CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
REVENUES
Revenues	$ 413,275	$ 383,110	$ 227,455
COST OF REVENUES
Cost of revenues	313,810	299,507	148,607
GROSS PROFIT	99,465	83,603	78,848
Selling, general and administrative expenses	25,060	19,470	12,918
INCOME FROM OPERATIONS	74,405	64,133	65,930
Gains on the deconsolidation of variable interest entities	349		2,444
Other income, net	752	234	961
INCOME BEFORE INCOME TAXES	75,506	64,367	69,335
Income tax expense	25,302	20,912	25,991
NET INCOME	50,204	43,455	43,344
Net income attributable to noncontrolling interests	13,859	13,010	3,219
NET INCOME ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.	$ 36,345	$ 30,445	$ 40,125
EARNINGS PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.
Basic (in Dollars per share)	$ 2.46	$ 2.11	$ 2.85
Diluted (in Dollars per share)	$ 2.42	$ 2.05	$ 2.78
WEIGHTED AVERAGE NUMBER OF SHARES OUTSTANDING
Basic (in shares)	14,757	14,433	14,072
Diluted (in shares)	15,024	14,823	14,427
CASH DIVIDENDS PER COMMON SHARE	$ 0.70	$ 0.70	$ 0.75
Power Industry Services
REVENUES
Revenues	$ 387,636	$ 376,676	$ 218,649
COST OF REVENUES
Cost of revenues	290,823	294,643	141,807
GROSS PROFIT	96,813	82,033	76,842
Selling, general and administrative expenses	15,303	11,930	7,575
INCOME FROM OPERATIONS	81,510	70,103	69,267
Gains on the deconsolidation of variable interest entities	349		2,444
Other income, net	478	231	958
INCOME BEFORE INCOME TAXES	82,337	70,334	72,669
Industrial Fabrication And Field Services
REVENUES
Revenues	15,260
COST OF REVENUES
Cost of revenues	15,527
GROSS PROFIT	(267)
Selling, general and administrative expenses	1,151
INCOME FROM OPERATIONS	(1,418)
INCOME BEFORE INCOME TAXES	(1,418)
Telecommunications Infrastructure Services
REVENUES
Revenues	10,379	6,434	8,806
COST OF REVENUES
Cost of revenues	7,460	4,864	6,800
GROSS PROFIT	2,919	1,570	2,006
Selling, general and administrative expenses	1,323	1,299	1,331
INCOME FROM OPERATIONS	1,596	271	675
INCOME BEFORE INCOME TAXES	$ 1,596	$ 271	$ 675