| 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 | S-1/A |
| Operating Activities | | | | | | | | |
| Net loss | -109.6 | -18.5 | -80.8 | -42.0 | -15.0 | -22.5 | -30.2 | -24.7 |
| |
| Adjustments to reconcile net loss to net cash provided by operating activities: | | | | | | | | |
| Depreciation and amortization | 46.9 | 14.6 | 9.2 | 8.5 | 7.2 | 6.3 | 4.4 | 2.7 |
| Stock-based compensation | 54.7 | 37.0 | 27.8 | 20.4 | 11.1 | 8.4 | 5.6 | 5.2 |
| Amortization of debt discount and issuance costs | 5.0 | 12.0 | 6.4 | 2.6 | | | | |
| Non-cash lease expense | 11.6 | 9.2 | 6.9 | | | | | |
| Impairment costs | | 2.1 | | | | | | |
| Gain on extinguishment of convertible senior notes | | 4.6 | | | | | | |
| Other | -4.2 | -0.3 | -0.7 | | | | | |
| Change in assets and liabilities: | | | | | | | | |
| Accounts receivable, net | -7.1 | -35.5 | -3.9 | -2.0 | -2.7 | -5.0 | -2.7 | |
| Inventory | -309.1 | 25.4 | -51.9 | -19.3 | -3.4 | | | |
| Prepaid expenses and other assets | -12.2 | 2.3 | -3.3 | -5.5 | 4.5 | -6.0 | 0.0 | -0.5 |
| Accounts payable | 3.1 | 2.1 | -0.4 | 0.6 | -0.3 | 0.6 | 0.2 | 0.9 |
| Accrued and other liabilities, deferred tax liabilities, and payroll tax liabilities, noncurrent | | | | 4.4 | 5.1 | 6.6 | 3.9 | 3.4 |
| Lease liabilities | -13.3 | -11.3 | -7.2 | | | | | |
| Origination of loans held for sale | -987.0 | -677.3 | -395.4 | -86.0 | -11.0 | | | |
| Proceeds from sale of loans originated as held for sale | 993.1 | 657.8 | 378.6 | 83.0 | 9.1 | | | |
| Net cash used in operating activities | -301.6 | 61.3 | -107.6 | -36.7 | 5.4 | -9.4 | -22.2 | -13.6 |
| |
| Investing activities | | | | | | | | |
| Purchases of property and equipment | -27.5 | -14.7 | -15.5 | -8.3 | -12.1 | -13.6 | -4.6 | |
| Purchases of investments | | | | | | -1.7 | -1.6 | -1.5 |
| Sales of investments | 98.7 | 7.9 | 11.5 | | 2.7 | | | |
| Maturities of investments | 106.8 | 147.9 | 24.4 | | 2.7 | 1.7 | 1.6 | 1.5 |
| Cash paid for acquisition, net of cash, cash equivalents, and restricted cash acquired | -608.0 | | | | | | | |
| Net cash provided by (used in) investing activities | -576.3 | -57.1 | -115.9 | -10.3 | -10.4 | -13.6 | -4.6 | -9.0 |
| |
| Financing activities | | | | | | | | |
| Proceeds from the issuance of common stock pursuant to employee equity plans | 22.8 | 21.1 | 16.1 | 23.4 | 3.0 | 1.5 | 1.7 | 1.0 |
| Tax payments related to net share settlements on restricted stock units | -27.1 | -16.9 | -5.1 | -1.4 | | | | |
| Borrowings from secured revolving credit facility | 943.0 | 662.3 | 388.6 | 222.8 | 10.7 | | | |
| Repayments to secured revolving credit facility | -449.0 | -70.1 | | | | | | |
| Cash paid for secured revolving credit facility issuance costs | -0.5 | 0.0 | -0.9 | | | | | |
| Net cash (used in) provided by financing activities | 650.3 | 694.2 | 31.9 | 273.4 | 149.8 | 1.7 | 3.5 | 69.6 |
| Effect of exchange rate changes on cash, cash equivalents, and restricted cash | 0.0 | 0.0 | 0.0 | | | | | |
| Net change in cash, cash equivalents, and restricted cash | -227.5 | 698.4 | -191.6 | 226.4 | 144.8 | -21.2 | | |
| |
| Cash, cash equivalents, and restricted cash: | | | | | | | | |
| Supplemental disclosure of cash flow information | | | | | | | | |
| Cash paid for interest | 7.6 | 5.0 | 2.5 | | | | | |
| Non-cash transactions | | | | | | | | |
| Stock-based compensation capitalized in property and equipment | 4.1 | 2.3 | 1.3 | 0.5 | -0.3 | -0.1 | 0.0 | |
| Capital expenditures | 0.7 | 1.7 | 0.2 | 0.1 | | -3.5 | | |