Miscellaneous Other Income - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Income and Expenses [Abstract]
Royalty Income - Non-Operated Coal	$ 10,258	$ 8,661	$ 12,032
Interest Income	6,031	3,287	1,230
Rental Income	2,239	1,095	1,314
Sale of Certain Mining Rights	0	21,756	39,437
Contract Buyout	0	0	44,703
Sale of Certain Coal Lease Contracts	0	0	17,847
Other	5,826	3,595	10,323
Miscellaneous Other Income	$ 24,354	$ 38,394	$ 126,886