CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total
Balance at Mar. 31, 2018	$ 142	$ 130,000	$ (36,016)	$ 277,945	$ 532	$ 372,603
Balance (in shares) at Mar. 31, 2018	13,761
Issuance of restricted stock awards	$ 1	0	0	0	0	1
Issuance of restricted stock awards (in shares)	75
Share-based compensation	$ 0	7,243	0	0	0	7,243
Share-based compensation (in shares)	0
Repurchase of common stock	$ 0	0	$ (17,983)	0	0	(17,983)
Repurchase of common stock (in shares)			(225)
Net earnings	0	0	$ 0	63,192	0	63,192
Foreign currency translation adjustment	0	0	0	0	(803)	(803)
Balance at Mar. 31, 2019	$ 143	137,243	(53,999)	341,137	(271)	424,253
Balance (in shares) at Mar. 31, 2019	13,611
Issuance of restricted stock awards	$ 1	0	0	0	0	1
Issuance of restricted stock awards (in shares)	93
Share-based compensation	$ 0	7,954	0	0	0	7,954
Share-based compensation (in shares)	0
Repurchase of common stock	$ 0	0	$ (14,425)	0	0	(14,425)
Repurchase of common stock (in shares)			(204)
Net earnings	0	0	$ 0	69,082	0	69,082
Foreign currency translation adjustment	0	0	0	0	(720)	(720)
Balance at Mar. 31, 2020	$ 144	145,197	(68,424)	410,219	(991)	$ 486,145
Balance (in shares) at Mar. 31, 2020	13,500					13,500
Issuance of restricted stock awards	$ 1	0	0	0	0	$ 1
Issuance of restricted stock awards (in shares)	100
Share-based compensation	$ 0	7,169	0	0	0	7,169
Share-based compensation (in shares)	0
Repurchase of common stock	$ 0	0	$ (6,948)	0	0	(6,948)
Repurchase of common stock (in shares)			(97)
Net earnings	0	0	$ 0	74,397	0	74,397
Foreign currency translation adjustment	0	0	0	0	1,646	1,646
Balance at Mar. 31, 2021	$ 145	$ 152,366	$ (75,372)	$ 484,616	$ 655	$ 562,410
Balance (in shares) at Mar. 31, 2021	13,503					13,503