Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 item	Dec. 31, 2012
Liabilities
Warrant liability	$ 1,992	$ 830
Number of work statements executed with the Nordic Work Statements	3
Level 3
Liabilities
Warrant liability	2,000
Other liability	18,200
Stock liability	3,400
Recurring basis | Level 2
Assets
Assets fair value	17,058	4,000
Recurring basis | Level 2 | Domestic corporate debt securities
Assets
Marketable securities	5,810
Recurring basis | Level 2 | Domestic corporate commercial paper
Assets
Marketable securities	11,248	4,000
Recurring basis | Level 3
Assets
Stock asset	25	407
Assets fair value	25	407
Liabilities
Warrant liability	1,992	830
Other liability	18,225	24,387
Stock liability	3,401	245
Total liabilities carried at fair value	23,618	25,462
Recurring basis | Estimated Fair Value
Assets
Stock asset	25	407
Assets fair value	17,083	4,407
Liabilities
Warrant liability	1,992	830
Other liability	18,225	24,387
Stock liability	3,401	245
Total liabilities carried at fair value	23,618	25,462
Recurring basis | Estimated Fair Value | Domestic corporate debt securities
Assets
Marketable securities	5,810
Recurring basis | Estimated Fair Value | Domestic corporate commercial paper
Assets
Marketable securities	$ 11,248	$ 4,000