Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Schedule of effects of revenue recognition

	PRB		MET		Other Thermal		Corporate, Other and Eliminations		Consolidated
	(in thousands)
Year Ended December 31, 2019
North America revenues	$	915,750	$	217,381	$	190,051	$	10,850	$	1,334,032
Seaborne revenues	—		773,169		187,151		—		960,320
Total revenues	$	915,750	$	990,550	$	377,202	$	10,850	$	2,294,352
Year Ended December 31, 2018
North America revenues	$	971,337	$	160,969	$	195,547	$	13,034	$	1,340,887
Seaborne revenues	1,911		875,652		233,337		—		1,110,900
Total revenues	$	973,248	$	1,036,621	$	428,884	$	13,034	$	2,451,787
Year Ended December 31, 2017
North America revenues	$	1,024,197	$	312,874	$	269,007	$	16,083	$	1,622,161
Seaborne revenues	—		574,965		127,497		—		702,462
Total revenues	$	1,024,197	$	887,839	$	396,504	$	16,083	$	2,324,623