Segment Information - Revenue from External Customers (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) customer	Mar. 31, 2021 USD ($) customer
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues | $	$ 1,069,738	$ 385,452
Export Coal Revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues | $	$ 894,525	$ 243,783
Revenues | Geographic Concentration Risk | Export Coal Revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as a percent)	84.00%	63.00%
Revenues | Customer Concentration Risk
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of customers | customer	1	1
Revenues | Customer Concentration Risk | Top Customer
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as a percent)	29.00%	13.00%
Revenues | Customer Concentration Risk | Top 10 Customers
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as a percent)	73.00%	63.00%
Accounts Receivable | Customer Concentration Risk
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of customers | customer	1	3