Earnings Per Share - Reconciliation of Basic and Diluted Shares Amounts (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Numerator
Net income	$ 40,405	$ 33,498	$ 137,230	$ 99,181
Effect of dilutive securities
Charges associated with convertible debt instruments, net of tax	0	0	387	0
Numerator for diluted earnings per share - net income available to common stockholders after the effect of dilutive securities	$ 40,405	$ 33,498	$ 137,617	$ 99,181
Denominator
Weighted average shares used in computing net income per share - basic	55,498	55,015	55,432	54,918
Effect of dilutive shares
Options and stock units	673	919	663	913
Convertible senior notes	1,131	1,373	1,501	1,180
Dilutive effect of unvested performance stock units	2	61	2	61
Dilutive potential common shares	1,806	2,353	2,166	2,154
Denominator for diluted earnings per share - adjusted weighted average shares used in computing net income per share - diluted	57,304	57,368	57,598	57,072
Earnings per share:
Basic	$ 0.73	$ 0.61	$ 2.48	$ 1.81
Diluted (Note 12)	$ 0.71	$ 0.58	$ 2.39	$ 1.74