Derivatives, Hedges, Financial Instruments and Carbon Credits - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($) $ / shares $ / MMBTU $ / € shares	Dec. 31, 2015 $ / shares $ / MMBTU shares	Mar. 31, 2016 EUR (€) MMBTU Unit lb $ / Transaction $ / €	Dec. 31, 2015 EUR (€) MMBTU Unit lb $ / Transaction	Feb. 28, 2011 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Contractual weighted-average cost | $ / MMBTU	1.99	2.35
Estimated weighted-average market value | $ / MMBTU	1.96
Contractual weighted-average exchange rate | $ / €			1.12
Carbon credit fair value per unit | $ / Transaction			2.35	2.35
Derivative future or forward contracts in pounds | lb			0	0
Derivative future or forward contracts in volume | MMBTU			611,000	1,820,000
The month future or forward natural gas contract period ends	2016-12	2016-12
Amount of foreign currency contract | €			€ 228,000	€ 280,000
Future or forward foreign exchange contracts settlement period	2017-02	2017-02
LIBOR rate					3.23%
Interest rate contracts fixed rate description	fixed three-month LIBOR rate of 3.23% on a declining balance
Interest rate swap declining balance beginning balance | $					$ 23,800,000
Interest rate swap declining balance ending balance | $					$ 18,800,000
Maturity period interest rate contracts held	Mar. 31, 2016
Number of carbon credits | Unit			516,000	495,000
Assets or liabilities measured at fair value on a recurring basis transferred between Level 1 and Level 2 classifications | $	$ 0
7.75% Senior Secured Notes [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Debt instrument, interest rate			7.75%
Foreign Exchange Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Contractual weighted-average exchange rate | $ / €			1.12
Total estimated market weighted-average exchange rate | $ / €	1.14
Embedded Derivative [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Participating right in dividends and liquidating distributions expressed in number of common shares | shares	456,225	456,225
Embedded Derivative [Member] | Common Stock Shares [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Market price of common stock per share | $ / shares	$ 12.75	$ 7.25