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, 2016	$ 132	$ 117,511	$ (129,518)	$ 331,224	$ (471)	$ 318,878
Balance (in shares) at Mar. 31, 2016	14,731
Issuance of restricted stock awards	$ 1	0	0	0	0	1
Issuance of restricted stock awards (in shares)	146
Share-based compensation		6,025	0	0	0	6,025
Repurchase of common stock	$ 0	0	(29,430)	0	0	(29,430)
Repurchase of common stock (in shares)	716
Stock split effected in the form of a dividend	$ 71	0	0	(71)	0	0
Retirement of treasury stock	(62)	0	158,948	(158,886)		0
Net earnings	0	0	0	50,556	0	50,556
Foreign currency translation adjustment	0	0	0	0	(112)	(112)
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		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					13,761
Issuance of restricted stock awards	$ 1	0	0	0	0	$ 1
Issuance of restricted stock awards (in shares)	75
Share-based compensation		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