Revenues from Customers Accounted for More Than Ten Percent of Revenues (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Apple
Revenue, Major Customer [Line Items]
Receivables from customers	41.30%	26.50%	10.70%
Google
Revenue, Major Customer [Line Items]
Receivables from customers	20.30%
Tapjoy
Revenue, Major Customer [Line Items]
Receivables from customers	10.70%	11.60%
Verizon Wireless
Revenue, Major Customer [Line Items]
Receivables from customers			14.70%