Consolidated Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Temporary timing differences:
Stock-based compensation expense	$ 2,874	$ 1,662
Contingent consideration	2,263	2,196
Other	2,632	1,704
Total temporary timing differences	7,769	5,562
Net operating loss carryforwards	0	4,361
Tax business credits carryforwards	2,004	1,265
Total deferred tax assets	9,773	11,188
Less: Valuation allowance	(131)	(6)
Net deferred tax assets	9,642	11,182
Deferred tax liabilities:
Goodwill	(1,076)	(807)
Acquired intangible assets	(26,903)	(32,359)
Conversion option on convertible notes	(2,394)	(3,183)
Total deferred tax liabilities	(30,373)	(36,349)
Total net deferred tax liabilities	$ (20,731)	$ (25,167)