Summary of Significant Accounting Policies - Schedule of Reconciliation of Financial Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Financial liabilities:
Beginning balance	$ 5,470	$ 4,870
Unrealized change in fair value	(3,517)	600
Ending balance	$ 1,953	$ 5,470