Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income tax expense from continuing operations
Current income tax expense (benefit)		$ (4,000)	$ 15,000
Deferred Income Tax Expense (Benefit)	445,672	190,210	106,229
Total income tax expense from continuing operations	445,672	186,210	121,229
U.S. Statutory federal income tax rate (as a percent)	35.00%	35.00%	35.00%
Reconciliation of income tax expense from continuing operations differs from the amount that would be computed by applying the U.S. statutory federal income tax rate to consolidated income
Federal income tax expense	391,754	56,708	121,276
State income tax expense , net of federal benefit	25,545	21,429	4,761
Nondeductible stock compensation	29,141	127,736
Noncontrolling interest in Antero Midstream Partners LP	(787)
Change in valuation allowance	(120)	(20,919)	(4,872)
Other	139	1,256	64
Total income tax expense from continuing operations	445,672	186,210	121,229
Income tax expense (benefit) allocated to continuing and discontinued operations
Total income tax expense from continuing operations	445,672	186,210	121,229
Discontinued operations and sale of discontinued operations	1,354	3,249	(272,553)
Total income tax expense (benefit)	447,026	189,459	(151,324)
Deferred tax assets:
Net operating loss carryforwards	431,681	449,961
Minimum tax credit carryforward	11,000	11,000
Equity based compensation	10,032
Other	12,785	5,373
Total deferred tax assets	465,498	466,334
Valuation allowance	(26,639)	(26,759)
Net deferred tax assets	438,859	439,575
Deferred tax liabilities:
Unrealized gains on derivative instruments	601,859	328,534
Oil and gas properties	600,050	458,812
Investment in Antero Midstream Partners LP	31,746
Total deferred tax liabilities	1,233,655	787,346
Net deferred tax liabilities	$ (794,796)	$ (347,771)