Details of Basic and Diluted EPS (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Line Items]
Net income	$ 62,430	$ 51,619	$ 169,398	$ 147,420
Weighted average shares outstanding - basic	92,541	92,448	92,770	92,631
Dilutive effect of stock plans	2,724	2,307	2,387	2,327
Weighted average shares outstanding - diluted	95,265	94,755	95,157	94,958
Basic earnings per share	$ 0.67	$ 0.56	$ 1.83	$ 1.59
Diluted earnings per share	$ 0.66	$ 0.54	$ 1.78	$ 1.55
Anti-dilutive options	1,148	1,216	1,145	1,291