Workers Compensation Expense (Details) - USD ($) $ in Millions			1 Months Ended
	Jan. 19, 2023	Jan. 18, 2023	Feb. 29, 2020
Workers Compensation Expense
Self-insured operators must post security percent		120.00%
Coal operators must post security percent	70.00%
Additional collateral amount	$ 71.1		$ 71.1
Number of days required to submit additional collateral to retain self-insurance status			30 days