Organization and Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) Customer	Mar. 31, 2017 Customer	Dec. 31, 2017 USD ($) Customer	Jan. 01, 2018 USD ($)
Accounting Policies [Line Items]
Number of major customer represented stated percentage of total net revenue | Customer	0	0
Number of customers who accounted for 10% or more of accounts receivable balance | Customer	0		0
Concentration Risk, Customer	No customer represented more than 10% of net revenue for either of the three months ended March 31, 2018 or 2017. No customer represented 10% or more of the Company’s accounts receivable balance at March 31, 2018 or December 31, 2017.
Capitalized software development costs	$ 400,000		$ 400,000
Accumulated deficit	(401,951,000)		(399,647,000)
Deferred Revenue	$ 4,327,000		$ 1,090,000
Topic 606
Accounting Policies [Line Items]
Accumulated deficit				$ (399,645,000)
Deferred Revenue				1,088,000
Capitalized incremental sales commision costs or other costs				0
Topic 606 | On Delivery
Accounting Policies [Line Items]
Percentage of revenue recognized	95.00%
Topic 606 | Over Time
Accounting Policies [Line Items]
Percentage of revenue recognized	5.00%
Topic 606 | Adjustments
Accounting Policies [Line Items]
Accumulated deficit				2,000
Deferred Revenue				$ (2,000)
Minimum
Accounting Policies [Line Items]
Estimated useful lives of intangible asset	3 years
Maximum
Accounting Policies [Line Items]
Estimated useful lives of intangible asset	12 years