Segment Information (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 1,032,704	$ 424,256	$ 1,979,829	$ 800,367
Other revenues	11,707	10,492	22,204	19,401
Total	1,032,704	424,256	1,979,829	800,367
Other and Corporate [Member]
Disaggregation of Revenue [Line Items]
Total			0	0
Product Groups [Member]
Disaggregation of Revenue [Line Items]
Total	1,032,704	424,256
Metallurgical Coal [Member]
Disaggregation of Revenue [Line Items]
Revenues	994,203	390,131	1,885,932	733,566
Thermal Coal [Member]
Disaggregation of Revenue [Line Items]
Revenues	26,794	23,633	71,693	47,400
Total Coal Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,020,997	413,764	1,957,625	780,966
Australia Segment [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Other revenues	10,042	8,683	19,042	17,527
Total	578,388	251,432	1,183,686	489,726
Australia Segment [Member] | Metallurgical Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	543,345	221,659	1,097,353	428,110
Australia Segment [Member] | Thermal Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	25,001	21,090	67,291	44,089
Australia Segment [Member] | Total Coal Revenue [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	568,346	242,749	1,164,644	472,199
United States Segment [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Other revenues	1,665	1,809	3,162	1,874
Total	454,316	172,824	796,143	310,641
United States Segment [Member] | Metallurgical Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	450,858	168,472	788,579	305,456
United States Segment [Member] | Thermal Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,793	2,543	4,402	3,311
United States Segment [Member] | Total Coal Revenue [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 452,651	$ 171,015	$ 792,981	$ 308,767