Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets by Major Asset Class (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross	$ 1,353	$ 1,353
Accumulated amortization	(455)	(197)
Net book value before impairment	898	1,156
Impairment charge	(411)	(411)
Net book value	$ 487	745
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	2 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	6 years
Purchased Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 265	265
Accumulated amortization	(78)	(32)
Net book value before impairment	187	233
Net book value	$ 187	233
Purchased Technology [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	5 years
Purchased Technology [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	6 years
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 999	999
Accumulated amortization	(324)	(147)
Net book value before impairment	675	852
Impairment charge	(411)	(411)
Net book value	$ 264	441
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	3 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	6 years
Trademarks/Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	2 years
Gross	$ 38	38
Accumulated amortization	(28)	(9)
Net book value before impairment	10	29
Net book value	$ 10	29
Non-Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life	3 years
Gross	$ 51	51
Accumulated amortization	(25)	(9)
Net book value before impairment	26	42
Net book value	$ 26	$ 42