Debt (Narrative) (Details) (USD $)							6 Months Ended		6 Months Ended			6 Months Ended					6 Months Ended						6 Months Ended
	Nov. 18, 2010	Jun. 30, 2014 7.875% Senior Unsecured Notes [Member]	Dec. 31, 2013 7.875% Senior Unsecured Notes [Member]	Feb. 01, 2012 7.875% Senior Unsecured Notes [Member]	Feb. 01, 2012 Unsecured Debt [Member]	Jun. 30, 2014 Senior Secured Credit Facility [Member]	Jun. 30, 2014 Senior Secured Credit Facility [Member] Letters Of Credit [Member]	Jun. 30, 2014 Senior Secured Credit Facility [Member] Accordion Feature [Member]	Jun. 30, 2014 Five Point Seventy Five Percentage Senior Unsecured Notes [Member]	Dec. 31, 2013 Five Point Seventy Five Percentage Senior Unsecured Notes [Member]	Feb. 08, 2013 Five Point Seventy Five Percentage Senior Unsecured Notes [Member]	Jun. 30, 2014 Five Point Six Two Five Percentage Senior Unsecured Notes [Member] [Domain]	May 15, 2014 Five Point Six Two Five Percentage Senior Unsecured Notes [Member] [Domain]	Jun. 30, 2014 Petroleum Products [Member] Senior Secured Credit Facility [Member]	Jun. 30, 2014 Amended Facility [Member]	Jun. 30, 2014 Amended Facility [Member] Senior Secured Credit Facility [Member] Accordion Feature [Member]	Jun. 30, 2014 Minimum [Member]	Jun. 30, 2014 Minimum [Member] Eurodollar Rate [Member]	Jun. 30, 2014 Minimum [Member] Alternate Base Rate [Member]	Jun. 30, 2014 Maximum [Member]	Jun. 30, 2014 Maximum [Member] Eurodollar Rate [Member]	Jun. 30, 2014 Maximum [Member] Senior Secured Credit Facility [Member] Letters Of Credit [Member]	Jun. 30, 2014 Maximum [Member] Alternate Base Rate [Member]
Debt Instrument [Line Items]
Credit facility, amount outstanding						$ 492,200,000								$ 105,900,000
Credit facility, maximum borrowing capacity								300,000,000							1,000,000,000	500,000,000
Line Of Credit Facility Aggregate Maximum Borrowing Capacity						1,500,000,000
Letters of credit, outstanding amount							19,900,000															100,000,000
Credit facility and senior unsecured notes, maturity dates							Jul. 25, 2019		Feb. 15, 2021			Jun. 15, 2024
Letter of Credit, Fee Percentage																	1.50%	1.50%	0.50%	2.50%	2.50%		1.50%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage																	0.25%			0.375%
Total amount available for borrowings under credit facility						487,900,000
Senior unsecured notes, principal amount	250,000,000			100,000,000	350,000,000						350,000,000		350,000,000
Senior unsecured notes, stated rate	7.875%	7.875%	7.875%						5.75%	5.75%	5.75%		5.63%
Senior unsecured notes, percentage of face value					101.00%
Debt Instrument, Interest Rate, Effective Percentage					7.682%
Debt Instrument, Unamortized Premium		$ 740,000	$ 772,000
Maximum Percentage Of Principal, Early Debt Redemption									35.00%			35.00%
Redemption premium for notes									105.75%			105.63%