CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Beginning balance (in shares) at Mar. 31, 2017		31,987,000
Beginning balance at Mar. 31, 2017	$ 954,255	$ 320	$ 160,797	$ 819,589	$ (26,451)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense (in shares)		15,000
Stock-based compensation expense	14,302		14,302
Shares issued upon vesting (in shares)		148,000
Shares issued upon vesting	765	$ 1	764
Shares withheld for taxes	$ (8,276)		(8,276)
Repurchases of common stock (in shares)	(1,702,653)	(1,703,000)
Repurchases of common stock	$ (149,687)	$ (17)		(149,670)
Net income	114,394			114,394
Total other comprehensive income	13,468				13,468
Ending balance (in shares) at Mar. 31, 2018		30,447,000
Ending balance at Mar. 31, 2018	940,779	$ 304	167,587	785,871	(12,983)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense (in shares)		10,000
Stock-based compensation expense	14,773		14,773
Shares issued upon vesting (in shares)		85,000
Shares issued upon vesting	1,025	$ 1	1,024
Shares withheld for taxes	$ (5,157)		(5,157)
Repurchases of common stock (in shares)	(1,400,699)	(1,401,000)
Repurchases of common stock	$ (161,395)	$ (14)		(161,381)
Net income	264,308			264,308
Total other comprehensive income	(9,671)				(9,671)
Ending balance (in shares) at Mar. 31, 2019		29,141,000
Ending balance at Mar. 31, 2019	1,045,130	$ 291	178,227	889,266	(22,654)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense (in shares)		10,000
Stock-based compensation expense	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 (in shares)	(1,296,201)	(1,296,000)
Repurchases of common stock	$ (190,405)	$ (13)		(190,392)
Net income	276,142			276,142
Total other comprehensive income	(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)