Details of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 86,230	$ 84,280
Weighted average shares outstanding - basic	83,764	83,931
Dilutive effect of stock plans	1,729	2,221
Weighted average shares outstanding - diluted	85,493	86,152
Basic earnings per share	$ 1.03	$ 1.00
Diluted earnings per share	$ 1.01	$ 0.98
Anti-dilutive shares	0	0