Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 33,269	$ 39,490
Certificates of deposit	2,490	2,490
Prepaid expenses	292	409
State research and development credit receivable	247	202
Interest receivable	2	1
Other receivables	918	196
Total current assets	37,218	42,788
Leasehold improvements and equipment:
Leasehold improvements	4,873	4,459
Computer equipment	744	710
Lab equipment	3,629	3,333
Total leasehold improvements and equipment	9,246	8,502
Less accumulated depreciation and amortization	(3,017)	(2,911)
Leasehold improvements and equipment, net	6,229	5,591
Total assets	43,447	48,379
Liabilities and Equity
Accounts payable	803	1,670
Accrued expenses	1,226	1,867
Deferred rent	65	913
Notes payable to Iowa Department of Economic Development	0	6,000
Obligations under capital leases	123	121
Current portion of long term debt	93	93
Total current liabilities	2,310	10,664
Long term liabilities:
Obligations under capital leases	61	94
Deferred rent	1,454	0
Total long-term liabilities	8,339	942
Total liabilities	10,649	11,606
Equity (deficit):
Common stock, $0.01 par value: Authorized shares — 38,833,334 at March 31, 2012, and December 31, 2011; issued and outstanding shares — 20,672,029 at March 31, 2012, and 20,591,240 at December 31, 2011	207	206
Additional paid-in capital	118,909	118,043
Deficit accumulated during the development stage	(86,318)	(81,476)
Total deficit	32,798	36,773
Commitments
Total liabilities and equity	43,447	48,379
Blank Check Preferred Stock [Member]
Equity (deficit):
Preferred stock	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	524	548
City of Ames [Member]
Long term liabilities:
Notes payable	$ 300	$ 300