CONSOLIDATED STATEMENT OF SHAREHOLDERS EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balance (in shares) at Jan. 31, 2019		31,788,162
Balance at Jan. 31, 2019	$ 619,975	$ 318	$ 111,185	$ 508,472
Balance (Accounting Standards Update 2016-02 [Member]) at Feb. 01, 2019	$ 6,160			6,160
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201026Member
Balance (in shares) at Jan. 31, 2019		31,788,162
Balance at Jan. 31, 2019	$ 619,975	$ 318	111,185	508,472
Exercise of options and vesting of restricted stock, net of tax (in shares)		136,206
Exercise of options and vesting of restricted stock, net of withholding tax	(1,240)	$ 1	(1,241)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		12,158
Issuance of common stock under Employee Stock Purchase Plan	198		198
Stock-based compensation	3,217		3,217
Net income (loss)	19,509			19,509
Balance (in shares) at Apr. 30, 2019		31,936,526
Balance at Apr. 30, 2019	647,819	$ 319	113,359	534,141
Balance (in shares) at Jan. 31, 2019		31,788,162
Balance at Jan. 31, 2019	619,975	$ 318	111,185	508,472
Net income (loss)	50,952
Balance (in shares) at Oct. 31, 2019		32,037,932			(3,136,665)
Balance at Oct. 31, 2019	626,703	$ 320	119,870	565,584	$ (59,071)
Balance (in shares) at Apr. 30, 2019		31,936,526
Balance at Apr. 30, 2019	647,819	$ 319	113,359	534,141
Exercise of options and vesting of restricted stock, net of tax (in shares)		51,384
Exercise of options and vesting of restricted stock, net of withholding tax	(326)	$ 1	(327)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		12,638
Issuance of common stock under Employee Stock Purchase Plan	194		194
Stock-based compensation	3,419		3,419
Stock Repurchased During Period, Value	34,344				$ (34,344)
Stock Repurchased During Period, Shares					(1,874,846)
Net income (loss)	19,974			19,974
Balance (in shares) at Jul. 31, 2019		32,000,548			(1,874,846)
Balance at Jul. 31, 2019	636,736	$ 320	116,645	554,115	$ (34,344)
Exercise of options and vesting of restricted stock, net of tax (in shares)		19,043
Exercise of options and vesting of restricted stock, net of withholding tax	(211)		(211)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		18,341
Issuance of common stock under Employee Stock Purchase Plan	220		220
Stock-based compensation	3,216		3,216
Stock Repurchased During Period, Value	24,727				$ (24,727)
Stock Repurchased During Period, Shares					(1,261,819)
Net income (loss)	11,469			11,469
Balance (in shares) at Oct. 31, 2019		32,037,932			(3,136,665)
Balance at Oct. 31, 2019	626,703	$ 320	119,870	565,584	$ (59,071)
Balance (in shares) at Jan. 31, 2020		32,125,055
Balance at Jan. 31, 2020	627,180	$ 321	122,513	570,636	(66,290)
Balance (98662000) at Feb. 01, 2020	$ (76,490)			(76,490)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance (in shares) at Jan. 31, 2020		32,125,055
Balance at Jan. 31, 2020	$ 627,180	$ 321	122,513	570,636	$ (66,290)
Exercise of options and vesting of restricted stock, net of tax (in shares)		321,468
Exercise of options and vesting of restricted stock, net of withholding tax	(1,285)	$ 3	(1,288)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		47,450
Issuance of common stock under Employee Stock Purchase Plan	177	$ 1	176
Stock-based compensation	2,430		2,430
Net income (loss)	(56,202)			(56,202)
Balance (in shares) at Apr. 30, 2020		32,493,973			(3,485,441)
Balance at Apr. 30, 2020	495,810	$ 325	123,831	437,944	$ (66,290)
Balance (in shares) at Jan. 31, 2020		32,125,055
Balance at Jan. 31, 2020	627,180	$ 321	122,513	570,636	$ (66,290)
Net income (loss)	(28,263)
Balance (in shares) at Oct. 31, 2020		32,645,472			(3,485,441)
Balance at Oct. 31, 2020	528,471	$ 326	128,552	465,883	$ (66,290)
Balance (in shares) at Apr. 30, 2020		32,493,973			(3,485,441)
Balance at Apr. 30, 2020	495,810	$ 325	123,831	437,944	$ (66,290)
Exercise of options and vesting of restricted stock, net of tax (in shares)		70,271
Exercise of options and vesting of restricted stock, net of withholding tax	(158)	$ 1	(159)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		51,643
Issuance of common stock under Employee Stock Purchase Plan	160		160
Stock-based compensation	2,254		2,254
Net income (loss)	20,520			20,520
Balance (in shares) at Jul. 31, 2020		32,615,887			(3,485,441)
Balance at Jul. 31, 2020	518,586	$ 326	126,086	458,464	$ (66,290)
Exercise of options and vesting of restricted stock, net of tax (in shares)		6,856
Exercise of options and vesting of restricted stock, net of withholding tax	(32)		(32)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		22,729
Issuance of common stock under Employee Stock Purchase Plan	194		194
Stock-based compensation	2,304		2,304
Net income (loss)	7,419			7,419
Balance (in shares) at Oct. 31, 2020		32,645,472			(3,485,441)
Balance at Oct. 31, 2020	$ 528,471	$ 326	$ 128,552	$ 465,883	$ (66,290)