Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activties
Net income (loss)	$ (641,832)	$ (683,687)	$ 142,840
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation, depletion and amortization	447,704	525,508	466,587
Amortization of acquired sales contracts, net	(9,457)	(25,189)	(22,069)
Sales contract amortization	(9,457)	(25,189)	(22,069)
Amortization relating to financing activities	24,789	20,238	14,067
Prepaid royalties expensed	13,706	22,650	34,842
Employee stock-based compensation expense	11,790	11,822	10,882
Net loss resulting from early retirement of debt and financing activities	(42,921)	(23,668)	(51,448)
Amortization of premiums on debt securities held	3,680
Gain on sale of Canyon Fuel	(120,321)	0	0
Asset impairment and mine closure costs	220,879	539,182	7,316
Payments for Restructuring		531,234
Goodwill impairment	265,423	330,680	0
Changes in:
Receivables	62,881	113,531	(74,914)
Inventories	44,635	9,468	(50,900)
Accounts payable, accrued expenses and other current liabilities	(77,521)	(171,580)	52,191
Income taxes, net	(4,520)	27,545	(21,759)
Deferred income taxes	(263,099)	(336,036)	10,519
Asset retirement obligations	17,432	(42,531)	3,868
Other	13,046	(11,359)	11,245
Cash provided by operating activities	55,742	332,804	642,242
Investing activities
Capital expenditures	(296,984)	(395,225)	(540,936)
Acquisition of businesses, net of cash acquired		0	(2,894,339)
Additions to prepaid royalties	(14,947)	(13,269)	(29,957)
Proceeds from dispositions of property, plant and equipment	10,790	22,825	25,887
Proceeds from sale-leaseback transactions	34,919
Proceeds from sale of Canyon Fuel	422,663
Purchases of short term investments	213,726	236,862	0
Proceeds from sales of short term investments	194,537	1,754	0
Investments in and advances to affiliates	(15,260)	(17,758)	(61,909)
Purchase of noncontrolling interest	0		0
Change in restricted cash	3,453	6,869	5,167
Consideration paid related to prior business acquisitions		0	(829)
Cash provided by (used in) investing activities	125,445	(649,166)	(3,496,916)
Financing activities
Proceeds from Issuance of Secured Debt	294,000	1,633,500
Proceeds from issuance of senior notes	350,000	359,753	2,000,000
Proceeds from the issuance of common stock, net		0	1,267,933
Payments to retire debt	(629,172)	(452,934)	(605,178)
Payments on term loan	(17,250)	(7,625)
Net decrease in borrowings under lines of credit		(481,300)	424,396
Net payments on other debt	(6,324)	(682)	5,334
Debt financing costs	(20,489)	(50,568)	(114,823)
Dividends paid	(25,475)	(42,440)	(80,748)
Proceeds from exercise of options under incentive plans		5,131	2,316
Cash provided by (used in) financing activities	(54,710)	962,835	2,899,230
Increase in cash and cash equivalents	126,477	646,473	44,556
Cash and cash equivalents, beginning of period	784,622	138,149	93,593
Cash and cash equivalents, end of period	911,099	784,622	138,149
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid during the year for interest	380,389	310,241	213,697
Cash paid (refunded) during the year for income taxes, net	(18,741)	(28,057)	7,094
Coal Contract [Member]
Changes in:
Coal derivative assets and liabilities	$ 3,606	$ (13,158)	$ 6,079