CONSOLIDATED STATEMENTS OF OPERATIONS (Cloud Peak Energy Inc. and Subsidiaries) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2009
Revenues	$ 1,370,761	$ 1,398,200
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization and accretion, shown separately)	978,914	933,489
Depreciation and depletion	100,023	97,869
Amortization	3,197	28,719
Accretion	12,499	12,587
Selling, general and administrative expenses	63,594	69,835
Asset impairment charges	659	698
Total costs and expenses	1,158,886	1,143,197
Operating income	211,875	255,003
Other income (expense)
Interest income	565	320
Interest expense	(46,938)	(5,992)
Tax agreement expense	(19,669)
Other, net	157	9
Total other expense	(65,885)	(5,663)
Income from continuing operations before income tax provision and earnings from unconsolidated affiliates	145,990	249,340
Income tax (expense) benefit	(31,982)	(68,249)
Earnings from unconsolidated affiliates, net of tax	3,189	1,381
Income from continuing operations	117,197	182,472
Income from discontinued operations, net of tax		211,078
Net income	117,197	393,550
Less: Net income attributable to noncontrolling interest	83,460	11,849
Net income attributable to controlling interest	33,737	381,701
Amounts attributable to controlling interest common stockholders:
Income from continuing operations	33,737	170,623
Income from discontinued operations		211,078
Net income	$ 33,737	$ 381,701
Basic
Income from continuing operations (in dollars per share)	$ 1.06	$ 3.01
Income from discontinued operations (in dollars per share)		$ 3.73
Net income (in dollars per share)	$ 1.06	$ 6.74
Weighted-average shares outstanding-basic (in shares)	31,889	56,617
Diluted
Income from continuing operations (in dollars per share)	$ 1.06	$ 2.97
Income from discontinued operations (in dollars per share)		$ 3.52
Net income (in dollars per share)	$ 1.06	$ 6.49
Weighted-average shares outstanding-diluted (in shares)	31,889	60,000