Summarized Financial Information Related to Companies Accounted for Under Equity Method of Accounting (Parenthetical) (Detail)	Dec. 31, 2012	Dec. 31, 2011
Acquirgy
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	25.00%	25.00%
Channel Intelligence
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		49.00%
Freeborders
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	31.00%	31.00%
GoIndustry
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		26.00%
SeaPass
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	53.00%	26.00%
WhiteFence
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	36.00%	36.00%