BUSINESS COMBINATIONS - Proforma information (Details) - APC and Roberts - USD ($)	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Pro Forma information
Adjustments to net income for pro forma presentation	$ (23,643,000)	$ 667,000
Adjustments to net income per share for pro forma presentation (in dollars per share)	$ (1.57)	$ 0.04
Revenue since acquisition	$ 29,454,000
Loss before income tax benefit since acquisition	(1,509,000)
Pro forma revenues	575,961	$ 524,795
Pro forma net income	26,561	44,122
Pro forma net income attributable to the stockholders of Argan, Inc.	$ 12,702	$ 31,112
Pro forma earnings per share attributable to the stockholders of Argan, Inc.
Basic (in dollars per share)	$ 0.86	$ 2.14
Diluted (in dollars per share)	$ 0.84	$ 2.06