Condensed consolidated statements of stockholders' equity (unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated comprehensive loss	Accumulated earnings
Beginning balance at Jan. 31, 2018	$ 346,274	$ 6	$ 261,237	$ (269)	$ 85,300
Issuance of common stock upon exercise of stock options, and for restricted stock		0	18,604
Issuance of common stock		0
Other issuance of common stock			0
Stock-based compensation			9,727
Net income	45,094				45,094
Ending balance at Jul. 31, 2018	432,619	6	289,568	0	143,045
Beginning balance at Apr. 30, 2018	396,974	6	276,440	0	120,528
Issuance of common stock upon exercise of stock options, and for restricted stock		0	7,640
Issuance of common stock		0
Other issuance of common stock			0
Stock-based compensation			5,488
Net income	22,517				22,517
Ending balance at Jul. 31, 2018	432,619	6	289,568	0	143,045
Beginning balance at Jan. 31, 2019	477,079	6	305,223	0	171,850
Issuance of common stock upon exercise of stock options, and for restricted stock		0	6,651
Issuance of common stock		1
Other issuance of common stock			458,494
Stock-based compensation			13,618
Net income	61,188				61,188
Ending balance at Jul. 31, 2019	1,017,031	7	783,986	0	233,038
Beginning balance at Apr. 30, 2019	529,299	6	315,621	0	213,672
Issuance of common stock upon exercise of stock options, and for restricted stock		0	2,281
Issuance of common stock		1
Other issuance of common stock			458,494
Stock-based compensation			7,590
Net income	19,366				19,366
Ending balance at Jul. 31, 2019	$ 1,017,031	$ 7	$ 783,986	$ 0	$ 233,038