Earnings per Share (Detail) - Calculations Of Basic And Diluted Earnings Per Share (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Numerator:
Net income used for calculating basic and diluted earnings per share	$ 53,040		$ 46,514		$ 90,776		$ 83,189
Denominator:
Weighted average number of common shares used in the calculation of basic earnings per share	89,521		93,574		90,595		93,584
Common stock equivalents associated with stock-based compensation plans	1,223	[1]	1,614	[1]	1,417	[1]	1,842	[1]
Shares used in the calculation of diluted earnings per share	90,744		95,188		92,012		95,426
Basic earnings per share (in Dollars per share)	$ 0.59		$ 0.50		$ 1.00		$ 0.89
Diluted earnings per share (in Dollars per share)	$ 0.58		$ 0.49		$ 0.99		$ 0.87

[1] Certain common stock equivalents were not included in the computation of diluted earnings per share because the effect would have been anti-dilutive. These shares totaled 0.4 million for both the three months ended June 30, 2014 and 2013, and 0.3 million for both the six months ended June 30, 2014 and 2013.