CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ (144,815)		$ 175,173		$ (525,211)		$ 479,236
Change in derivatives:
Reclassification to earnings	(94,996)	[1]	(49,436)	[1]	(310,882)	[1]	(113,850)	[1]
Ineffectiveness	322	[2]	1,574	[2]	(1,215)	[2]	307	[2]
Change in fair value of derivative instruments	(36,468)	[3]	170,251	[3]	93,985	[3]	259,559	[3]
Total change in derivatives	(131,142)		122,389		(218,112)		146,016
Change in value of pension and other postretirement liabilities:
Amortization of prior service cost included in net periodic pension cost	254	[4]	197	[4]	762	[4]	590	[4]
Change in currency translation adjustment	997		(1,219)		962		(831)
Comprehensive income (loss)	$ (274,706)		$ 296,540		$ (741,599)		$ 625,011

[1] Net of $(62.2), $(31.6), $(202.6) and $(72.8) million in taxes for the three months ended September 30, 2012 and 2011, and the nine months ended September 30, 2012 and 2011, respectively.

[2] Net of $0.2, $1.0, $(0.8) and $0.2 million in taxes for the three months ended September 30, 2012 and 2011, and the nine months ended September 30, 2012 and 2011, respectively.

[3] Net of $ (22.1), $108.8, $62.7 and $165.9 million in taxes for the three months ended September 30, 2012 and 2011, and the nine months ended September 30, 2012 and 2011, respectively.

[4] Net of $0.2,$0.2, $0.5 and $0.4 million in taxes for the three months ended September 30, 2012 and 2011, and the nine months ended September 30, 2012 and 2011, respectively.