EARNINGS (LOSS) PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC. (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
EARNINGS (LOSS) PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.
Net (loss) income attributable to the stockholders of Argan, Inc.	$ 1,154	$ 16,972	$ (28,646)	$ 21,809
Weighted average number of shares outstanding - basic	15,633	15,568	15,608	15,568
Effects of stock awards	124	105		105
Weighted average number of shares outstanding - diluted	15,757	15,673	15,608	15,673
Basic (in Dollars per share)	$ 0.07	$ 1.09	$ (1.84)	$ 1.40
Diluted (in Dollars per share)	$ 0.07	$ 1.08	$ (1.84)	$ 1.39