Income Tax Expense - Reconciliation of Income Tax Expense (Detail) ¥ in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2020 CNY (¥)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 CNY (¥)	Dec. 31, 2018 CNY (¥)
Reconciliation of accounting profit multiplied by applicable tax rates [abstract]
Accounting profit before tax	¥ 971,864	$ 150,180	¥ 1,033,319	¥ 1,181,067
Computed tax expense at 15% (2019: 15%, 2018: 15%)	145,780	22,527	154,998	177,160
Adjustments resulting from:
Non-deductible expenses	9,188	1,420	3,982	5,146
Tax-exempt income	(601)	(93)	(6,171)	(3,634)
Utilization of deferred tax benefits previously not recognized	(1,996)	(308)	(5,076)	(5,518)
Deferred tax benefits not recognized	6,097	942	6,613	2,183
Tax credits for research and development expense	(26,329)	(4,068)	(31,863)	(22,407)
Tax rate differential	24,251	3,747	26,223	24,437
Over provision in respect of previous years	(259)	(39)	(6,985)	(729)
Withholding tax expense	36,332	5,614	30,898	30,029
Others	75	11
Consolidated income tax expense reported in the statement of profit or loss	¥ 192,538	$ 29,753	¥ 172,619	¥ 206,667

Reconciliation of adjustments resulting from accounting profit multiplied by applicable tax rates.

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Tax credits for research and development expense.

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Tax effect of deferred tax benefits not recognized.

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Tax effect of over/under provision in respect of previous years current tax.

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Tax effect of utilization of deferred tax benefits previously not recognized.

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Tax effect of withholding tax expense.

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The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that the entity does not separately disclose in the same statement or note. [Refer: Accounting profit; Applicable tax rate]

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The profit (loss) before tax expense or income. [Refer: Profit (loss)]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to changes in the tax rate. [Refer: Accounting profit]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to expenses not deductible in determining taxable profit (tax loss). [Refer: Accounting profit]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to revenues that are exempt from taxation. [Refer: Accounting profit]

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The product of the accounting profit multiplied by the applicable tax rate(s). [Refer: Accounting profit; Applicable tax rate]

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