Income Taxes - Schedule of Federal Statutory Income Tax Rate Reconciliation (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax benefit at statutory rates				$ (6,666)	$ (7,822)
Permanent differences				70	324
Foreign rate differential				14	13
State income taxes, net of federal tax benefit				(1,081)	(683)
Effect of tax rate change					4,045
Other				441
Valuation allowance				7,277	4,161
Income tax provision	$ 8	$ 23	$ 3	$ 55	$ 38

Income Tax Rate Reconciliation Permanent Differences

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Valuation Allowance Deferred Tax Asset Change In Amount Charged To Costs And Expenses

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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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 tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

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