Segment Information - Additional Information (Detail)	6 Months Ended
Jun. 30, 2011
Segment Reporting Disclosure [Line Items]
Description of rigs used	Our rigs consist of various sizes and capabilities, allowing us to service all types of wells with depths up to 20,000 feet.
Maintenance period, description	Maintenance services generally take less than 48 hours to complete

Description of the types of products and services from which the reportable segment derives its revenue.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 26
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_DescriptionOfTypesOfProductsAndServicesFromWhichEachReportableSegmentDerivesItsRevenues
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration