CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues:
Sales	$ 668,605	$ 764,587	$ 1,295,903	$ 1,171,162
Miscellaneous income	8,969	6,284	13,234	8,443
Total revenues	677,574	770,871	1,309,137	1,179,605
Costs and expenses:
Cost of sales (exclusive of depreciation and depletion)	486,084	466,074	917,618	684,534
Depreciation and depletion	74,459	72,470	140,952	100,828
Selling, general and administrative	35,845	57,521	72,092	89,403
Postretirement benefits	13,213	10,343	26,426	20,610
Total costs and expenses	609,601	606,408	1,157,088	895,375
Operating income	67,973	164,463	152,049	284,230
Interest expense	(31,104)	(32,047)	(59,171)	(35,603)
Interest income	341	160	618	316
Other income (loss)	(5,919)	24,503	(12,912)	24,503
Income from continuing operations before income tax expense	31,291	157,079	80,584	273,446
Income tax expense	4,535	42,626	13,212	77,180
Income from continuing operations	26,756	114,453	67,372	196,266
Income from discontinued operations	5,180		5,180
Net income	31,936	114,453	72,552	196,266
Basic income per share:
Income from continuing operations (in dollars per share)	$ 0.43	$ 1.84	$ 1.08	$ 3.36
Income from discontinued operations (in dollars per share)	$ 0.08		$ 0.08
Net income (in dollars per share)	$ 0.51	$ 1.84	$ 1.16	$ 3.36
Diluted income per share:
Income from continuing operations (in dollars per share)	$ 0.43	$ 1.83	$ 1.08	$ 3.34
Income from discontinued operations (in dollars per share)	$ 0.08		$ 0.08
Net income (in dollars per share)	$ 0.51	$ 1.83	$ 1.16	$ 3.34
Comprehensive income	$ 30,637	$ 101,722	$ 75,918	$ 196,192
Dividends per share (in dollars per share)	$ 0.125	$ 0.125	$ 0.25	$ 0.25