Quantitative Information about Significant Unobservable Input used in Fair Value Measurement on Recurring Basis (Detail) (Significant Unobservable Inputs (Level 3))	9 Months Ended
Sep. 30, 2012
Minimum
Business Acquisition, Contingent Consideration [Line Items]
Revenue growth percentage	5.00%
Maximum
Business Acquisition, Contingent Consideration [Line Items]
Revenue growth percentage	36.00%

Percentage of assumed long-term growth in revenues, used as an input to measure fair value.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Name:	us-gaap_FairValueInputsLongTermRevenueGrowthRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration