Consolidated Condensed Statements 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
Net Income (Loss)	$ (19,298)	$ 2,046	$ 120,461	$ 190,739
Other comprehensive income (loss):
Total cash flow hedges	(5,220)	(58,430)	(28,831)	25,167
Pension and postretirement plans:
Amortization of net obligation at transition, net of taxes of $26, $25, $77 and $75	48	47	143	140
Amortization of prior service cost, net of taxes of $28, $30, $82 and $89	51	55	153	166
Amortization of net loss, including settlement charges, net of taxes of $729, $413, $2,383 and $1,238	1,354	766	4,425	2,300
Current period change in fair value of pension and postretirement plans, net of taxes of $2,238, ($4,073), $2,238 and ($4,073)	4,157	(7,564)	4,157	(7,564)
Total pension and postretirement plans	5,610	(6,696)	8,878	(4,958)
Comprehensive Income (Loss)	(18,908)	(63,080)	100,508	210,948
Commodity contracts
Other comprehensive income (loss):
Current period change in fair value	69	(49,962)	(10,882)	49,961
Reclassification adjustment for commodity derivative instruments, net of tax	(5,229)	(8,034)	(18,740)	(23,337)
Interest rate swap
Other comprehensive income (loss):
Current period change in fair value	(350)	(697)	(42)	(2,240)
Reclassification adjustment for commodity derivative instruments, net of tax	$ 290	$ 263	$ 833	$ 783