Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financial Instruments and Fair Value [Line Items]
Impairment loss recorded	$ 1,000	$ 800	$ 3,500
Cost-method investments
Financial Instruments and Fair Value [Line Items]
Impairment loss recorded	995	753
Level 3 \| Cost-method investments
Financial Instruments and Fair Value [Line Items]
Cost-basis investments, at fair value	$ 1,000	$ 1,640

For investments in debt and equity securities accounted for at cost, the excess of the carrying amount over net sale proceeds of investments disposed of during the period and any losses recognized thereon for impairments of other than a temporary nature.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5

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 210.5-03.9(a))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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