Debt - Additional Information (Detail)								3 Months Ended		6 Months Ended
	Mar. 01, 2017 USD ($)	Jun. 14, 2016 USD ($)	Jun. 13, 2016 USD ($)	Jun. 10, 2016 $ / shares	May 27, 2016	May 13, 2016 USD ($)	Mar. 06, 2012 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) $ / shares	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) $ / shares	Jun. 30, 2015 USD ($)	Aug. 02, 2016 USD ($)	Apr. 13, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 24, 2014 USD ($)
Debt Instrument [Line Items]
Current portion of long-term debt								$ 288,336,000		$ 288,336,000					$ 0
Fair value of amount outstanding								$ 341,500,000		$ 341,500,000			$ 457,000,000
Long-term debt, weighted average interest rate								4.30%		4.30%
Consolidated funded debt to consolidated EBITDA ratio								3.75		3.75
Consolidated EBITDA To consolidated net interest expense								2.5		2.5
Long-term debt								$ 1,411,200,000		$ 1,411,200,000					1,061,000,000
Interest expense related to contractual interest coupon of convertible notes								1,300,000	$ 1,300,000	$ 2,600,000	$ 2,600,000
Repayments of Lines of Credit		$ 56,800,000
Stock split, conversion ratio					0.1
Minimum
Debt Instrument [Line Items]
Percentage of borrowing base utilization, percent										1.50%
Maximum
Debt Instrument [Line Items]
Percentage of borrowing base utilization, percent										2.50%
1 3⁄4% Senior Convertible Notes due 2017
Debt Instrument [Line Items]
Current portion of long-term debt								$ 287,900,000		$ 287,900,000
Aggregate principal amount of senior subordinated notes							$ 300,000,000
Initial conversion rate of convertible note 2017										An initial conversion rate of 23.4449 shares of our common stock per $1,000 principal amount of 2017 Convertible Notes,
Initial conversion rate of common stock				0.0023449			0.0234449			1
Initial conversion price of convertible note 2017 (in usd per share) | $ / shares				$ 426.50			$ 42.65
Closing share price (in usd per share) | $ / shares								$ 12.06		$ 12.06
Payment for call option							$ 70,800,000
Anti-dilution adjustments for purchases of call option (in shares) | shares							703,347
Strike price per share (in usd per share) | $ / shares							$ 559.10
Proceeds from sale of warrants							$ 40,100,000
Long-term debt								$ 287,900,000		$ 287,900,000					279,300,000
Interest expense related to amortization of discount								4,000,000	3,700,000	7,900,000	7,400,000
Amortization of deferred financing costs								400,000	$ 400,000	$ 800,000	$ 700,000
Revolving credit facility
Debt Instrument [Line Items]
Current portion of long-term debt													175,300,000
Credit facility initial date										Jun. 24, 2014
Redetermined base borrowing and credit facility																$ 900,000,000
Maturity of new credit facility if note issue under 2004 indenture are retired on or before April 15, 2014										Jul. 01, 2019
Borrowing base		360,000,000											300,000,000	$ 500,000,000
Outstanding borrowing under bank credit facility								18,300,000		$ 18,300,000			$ 18,300,000
Initial bank and availability under facility								200,000		$ 200,000
Period in which outstanding amount has to be repaid to cure deficiency										10 days
Period in which bank has to add new properties to borrowing base and has to grant mortgage to banks										30 days
Oil and gas reserve as proportion of discounted present value of future net cash flow, for mortgage, percent										86.00%
Long-term debt								341,500,000		$ 341,500,000					0
Line of Credit Facility, Minimum Liquidity Requirement		125,000,000
Line of Credit Facility, Limitations on Capital Expenditures		60,000,000
Line of Credit Facility, Amount of Cash to Which Anti-Hoarding Cash Provisions Apply		$ 50,000,000
Repayments of Lines of Credit			$ 29,200,000			$ 29,200,000
4.20% Building Loan
Debt Instrument [Line Items]
Current portion of long-term debt								400,000		400,000
Long-term debt								$ 11,500,000		$ 11,500,000					$ 11,700,000
Scenario, Forecast | 1 3⁄4% Senior Convertible Notes due 2017
Debt Instrument [Line Items]
Cash share holders receive for each dollar In principle	$ 1,000
Subsequent Event
Debt Instrument [Line Items]
Fair value of amount outstanding												$ 341,500,000
Subsequent Event | Revolving credit facility
Debt Instrument [Line Items]
Outstanding borrowing under bank credit facility												18,300,000
Initial bank and availability under facility												$ 200,000
Quarter ended June 30, 2016
Debt Instrument [Line Items]
Consolidated funded debt to consolidated EBITDA ratio		5.25
Quarter ending September 30, 2016
Debt Instrument [Line Items]
Consolidated funded debt to consolidated EBITDA ratio		6.50
Quarter ending December 31, 2016
Debt Instrument [Line Items]
Consolidated funded debt to consolidated EBITDA ratio		9.50
Thereafter
Debt Instrument [Line Items]
Consolidated funded debt to consolidated EBITDA ratio		3.75
Uncompleted Wells | Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Limitations on Capital Expenditures		$ 25,000,000