Derivatives, Hedges, Financial Instruments and Carbon Credits (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Total net gains (losses) included in earnings:
Derivative instruments and carbon credits, gains and losses recognized in earnings	$ (40)	$ (1,231)	$ (449)	$ (2,311)
Derivative instruments and carbon credits change in unrealized gains and losses recognized in earnings	151	(827)	291	(1,117)
Cost of Sales [Member] | Commodities Contracts [Member]
Total net gains (losses) included in earnings:
Derivative instruments and carbon credits, gains and losses recognized in earnings	157	(430)	85	(624)
Derivative instruments and carbon credits change in unrealized gains and losses recognized in earnings	171	(430)	85	(482)
Cost of Sales [Member] | Foreign Exchange Contracts [Member]
Total net gains (losses) included in earnings:
Derivative instruments and carbon credits, gains and losses recognized in earnings	(11)		(19)	46
Other Income [Member] | Carbon Credits [Member]
Total net gains (losses) included in earnings:
Derivative instruments and carbon credits, gains and losses recognized in earnings	248	(2)	248	1,028
Derivative instruments and carbon credits change in unrealized gains and losses recognized in earnings	184	(2)	184	7
Other Expenses [Member] | Contractual obligations relating to carbon credits [Member]
Total net gains (losses) included in earnings:
Derivative instruments and carbon credits, gains and losses recognized in earnings	(248)		(248)	(936)
Derivative instruments and carbon credits change in unrealized gains and losses recognized in earnings	(184)		(184)	(7)
Interest Expense [Member] | Interest Rate Contracts [Member]
Total net gains (losses) included in earnings:
Derivative instruments and carbon credits, gains and losses recognized in earnings	(186)	(799)	(515)	(1,825)
Derivative instruments and carbon credits change in unrealized gains and losses recognized in earnings	$ (20)	$ (395)	$ 206	$ (635)