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, 2019	Mar. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 49,340	$ 37,777
Net income, Diluted	$ 49,340	$ 37,777
Weighted average common shares outstanding, Basic	118,836	118,359
Weighted average common shares outstanding, Basic	118,836	118,359
Weighted average shares and assumed conversions	118,918	118,509
BASIC EARNINGS PER SHARE	$ 0.42	$ 0.32
DILUTED EARNINGS PER SHARE	$ 0.41	$ 0.32
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	36	101
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	46	49