Property, Plant and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment, Net [Abstract]

Property, Plant and Equipment

Property, plant and equipment, net includes the following:

	December 31
	2021		2020
Coal lands and real estate	$	52,011	$	50,887
Mineral interests	19,512		14,181
Plant and equipment	264,110		231,190
Property, plant and equipment, at cost	335,633		296,258
Less allowances for depreciation, depletion and amortization	142,466		123,841
	$	193,167	$	172,417