Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Mar. 31, 2020	$ 1,065,466	$ 450	$ (265,411)	$ 739,133	$ 602,482	$ (11,189)
Beginning Balance (in shares) at Mar. 31, 2020		45,008,687	2,533,374
Restricted stock units issued		$ 1		(1)
Restricted stock units issued (in shares)		124,749
Stock options exercised	1,010			1,010
Stock options exercised (in shares)		31,488
Return of common stock to pay withholding taxes on restricted stock	(9,857)		$ (9,857)
Return of common stock to pay withholding taxes on restricted stock (in shares)		52,515	(52,515)
Stock compensation expense	9,298			9,298
Stock repurchase program	(11,310)	$ (1)	$ (11,309)
Stock Repurchased During Period, Shares		(67,649)	67,649
Other comprehensive loss income	2,654					2,654
Net income	44,588				44,588
Ending Balance at Jun. 30, 2020	1,101,848	$ 450	$ (286,577)	749,440	647,070	(8,535)
Ending Balance (in shares) at Jun. 30, 2020		45,044,760	2,653,538
Beginning Balance at Mar. 31, 2020	1,065,466	$ 450	$ (265,411)	739,133	602,482	(11,189)
Beginning Balance (in shares) at Mar. 31, 2020		45,008,687	2,533,374
Stock repurchase program	$ (11,300)
Stock Repurchased During Period, Shares	(67,649)
Other comprehensive loss income	$ 3,990
Net income	106,801
Ending Balance at Sep. 30, 2020	1,182,409	$ 452	$ (287,654)	767,527	709,283	(7,199)
Ending Balance (in shares) at Sep. 30, 2020		45,189,883	2,657,140
Beginning Balance at Jun. 30, 2020	1,101,848	$ 450	$ (286,577)	749,440	647,070	(8,535)
Beginning Balance (in shares) at Jun. 30, 2020		45,044,760	2,653,538
Restricted stock units issued (in shares)		11,554
Stock options exercised	4,545	$ 1		4,544
Stock options exercised (in shares)		121,066
Return of common stock to pay withholding taxes on restricted stock	(1,077)		$ (1,077)
Return of common stock to pay withholding taxes on restricted stock (in shares)		3,602	(3,602)
Stock issued under employee stock purchase plan	1,979	$ 1		1,978
Stock issued under employee stock purchase plan (in shares)		16,105
Stock compensation expense	11,565			11,565
Other comprehensive loss income	1,336					1,336
Net income	62,213				62,213
Ending Balance at Sep. 30, 2020	1,182,409	$ 452	$ (287,654)	767,527	709,283	(7,199)
Ending Balance (in shares) at Sep. 30, 2020		45,189,883	2,657,140
Beginning Balance at Mar. 31, 2021	$ 1,329,675	$ 453	$ (288,030)	800,690	828,007	(11,445)
Beginning Balance (in shares) at Mar. 31, 2021	45,270,948	45,270,948	2,658,454
Restricted stock units issued		$ 1		(1)
Restricted stock units issued (in shares)		85,284
Stock options exercised	$ 2,120	$ 1		2,119
Stock options exercised (in shares)		55,757
Return of common stock to pay withholding taxes on restricted stock	(9,590)	$ (1)	$ (9,589)
Return of common stock to pay withholding taxes on restricted stock (in shares)		34,274	(34,274)
Stock compensation expense	12,608			12,608
Other comprehensive loss income	(766)					(766)
Net income	(26,525)				(26,525)
Ending Balance at Jun. 30, 2021	1,307,522	$ 454	$ (297,619)	815,416	801,482	(12,211)
Ending Balance (in shares) at Jun. 30, 2021		45,377,715	2,692,728
Beginning Balance at Mar. 31, 2021	$ 1,329,675	$ 453	$ (288,030)	800,690	828,007	(11,445)
Beginning Balance (in shares) at Mar. 31, 2021	45,270,948	45,270,948	2,658,454
Stock options exercised (in shares)	152,000
Other comprehensive loss income	$ (3,111)
Net income	30,428
Ending Balance at Sep. 30, 2021	$ 1,384,563	$ 455	$ (300,158)	840,387	858,435	(14,556)
Ending Balance (in shares) at Sep. 30, 2021	45,496,563	45,496,563	2,700,481
Beginning Balance at Jun. 30, 2021	$ 1,307,522	$ 454	$ (297,619)	815,416	801,482	(12,211)
Beginning Balance (in shares) at Jun. 30, 2021		45,377,715	2,692,728
Restricted stock units issued (in shares)		19,638
Stock options exercised	6,262	$ 1		6,261
Stock options exercised (in shares)		95,916
Return of common stock to pay withholding taxes on restricted stock	(2,539)		$ (2,539)
Return of common stock to pay withholding taxes on restricted stock (in shares)		7,753	(7,753)
Stock issued under employee stock purchase plan	2,961			2,961
Stock issued under employee stock purchase plan (in shares)		11,047
Stock compensation expense	15,749			15,749
Other comprehensive loss income	(2,345)					(2,345)
Net income	56,953				56,953
Ending Balance at Sep. 30, 2021	$ 1,384,563	$ 455	$ (300,158)	$ 840,387	$ 858,435	$ (14,556)
Ending Balance (in shares) at Sep. 30, 2021	45,496,563	45,496,563	2,700,481