CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative adjustment from adoption of recent accounting pronouncements	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative adjustment from adoption of recent accounting pronouncements	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Mar. 31, 2019			29,141,000
Beginning balance at Mar. 31, 2019	$ 1,045,130	$ (1,068)	$ 291	$ 178,227	$ 889,266	$ (1,068)	$ (22,654)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)			10,000
Stock-based compensation	14,471			14,471
Shares issued upon vesting (in shares)			86,000
Shares issued upon vesting	1,288		$ 1	1,287
Exercise of stock options (in shares)			58,000
Exercise of stock options	3,615		$ 1	3,614
Shares withheld for taxes	$ (6,148)			(6,148)
Repurchases of common stock (Note 10) (in shares)	(1,296,201)		(1,296,000)
Repurchases of common stock (Note 10)	$ (190,405)		$ (13)		(190,392)
Net income	276,142				276,142
Total other comprehensive income (loss)	(2,905)						(2,905)
Ending balance (in shares) at Mar. 31, 2020			27,999,000
Ending balance at Mar. 31, 2020	1,140,120		$ 280	191,451	973,948		(25,559)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)			4,000
Stock-based compensation	22,695			22,695
Shares issued upon vesting (in shares)			107,000
Shares issued upon vesting	1,502		$ 1	1,501
Exercise of stock options (in shares)			107,000
Exercise of stock options	6,775		$ 1	6,774
Shares withheld for taxes	$ (19,111)			(19,111)
Repurchases of common stock (Note 10) (in shares)	(307,080)		(307,000)
Repurchases of common stock (Note 10)	$ (99,147)		$ (3)		(99,144)
Net income	382,575				382,575
Total other comprehensive income (loss)	8,816						8,816
Ending balance (in shares) at Mar. 31, 2021			27,910,000
Ending balance at Mar. 31, 2021	1,444,225		$ 279	203,310	1,257,379		(16,743)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)			4,000
Stock-based compensation	26,780			26,780
Shares issued upon vesting (in shares)			83,000
Shares issued upon vesting	1,991		$ 1	1,990
Exercise of stock options (in shares)			29,000
Exercise of stock options	1,204			1,204
Shares withheld for taxes	$ (22,459)			(22,459)
Repurchases of common stock (Note 10) (in shares)	(1,043,554)		(1,044,000)
Repurchases of common stock (Note 10)	$ (356,653)		$ (10)		(356,643)
Net income	451,949				451,949
Total other comprehensive income (loss)	(8,212)						(8,212)
Ending balance (in shares) at Mar. 31, 2022			26,982,000
Ending balance at Mar. 31, 2022	$ 1,538,825		$ 270	$ 210,825	$ 1,352,685		$ (24,955)