Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions		3 Months Ended		9 Months Ended
	May 09, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Operating Expenses		$ 46,756	$ 58,967	$ 142,938	$ 153,308
Accounts receivable, net		48,788		48,788				$ 43,202
Amount payable to related parties		670		670				940
Operating and maintenance expenses—affiliates, net		2,154	4,062	6,928	9,948
Revenues and other income		93,116	91,448	273,339	284,667
Operating and maintenance expenses		32,441	31,242	93,089	87,824
Accounts receivable—affiliates		243		243				6,658
Intangible assets, net		50,370		50,370				3,236
Intangible assets, net—affiliate		0		0				49,811
Long-term contracts receivable		41,211		41,211				0
Due from Affiliate, Noncurrent		0		0				43,785
Deferred revenue		106,391		106,391		$ 110,885	$ 46,008	44,931
Deferred revenue—affiliates		0		0			$ 68,735	71,632
Quintana Minerals
Related Party Transaction [Line Items]
Amount payable to related parties		500		500				400
Operating and maintenance expenses—affiliates, net		0	400	100	1,200
Western Pocahontas Properties
Related Party Transaction [Line Items]
Amount payable to related parties		200		200				600
Cline Affiliates
Related Party Transaction [Line Items]
Operating and maintenance expenses—affiliates, net		0	392	$ 452	973
Rate of interest in the partnerships general partner	31.00%			31.00%
Related Party Transaction Number Of Units Hold By Related Party In Partnerships General Partner				0.5
Cline Affiliates
Related Party Transaction [Line Items]
Accounts receivable, net		6,828		$ 6,828				0
Accounts receivable—affiliates		0		0				6,496
Deferred revenue		59,009		59,009				0
Deferred revenue—affiliates		0		0				71,632
Foresight Energy Lp
Related Party Transaction [Line Items]
Operating Expenses		415	0	700	0
Operating and maintenance expenses		415	392	1,152	973
Foresight Energy Lp | Coal Sales
Related Party Transaction [Line Items]
Revenues and other income		18,781	20,635	50,827	47,648
Coal royalty and other—affiliates		0	20,635	27,216	47,648
Revenues		18,781	0	23,611	0
Sugar Camp
Related Party Transaction [Line Items]
Unearned income		29,213		29,213				31,803
Net amount receivable		72,531		72,531				76,424
Long-term contracts receivable		41,211		41,211				0
Due from Affiliate, Noncurrent		0		0				43,785
Corsa
Related Party Transaction [Line Items]
Accounts receivable—affiliates		200		200				200
Royalty Revenue from Coal		300	800	1,000	1,900
Western Pocahontas Properties Limited Partnership | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses—affiliates, net		400	0	700	700
Other assets—affiliate		900		900				1,000
Quinwood Coal Company [Member]
Related Party Transaction [Line Items]
Deferred Revenue, Revenue Recognized		900		900
Discontinued Operations, Held-for-sale | Quintana Minerals
Related Party Transaction [Line Items]
Amount payable to related parties		100		100				$ 100
Foresight Energy Lp
Related Party Transaction [Line Items]
Revenues		$ 18,781	$ 20,635	$ 50,827	$ 47,648