| **Segment Information - Schedule of Revenue by similar Products and Services (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------------------------------------|----------------|-----------------|
||
| **Segment Reporting Information**                                                                                                       |           |            |   |   |   |   |   |   |   |   |   |
| Revenue                                                                                                                                 | $ 5,860        | $ 5,787         | $ 5,487 | $ 5,230 | $ 5,325 | $ 5,355 | $ 5,326 | $ 5,355 | $ 22,364 | $ 21,361 | $ 19,831 |
| Completion and Production                                                                                                               |           |            |   |   |   |   |   |   |   |   |   |
| **Segment Reporting Information**                                                                                                       |           |            |   |   |   |   |   |   |   |   |   |
| Revenue                                                                                                                                 |           |            |   |   |   |   |   |   | 13,323 | 12,949 | 12,469 |
| Drilling and Evaluation                                                                                                                 |           |            |   |   |   |   |   |   |   |   |   |
| **Segment Reporting Information**                                                                                                       |           |            |   |   |   |   |   |   |   |   |   |
| Revenue                                                                                                                                 |           |            |   |   |   |   |   |   | 7,762 | 7,195 | 6,224 |
| Industrial Services                                                                                                                     |           |            |   |   |   |   |   |   |   |   |   |
| **Segment Reporting Information**                                                                                                       |           |            |   |   |   |   |   |   |   |   |   |
| Revenue                                                                                                                                 |           |            |   |   |   |   |   |   | 1,279 | 1,217 | 1,138 |
| Total                                                                                                                                   |           |            |   |   |   |   |   |   |   |   |   |
| **Segment Reporting Information**                                                                                                       |           |            |   |   |   |   |   |   |   |   |   |
| Revenue                                                                                                                                 |           |            |   |   |   |   |   |   | $ 22,364 | $ 21,361 | $ 19,831 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 5
+ Details**Name:**us-gaap_SalesRevenueNet**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_SegmentReportingInformationLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |