CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 302,258	$ 336,553	$ 304,158
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	268,981	336,509	323,983
Non-cash compensation expense	12,279	14,229	12,854
Settlement of deferred directors compensation	(26)	(218)	(177)
Asset retirement obligations	3,793	3,769	3,192
Coal inventory adjustment to market	449		1,952
Equity investment (income) loss	(13,860)	(3,543)	49,046
Distributions received from investments	13,939	2,719
Paid-in-kind distributions received from cost investment	(6,398)
Net gain on sale of property, plant and equipment	(696)	(76)	(1)
Asset impairment			100,130
Acquisition gain, net			(22,548)
Valuation allowance of deferred tax assets	(3,339)	(1,365)	1,557
Debt extinguishment loss	8,148
Other	6,212	3,300	6,388
Changes in operating assets and liabilities:
Trade receivables	(29,639)	(29,157)	64,412
Other receivables	133	417	422
Inventories, net	(1,449)	44,948	(21,898)
Prepaid expenses and other assets	(6,064)	17,023	(3,402)
Advance royalties, net	(13,591)	(2,464)	(6,915)
Accounts payable	25,507	(15,196)	(41,506)
Due to/from affiliates	(123)	778	(11,076)
Accrued taxes other than income taxes	2,078	2,667	(4,322)
Accrued payroll and related benefits	(5,775)	4,545	(24,527)
Pneumoconiosis benefits	(159)	447	2,808
Workers' compensation	(4,371)	(6,427)	(2,491)
Other	(4,205)	(8,733)	(17,631)
Total net adjustments	251,824	364,172	410,250
Net cash provided by operating activities	554,082	700,725	714,408
Property, plant and equipment:
Capital expenditures	(145,088)	(91,056)	(212,797)
Increase (decrease) in accounts payable and accrued liabilities	7,404	(4,402)	(3,021)
Proceeds from sale of property, plant and equipment	2,139	1,165	2,062
Contributions to equity investments	(20,688)	(76,797)	(64,540)
Purchase of cost investment	(100,000)
Distributions received from investments in excess of cumulative earnings	11,462	3,313	444
Payments for acquisitions of businesses, net of cash acquired		(1,011)	(74,953)
Payment for acquisition of customer contracts		(23,000)
Advances/loans to affiliate			(7,300)
Other			4,190
Net cash used in investing activities	(244,771)	(191,788)	(355,915)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under securitization facility	100,000	44,600	6,500
Payments under securitization facility	(127,600)	(27,700)	(23,400)
Payments on term loan	(50,000)	(156,250)	(108,502)
Borrowings under revolving credit facilities	215,486	140,000	543,000
Payments under revolving credit facilities	(440,486)	(270,000)	(308,000)
Borrowings under long-term debt	400,000
Payment on long-term debt	(145,000)		(205,000)
Proceeds on capital lease transactions		33,881	100,000
Payments on capital lease obligations	(27,071)	(24,456)	(4,312)
Payment of debt issuance costs	(16,487)	(101)
Payment for debt extinguishment	(8,148)
Contributions to consolidated company from affiliate noncontrolling interest	251	3,014	2,147
Net settlement of employee withholding taxes on vesting of ARLP Long-Term Incentive Plan	(2,988)	(1,336)	(2,719)
Contribution by limited partner - affiliate	1,000	1,000	1,500
Distributions paid by consolidated partnership to non-controlling interests	(84,973)	(89,311)	(117,362)
Distributions paid to Partners	(153,549)	(156,242)	(225,833)
Other	(5,628)	(189)	(6,108)
Net cash used in financing activities	(345,193)	(503,090)	(348,089)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(35,882)	5,847	10,404
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	44,525	38,678	28,274
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 8,643	$ 44,525	$ 38,678