Earnings per Share (Detail) - Calculations Of Basic And Diluted Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Net income used for calculating basic and diluted earnings per common share	$ 30,366	$ 33,846	$ 109,872	$ 124,622
Denominator:
Weighted average number of common shares used in the calculation of basic earnings per share	82,989	88,513	84,244	89,901
Common stock equivalents associated with stock-based compensation plans	1,124	1,195	1,191	1,372
Shares used in the calculation of diluted earnings per share	84,113	89,708	85,435	91,273
Basic earnings per share (in Dollars per share)	$ 0.37	$ 0.38	$ 1.30	$ 1.39
Diluted earnings per share (in Dollars per share)	$ 0.36	$ 0.38	$ 1.29	$ 1.37