In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 |
| 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
ASSETS | | | | | | | | |
Current assets: | | | | | | | | |
Cash and cash equivalents | 11.0 | 35.3 | 6.3 | 9.1 | 11.7 | 15.0 | 6.6 | 1.2 |
Accounts receivable | 0.1 | | | | | | | |
Prepaid expenses and other current assets | 0.4 | 0.5 | 0.5 | 0.4 | 1.7 | 0.3 | 0.2 | 0.3 |
Total current assets | 11.6 | 35.7 | 6.8 | 23.4 | 13.4 | 15.3 | 37.3 | 1.6 |
Property and equipment, net | 32.6 | 30.9 | 24.6 | 11.9 | 4.2 | 5.5 | 7.7 | 9.7 |
Operating lease right-of-use assets | 3.8 | 4.9 | 5.8 | | | | | |
Total assets | 48.4 | 72.0 | 37.7 | 35.8 | 18.0 | 20.9 | 45.3 | 13.3 |
|
LIABILITIES AND STOCKHOLDERS’ EQUITY | | | | | | | | |
Current liabilities: | | | | | | | | |
Accounts payable | 2.1 | 1.9 | 4.4 | 4.5 | 1.5 | 1.4 | 1.2 | 1.4 |
Accrued compensation | 1.8 | 2.3 | 2.0 | 2.1 | 1.6 | 1.4 | 1.3 | 1.7 |
Build-to-suit obligation, current portion, net of debt issuance costs and discount | 3.8 | 4.8 | | | | | | |
Operating lease liabilities, current portion | 1.6 | 1.4 | 1.1 | | | | | |
Other accrued liabilities | 1.8 | 3.4 | 4.2 | 2.4 | 0.7 | 1.0 | 1.0 | 1.0 |
Total current liabilities | 11.1 | 14.5 | 16.2 | 11.3 | 10.5 | 9.8 | 6.9 | 13.4 |
Build-to-suit obligation, long-term portion, net of debt issuance costs and discount | 1.0 | 4.4 | 6.1 | 4.5 | | | | |
Operating lease liabilities, long-term portion | 3.1 | 4.7 | 5.9 | | | | | |
Other long-term liabilities | 0.2 | 0.1 | 0.0 | | | | | |
Total liabilities | 15.4 | 24.5 | 28.3 | 17.1 | 11.0 | 16.4 | 18.8 | 26.7 |
|
Commitments and contingencies (see note 11) | | | | | | | | |
Stockholders’ equity: | | | | | | | | |
Common stock | 0.0 | 0.0 | 0.0 | 0.0 | | | 0.0 | 0.0 |
Additional paid-in capital | 395.1 | 379.7 | 308.2 | 279.9 | 232.9 | 201.3 | 193.4 | 125.1 |
Accumulated deficit | -362.1 | -332.2 | -298.8 | -261.2 | -225.9 | -196.8 | -166.9 | -138.5 |
Total stockholders’ equity | 33.0 | 47.5 | 9.4 | 18.7 | 7.0 | 4.5 | 26.5 | -13.4 |
Total liabilities and stockholders’ equity | 48.4 | 72.0 | 37.7 | 35.8 | 18.0 | 20.9 | 45.3 | 13.3 |