Net Earnings Per Share ("EPS") - Reconciliation of Denominators of Basic and Diluted EPS Calculations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net earnings	$ 39,327	$ 33,003
Denominator:
Weighted average shares used to compute basic EPS	35,609	35,913
Dilutive potential common shares due to dilutive RSUs, net of tax effect	494	350
Weighted average shares used to compute diluted EPS	36,103	36,263
Net earnings per share:
Basic	$ 1.10	$ 0.92
Diluted	$ 1.09	$ 0.91