CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests	Total
Balances at Jan. 31, 2014	$ 2,143	$ 100,830	$ 53,335		$ 1,469	$ 157,777
Balances (in shares) at Jan. 31, 2014	14,285,901
Net income			30,445		13,010	43,455
Exercise of stock options	$ 52	5,336				$ 5,388
Exercise of stock options (in shares)	345,300					346,000
Stock option vesting		2,017				$ 2,017
Excess tax benefit on exercised stock options		1,480				1,480
Cash dividends			(10,166)			(10,166)
Cash distributions to joint venture partner					(25,000)	(25,000)
Formation of VIE					1	1
Balances at Jan. 31, 2015	$ 2,195	109,663	73,614		(10,520)	174,952
Balances (in shares) at Jan. 31, 2015	14,631,201
Net income			36,345		13,859	50,204
Foreign currency translation loss				$ (565)		(565)
Acquisition of APC	$ 15	3,521				3,536
Acquisition of APC (in shares)	98,818
Exercise of stock options	$ 16	1,802				$ 1,818
Exercise of stock options (in shares)	106,450					106,000
Stock option vesting		2,374				$ 2,374
Excess tax benefit on exercised stock options		(86)				(86)
Cash dividends			(10,378)			(10,378)
Balances at Jan. 31, 2016	$ 2,226	117,274	99,581	(565)	3,339	221,855
Balances (in shares) at Jan. 31, 2016	14,836,469
Net income			70,328		7,098	77,426
Foreign currency translation loss				(197)		(197)
Exercise of stock options	$ 93	15,808				$ 15,901
Exercise of stock options (in shares)	621,750					622,000
Stock option vesting		2,344				$ 2,344
Cash dividends			(15,260)			(15,260)
Cash distributions to joint venture partner					(9,500)	(9,500)
Balances at Jan. 31, 2017	$ 2,319	$ 135,426	$ 154,649	$ (762)	$ 937	$ 292,569
Balances (in shares) at Jan. 31, 2017	15,458,219