Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 46,307	$ 57,277
Weighted average shares and assumed conversions	117,769	117,768
BASIC EARNINGS PER SHARE	$ 0.39	$ 0.49
DILUTED EARNINGS PER SHARE	$ 0.39	$ 0.49
Basic Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 46,307	$ 57,277
Weighted average common shares outstanding, basic	117,235	116,634
Diluted Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 46,307	$ 57,277
Weighted average common shares outstanding, diluted	117,235	116,634
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	432	869
Restricted stock based compensation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	102	265