Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities:
Net loss	$ (754,710)	$ (2,309,568)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion, accretion and amortization	733,282	878,924
Amortization of acquired intangibles, net	908	(64,480)
Mark-to-market adjustments for derivatives	1,312	(12,820)
Share-based Compensation	18,360	3,945
Goodwill impairment	253,102	1,525,332
Asset impairment and restructuring	24,358	1,028,610
Employee benefit plans, net	43,352	56,033
Loss on early extinguishment of debt	33,039	0
Deferred income taxes	(306,488)	(577,744)
Other, net	(16,020)	(16,271)
Changes in operating assets and liabilities:
Trade accounts receivable, net	118,216	186,737
Inventories, net	61,116	34,826
Prepaid expenses and other current assets	30,728	170,642
Other non-current assets	7,052	(729)
Trade accounts payable	(28,332)	(195,607)
Accrued expenses and other current liabilities	152,816	(342,838)
Pension and postretirement medical benefit obligations	(36,647)	(35,667)
Asset retirement obligations	(31,519)	(37,611)
Other non-current liabilities	(125,346)	13,933
Net cash provided by operating activities	178,579	305,647
Investing activities:
Capital expenditures	(163,129)	(332,592)
Acquisition of mineral rights under federal lease	0	(53,501)
Purchase of equity-method investments	0	(10,100)
Purchases of marketable securities	(738,800)	(419,275)
Sales of marketable securities	680,452	307,137
Other, net	7,075	7,420
Net cash used in investing activities	(214,402)	(500,911)
Financing activities:
Principal repayments of long-term debt	(951,894)	(30,000)
Principal repayments of capital lease obligations	(12,604)	(3,862)
Proceeds from borrowings on long-term debt	964,369	0
Debt issuance costs	(24,317)	(6,737)
Common stock repurchases	(1,352)	(6,985)
Other	(1,000)	(830)
Net cash (used in) provided by financing activities	(26,798)	(48,414)
Net increase (decrease) in cash and cash equivalents	(62,621)	(243,678)
Cash and cash equivalents at beginning of period	730,723	585,882
Cash and cash equivalents at end of period	$ 668,102	$ 342,204