Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 57,583	$ 65,303	$ 103,890	$ 122,580
Net income, Diluted	$ 57,583	$ 65,303	$ 103,890	$ 122,580
Weighted average common shares outstanding, Basic	117,401	116,962	117,318	116,799
Weighted average common shares outstanding, Basic	117,401	116,962	117,318	116,799
Weighted average shares and assumed conversions	118,009	117,812	117,889	117,790
BASIC EARNINGS PER SHARE	$ 0.49	$ 0.56	$ 0.89	$ 1.05
DILUTED EARNINGS PER SHARE	$ 0.49	$ 0.55	$ 0.88	$ 1.04
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	514	720	473	794
Restricted stock based compensation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	94	130	98	197