v2.4.0.6

Goodwill and Intangible Assets (Weighted Average Remaining Amortization Period) (Detail)	9 Months Ended
	Sep. 30, 2012
Acquired Methodologies/Technology [Member]
Intangible Assets [Line Items]
Weighted average remaining amortization period	2 years 6 months
Customer Relationships [Member]
Intangible Assets [Line Items]
Weighted average remaining amortization period	6 years 10 months 24 days
Panel [Member]
Intangible Assets [Line Items]
Weighted average remaining amortization period	2 years 8 months 12 days
Intellectual Property [Member]
Intangible Assets [Line Items]
Weighted average remaining amortization period	8 years 6 months
Trade Names [Member]
Intangible Assets [Line Items]
Weighted average remaining amortization period	2 years 8 months 12 days

X

- Details

Name:	us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Weighted average period before the next renewal or extension for intangible assets with renewal or extension terms, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_AcquiredFiniteLivedIntangibleAssetWeightedAveragePeriodBeforeRenewalOrExtension
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration