Borrowings (Senior Secured Revolving Credit Facility) (Details) (USD $)
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12 Months Ended | 12 Months Ended | 0 Months Ended | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2012
Revolving Credit Facility [Member]
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Dec. 31, 2011
Revolving Credit Facility [Member]
|
Dec. 31, 2012
Revolving Credit Facility [Member]
Regions Bank [Member]
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Oct. 31, 2012
Revolving Credit Facility [Member]
Regions Bank [Member]
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Jun. 20, 2012
Revolving Credit Facility [Member]
Regions Bank [Member]
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Jun. 19, 2012
Revolving Credit Facility [Member]
Regions Bank [Member]
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Dec. 31, 2012
Revolving Credit Facility [Member]
Minimum [Member]
Regions Bank [Member]
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Dec. 31, 2012
Revolving Credit Facility [Member]
Maximum [Member]
Regions Bank [Member]
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Mar. 13, 2013
Subsequent Event [Member]
Revolving Credit Facility [Member]
Regions Bank [Member]
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Dec. 28, 2012
Habanero Field (Garden Banks Block 341) [Member]
Shell Offshore Inc. [Member]
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Line of Credit Facility [Line Items] | |||||||||||||
Maximum borrowing capacity | $ 200,000,000 | ||||||||||||
Current borrowing capacity | 65,000,000 | 45,000,000 | 80,000,000 | 60,000,000 | |||||||||
Business Combination, Consideration Transferred, After Customary Purchase Price Adjustments | 39,410,000 | ||||||||||||
Credit Facility | 10,000,000 | 0 | 10,000,000 | 0 | |||||||||
Line of Credit Facility, Current Borrowing Capacity, Percent Increase | 44.00% | ||||||||||||
Proceeds from Divestiture of Businesses | 39,936,000 | 7,615,000 | 0 | ||||||||||
Interest rate at period end (as a percent) | 2.72% | ||||||||||||
Basis Spread on LIBOR (as a percent) | 2.50% | 3.00% | |||||||||||
Unused capacity, commitment fee (as a percent) | 0.50% | ||||||||||||
Credit Facility | 25,000,000 | ||||||||||||
Line of Credit Facility, Increase, Additional Borrowings | $ 15,000,000 |