Income Taxes - Schedule of Expense/(Benefit) for Income Taxes from Continuing Operations (Detail) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Current Tax Expense/(Benefit)
United Kingdom	$ 0	$ 0
United States	0	0
Total Current	0	0
Deferred Tax Expense/(Benefit)
United Kingdom	(8,888,096)	(3,759,109)
United States	(3,606,275)	(1,183,746)
Total Deferred	(12,494,371)	(4,942,855)
Change in valuation allowance	12,495,426	4,942,855
Actual income tax benefit effective tax rate	$ (474,391)	$ 0

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

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Amount of current foreign income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

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Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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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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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 increase (decrease) in the valuation allowance for deferred tax assets.

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