Average oil price per barrel.

No definition available.

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- Definition

Expected cash flows from backlog of commitments for contract drilling revenues.

+ References

No definition available.

+ Details

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- Definition

Number of rigs.

+ References

No definition available.

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- Definition

The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=51719941&loc=d3e2921-110230

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 360

-Section 35

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=28370743&loc=d3e66150-109466

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

+ References

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- Details

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Property and Equipment - Additional Information (Detail) $ in Millions			3 Months Ended			9 Months Ended
	Aug. 24, 2015 $ / bbl	Mar. 17, 2015 $ / bbl	Sep. 30, 2015 USD ($) Rigs $ / bbl	Jun. 30, 2015 $ / bbl	Mar. 31, 2015 $ / bbl	Sep. 30, 2015 USD ($) Rigs
Property Plant And Equipment [Line Items]
Expected cash flows from contract drilling segment			$ 801.0			$ 801.0
Average oil price per barrel \| $ / bbl	38.22	43.39	46.42	57.85	48.54
Impairment charges related to oil and natural gas properties			$ 1.9			$ 9.3
Drilling Rigs That Would No Longer Be Marketed As Rigs
Property Plant And Equipment [Line Items]
Number of drilling rings \| Rigs			33			33
Impairment charges of fleets						$ 131.0
Mechanically Powered Drilling Rigs That Would No Longer Be Marketed as Rigs
Property Plant And Equipment [Line Items]
Number of drilling rings \| Rigs			24			24
Non-APEX® electric Drilling Rigs That Would No Longer Be Marketed as Rigs
Property Plant And Equipment [Line Items]
Number of drilling rings \| Rigs			9			9
Mechanically powered drilling rigs that remain marketable but are not operating
Property Plant And Equipment [Line Items]
Number of drilling rings \| Rigs			15			15
Pressure Pumping
Property Plant And Equipment [Line Items]
Impairment charges of fleets			$ 22.0