Condensed consolidated statements of stockholders' equity (unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated earnings
Beginning balance at Jan. 31, 2019	$ 477,079	$ 6	$ 305,223	$ 171,850
Stockholders' Equity
Issuance of common stock upon exercise of stock options, and for restricted stock		0	7,363
Other issuance of common stock		1	462,270
Stock-based compensation			31,194
Net income (loss)	39,854			39,854
Ending balance at Oct. 31, 2019	1,017,761	7	806,050	211,704
Beginning balance at Jul. 31, 2019	1,017,031	7	783,986	233,038
Stockholders' Equity
Issuance of common stock upon exercise of stock options, and for restricted stock		0	712
Other issuance of common stock		0	3,776
Stock-based compensation			17,576
Net income (loss)	(21,334)			(21,334)
Ending balance at Oct. 31, 2019	1,017,761	7	806,050	211,704
Beginning balance at Jan. 31, 2020	1,030,295	7	818,774	211,514
Stockholders' Equity
Issuance of common stock upon exercise of stock options, and for restricted stock		0	4,402
Other issuance of common stock		1	286,779
Stock-based compensation			30,313
Net income (loss)	3,467			3,467
Ending balance at Oct. 31, 2020	1,355,257	8	1,140,268	214,981
Beginning balance at Jul. 31, 2020	1,340,336	8	1,127,136	213,192
Stockholders' Equity
Issuance of common stock upon exercise of stock options, and for restricted stock		0	1,651
Other issuance of common stock		0	2
Stock-based compensation			11,479
Net income (loss)	1,789			1,789
Ending balance at Oct. 31, 2020	$ 1,355,257	$ 8	$ 1,140,268	$ 214,981