Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	May 31, 2013 San Francisco	Jun. 30, 2013 San Francisco	Apr. 30, 2011 San Francisco Third Floor	Jun. 30, 2013 San Francisco Third Floor	Apr. 30, 2013 San Francisco Third Floor	Jul. 31, 2012 San Francisco Second Floor	Jun. 30, 2013 San Francisco Second Floor	May 31, 2013 San Francisco Additional Floors Phase One	May 31, 2013 San Francisco Additional Floors Phase Two	Dec. 31, 2012 New York	Jun. 30, 2013 New York sqft
Commitments and Contingencies [Line Items]
Monthly rent expenses	$ 400,000	$ 100,000	$ 800,000	$ 300,000		$ 100,000		$ 40,000			$ 60,000
Lease agreement commencement date							May 01, 2011			Sep. 15, 2012		Jun. 01, 2013	Dec. 01, 2013
Lease contract expiration date							Jun. 01, 2017				Jun. 01, 2017			Jan. 31, 2014
Security deposit made under operating lease agreement									160,000	60,000
Lease agreement expiration date					Jun. 01, 2017
Security deposit					100,000
Minimum short-term lease agreements for the lease of office space															250
Maximum short-term lease agreements for the lease of office space															400
Term of contract														One year
Monthly rent														3,000
Investment commitments of loan	10,000		10,000
Maximum cash pledged	5,000,000		5,000,000
Pledged and restricted to support contingent obligation	$ 3,000,000		$ 3,000,000