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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 48,994	$ 40,994	$ 146,912	$ 117,968
Net income, Diluted	$ 48,994	$ 40,994	$ 146,912	$ 117,968
Weighted average common shares outstanding, Basic	119,096	118,597	119,028	118,544
Weighted average common shares outstanding, Basic	119,096	118,597	119,028	118,544
Weighted average shares and assumed conversions	119,189	118,849	119,162	118,711
BASIC EARNINGS PER SHARE	$ 0.41	$ 0.35	$ 1.23	$ 1.00
DILUTED EARNINGS PER SHARE	$ 0.41	$ 0.34	$ 1.23	$ 0.99
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	3	178	30	123
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	90	74	104	44