Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic									$ 188,886	$ 159,207	$ 178,040
Net income, Diluted									$ 188,886	$ 159,207	$ 178,040
Weighted average common shares outstanding, Basic									119,028	118,544	118,084
Weighted average common shares outstanding, Basic									119,028	118,544	118,084
Weighted average shares and assumed conversions									119,164	118,716	118,465
BASIC EARNINGS PER SHARE	$ 0.35	$ 0.41	$ 0.41	$ 0.42	$ 0.35	$ 0.35	$ 0.33	$ 0.32	$ 1.59	$ 1.34	$ 1.51
DILUTED EARNINGS PER SHARE	$ 0.35	$ 0.41	$ 0.41	$ 0.41	$ 0.35	$ 0.34	$ 0.33	$ 0.32	$ 1.59	$ 1.34	$ 1.50
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities									22	111	310
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities									114	61	71