Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 131,490	$ 195,620
Certificates of deposit	0	2,180
Prepaid expenses and other current assets	5,921	4,954
Income tax receivable	5,975	0
Other receivables	24,526	5,388
Total current assets	167,912	208,142
Property and equipment, net	6,835	10,400
Total assets	174,747	218,542
Current liabilities:
Accounts payable	22,883	3,661
Accrued expenses	14,309	8,761
Income taxes payable	0	859
Current portion of unearned revenue	391	892
Current portion of deferred rent	90	96
Current portion of notes payable and obligations under capital leases	232	571
Total current liabilities	37,905	14,840
Long term liabilities:
Royalty obligation payable to Iowa Economic Development Authority	6,000	6,000
Notes payable and obligations under capital leases	285	368
Unearned revenue	0	407
Deferred rent	1,091	1,153
Total long-term liabilities	7,376	7,928
Total liabilities	45,281	22,768
Stockholders' Equity
Blank check preferred stock, $0.01 par value: Authorized shares — 5,000,000 at December 31, 2016 and 2015; issued and outstanding shares — 0 at December 31, 2016 and 2015	0	0
Common stock, $0.01 par value: Authorized shares — 75,000,000 at December 31, 2016 and 2015; issued 29,193,718 and 28,838,176 at December 31, 2016 and 2015 and outstanding 29,163,673 and 28,814,142 at December 31, 2016 and December 31, 2015	292	288
Additional paid-in capital	295,535	276,610
Treasury stock, at cost: 30,045 and 24,034 shares at December 31, 2016 and 2015	(853)	(771)
Accumulated deficit	(165,508)	(80,353)
Total stockholders' equity	129,466	195,774
Total liabilities and stockholders' equity	$ 174,747	$ 218,542