Income Taxes (Deferred Tax Assets (Liabilities)) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 443	$ 1,716
Stock-based compensation	12,092	11,778
Research and development and other credits	2,170	6,961
Reserves	6,952	5,417
Intangible assets	2,141	947
Gross deferred tax assets	23,798	26,819
Deferred tax liabilities:
Property and equipment	(4,644)	(3,874)
Goodwill	(17,672)	(12,802)
Gross deferred tax liabilities	(22,316)	(16,676)
Net deferred tax assets	$ 1,482	$ 10,143