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Principal Accounting Policies - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) ¥ in Thousands, $ in Thousands | Sep. 30, 2020 CNY (¥) | Sep. 30, 2020 USD ($) | Dec. 31, 2019 CNY (¥)
--- | --- | --- | ---
Assets [Abstract] |  |  |
Short-term Investments | ¥ 28,526 | $ 4,201 | ¥ 32,000
Liabilities [Abstract] |  |  |
Put right liabilities | 124,100 | $ 18,278 |
Fair Value, Recurring [Member] |  |  |
Assets [Abstract] |  |  |
Short-term Investments | 28,526 |  | 32,000
Liabilities [Abstract] |  |  |
Put right liabilities | 124,100 |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Assets [Abstract] |  |  |
Short-term Investments | 28,526 |  | ¥ 32,000
Liabilities [Abstract] |  |  |
Put right liabilities | ¥ 124,100 |  |

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