Property and Equipment - Additional Information (Detail) (Drilling Rigs That Would No Longer Be Marketed As Rigs, USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2014 Rigs
Drilling Rigs That Would No Longer Be Marketed As Rigs
Property Plant And Equipment [Line Items]
Number of drilling rigs	55
Impairment Charges of fleets	$ 77.9

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Reference 2: 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=6391110&loc=d3e2921-110230

Name:	us-gaap_TangibleAssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration