Consolidated Condensed Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net Income	$ 56,692	$ 57,406
Other comprehensive income (loss):
Total cash flow hedges	(37,272)	(11,979)
Pension and postretirement plans:
Amortization of net obligation at transition, net of taxes of $26 and $25	48	47
Amortization of prior service cost, net of taxes of $27 and $30	51	55
Amortization of net loss, including settlement charges, net of taxes of $920 and $412	1,709	766
Total pension and postretirement plans	1,808	868
Comprehensive Income	21,228	46,295
Commodity contracts
Other comprehensive income (loss):
Reclassification adjustment for commodity derivative instruments, net of tax	(10,720)	493
Current period change in fair value of interest rate swap, net of tax of ($11) and ($265)	(26,798)	(12,234)
Interest rate swap
Other comprehensive income (loss):
Reclassification adjustment for commodity derivative instruments, net of tax	266	254
Current period change in fair value of interest rate swap, net of tax of ($11) and ($265)	$ (20)	$ (492)