Long-Term Debt - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 15, 2016	Jan. 16, 2016
Debt Disclosure [Line Items]
Interest on borrowings and related fees		$ 92,490,000	$ 91,866,000	$ 80,263,000
Amortization of Debt Discount (Premium)		0	0	431,000
Amortization of debt issuance costs		4,749,000	4,197,000	3,413,000
Interest Paid, Capitalized		6,288,000	7,232,000	5,266,000
Interest Expense		$ 90,951,000	88,831,000	$ 78,841,000
Line of Credit Facility, Asset Restrictions		0.8
Revolving credit facility 1		$ 170,000,000	$ 35,000,000
Debt Instrument Interest Additional Interest Above L I B O R Rate Subsequent Date					1.00%
Applicable Margin Rate Increase Subsequent Period					1.00%
Revolving credit facility
Debt Disclosure [Line Items]
Maximum borrowing capacity		275,000,000
Line of Credit Facility, Borrowing Capacity at Subsequent Period					$ 171,800,000
Letter of credit amount outstanding		$ 1,800,000
Credit facility interest rate option two, base rate over federal funds effective rate		0.50%
Debt Instrument, Description of Variable Rate Basis		one-month Adjusted LIBOR
Credit facility interest rate option two, base rate over one-month Adjusted LIBOR		1.00%
Credit facility interest rate option two, applicable margin rate		1.00%
Line of Credit Facility, Interest Rate at Period End		4.50%
Line Of Credit Facility, Interest Rate at Period End, LIBOR Component		3.50%
Commitment fees for undrawn credit facility		0.375%
Debt To EBITDAX Ratio, Threshold to Preclude Payment of Cash Dividends		500.00%
Revolving credit facility | Minimum
Debt Disclosure [Line Items]
Line of Credit Facility, Borrowing Capacity at Subsequent Period					$ 170,000,000
Credit facility interest rate option one, applicable margin rate over Adjusted LIBOR		1.50%
Debt Instrument Interest Additional Interest Above L I B O R Rate Subsequent Date					2.50%
Credit facility interest rate option two, applicable margin rate		0.50%
Applicable Margin Rate Subsequent Period					1.50%
Commitment fees for undrawn credit facility		0.375%
Required covenant, current ratio		1.0
Revolving credit facility | Maximum
Debt Disclosure [Line Items]
Credit facility interest rate option one, applicable margin rate over Adjusted LIBOR		2.50%
Debt Instrument Interest Additional Interest Above L I B O R Rate Subsequent Date					3.50%
Credit facility interest rate option two, applicable margin rate		1.50%
Applicable Margin Rate Subsequent Period					2.50%
Commitment fees for undrawn credit facility		0.50%
Revolving credit facility | through maturity
Debt Disclosure [Line Items]
Required covenant, debt to EBITDAX ratio		4.75
Revolving credit facility | (Beginning in April 2015)
Debt Disclosure [Line Items]
Required covenant, debt to EBITDAX ratio		5.25
Revolving credit facility | (June 2017 and thereafter)
Debt Disclosure [Line Items]
Required covenant, debt to EBITDAX ratio		5.50
Revolving credit facility | Future Period Six [Member]
Debt Disclosure [Line Items]
Required covenant, debt to EBITDAX ratio		4.50
Revolving credit facility | Future Period Seven [Member]
Debt Disclosure [Line Items]
Required covenant, debt to EBITDAX ratio		4.0
Revolving credit facility | Future Period Eight [Member] | Minimum
Debt Disclosure [Line Items]
Required covenant, current ratio		2.75
Revolving credit facility | Letter of Credit
Debt Disclosure [Line Items]
Maximum borrowing capacity		$ 20,000,000
Line of Credit, Maximum Borrowing Capacity at Subsequent Period					$ 1,800,000
7.25% Senior Notes due 2019
Debt Disclosure [Line Items]
Annual interest rate		7.25%
Debt Instrument, Redemption Price, Percentage		103.625%
7.25% Senior Notes due 2019 | Future Period Seven [Member]
Debt Disclosure [Line Items]
Debt Instrument, Redemption Price, Percentage		100.00%
8.50% Senior Notes due 2020
Debt Disclosure [Line Items]
Annual interest rate		8.50%
8.50% Senior Notes due 2020 | Future Period Seven [Member]
Debt Disclosure [Line Items]
Debt Instrument, Redemption Price, Percentage		104.25%
8.50% Senior Notes due 2020 | Future Period Nine [Member]
Debt Disclosure [Line Items]
Debt Instrument, Redemption Price, Percentage		10000.00%
Subsequent Event [Member]
Debt Disclosure [Line Items]
Line of Credit Facility, Asset Restrictions	1
Subsequent Event [Member] | Revolving credit facility
Debt Disclosure [Line Items]
Credit facility interest rate option two, applicable margin rate						200.00%
Line of Credit Facility, Interest Rate at Subsequent Period						0.00%
Line of Credit Facility, LIBOR Rate at Subsequent Period						43.75%