Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss)	$ (111,601)	$ (7,953)	$ (127,021)	$ 45,363
Other comprehensive income (loss):
Total cash flow hedges	0	(2,698)	0	(5,035)
Pension and postretirement plans:
Amortization of net benefit obligation at transition, net of tax of $0, $3, $0 and $7, respectively	0	6	0	12
Amortization of prior service cost, net of tax of $0, $26, $0 and $52, respectively	0	48	0	96
Amortization of net loss, including settlement charges, net of tax of $309, $577, $1,305 and $3,571, respectively	576	1,072	2,427	6,631
Current period change in fair value of pension and postretirement plans, net of tax of $0, ($1,151), $0 and ($1,151), respectively	0	(2,136)	0	(2,136)
Total pension and postretirement plans	576	(1,010)	2,427	4,603
Comprehensive Income (Loss)	(111,025)	(11,661)	(124,594)	44,931
Commodity contracts
Other comprehensive income (loss):
Current period change in fair value of derivative commodity instruments, net of tax	0	9	0	11
Reclassification adjustment for derivative commodity instruments, net of tax	0	(3,556)	0	(6,069)
Interest rate swap
Other comprehensive income (loss):
Current period change in fair value of derivative commodity instruments, net of tax	0	(183)	0	(298)
Reclassification adjustment for derivative commodity instruments, net of tax	$ 0	$ 1,032	$ 0	$ 1,321