CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
OPERATING ACTIVITIES
Net income	$ 40,616	$ 81,813
Adjustments to reconcile net income to net cash flows provided by (used in) operating activities:
Depreciation and depletion	66,493	28,358
Deferred income tax credit	(10,894)
Amortization of debt issuance costs	3,644	786
Other	8,756	3,175
Decrease (increase) in current assets:
Receivables	16,889	(1,753)
Inventories	(63,192)	1,190
Prepaid expenses and other current assets	5,462	6,488
Increase (decrease) in current liabilities:
Accounts payable	37,604	(5,444)
Accrued expenses and other current liabilities	(34,524)	33,912
Cash flows provided by operating activities	70,854	148,525
INVESTING ACTIVITIES
Additions to property, plant and equipment	(120,845)	(44,293)
Investment in Western Coal Corp.		(293,678)
Proceeds from sales of investments	12,228
Other	(85)	211
Cash flows used in investing activities	(108,702)	(337,760)
FINANCING ACTIVITIES
Borrowings under revolving credit agreement	135,294
Repayments on revolving credit agreement	(70,156)
Retirements of debt	(9,177)	(7,199)
Dividends paid	(7,806)	(6,642)
Other	(624)	2,336
Cash flows provided by (used in) financing activities	47,531	(11,505)
Effect of foreign exchange rates on cash	87
Net increase (decrease) in cash and cash equivalents	9,770	(200,740)
Cash and cash equivalents at beginning of period	128,430	293,410
Add: Cash and cash equivalents of discontinued operations at beginning of period		535
Net increase (decrease) in cash and cash equivalents	9,770	(200,740)
Cash and cash equivalents at end of period	$ 138,200	$ 93,205