Fair Value Measurements (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets and liabilities measured at fair value on a recurring basis
Cash and Cash equivalents	$ 24,491	$ 39,904
Total assets	24,491	39,904
Warrants	2,884	5,446
Total liabilities	2,884	5,446
Level 1 [Member]
Assets and liabilities measured at fair value on a recurring basis
Cash and Cash equivalents	24,491	39,904
Total assets	24,491	39,904
Warrants
Total liabilities
Level 2 [Member]
Assets and liabilities measured at fair value on a recurring basis
Cash and Cash equivalents
Total assets
Warrants
Total liabilities
Level 3 [Member]
Assets and liabilities measured at fair value on a recurring basis
Cash and Cash equivalents
Total assets
Warrants	2,884	5,446
Total liabilities	$ 2,884	$ 5,446