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v2.4.0.6

Segment Reporting - Revenues and Percentage of Consolidated Revenues (Parenthetical) (Detail) (Maximum [Member]) | 12 Months Ended
--- | ---
Dec. 31, 2012
Maximum [Member] |
Segment Reporting Information [Line Items] |
Percentage of revenue for BP PLC | 10.00%

X
- Definition Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues. + References No definition available. + Details
Name: | us-gaap_EntityWideRevenueMajorCustomerPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration