Income Taxes - Schedule of Reconciliation of Effective Tax Rate and Statutory Income Tax Rate Applicable to PRC Operations (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2019 CNY (¥)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 CNY (¥)	Dec. 31, 2017 CNY (¥)
Income Tax Disclosure [Abstract]
Loss before income tax expenses	¥ (392,589)		¥ (928,660)	¥ (913,824)
Income tax expenses computed at applicable tax rates of 25%	(98,147)		(232,165)	(228,456)
Non-deductible and super deduction expenses	(40,711)		(8,013)	(3,490)
Effect of tax holidays and preferential tax rates	22,595		64,029	130,296
Change in valuation allowance	118,703		176,149	101,650
Income tax expenses	¥ 2,440	$ 350	¥ 0	¥ 0

Income tax reconciliation non-deductible and (super deduction) expense.

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- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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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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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 income exempt from income tax because of a tax holiday.

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