Accounts receivable by major customers.

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- Definition

Accounts receivable balance due from.

+ Details

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- Definition

Accounts receivable expected to be collected within one year.

+ Details

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- Definition

Aggregate drilling rate.

+ Details

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- Definition

Portion of daily operating rate payable in accordance with normal credit terms.

+ Details

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- Definition

Portion of daily operating rate payable from net profits interest in oil and gas producing properties.

+ Details

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- Definition

Financial Instruments and Fair Value Disclosures Textuals Abstract.

+ Details

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- Definition

Percentage of net profits interest in oil and gas producing properties which is to be used to settle the remaining contractual day rate pertaining to a specific customer contract.

+ Details

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- Definition

Amount of time from receipt of invoice that customer payment is due.

+ Details

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- Definition

Percentage of total consolidated trade accounts receivable balance due from a major customer.

+ Details

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- Definition

Total amount payable through the net profits interest.

+ Details

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- Definition

Included within accounts receivable and expected to be paid within 12 months.

+ Details

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- Definition

Included within Long-term receivable and expected to be paid beyond the next 12 months.

+ Details

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 4
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5074-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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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.

+ Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Available-for-Sale Securities
-URI http://asc.fasb.org/extlink&oid=6505594

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13
-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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Trading Securities
-URI http://asc.fasb.org/extlink&oid=6526789

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 12
-Subparagraph a
-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.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 7
-Section 03
-Paragraph 1
-Subparagraph a, f, g

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6956420&loc=d3e24584-111560

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Financial Instruments and Fair Value Disclosures (Details Textuals) (USD $)	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Cash held in money market funds [Member] Level 1 [Member]	Dec. 31, 2010 Cash held in money market funds [Member] Level 1 [Member]	Jun. 30, 2011 U.S. Treasury Bills [Member] Level 1 [Member]	Dec. 31, 2010 U.S. Treasury Bills [Member] Level 1 [Member]	Jun. 30, 2011 Petrobras [Member]	Dec. 31, 2010 Petrobras [Member]	Jun. 30, 2011 OGX [Member]	Jun. 30, 2010 OGX [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of investments			$ 244,300,000	$ 442,200,000	$ 700,000,000	$ 600,000,000
Accounts Receivable By Major Customers [Line Items]
Accounts receivable due from major customer							132,500,000	180,800,000	68,300,000	52,400,000
Percentage of accounts receivable due from major customer							23.00%	29.00%	12.00%	8.00%
Financial Instruments and Fair Value Disclosures (Textuals) [Abstract]
Provision for bad debts on trade receivables	3,429,000	31,908,000
Aggregate drilling rate, per day	560,000
Daily payment under amended six-well drilling program	75,000
Receipt of invoice due, in days	due 30 days after receipt of invoice
Remainder of the contractual dayrate	485,000
Net profits interest percent	27.00%
Accounts receivable	80,700,000	49,600,000
Long-term receivable		35,400,000
Total amount payable through the net profits interest	80,700,000	85,000,000
Accounts receivable expected to be collected within one year	$ 80,700,000