Commitments and Contingencies - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Aug. 29, 2013 sqft	Dec. 31, 2013 Subsidiary Agreement	Dec. 31, 2012	Dec. 31, 2011
Loss Contingencies [Line Items]
Rental expense		$ 4,800,000	$ 2,100,000	$ 1,900,000
Company executed lease	16,000
Lease expires date	2027-01
Number of lease agreements assigned to third parties		2
Lease termination dates		November 2015 and November 2020
Future lease obligations under sublease arrangements		2,800,000
Possible range of loss		0
Number of subsidiaries		2
Settlement days of bond transaction		Within one to three trading days
Revenues from riskless principal trading		6,000,000
Collateral deposit		900,000
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Contingent obligation for standby letter of credit issued to Landlord		$ 1,300,000