DERIVATIVE INSTRUMENTS - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2011
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Fair value of the energy derivatives, pre-tax	$ 800,000
1.00% Senior Convertible Debentures due 2027
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Date of contingent interest feature	holders may require us to repurchase their Debentures on February 1, 2012, February 1, 2017 and February 1, 2022
1.00% Senior Convertible Debentures due 2027 | Contingent interest features of the Notes and Debentures
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Date of contingent interest feature	The first contingent cash interest payment period would not commence until February 1, 2012
Fair value of the contingent interest feature	$ 0