Earnings per Share (Detail) - Calculations Of Basic And Diluted Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net income used for calculating basic and diluted earnings per common share	$ 40,167	$ 28,351
Denominator:
Weighted average number of common shares used in the calculation of basic earnings per share	82,451	86,539
Common stock equivalents associated with stock-based compensation plans	1,013	1,234
Shares used in the calculation of diluted earnings per share	83,464	87,773
Basic earnings per share (in Dollars per share)	$ 0.49	$ 0.33
Diluted earnings per share (in Dollars per share)	$ 0.48	$ 0.32