Derivatives - Summary of Gross Fair Values of Derivative Instruments, Presenting the Impact of Offsetting Derivative Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$ (33.0)	$ (164.0)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	10.7	158.4
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(22.3)	(5.6)
Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	0	(13.8)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	14.4
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	0	0.6
Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(33.0)	(150.2)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	10.7	144.0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(22.3)	(6.2)
Commodity Contract [Member] | Fuel Product [Member] | Crude Oil Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(8.8)	(102.4)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0.8	111.2
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(8.0)	8.8
Commodity Contract [Member] | Fuel Product [Member] | Gasoline Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(2.1)	(1.0)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	1.3	0.4
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(0.8)	(0.6)
Commodity Contract [Member] | Fuel Product [Member] | Crude Oil Percent Basis Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(0.1)	(0.2)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0.3	0.2
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	0.2	0
Commodity Contract [Member] | Fuel Product [Member] | Crude Oil Options [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(0.8)	0
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	2.4	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	1.6	0
Commodity Contract [Member] | Fuel Product [Member] | Gasoline Crack Spread Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(2.0)	0
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0.2	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(1.8)	0
Commodity Contract [Member] | Fuel Product [Member] | Diesel Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	0	(28.1)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	5.3	19.1
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	5.3	(9.0)
Commodity Contract [Member] | Fuel Product [Member] | Diesel Crack Spread Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(2.2)	0
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0.3	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(1.9)	0
Commodity Contract [Member] | Fuel Product [Member] | Jet Fuel Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	0	(5.2)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	5.2
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	0	0
Commodity Contract [Member] | Fuel Product [Member] | Platinum Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(0.3)	(0.1)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0.1
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(0.3)	0
Commodity Contract [Member] | Fuel Product [Member] | Natural Gas Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(0.3)	0
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(0.3)	0
Commodity Contract [Member] | Specialty Product [Member] | Natural Gas Swaps [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(15.2)	(12.1)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0.1	7.2
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(15.1)	(4.9)
Commodity Option [Member] | Specialty Product [Member] | Natural Gas Collars [Member] | Not Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(1.2)	(1.1)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0.6
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	(1.2)	(0.5)
Cash Flow Hedging [Member] | Commodity Contract [Member] | Fuel Product [Member] | Crude Oil Swaps [Member] | Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	0	(13.8)
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	10.0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	0	(3.8)
Cash Flow Hedging [Member] | Commodity Contract [Member] | Fuel Product [Member] | Gasoline Swaps [Member] | Designated as Hedging Instrument [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	0	0
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	4.4
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	$ 0	$ 4.4