The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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The amortization method of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company. The straight-line method is the preferred amortization method, unless another method better reflects the pattern in which the asset is consumed.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Remaining amortization period 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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Balance sheet components.

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Balance Sheet Components - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Balance Sheet Components [Line Items]
Depreciation and amortization	$ 1,200,000	$ 900,000	$ 3,200,000	$ 2,500,000
Intangible assets, net	57,000		57,000		$ 0
Intangible assets amortization expense	0	$ 0	0	$ 0
License Cost
Balance Sheet Components [Line Items]
Intangible assets, net	$ 57,000		$ 57,000
Intangible assets amortizable period			10 years
Intangible assets, amortization method			straight-line basis