EARNINGS 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, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
EARNINGS PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.
Net income attributable to the stockholders of Argan, Inc.	$ 16,972	$ 27,139	$ 21,809	$ 47,764
Weighted average number of shares outstanding - basic	15,568	15,514	15,568	15,491
Effect of stock awards	105	273	105	297
Weighted average number of shares outstanding - diluted	15,673	15,787	15,673	15,788
Basic (in Dollars per share)	$ 1.09	$ 1.75	$ 1.40	$ 3.08
Diluted (in Dollars per share)	$ 1.08	$ 1.72	$ 1.39	$ 3.03