Shareholders' Equity - Summary of Activities in Common Stock (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Purchases of treasury shares	$ (15,482)	$ (14,289)
Purchases of treasury (in shares)	(59)	(72)
Stock option exercises	$ 46,236	$ 6,564
Stock option exercises (in shares)	481	94
Employee stock plan purchases	$ 2,469	$ 2,349
Employee stock plan purchases (in shares)	10	15
Restricted stock units vested, net of withheld shares upon award settlement	$ (2,301)	$ (1,373)
Restricted stock units vested, net of withheld shares upon award settlement (in shares)	10	10