Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 20,250	$ 39,490
Certificates of deposit	1,494	2,490
Prepaid expenses	907	409
State research and development credit receivable	542	202
Other receivables	196	197
Total current assets	23,389	42,788
Leasehold improvements and equipment:
Leasehold improvements	5,085	4,459
Computer equipment	636	710
Lab equipment	3,297	3,333
Total leasehold improvements and equipment	9,018	8,502
Less accumulated depreciation and amortization	(2,978)	(2,911)
Leasehold improvements and equipment, net	6,040	5,591
Total assets	29,429	48,379
Current liabilities:
Accounts payable	972	1,670
Accrued expenses	1,659	1,867
Deferred rent	84	913
Note payable to Iowa Department of Economic Development	0	6,000
Obligations under capital leases	55	121
Current portion of long term debt	149	93
Total current liabilities	2,919	10,664
Long term liabilities:
Royalty obligation payable to Iowa Economic Development Authority	6,000	0
Obligations under capital leases	38	94
Deferred rent, excluding current portion	1,405	0
Total long-term liabilities	8,583	942
Total liabilities	11,502	11,606
Equity (deficit):
Blank check preferred stock, $0.01 par value: Authorized shares — 5,000,000 at December 31, 2012 and 2011; issued and outstanding shares — 0 at December 31, 2012 and 2011	0	0
Common stock, $0.01 par value: Authorized shares — 38,833,334 at December 31, 2012 and 2011; issued and outstanding shares — 20,985,192 at December 31, 2012, and 20,591,240 at December 31, 2011	210	206
Additional paid-in capital	122,514	118,043
Deficit accumulated during the development stage	(104,797)	(81,476)
Total equity	17,927	36,773
Total liabilities and equity	29,429	48,379
Iowa State University Research Park [Member]
Long term liabilities:
Notes Payable, Noncurrent	840	548
City of Ames [Member]
Long term liabilities:
Notes Payable, Noncurrent	$ 300	$ 300