Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Basic Net Income Per Share
Net income	$ 37,374	$ 12,910
Weighted average shares used in computing basic net income per share	43,895	42,811
Net income per share - basic	$ 0.85	$ 0.30
Diluted Net Income Per Share
Net income	$ 37,374	$ 12,910
Weighted average shares used in computing basic net income per share	43,895	42,811
Effect of dilutive securities	1,713	2,367
Weighted average shares used in computing diluted net income per share	45,608	45,178
Net income per share - diluted	$ 0.82	$ 0.29