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, 2018	Mar. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 37,777	$ 50,047
Net income, Diluted	$ 37,777	$ 50,047
Weighted average common shares outstanding, Basic	118,359	117,782
Weighted average common shares outstanding, Basic	118,359	117,782
Weighted average shares and assumed conversions	118,509	118,259
BASIC EARNINGS PER SHARE	$ 0.32	$ 0.42
DILUTED EARNINGS PER SHARE	$ 0.32	$ 0.42
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	101	420
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	49	57