Consolidated Statements of Operations (USD $)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Revenues
Revenues	$ 227,455,000	$ 278,635,000	$ 141,850,000
Cost of revenues
Cost of revenues	148,607,000	228,500,000	118,748,000
Gross profit	78,848,000	50,135,000	23,102,000
Selling, general and administrative expenses	12,918,000	14,350,000	11,186,000
Income from operations	65,930,000	35,785,000	11,916,000
Gains on the deconsolidation of variable interest entities	2,444,000
Other income (expense), net	961,000	(43,000)	48,000
Income (loss) from continuing operations before income taxes	69,335,000	35,742,000	11,964,000
Income tax expense	25,991,000	13,640,000	4,556,000
Income from continuing operations	43,344,000	22,102,000	7,408,000
Discontinued operations
(Loss) income from discontinued operations before income tax benefit (see Note 19)		(405,000)	282,000
Income tax benefit		120,000	1,280,000
(Loss) income from discontinued operations		(285,000)	1,562,000
Net income	43,344,000	21,817,000	8,970,000
Income (loss) attributable to noncontrolling interests	3,219,000	(1,448,000)	(302,000)
Net income attributable to the stockholders of Argan, Inc.	40,125,000	23,265,000	9,272,000
Continuing operations (see Note 15)
Basic	$ 2.85	$ 1.71	$ 0.57
Diluted	$ 2.78	$ 1.67	$ 0.56
Discontinued operations
Basic		$ (0.02)	$ 0.11
Diluted		$ (0.02)	$ 0.11
Net income
Basic	$ 2.85	$ 1.69	$ 0.68
Diluted	$ 2.78	$ 1.65	$ 0.67
Weighted average number of shares outstanding
Basic	14,072,000	13,784,000	13,612,000
Diluted	14,427,000	14,116,000	13,792,000
Cash dividend per common share	$ 0.75	$ 0.60	$ 0.50
Power Industry Services [Member]
Revenues
Revenues	218,649,000	261,327,000	132,519,000
Cost of revenues
Cost of revenues	141,807,000	214,817,000	111,193,000
Telecommunications Infrastructure Services [Member]
Revenues
Revenues	8,806,000	17,308,000	9,331,000
Cost of revenues
Cost of revenues	$ 6,800,000	$ 13,683,000	$ 7,555,000