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	$ 6,159			6,159
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	647,818	$ 319	113,359	534,140
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)	39,483
Balance (in shares) at Jul. 31, 2019		32,000,548			(1,874,846)
Balance at Jul. 31, 2019	636,735	$ 320	116,645	554,114	$ (34,344)
Balance (in shares) at Apr. 30, 2019		31,936,526
Balance at Apr. 30, 2019	647,818	$ 319	113,359	534,140
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	636,735	$ 320	116,645	554,114	$ (34,344)
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)	(35,682)
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)
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	$ 0	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)