Allocation of Purchase Price for Acquisitions and Enterprise Value of Channel Intelligence (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life		10 years
Minimum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Minimum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	2 years	2 years
Maximum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	10 years
Maximum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years	5 years
SeaPass | Minimum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
SeaPass | Minimum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
SeaPass | Minimum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
SeaPass | Minimum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	3 years
SeaPass | Maximum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
SeaPass | Maximum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	10 years
SeaPass | Maximum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
SeaPass | Maximum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
MSDSonline | Minimum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
MSDSonline | Minimum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
MSDSonline | Minimum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
MSDSonline | Minimum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	3 years
MSDSonline | Maximum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
MSDSonline | Maximum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	10 years
MSDSonline | Maximum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
MSDSonline | Maximum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Media Iq | Minimum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
Media Iq | Minimum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Media Iq | Minimum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Media Iq | Minimum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	3 years
Media Iq | Maximum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Media Iq | Maximum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	10 years
Media Iq | Maximum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
Media Iq | Maximum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Uai | Minimum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	8 years
Uai | Minimum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years
Uai | Minimum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Uai | Minimum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	3 years
Uai | Maximum | Customer Lists
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	11 years
Uai | Maximum | Technology
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	10 years
Uai | Maximum | Trademarks, trade names and domain names
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	15 years
Uai | Maximum | Noncompete Agreements
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]
Finite-lived intangible assets, useful life	5 years