Summary of Activity Related to Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Goodwill And Intangible Assets [Line Items]
Goodwill, Gross Carrying Amount Beginning Balance	$ 21,843	$ 19,622
Increase in goodwill, Gross Carrying Amount		2,221
Goodwill, Gross Carrying Amount Ending Balance	108,098	21,843
Decrease in goodwill for GovDelivery impairment charge	(304)
Goodwill, Accumulated Impairment Losses Ending Balance	(304)
Goodwill, Net Carrying Amount Beginning Balance	21,843	19,622
Increase in goodwill, Net Carrying Amount		2,221
Goodwill, Net Carrying Amount Ending Balance	107,794	21,843
MSDSonline
Goodwill And Intangible Assets [Line Items]
Increase in goodwill, Gross Carrying Amount	15,847
Increase in goodwill, Net Carrying Amount	15,847
Media Iq
Goodwill And Intangible Assets [Line Items]
Increase in goodwill, Gross Carrying Amount	9,490
Increase in goodwill, Net Carrying Amount	9,490
Uai
Goodwill And Intangible Assets [Line Items]
Increase in goodwill, Gross Carrying Amount	2,922
Increase in goodwill, Net Carrying Amount	2,922
SeaPass
Goodwill And Intangible Assets [Line Items]
Increase in goodwill, Gross Carrying Amount	57,996
Increase in goodwill, Net Carrying Amount	57,996
GovDelivery
Goodwill And Intangible Assets [Line Items]
Increase in goodwill, Net Carrying Amount	$ (304)