| In millions, except per share items | Jun-30-23 | Mar-31-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 |
| | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Revenue | 798.2 | 721.4 | 653.6 | 597.8 | 549.8 | 503.6 | 458.6 | 403.4 |
| Revenue growth | 45.2% | 43.3% | 42.5% | 48.2% | 55.3% | | | |
| Costs and expenses | | | | | | | | |
| Cost of revenue | | | | | | | | |
| Marketing | 184.2 | 174.5 | 171.0 | 166.1 | 153.1 | 135.4 | 120.9 | 105.5 |
| Technology and development | 182.7 | 164.5 | 138.7 | 115.0 | 96.9 | 76.0 | 64.1 | 56.3 |
| General and administrative | 151.3 | 149.3 | 131.3 | 119.9 | 108.9 | 83.4 | 70.9 | 57.1 |
| Depreciation and amortization | 9.9 | 8.2 | 6.7 | 6.2 | 5.7 | 5.5 | 5.3 | 5.1 |
| Total costs and expenses | 903.0 | 847.3 | 774.6 | 712.5 | 641.5 | 557.9 | 498.3 | 435.4 |
| Loss from operations | -104.8 | -125.9 | -121.0 | -114.7 | -91.8 | -54.3 | -39.7 | -32.0 |
| Operating margin | -13.1% | -17.5% | -18.5% | -19.2% | -16.7% | -10.8% | -8.7% | -7.9% |
| Interest income | 7.1 | 6.1 | 4.1 | 1.9 | 0.6 | 0.2 | 0.1 | 0.2 |
| Interest expense | -1.6 | -1.4 | -1.3 | -1.2 | -1.4 | -1.3 | -1.3 | -1.2 |
| Other (expense) income, net | -0.2 | 3.0 | 5.2 | 4.2 | 2.8 | 2.4 | 3.1 | 3.5 |
| Loss before provision for income taxes | -99.5 | -118.1 | -113.0 | -109.8 | -89.7 | -53.1 | -37.7 | -29.6 |
| (Benefit) provision for income taxes | 0.1 | 0.9 | 1.0 | 1.4 | 1.4 | 1.2 | 1.0 | 1.6 |
| Net loss attributable to common stockholders | -99.6 | -119.0 | -114.0 | -111.2 | -91.1 | -54.3 | -38.8 | -31.2 |
| |
| Net loss per share attributable to common stockholders: | | | | | | | | |
| Basic (in dollars per share) | ($0.58) | ($0.70) | ($0.68) | ($0.36) | ($0.57) | ($0.40) | ($0.60) | ($1.22) |
| Diluted (in dollars per share) | ($0.58) | ($0.70) | ($0.68) | ($0.36) | ($0.57) | ($0.40) | ($0.60) | ($1.22) |
| |
| Weighted-average shares used in computing net loss per share attributable to common stockholders: | | | | | | | | |
| Basic (in shares) | 172.6 | 169.5 | 166.8 | 140.1 | 105.8 | 70.1 | 34.7 | 24.9 |
| Diluted (in shares) | 172.6 | 169.5 | 166.8 | 140.1 | 105.8 | 70.1 | 34.7 | 24.9 |