CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
REVENUES
Revenues	$ 675,047	$ 413,275	$ 383,110
COST OF REVENUES
Cost of revenues	528,336	313,810	299,507
GROSS PROFIT	146,711	99,465	83,603
Selling, general and administrative expenses	32,478	25,060	19,470
Impairment loss	1,979
INCOME FROM OPERATIONS	112,254	74,405	64,133
Other income, net	2,278	1,101	234
INCOME BEFORE INCOME TAXES	114,532	75,506	64,367
Income tax expense	37,106	25,302	20,912
NET INCOME	77,426	50,204	43,455
Net income attributable to noncontrolling interests	7,098	13,859	13,010
NET INCOME ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.	70,328	36,345	30,445
OTHER COMPREHENSIVE LOSS
Foreign currency translation adjustments, net of tax	(197)	(565)
COMPREHENSIVE INCOME ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.	$ 70,131	$ 35,780	$ 30,445
EARNINGS PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.
Basic (in Dollars per share)	$ 4.67	$ 2.46	$ 2.11
Diluted (in Dollars per share)	$ 4.50	$ 2.42	$ 2.05
WEIGHTED AVERAGE NUMBER OF SHARES OUTSTANDING
Basic (in shares)	15,066	14,757	14,433
Diluted (in shares)	15,625	15,024	14,823
CASH DIVIDENDS PER COMMON SHARE (Note 16)	$ 1.00	$ 0.70	$ 0.70
Power industry services
REVENUES
Revenues	$ 586,628	$ 387,636	$ 376,676
COST OF REVENUES
Cost of revenues	452,599	290,823	294,643
GROSS PROFIT	134,029	96,813	82,033
Selling, general and administrative expenses	17,588	15,303	11,930
Impairment loss	1,979
INCOME FROM OPERATIONS	114,462	81,510	70,103
Other income, net	2,145	827	231
INCOME BEFORE INCOME TAXES	116,607	82,337	70,334
Industrial fabrication and field services
REVENUES
Revenues	78,994	15,260
COST OF REVENUES
Cost of revenues	68,354	15,527
GROSS PROFIT	10,640	(267)
Selling, general and administrative expenses	6,264	1,151
INCOME FROM OPERATIONS	4,376	(1,418)
INCOME BEFORE INCOME TAXES	4,376	(1,418)
Telecommunications infrastructure services
REVENUES
Revenues	9,425	10,379	6,434
COST OF REVENUES
Cost of revenues	7,383	7,460	4,864
GROSS PROFIT	2,042	2,919	1,570
Selling, general and administrative expenses	1,430	1,323	1,299
INCOME FROM OPERATIONS	612	1,596	271
INCOME BEFORE INCOME TAXES	$ 612	$ 1,596	$ 271