Goodwill (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2020 CNY (¥)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 CNY (¥)
Changes in the carrying amount of goodwill
Balance at the beginning of year	¥ 232,007	$ 35,557	¥ 159,409
Increase in goodwill related to acquisitions during the year	0	0	72,598
Accumulated impairment loss	0	0	0
Balance at the end of year	¥ 232,007	$ 35,557	¥ 232,007

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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