Income Taxes - Provision (Benefit) for Income Taxes (Parenthetical) (Detail)
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1 Months Ended | |
---|---|---|
Jul. 31, 2011
Petroleum Operations [Member]
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Jul. 31, 2012
Dismantlement Expenses [Member]
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Income Tax Expense Benefit [Line Items] | ||
Old supplementary tax rate (in percentage) | 20.00% | 32.00% |
New supplementary tax rate (in percentage) | 32.00% | 20.00% |