CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME
Net income	$ 69,889		$ 36,608		$ 201,827		$ 90,864
Other comprehensive income / (loss), net of taxes:
Reclassification adjustment for settled hedge contracts	(11,942)	[1]	(37,294)	[1]	(22,372)	[1]	(115,943)	[1]
Changes in fair value of hedge contracts	(1,447)	[2]	(24,361)	[2]	31,417	[2]	30,091	[2]
Pension and postretirement benefits:
Amortization of prior service cost							135	[3]
Amortization of net loss	70	[4]	79	[4]	319	[4]	8,428	[4]
Total other comprehensive income / (loss)	(13,319)		(61,576)		9,364		(77,289)
Comprehensive income / (loss)	$ 56,570		$ (24,968)		$ 211,191		$ 13,575

[1] Net of income taxes of $7,742 and $23,644 for the three months ended September 30, 2013 and 2012, respectively, and $14,504 and $73,507 for the nine months ended September 30, 2013 and 2012, respectively.

[2] Net of income taxes of $937 and $15,444 for the three months ended September 30, 2013 and 2012, respectively, and $(20,366) and $(19,208) for the nine months ended September 30, 2013 and 2012, respectively.

[3] Net of income taxes of $0 and $0 for the three months ended September 30, 2013 and 2012, respectively, and $0 and $(86) for the nine months ended September 30, 2013 and 2012, respectively.

[4] Net of income taxes of $(46) and $(53) for the three months ended September 30, 2013 and 2012, respectively, and $(206) and $(5,347) for the nine months ended September 30, 2013 and 2012, respectively.