Basis of presentation and summary of significant accounting policies.

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Highly liquid investments maturity period description.

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Number of entity wide revenue major customers.

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Percentage of long lived assets.

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For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to repatriation of foreign earnings.

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Gross number of share options (or share units) granted during the period.

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Summary of Significant Accounting Policies and Basis of Presentation - Additional Information (Detail)	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2018	Dec. 31, 2017 USD ($) Segment Customer shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Marketable securities	$ 0				$ 79,402,000					$ 0	$ 79,402,000
Number of operating segment \| Segment										1
Number of major customers \| Customer										4
Revenue	48,913,000	$ 42,658,000	$ 35,004,000	$ 26,328,000	28,824,000	$ 29,426,000	$ 28,237,000	$ 30,378,000		$ 152,903,000	116,865,000	$ 93,203,000
Liquid investments maturity date										Three months or less
Impairment loss										$ 0	0	$ 0
Restricted cash	2,305,000				1,395,000					$ 2,305,000	$ 1,395,000
Expected dividend yield										0.00%
Options awarded \| shares										0
Federal corporate tax rate										34.00%	34.00%	34.00%
Transition tax recognized										$ 0
ASU 2016-09 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings	100,000									$ 100,000
Scenario Plan [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Federal corporate tax rate									21.00%
Software and Software Development Costs [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Capitalized internal-use software, depreciation period										3 years
Minimum [Member] \| Accounting Standards Update 2014-09 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings	16,000,000									$ 16,000,000
Minimum [Member] \| Customer Concentration Risk [Member] \| Accounts Receivable [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable										10.00%	10.00%
Minimum [Member] \| Customer Concentration Risk [Member] \| Sales Revenue, Net [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable										10.00%	10.00%	10.00%
Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Federal corporate tax rate										35.00%
Maximum [Member] \| Accounting Standards Update 2014-09 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings	$ 20,000,000									$ 20,000,000
United States [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of long-lived assets	91.00%									91.00%
Germany [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of long-lived assets	9.00%									9.00%
Foreign Customers [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Revenue										$ 9,397,000	$ 7,283,000	$ 3,170,000
Customer One [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Revenue										50,286,000	43,477,000	$ 13,444,000
Customer account balance	$ 10,159,000				2,079,000					$ 10,159,000	$ 2,079,000
Customer One [Member] \| Customer Concentration Risk [Member] \| Accounts Receivable [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable										34.00%	20.00%
Customer One [Member] \| Customer Concentration Risk [Member] \| Sales Revenue, Net [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable										33.00%	37.00%	14.00%
Customer Two [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Revenue										$ 15,450,000	$ 11,735,000	$ 10,618,000
Customer account balance	$ 8,990,000				2,007,000					$ 8,990,000	$ 2,007,000
Customer Two [Member] \| Customer Concentration Risk [Member] \| Accounts Receivable [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable										30.00%	20.00%
Customer Two [Member] \| Customer Concentration Risk [Member] \| Sales Revenue, Net [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable										10.00%	10.00%	11.00%
Customer Three [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Customer account balance					$ 1,319,000						$ 1,319,000
Customer Three [Member] \| Customer Concentration Risk [Member] \| Accounts Receivable [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of Accounts receivable											13.00%