Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 25,557	$ 39,490
Certificates of deposit	2,739	2,490
Prepaid expenses	145	409
State research and development credit receivable	454	202
Other receivables	26	197
Total current assets	28,921	42,788
Leasehold improvements and equipment:
Leasehold improvements	5,041	4,459
Computer equipment	773	710
Lab equipment	3,686	3,333
Total leasehold improvements and equipment	9,500	8,502
Less accumulated depreciation and amortization	(3,413)	(2,911)
Leasehold improvements and equipment, net	6,087	5,591
Total assets	35,008	48,379
Liabilities and Equity
Accounts payable	708	1,670
Accrued expenses	2,136	1,867
Deferred rent	76	913
Notes payable to Iowa Department of Economic Development	0	6,000
Obligations under capital leases	82	121
Current portion of long term debt	148	93
Total current liabilities	3,150	10,664
Long term liabilities:
Obligations under capital leases, excluding current portion	43	94
Deferred rent, excluding current portion	1,414	0
Total long-term liabilities	8,635	942
Total liabilities	11,785	11,606
Equity (deficit):
Common stock, $0.01 par value: Authorized shares — 38,833,334 at September 30, 2012, and December 31, 2011; issued and outstanding shares — 20,908,789 at September 30, 2012, and 20,591,240 at December 31, 2011	209	206
Additional paid-in capital	121,492	118,043
Deficit accumulated during the development stage	(98,478)	(81,476)
Total equity	23,223	36,773
Commitments
Total liabilities and equity	35,008	48,379
Blank Check Preferred Stock [Member]
Equity (deficit):
Blank check preferred stock, $0.01 par value: Authorized shares — 5,000,000 at September 30, 2012, and December 31, 2011; issued and outstanding shares — 0 at September 30, 2012, and December 31, 2011	0	0
Iowa Economic Development Authority [Member]
Long term liabilities:
Royalty obligation payable to Iowa Economic Development Authority	6,000	0
Iowa State University Research Park [Member]
Long term liabilities:
Notes payable	878	548
City of Ames [Member]
Long term liabilities:
Notes payable	$ 300	$ 300