Balance Sheet Components - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Balance Sheet Components [Line Items]
Depreciation	$ 2,368	$ 1,846	$ 1,975
Accounts receivable write-offs	0	0	0
Accounts receivable recoveries	0	0	0
Deferred platform processing fee
Balance Sheet Components [Line Items]
Prepaid expenses and other	$ 2,680	$ 2,206