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Commitments and Contingencies - Additional Information (Detail) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 CNY (¥)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2015 CNY (¥)	Dec. 21, 2017 CNY (¥)
Total rental expense for offices	¥ 78,303	$ 12,035	¥ 88,694	¥ 82,710
Total other operating lease expenses	333,813	$ 51,306	¥ 347,711	¥ 222,138
Loan facility drawn					¥ 22,000
Beijing Security
Loan facility granted	¥ 44,000

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- Definition

Loan receivable maximum lending.

+ References

No definition available.

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- Definition

Expenses for the reporting period incurred under operating leases, excluding rental expenses incurred under operating leases.

+ References

No definition available.

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Balance Type:	debit
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X

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

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- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

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