Debt - Additional Information (Detail)			3 Months Ended
	Mar. 01, 2017 USD ($)	Mar. 06, 2012 USD ($) $ / shares shares	Mar. 31, 2016 USD ($) $ / shares	Mar. 31, 2015 USD ($)	Jun. 30, 2016	Apr. 13, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 24, 2014 USD ($)
Debt Instrument [Line Items]
Current portion of long-term debt			$ 459,201,000				$ 0
Fair value of amount outstanding			$ 457,000,000
Long-term Debt, Weighted Average Interest Rate			3.50%
Long-term debt			$ 1,522,300,000				1,061,000,000
Interest expense related to contractual interest coupon of convertible notes			$ 1,300,000	$ 1,300,000
Minimum
Debt Instrument [Line Items]
Percentage of borrowing base utilization			1.50%
Maximum
Debt Instrument [Line Items]
Percentage of borrowing base utilization			2.50%
Subsequent Event
Debt Instrument [Line Items]
Fair value of amount outstanding						$ 457,000,000
7 1⁄2% Senior Notes due 2022
Debt Instrument [Line Items]
Long-term debt			$ 770,200,000				770,000,000
1 3⁄4% Senior Convertible Notes due 2017
Debt Instrument [Line Items]
Current portion of long-term debt			$ 283,500,000
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		0.0234449	1
Initial conversion price of convertible note 2017 (in usd per share) | $ / shares		$ 42.65
Closing share price (in usd per share) | $ / shares			$ 0.79
Payment for call option		$ 70,800,000
Anti-dilution adjustments for purchases of call option (in shares) | shares		7,033,470
Strike price per share (in usd per share) | $ / shares		$ 55.91
Proceeds from sale of warrants		$ 40,100,000
Long-term debt			$ 283,500,000				279,300,000
Interest expense related to amortization of discount			3,900,000	3,600,000
Amortization of deferred financing costs			400,000	$ 300,000
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			$ 500,000,000
Outstanding borrowing under bank credit facility			19,200,000
Initial bank and availability under facility			$ 23,800,000
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			80.00%
Long-term debt			$ 457,000,000				0
Revolving credit facility | Subsequent Event
Debt Instrument [Line Items]
Current portion of long-term debt						175,300,000
Borrowing base						300,000,000
Outstanding borrowing under bank credit facility						$ 18,300,000
4.20% Building Loan
Debt Instrument [Line Items]
Current portion of long-term debt			400,000
Long-term debt			$ 11,600,000				$ 11,700,000
Covenant Compliance
Debt Instrument [Line Items]
Consolidated funded debt to consolidated EBITDA ratio			3.75
Consolidated EBITDA To consolidated net interest expense			2.5
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
Scenario, Forecast | Covenant Compliance
Debt Instrument [Line Items]
Consolidated funded debt to consolidated EBITDA ratio					3.75