.2
Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Foreign exchange contracts	0.0	0.0
Commodity hedge contracts - current	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Foreign exchange contracts	0.1	0.2
Commodity hedge contracts - current	20.1	35.2
Fair Value, Measurements, Recurring [Member] | Other Non-current Assets [Member]
Assets measured at fair value
Foreign exchange contracts	0.9	1.7
Commodity hedge contracts - noncurrent	4.1	10.6
Fair Value, Measurements, Recurring [Member] | Other Non-current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Foreign exchange contracts	0.0	0.0
Commodity hedge contracts - noncurrent	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Other Non-current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Foreign exchange contracts	0.9	1.7
Commodity hedge contracts - noncurrent	4.1	10.6
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Liabilities measured at fair value
Foreign exchange contracts	(0.9)	(0.3)
Commodity hedge contracts - current	(2.8)	(4.9)
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Foreign exchange contracts	0.0	0.0
Commodity hedge contracts - current	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Foreign exchange contracts	(0.9)	(0.3)
Commodity hedge contracts - current	(2.8)	(4.9)
Fair Value, Measurements, Recurring [Member] | Other Non-current Liabilities [Member]
Liabilities measured at fair value
Foreign exchange contracts	(0.3)	0.0
Commodity hedge contracts - noncurrent	(1.4)	(0.5)
Fair Value, Measurements, Recurring [Member] | Other Non-current Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Foreign exchange contracts	0.0	0.0
Commodity hedge contracts - noncurrent	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Other Non-current Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities measured at fair value
Foreign exchange contracts	(0.3)	0.0
Commodity hedge contracts - noncurrent	$ (1.4)	$ (0.5)
Liability [Member] | Maximum [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Benchmark interest rates for contracts (in hundredths)	2.00%
Assets [Member] | Maximum [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Benchmark interest rates for contracts (in hundredths)	1.00%