CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
NET INCOME		$ 302,258	$ 336,553	$ 304,158
OTHER COMPREHENSIVE INCOME (LOSS):
Total recognized adjustments		(13,400)	(3,983)	1,290
OTHER COMPREHENSIVE INCOME		(13,400)	(3,983)	1,290
COMPREHENSIVE INCOME		288,858	332,570	305,448
Less: Comprehensive income attributable to noncontrolling interests		(111,952)	(148,311)	(93,555)
COMPREHENSIVE INCOME ATTRIBUTABLE TO AHGP		176,906	184,259	211,893
Pension Plan
OTHER COMPREHENSIVE INCOME (LOSS):
Prior service cost			(1,498)
Amortization of prior service cost (1)	[1]	186
Net actuarial loss		(6,610)	(2,589)	(863)
Amortization of actuarial (gain) loss (1)	[1]	3,054	2,952	3,354
Total recognized adjustments		(3,370)	(1,135)	2,491
Pneumoconiosis benefits
OTHER COMPREHENSIVE INCOME (LOSS):
Net actuarial loss		(7,938)	(205)	(750)
Amortization of actuarial (gain) loss (1)	[1]	(2,092)	(2,643)	(451)
Total recognized adjustments		$ (10,030)	$ (2,848)	$ (1,201)

[1] Amortization of prior service cost and actuarial gain or loss is included in the computation of net periodic benefit cost (see Notes 13 and 17 for additional details).