Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Jun. 30, 2013
Commitments and Contingencies
Purchase orders outstanding for drilling equipment	$ 120.5
Gain contingencies recognized in consolidated financial statements	0
Proceeds from settlement of arbitration dispute with a third party not affiliated with the Venezuelan government, Petroleo or PDVSA	$ 15.0

Amount of gain recognized in the period that had been disclosed in prior periods as a contingent gain.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 30

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 17

-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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant