Summary of Significant Accounting Policies - Fair Value of Liabilities and Their Placement With in Fair Value Hierarchy Levels (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Liabilities:
Warrant derivative liability	$ 1,953	$ 5,470
Embedded derivative-debt	0	0
Total derivative liabilities	1,953	5,470
Level 1 input [Member]
Liabilities:
Warrant derivative liability	0	0
Embedded derivative-debt	0	0
Total derivative liabilities	0	0
Level 2 input [Member]
Liabilities:
Warrant derivative liability	0	0
Embedded derivative-debt	0	0
Total derivative liabilities	0	0
Level 3 input [Member]
Liabilities:
Warrant derivative liability	1,953	5,470
Embedded derivative-debt	0	0
Total derivative liabilities	$ 1,953	$ 5,470