Common Stock - Additional Information (Detail) (Hercules Note [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended	90 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Hercules Note [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of Warrant related to Hercules Note	$ 0	$ 323	$ 0	$ 323

The cash inflow associated with the amount received from holders exercising their stock warrants.

No definition available.

Name:	us-gaap_ProceedsFromWarrantExercises
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration