Major Customer and Concentrations of Credit Risk (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Major Customer and Concentrations of Credit Risk [Abstract]
Percentage of revenue from Tesoro	91.00%	89.00%	67.00%

Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

No definition available.

Name:	us-gaap_EntityWideRevenueMajorCustomerPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration