Income Tax - Schedule of Reconciliations of PRC Statutory Income Tax Rate and Group's Effective Income Tax Rate (Details) - PRC	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Statutory income tax rate	25.00%	25.00%	25.00%
Share-based compensations	(1.93%)	(3.27%)	(2.92%)
Non-deductible expenses	(0.38%)	(0.79%)	(1.59%)
Prior year tax filing adjustment	1.55%
Effect of different tax rate of subsidiary operation in other jurisdictions	(0.76%)	(3.06%)	(3.33%)
Changes in valuation allowance	(23.48%)	(17.88%)	(17.16%)

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 attributable to revisions of previously reported income tax expense.

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