Sale of Piceance and Arkoma Properties - Discontinued Operations (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Discontinued Operations:
Income from discontinued operations before income taxes		$ 3,564	$ 8,506
Income tax expense		(1,354)	(3,249)
IncomeLossFromDiscontinuedOperationsNetOfTax	$ 2,210	$ 2,210	$ 5,257

Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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- Definition

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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Reference 10: http://www.xbrl.org/2003/role/presentationRef
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