Earnings Per Share - (Reconciliation of Basic and Diluted Shares Amounts) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	$ 8,095	$ 2,738	$ 16,148	$ 6,185
Weighted average shares used in computing net income per share - basic	46,367	43,743	45,174	43,683
Effect of dilutive shares:
Stock options and restricted stock awards	791	481	760	434
Convertible senior notes	1,898	792	1,758	578
Dilutive potential common shares	2,689	1,273	2,518	1,012
Weighted average shares used in computing net income per share - diluted	49,056	45,016	47,692	44,695
Earnings per share:
Basic	$ 0.17	$ 0.06	$ 0.36	$ 0.14
Diluted	$ 0.17	$ 0.06	$ 0.34	$ 0.14