Common Stock - Schedule of Shares Reserved for Future Issuance (Detail) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Equity [Abstract]
Common stock warrants	2,777	2,842
Options to purchase common stock	20,107	18,066
Conversion of the Notes	25,000

Number of common shares reserved for future issuance related to deferred compensation arrangements with individuals.

No definition available.

Name:	us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant