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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	$ 1,659	$ 4,794	$ 17,807	$ 10,979
Weighted average shares used in computing net income per share - basic	50,852	43,822	47,087	43,729
Effect of dilutive shares:
Stock options and restricted stock awards	957	651	843	511
Convertible senior notes		1,355		892
Dilutive potential common shares	957	2,006	843	1,403
Weighted average shares used in computing net income per share - diluted	51,809	45,828	47,930	45,132
Earnings per share:
Basic	$ 0.03	$ 0.11	$ 0.38	$ 0.25
Diluted	$ 0.03	$ 0.10	$ 0.37	$ 0.24