2.2.0.7 false Ceiling Test - Additional Information (Detail) (USD $) 144 - Disclosure - Ceiling Test - Additional Information (Detail) true false In Millions false false 1 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 shares Standard http://www.xbrl.org/2003/instance shares 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 pure Standard http://www.xbrl.org/2003/instance pure 0 $ 5 Ceiling test impairment charge, before tax 3 d_CeilingTestImpairmentCharge d false debit duration This item represents the entity's ceiling test impairment charge calculated in accordance with the full cost method of... false false false false false false false false false false false false 1 true true false false 455000000 455 false false false xbrli:monetaryItemType monetary This item represents the entity's ceiling test impairment charge calculated in accordance with the full cost method of accounting for gas and oil E&P activities prescribed by the SEC. No authoritative reference available. false 6 Ceiling test impairment charge, after tax 3 d_CeilingTestImpairmentChargeNetOfTax d false debit duration This item represents the entity's ceiling test impairment charge calculated in accordance with the full cost method of... false false false false false false false false false false false false 1 false true false false 281000000 281 false false false xbrli:monetaryItemType monetary This item represents the entity's ceiling test impairment charge calculated in accordance with the full cost method of accounting for gas and oil E&P activities prescribed by the SEC, net of tax. No authoritative reference available. false 7 Ceiling test impairment excluding the effects of hedge-adjusted prices, before tax 3 d_CashFlowHedgesNotConsideredInCalculatingCeilingLimitationAmount d false debit duration This item represents the entity's hypothetical ceiling test impairment charge that would have been incurred if cash flow... false false false false false false false false false false false false 1 false true false false 631000000 631 false false false xbrli:monetaryItemType monetary This item represents the entity's hypothetical ceiling test impairment charge that would have been incurred if cash flow hedges had not been considered in calculating the ceiling test limitation in accordance with the full cost method of accounting for gas and oil E&P activities prescribed by the SEC. No authoritative reference available. false 8 Ceiling test impairment excluding the effects of hedge-adjusted prices, after tax 3 d_CashFlowHedgesNotConsideredInCalculatingCeilingLimitationAmountNetOfTax d false debit duration This item represents the entity's hypothetical ceiling test impairment charge, net of tax, that would have been incurred if... false false false false false false false false false false false false 1 true true false false 378000000 378 false false false xbrli:monetaryItemType monetary This item represents the entity's hypothetical ceiling test impairment charge, net of tax, that would have been incurred if cash flow hedges had not been considered in calculating the ceiling test limitation in accordance with the full cost method of accounting for gas and oil E&P activities prescribed by the SEC. No authoritative reference available. false 1 4 false Millions UnKnown UnKnown false true