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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 48,578	$ 39,197	$ 97,918	$ 76,974
Net income, Diluted	$ 48,578	$ 39,197	$ 97,918	$ 76,974
Weighted average common shares outstanding, Basic	119,080	118,546	119,026	118,501
Weighted average common shares outstanding, Basic	119,080	118,546	119,026	118,501
Weighted average shares and assumed conversions	119,262	118,648	119,181	118,626
BASIC EARNINGS PER SHARE	$ 0.41	$ 0.33	$ 0.82	$ 0.65
DILUTED EARNINGS PER SHARE	$ 0.41	$ 0.33	$ 0.82	$ 0.65
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	51	92	43	96
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	131	10	112	29