Fair Value Measurements - Assets and Liabilities (Details) - USD ($) $ in Millions			9 Months Ended
		May 01, 2016	Sep. 30, 2016		Sep. 30, 2015		Dec. 31, 2015
Assets and liabilities measured at estimated fair value on a recurring basis
Debt			$ 1,138.9		$ 772.2
Derivative assets			268.8				$ 522.9
Derivative liability			276.3				468.7
Proceeds from sale of business		$ 29.3	29.3	[1]	$ 0.0	[1]
Amount to be received		$ 3.0
Level 1
Assets and liabilities measured at estimated fair value on a recurring basis
Inventories asset			0.0
Subtotal assets			168.7				255.4
Inventories liability							0.0
Subtotal liabilities			179.4				340.1
Level 2
Assets and liabilities measured at estimated fair value on a recurring basis
Inventories asset			3.1
Subtotal assets			106.5				266.7
Inventories liability							14.3
Subtotal liabilities			100.2				142.7
Level 3
Assets and liabilities measured at estimated fair value on a recurring basis
Inventories asset			0.0
Subtotal assets			0.6				3.2
Inventories liability							0.0
Subtotal liabilities			0.3				0.2
Cash surrender value of life insurance
Assets and liabilities measured at estimated fair value on a recurring basis
Cash surrender value of life insurance	[1]		3.9
Cash surrender value of life insurance | Level 1
Assets and liabilities measured at estimated fair value on a recurring basis
Cash surrender value of life insurance			0.0				0.0
Cash surrender value of life insurance | Level 2
Assets and liabilities measured at estimated fair value on a recurring basis
Cash surrender value of life insurance			3.9				2.4
Cash surrender value of life insurance | Level 3
Assets and liabilities measured at estimated fair value on a recurring basis
Cash surrender value of life insurance			0.0				0.0
Fair value measured on recurring basis
Assets and liabilities measured at estimated fair value on a recurring basis
Inventories asset			3.1
Subtotal assets			275.8				525.3
Netting and collateral, asset			(218.4)				(283.1)
Total, inventories asset	[1]		3.1
Total assets	[1]		57.3				242.2
Inventories liability							14.3
Subtotal liabilities			279.9				483.0
Netting and collateral, liability			(237.4)				(393.7)
Total, inventories liability	[1]						14.3
Total liabilities	[1]		42.4				89.3
Fair value measured on recurring basis | Level 3
Assets and liabilities measured at estimated fair value on a recurring basis
Debt			1,138.9				772.2
Notes receivable			17.4				7.4
Fair value measured on recurring basis | Cash surrender value of life insurance
Assets and liabilities measured at estimated fair value on a recurring basis
Cash surrender value of life insurance			3.9				2.4	[1]
Commodity contracts
Assets and liabilities measured at estimated fair value on a recurring basis
Total, derivative asset			43.3				231.5
Total, derivative liability			37.0				74.1
Commodity contracts | Level 1
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			168.7				255.4
Derivative liability			179.4				340.1
Commodity contracts | Level 2
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			87.9				251.9
Derivative liability			90.2				123.4
Commodity contracts | Level 3
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			0.6				3.2
Derivative liability			0.3				0.2
Commodity contracts | Fair value measured on recurring basis
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			257.2				510.5
Netting and collateral, derivative asset			(213.8)				(279.0)
Total, derivative asset	[1]		43.3				231.5
Derivative liability			269.9				463.7
Netting and collateral, derivative liability			(232.8)				(389.6)
Total, derivative liability	[1]		37.0				74.1
Foreign currency contracts
Assets and liabilities measured at estimated fair value on a recurring basis
Total, derivative asset			7.0				8.3
Total, derivative liability			1.9				0.9
Foreign currency contracts | Level 1
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			0.0				0.0
Derivative liability			0.0				0.0
Foreign currency contracts | Level 2
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			11.6				12.4
Derivative liability			6.5				5.0
Foreign currency contracts | Level 3
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			0.0				0.0
Derivative liability			0.0				0.0
Foreign currency contracts | Fair value measured on recurring basis
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative assets			11.6				12.4
Netting and collateral, derivative asset			(4.6)				(4.1)
Total, derivative asset	[1]		7.0				8.3
Derivative liability			6.5				5.0
Netting and collateral, derivative liability			(4.6)				(4.1)
Total, derivative liability	[1]		1.9				$ 0.9
Firm Commitments | Level 1
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative liability			0.0
Firm Commitments | Level 2
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative liability			3.5
Firm Commitments | Level 3
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative liability			0.0
Firm Commitments | Fair value measured on recurring basis
Assets and liabilities measured at estimated fair value on a recurring basis
Derivative liability			3.5
Netting and collateral, derivative liability			0.0
Total, derivative liability	[1]		$ 3.5

[1] Amounts may not add due to rounding