Analysis of Allowance for Doubtful Debt (Detail) ¥ in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2015 CNY (¥)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of the year	$ 12,436	¥ 80,910	¥ 40,070
Additional provision charged to expense	5,752	37,427	117,564	¥ 32,199
Write-off of accounts receivable	(3,038)	(19,766)	(38,797)
Provision included in disposed subsidiaries	(8,767)	(57,041)
Balance at the end of the year	11,321	73,656	80,910	¥ 40,070
Allowance for Account Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additional provision charged to expense	$ 10,690	¥ 69,553	¥ 79,637

Amount of expense related to write-down of receivables to the amount expected to be collected. Includes, but is not limited to, accounts receivable and notes receivable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130534-203044

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.5)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130543-203045

Name:	us-gaap_ProvisionForDoubtfulAccounts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration