Earnings per Share (Detail) - Calculations Of Basic And Diluted Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator:
Net income used for calculating basic and diluted earnings per common share		$ 51,155	$ 53,040	$ 79,506	$ 90,776
Denominator:
Weighted average number of common shares used in the calculation of basic earnings per share		83,203	89,521	84,871	90,595
Common stock equivalents associated with stock-based compensation plans	[1]	1,068	1,223	1,193	1,417
Shares used in the calculation of diluted earnings per share		84,271	90,744	86,064	92,012
Basic earnings per share (in Dollars per share)		$ 0.61	$ 0.59	$ 0.94	$ 1.00
Diluted earnings per share (in Dollars per share)		$ 0.61	$ 0.58	$ 0.92	$ 0.99

[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 common share equivalents totaled less than 0.3 million in each of the periods presented.