Earnings Per Share - Details of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income	$ 75,627	$ 96,564	$ 46,064	$ 89,463	$ 109,750	$ 86,230	$ 218,255	$ 285,443
Weighted average shares outstanding - basic	85,798			84,109			85,749	83,951
Dilutive effect of stock plans	1,426			1,624			1,427	1,619
Weighted average shares outstanding - diluted	87,224			85,733			87,176	85,570
Basic earnings per share	$ 0.88			$ 1.06			$ 2.55	$ 3.40
Diluted earnings per share	$ 0.87			$ 1.04			$ 2.50	$ 3.34
Anti-dilutive shares	30			25			28	8