Transactions with Related Parties (Narrative) (Details) (USD $)						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010		Nov. 30, 2010	Dec. 31, 2011 Sandhill [Member]	Dec. 31, 2012 Sandhill [Member]	Dec. 31, 2011 Quintana Group [Member]	Dec. 31, 2010 Compensation Recognized For Executive Management Team [Member]	Jul. 29, 2010 DG Marine [Member]	Dec. 31, 2011 Sandhill Group, LLC [Member]	Dec. 31, 2012 Common Class B [Member] Davison [Member]	Oct. 05, 2012 Common Class B [Member] Davison [Member]	Dec. 31, 2012 Common Class B [Member] Quintana Group [Member]	Dec. 31, 2012 Common Class A [Member] Davison [Member]	Oct. 05, 2012 Common Class A [Member] Davison [Member]	Dec. 31, 2012 Common Class A [Member] Quintana Group [Member]
Related Party Transaction [Line Items]
Percentage of equity interest											50.00%	76.90%	76.90%	74.00%	17.00%	17.20%	12.00%
Percentage of equity interest acquired										51.00%
Due from related parties						$ 200,000	$ 300,000	$ 1,900,000
Due to related parties	600,000	316,000	0	[1]				100,000
Percentage of obligation guaranteed						50.00%
Loan held by related party						1,700,000	1,200,000
Guaranty obligation	350,000,000					900,000	600,000
General partner made capital contributions			$ 2,500,000		$ 2,500,000				$ 76,900,000

[1] Affiliates of Denbury Resources, Inc. sold its interests in our general partner in February 2010. Transactions with Denbury are included in the table as a related party through that date.