Derivative Instruments, Hedging Activities and Fair Value Measurements, Level 3 Recurring Valuation Techniques (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Asset commodity derivatives	$ 2.9
Liability commodity derivatives	3.6
Liability commodity derivatives - Crude oil [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Liability commodity derivatives	0.9
Liability commodity derivatives - Propane [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Liability commodity derivatives	0.1
Liability commodity derivatives - Natural gasoline [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Liability commodity derivatives	2.5
Liability commodity derivatives - Natural gas [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Liability commodity derivatives	0.1
Asset commodity derivatives - Crude oil [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Asset commodity derivatives	2.6
Asset commodity derivatives - Crude oil [Member] | Liability commodity derivatives - Crude oil [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair Value Measurements, Valuation Techniques	Discounted cash flow
Input description	Forward commodity prices
Asset commodity derivatives - Crude oil [Member] | Liability commodity derivatives - Crude oil [Member] | Minimum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	70.32
Asset commodity derivatives - Crude oil [Member] | Liability commodity derivatives - Crude oil [Member] | Maximum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	91.82
Asset commodity derivatives - Propane [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Asset commodity derivatives	0
Asset commodity derivatives - Propane [Member] | Liability commodity derivatives - Propane [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair Value Measurements, Valuation Techniques	Discounted cash flow
Input description	Forward commodity prices
Asset commodity derivatives - Propane [Member] | Liability commodity derivatives - Propane [Member] | Minimum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	1.02
Asset commodity derivatives - Propane [Member] | Liability commodity derivatives - Propane [Member] | Maximum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	1.05
Asset commodity derivatives - Natural gasoline [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Asset commodity derivatives	0.1
Asset commodity derivatives - Natural gasoline [Member] | Liability commodity derivatives - Natural gasoline [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair Value Measurements, Valuation Techniques	Discounted cash flow
Input description	Forward commodity prices
Asset commodity derivatives - Natural gasoline [Member] | Liability commodity derivatives - Natural gasoline [Member] | Minimum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	1.84
Asset commodity derivatives - Natural gasoline [Member] | Liability commodity derivatives - Natural gasoline [Member] | Maximum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	1.94
Assets commodity derivatives - Natural gas [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Asset commodity derivatives	$ 0.2
Assets commodity derivatives - Natural gas [Member] | Liability commodity derivatives - Natural gas [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair Value Measurements, Valuation Techniques	Discounted cash flow
Input description	Forward commodity prices
Assets commodity derivatives - Natural gas [Member] | Liability commodity derivatives - Natural gas [Member] | Minimum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	3.72
Assets commodity derivatives - Natural gas [Member] | Liability commodity derivatives - Natural gas [Member] | Maximum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, forward commodity price (in dollars per unit)	4.54