Concentration of Credit Risk and Major Customers - Schedule of Concentration of Credit Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Concentration Risk [Line Items]
Accounts receivables, before allowance for credit loss	$ 148,078	$ 159,858
Less: Allowance for credit losses	(466)	(1,731)
Total Trade Receivables, net	147,612	158,127
Accounts Receivable | Customer Concentration Risk | Electric coal utilities
Concentration Risk [Line Items]
Accounts receivables, before allowance for credit loss	28,870	82,608
Accounts Receivable | Customer Concentration Risk | Coal exporters and industrial customers
Concentration Risk [Line Items]
Accounts receivables, before allowance for credit loss	85,080	51,548
Accounts Receivable | Customer Concentration Risk | Steel and coke producers
Concentration Risk [Line Items]
Accounts receivables, before allowance for credit loss	29,340	24,230
Accounts Receivable | Customer Concentration Risk | Other
Concentration Risk [Line Items]
Accounts receivables, before allowance for credit loss	$ 4,788	$ 1,472