Financial Instruments (Details Textual) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($) Customer	Sep. 30, 2015 USD ($) Customer	Dec. 31, 2014 USD ($)
Offsetting Assets [Line Items]
Margin Deposit Assets | $	$ (2.3)	$ (2.3)	$ 0.8
Commodity Contract [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral | $	$ 2.6	$ 2.6	$ 2.5
Customer Concentration Risk [Member] | Sales Revenue, Goods, Net [Member]
Offsetting Assets [Line Items]
Concentration Risk, Percentage	43.00%	38.00%
Customer Concentration Risk [Member] | Cost of Goods, Total [Member]
Offsetting Assets [Line Items]
Concentration Risk, Percentage	15.00%	13.00%
Number of Suppliers	1
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Offsetting Assets [Line Items]
Concentration Risk, Percentage		37.00%
Customer Concentration Risk [Member] | Crude [Member] | Sales Revenue, Goods, Net [Member]
Offsetting Assets [Line Items]
Number of Customers	2	2
Customer Concentration Risk [Member] | Crude [Member] | Cost of Goods, Total [Member]
Offsetting Assets [Line Items]
Purchases of product | $	$ 40.3	$ 93.2
Number of Suppliers		1
Customer Concentration Risk [Member] | Crude [Member] | Accounts Receivable [Member]
Offsetting Assets [Line Items]
Number of Customers		1