Consolidated Condensed Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net Income	$ 83,067	$ 131,287	$ 139,759	$ 188,693
Other comprehensive income (loss):
Total cash flow hedges	13,659	95,577	(23,611)	83,598
Pension and postretirement plans:
Amortization of net obligation at transition, net of taxes of $26, $25, $52 and $50	47	47	95	93
Amortization of prior service cost, net of taxes of $28, $30, $55 and $59	51	55	102	110
Amortization of net loss, including settlement charges, net of taxes of $734, $413, $1,654 and $826	1,363	766	3,071	1,533
Total pension and postretirement plans	(1,461)	(868)	(3,268)	(1,736)
Comprehensive Income	98,187	227,732	119,416	274,027
Commodity contracts
Other comprehensive income (loss):
Current period change in fair value	15,847	112,158	(10,951)	99,923
Reclassification adjustment for commodity derivative instruments, net of tax	(2,792)	(15,797)	(13,511)	(15,303)
Interest rate swap
Other comprehensive income (loss):
Current period change in fair value	327	(1,051)	307	(1,542)
Reclassification adjustment for commodity derivative instruments, net of tax	$ 277	$ 267	$ 544	$ 520