Allocation of Purchase Price for Acquisitions and Enterprise Value of Channel Intelligence (Parenthetical) (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Customer Lists | MSDSonline | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
Customer Lists | MSDSonline | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Customer Lists | Media IQ | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
Customer Lists | Media IQ | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Customer Lists | UAI | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
Customer Lists | UAI | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Customer Lists | Bolt | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
Customer Lists | Bolt | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Technology
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life		10 years
Technology | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Technology | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	10 years
Technology | MSDSonline | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Technology | MSDSonline | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Technology | Media IQ | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Technology | Media IQ | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Technology | UAI | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Technology | UAI | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Technology | Bolt | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Technology | Bolt | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Trademarks, trade names and domain names | MSDSonline | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	2 years
Trademarks, trade names and domain names | MSDSonline | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
Trademarks, trade names and domain names | Media IQ | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	2 years
Trademarks, trade names and domain names | Media IQ | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
Trademarks, trade names and domain names | UAI | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	2 years
Trademarks, trade names and domain names | UAI | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
Trademarks, trade names and domain names | Bolt | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	2 years
Trademarks, trade names and domain names | Bolt | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
Non-compete Agreements | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	2 years	2 years
Non-compete Agreements | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years	5 years
Non-compete Agreements | MSDSonline | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	1 year
Non-compete Agreements | MSDSonline | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Non-compete Agreements | Media IQ | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	1 year
Non-compete Agreements | Media IQ | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Non-compete Agreements | UAI | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	1 year
Non-compete Agreements | UAI | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Non-compete Agreements | Bolt | Minimum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	1 year
Non-compete Agreements | Bolt | Maximum
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years