Shareholders' Equity - Summary of Activities in Common Stock (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Purchases of treasury shares	$ 0	$ 0	$ (15,482)	$ (14,289)
Purchases of treasury (in shares)	0	0	(59)	(72)
Stock option exercises	$ 46,101	$ 15,604	$ 92,337	$ 22,132
Stock option exercises (in shares)	436	203	917	297
Employee stock plan purchases	$ 2,708	$ 2,260	$ 5,177	$ 4,609
Employee stock plan purchases (in shares)	10	13	20	28
Restricted stock units vested, net of withheld shares upon award settlement	$ (4,591)	$ (2,008)	$ (6,892)	$ (3,381)
Restricted stock units vested, net of withheld shares upon award settlement (in shares)	33	27	43	37