Consolidated Condensed Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net Income	$ 53,316	$ 56,692
Other comprehensive income (loss):
Total cash flow hedges	(2,337)	(37,272)
Pension and postretirement plans:
Amortization of net obligation at transition, net of tax of $3 and $26, respectively	6	48
Amortization of prior service cost, net of tax of $26 and $27, respectively	48	51
Amortization of net loss, including settlement charges, net of tax of $2,994 and $920, respectively	5,559	1,709
Total pension and postretirement plans	5,613	1,808
Comprehensive Income	56,592	21,228
Derivative commodity instruments
Other comprehensive income (loss):
Current period change in fair value	2	(26,798)
Reclassification adjustment for commodity derivative instruments, net of tax	(2,513)	(10,720)
Interest rate swap
Other comprehensive income (loss):
Current period change in fair value	(115)	(20)
Reclassification adjustment for commodity derivative instruments, net of tax	$ 289	$ 266