Balance Sheet Components - Property and Equipment) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Property and Equipment [Abstract]
Less: Accumulated depreciation	$ (19,953)	$ (17,732)
Property and equipment, net	6,565	7,145
Computer Hardware
Property and Equipment [Abstract]
Property, Plant and Equipment, Gross	$ 13,832	13,110
Useful life	3 years
Software and Software Development Costs
Property and Equipment [Abstract]
Property, Plant and Equipment, Gross	$ 5,042	5,159
Furniture And Fixtures
Property and Equipment [Abstract]
Property, Plant and Equipment, Gross	$ 4,472	3,772
Useful life	5 years
Leasehold Improvements
Property and Equipment [Abstract]
Property, Plant and Equipment, Gross	$ 3,172	$ 2,836
Useful life	5 years
Minimum \| Software and Software Development Costs
Property and Equipment [Abstract]
Useful life	1 year
Maximum \| Software and Software Development Costs
Property and Equipment [Abstract]
Useful life	7 years

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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