Discontinued Operations (Details) - Schedule Of Discontinued Items Statement of Operations - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Schedule Of Discontinued Items Statement of Operations [Abstract]
Net sales and revenue	[1]	$ 151	$ 34	$ 377	$ 134
Cost of Sales		3,033	1,284	8,015	4,375
Gross loss		(2,882)	(1,250)	(7,638)	(4,241)
Selling, general and administrative		230	(12)	665	(107)
Income before income taxes		(3,112)	(1,238)	(8,303)	(4,134)
Benefit for income taxes		4,927	985	12,566	4,863
Net income from discontinued operations, net of tax		1,815	(253)	4,263	729
Net loss attributable to noncontrolling interests		137	58	370	193
Net income (loss) attributable to REX common shareholders		$ 1,952	$ (195)	$ 4,633	$ 922

[1] Refined coal sales were recorded net of the cost of coal as the Company purchased the coal feedstock from the customer to which the processed refined coal was sold.