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, 2017	$ 142	$ 123,536	$ 0	$ 222,823	$ (583)	$ 345,918
Balance (in shares) at Mar. 31, 2017	14,161
Issuance of restricted stock awards	$ 0	0	0	0	0	0
Issuance of restricted stock awards (in shares)	67
Share-based compensation	$ 0	6,464	0	0	0	6,464
Repurchase of common stock	0	0	$ (36,016)	0	0	(36,016)
Repurchase of common stock (in shares)			(467)
Net earnings	0	0	$ 0	55,122	0	55,122
Foreign currency translation adjustment	0	0	0	0	1,115	1,115
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
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					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
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