Subsequent Event (Details) (Subsequent Event [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
Oct. 31, 2013 buyer rig
Subsequent Event [Member]
Subsequent Event [Line Items]
Drilling rigs considered for sale	5
Drilling rigs considered for sale, units sold	1
Drilling rigs considered for sale, remaining units	4
Number of buyers of the drilling rigs	2
Net book value of drilling rigs considered for sale	$ 17.2

Long-lived assets that are held for sale apart from normal operations and anticipated to be sold in less than one year.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1107-107759

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 46

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_AssetsHeldForSaleLongLived
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant