Fair Value Measurements (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Estimate of Fair Value, Fair Value Disclosure [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	$ (1,893.3)	$ (2,123.2)
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	(1,893.3)	(2,123.2)
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Liabilities measured at fair value
Debt Instrument, Fair Value Disclosure	(1,689.7)	(1,816.6)
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	(1,689.7)	(1,816.6)
Fair Value, Measurements, Recurring [Member]
Assets measured at fair value
Assets measured at fair value	167.9	235.6
Liabilities measured at fair value
Liabilities measured at fair value	(4.6)	(2.4)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Assets measured at fair value	91.3	48.2
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	76.6	187.4
Liabilities measured at fair value
Liabilities measured at fair value	(4.6)	(2.4)
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Assets measured at fair value
Cash and cash equivalents	136.3	173.2
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	91.3	48.2
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	45.0	125.0
Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member]
Assets measured at fair value
Foreign exchange contracts - current	0.0	0.1
Commodity hedge contracts - current	27.8	47.0
Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Foreign exchange contracts - current	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 - current	0.0	0.1
Commodity hedge contracts - current	27.8	47.0
Fair Value, Measurements, Recurring [Member] | Other Non-current Assets [Member]
Assets measured at fair value
Commodity hedge contracts - noncurrent	3.8	15.3
Fair Value, Measurements, Recurring [Member] | Other Non-current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
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
Commodity hedge contracts - noncurrent	3.8	15.3
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Liabilities measured at fair value
Foreign Currency Contracts, Liability, Fair Value Disclosure	(0.6)	0.0
Commodity hedge contracts - current	(3.3)	(1.8)
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
Foreign Currency Contracts, Liability, Fair Value Disclosure	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 Currency Contracts, Liability, Fair Value Disclosure	(0.6)	0.0
Commodity hedge contracts - current	(3.3)	(1.8)
Fair Value, Measurements, Recurring [Member] | Other Non-current Liabilities [Member]
Liabilities measured at fair value
Commodity hedge contracts - noncurrent	(0.7)	(0.6)
Fair Value, Measurements, Recurring [Member] | Other Non-current Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities measured at fair value
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
Commodity hedge contracts - noncurrent	$ (0.7)	$ (0.6)
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%