Income Taxes - Reconciliation Between Effect of Applying Federal Statutory Rate and Effective Income Tax Rate Used to Calculate Income Tax Benefit (Detail)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Corporate federal income tax rate	21.00%	34.00%
State income taxes, net of federal benefit	4.53%	1.20%
Foreign income tax rate differential	(0.15%)	(0.05%)
Effect of the Tax Cuts and Jobs Act (“TCJA”) on tax rates		(2.16%)
Stock compensation	(0.16%)	(2.49%)
Research and development tax credit	(1.30%)	(2.33%)
Acquisition costs		(0.77%)
Goodwill impairment	(0.22%)	(22.69%)
Loss on warrant exchange and warrant FMV changes	(1.33%)
Permanent differences and other	2.14%	(0.78%)
Change in valuation allowance	(10.94%)	6.90%
Effective tax rate	13.57%	10.83%

Effective income tax rate reconciliation acquisition costs.

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Effective income tax rate reconciliation loss on warrant exchange and warrant fair market value changes.

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Effective income tax rate reconciliation, nondeductible expense, goodwill impairment losses rate.

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Effective income tax rate reconciliation, share-based compensation cost, percent.

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

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

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Percentage 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 changes in the valuation allowance for deferred tax assets.

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Percentage 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 applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage 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 applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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