CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
NET INCOME (LOSS)	$ (46,679)	$ 58,184	$ (191,386)	$ 341,788
OTHER COMPREHENSIVE INCOME (LOSS)
OTHER COMPREHENSIVE INCOME (LOSS)	939	(118)	1,877	(3,702)
COMPREHENSIVE INCOME (LOSS)	(45,740)	58,066	(189,509)	338,086
Less: Comprehensive loss (income) attributable to noncontrolling interest	15	(114)	(61)	(7,290)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ARLP	(45,725)	57,952	(189,570)	330,796
Defined benefit pension plan
OTHER COMPREHENSIVE INCOME (LOSS)
Amortization of prior service cost	47	46	93	93
Amortization of net actuarial loss	1,063	982	2,127	1,961
Total adjustments	1,110	1,028	2,220	2,054
Pneumoconiosis benefits
OTHER COMPREHENSIVE INCOME (LOSS)
Amortization of net actuarial loss	(171)	(1,146)	(343)	(2,291)
Net actuarial loss				(3,465)
Total adjustments	$ (171)	$ (1,146)	$ (343)	$ (5,756)