Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Basic Net Income Per Share
Net income	$ 44,588	$ 88,923
Weighted average shares – basic	45,010	45,215
Net income per share – basic	$ 0.99	$ 1.97
Diluted Net Income Per Share
Net income	$ 44,588	$ 88,923
Weighted average shares – basic	45,010	45,215
Effect of dilutive securities	539	877
Weighted average shares – diluted	45,549	46,092
Net income per share – diluted	$ 0.98	$ 1.93