Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 55,340	$ 50,676	$ 159,230	$ 173,256
Net income, Diluted	$ 55,340	$ 50,676	$ 159,230	$ 173,256
Weighted average common shares outstanding, Basic	117,443	117,066	117,360	116,889
Weighted average common shares outstanding, Basic	117,443	117,066	117,360	116,889
Weighted average shares and assumed conversions	117,694	117,774	117,824	117,786
BASIC EARNINGS PER SHARE	$ 0.47	$ 0.43	$ 1.36	$ 1.48
DILUTED EARNINGS PER SHARE	$ 0.47	$ 0.43	$ 1.35	$ 1.47
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	207	559	384	716
Restricted stock based compensation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	44	149	80	181