XML 46 R27.htm IDEA: XBRL DOCUMENT

Major Customers	12 Months Ended
Major Customers	Dec. 31, 2017
Segment Reporting [Abstract]
Major Customers	Major Customers Sales to Royal Dutch Shell PLC constituted approximately 10% of our total revenues (before the effects of hedging) for the year ended December 31, 2017. Sales to BP PLC constituted approximately 10% and 14% of our total revenues (before the effects of hedging) for the years ended December 31, 2016 and 2015, respectively.