Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash Flows From Operating Activities
Net (loss) income	$ (264.3)	$ 48.6
(Income) loss from discontinued operations, net of income taxes	(6.0)	66.5
(Loss) income from continuing operations, net of income taxes	(270.3)	115.1
Adjustments to reconcile (loss) income from continuing operations, net of income taxes to net cash provided by operating activities:
Depreciation, depletion and amortization	483.9	542.8
Noncash interest expense	17.7	27.5
Deferred income taxes	(44.3)	(261.3)
Share-based compensation	35.8	39.5
Asset impairment	0	21.5
Net gain on disposal or exchange of assets	(25.9)	(49.9)
Loss from equity affiliates	44.0	35.6
Gains on previously monetized foreign currency hedge positions	(106.7)	0
Changes in current assets and liabilities:
Accounts receivable	142.0	54.7
Change in receivable from accounts receivable securitization program	(75.0)	40.9
Inventories	20.5	(15.0)
Net assets from coal trading activities	(14.6)	(41.2)
Other current assets	4.4	11.0
Accounts payable and accrued expenses	76.2	(21.9)
Asset retirement obligations	28.4	35.0
Accrued postretirement benefit costs	12.7	10.0
Accrued pension costs	14.6	37.1
Other, net	2.4	(3.8)
Net cash provided by continuing operations	345.8	577.6
Net cash used in discontinued operations	(95.7)	(33.6)
Net cash provided by operating activities	250.1	544.0
Cash Flows From Investing Activities
Additions to property, plant, equipment and mine development	(107.5)	(228.7)
Changes in accrued expenses related to capital expenditures	(22.8)	(102.6)
Federal coal lease expenditures	(89.4)	(89.5)
Proceeds from disposal of assets, net of notes receivable	152.5	133.3
Purchases of debt securities	(6.0)	(9.9)
Proceeds from sales and maturities of debt securities	7.7	17.7
Proceeds from the maturity of short-term investments	0	4.8
Contributions to joint ventures	(410.4)	(539.8)
Distributions from joint ventures	408.5	576.6
Advances to related parties	(19.7)	(39.5)
Repayments of loans from related parties	1.4	22.7
Other, net	(3.9)	(4.2)
Net cash used in continuing operations	(89.6)	(259.1)
Net cash used in discontinued operations	0	(1.0)
Net cash used in investing activities	(89.6)	(260.1)
Cash Flows From Financing Activities
Repayments of long-term debt	(15.6)	(1,384.0)
Proceeds from long-term debt	1.1	1,188.0
Payment of deferred financing costs	(10.1)	(22.8)
Repurchase of employee common stock relinquished for tax withholding	(2.3)	(2.9)
Dividends paid	(69.2)	(68.8)
Restricted cash for distributions to noncontrolling interests	(42.5)	0
Other, net	0.6	(0.9)
Net cash used in financing activities	(138.0)	(291.4)
Net change in cash and cash equivalents	22.5	(7.5)
Cash and cash equivalents at beginning of period	444.0	558.8
Cash and cash equivalents at end of period	$ 466.5	$ 551.3