In millions, except per share items | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 |
| 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
Cash flows from operating activities | | | | | | | | |
Net loss | -76.8 | -85.0 | -67.8 | -38.3 | -37.2 | | | |
|
Adjustments to reconcile net loss to net cash used in operating activities: | | | | | | | | |
Depreciation and amortization expense | 0.1 | 0.1 | 0.0 | | | | | |
Stock-based compensation expense | 26.2 | 13.9 | 8.6 | 7.4 | 5.2 | 4.4 | 4.8 | 0.6 |
Stock award - in-licensing | 0.5 | | | | | | | |
Employee Stock Purchase Plan compensation expense | 0.3 | 0.1 | 0.1 | 0.1 | 0.1 | | | |
Non-cash lease expense | 1.0 | | | | | | | |
Unrealized foreign exchange loss | 0.0 | | | | | | | |
Net loss on sale of marketable securities | 0.0 | 0.0 | 0.0 | | | | | |
Changes in operating assets and liabilities: | | | | | | | | |
Accounts receivable, net | -15.1 | | | | | | | |
Inventories, net | -0.9 | | | | | | | |
Other assets | -0.1 | | | -0.2 | | | | |
Prepaid expenses and other current assets | -1.5 | -2.5 | -0.2 | 0.4 | 1.0 | -1.3 | 0.0 | -0.1 |
Accounts payable and accrued expenses | 0.8 | 1.4 | 10.5 | 0.7 | 5.0 | -0.5 | 2.2 | 1.6 |
Operating lease liabilities | -1.0 | | | | | | | |
Other liabilities | 0.0 | 0.0 | 0.0 | 0.1 | 0.0 | | | |
Net cash used in operating activities | -67.7 | -72.2 | -49.6 | -30.1 | -25.6 | -25.7 | -16.1 | -4.1 |
|
Cash flows from investing activities | | | | | | | | |
Purchase of marketable securities | | | | -26.5 | -105.6 | -16.2 | -40.2 | |
Sale and maturities of marketable securities | | | | 53.1 | 54.7 | 22.6 | | |
Net cash provided by (used in) investing activities | -99.2 | 10.8 | -4.4 | 26.7 | -50.9 | 6.4 | -40.7 | |
|
Cash flows from financing activities | | | | | | | | |
Proceeds from issuance of common stock from follow-on public offering, net | 168.4 | 63.9 | 48.2 | | 64.1 | | 97.7 | |
Proceeds from issuance of common stock from ESPP | 0.4 | 0.2 | 0.2 | 0.1 | 0.0 | | | |
Proceeds from exercise of stock options | 2.1 | 1.6 | 0.1 | 0.3 | 0.7 | 0.1 | 1.3 | |
Net cash provided by financing activities | 171.0 | 66.0 | 48.5 | 0.4 | 64.9 | 0.1 | 99.0 | 0.3 |