Segment Information (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 947,125	$ 376,111
Other revenues	10,497	8,909
Total	947,125	376,111
Product Groups [Member]
Disaggregation of Revenue [Line Items]
Total	947,125	376,111
Metallurgical Coal [Member]
Disaggregation of Revenue [Line Items]
Revenues	891,729	343,436
Thermal Coal [Member]
Disaggregation of Revenue [Line Items]
Revenues	44,899	23,766
Total Coal Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	936,628	367,202
Australia Segment [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Other revenues	9,000	8,843
Total	605,298	238,293
Australia Segment [Member] | Metallurgical Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	554,009	206,452
Australia Segment [Member] | Thermal Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	42,289	22,998
Australia Segment [Member] | Total Coal Revenue [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	596,298	229,450
United States Segment [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Other revenues	1,497	66
Total	341,827	137,818
United States Segment [Member] | Metallurgical Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	337,720	136,984
United States Segment [Member] | Thermal Coal [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,610	768
United States Segment [Member] | Total Coal Revenue [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 340,330	$ 137,752