| In millions, except per share items | Jun-30-23 | Mar-31-23 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 | Jun-30-21 |
| | 10-Q | 10-Q | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q |
| Total revenue | 222.1 | 238.5 | 232.2 | 241.5 | 253.3 | 243.6 | 232.4 | 237.2 |
| Total revenue growth | -8.0% | -5.9% | -0.1% | 1.8% | 9.0% | 13.2% | 15.6% | 29.8% |
| Costs and expenses | | | | | | | | |
| Curriculum and teaching | 34.1 | 32.8 | 31.6 | 32.1 | 33.2 | 32.0 | 30.9 | 34.8 |
| Servicing and support | 33.6 | 36.1 | 36.1 | 37.1 | 39.6 | 36.6 | 33.9 | 34.9 |
| Technology and content development | 44.3 | 45.5 | 44.0 | 45.6 | 51.1 | 50.5 | 43.1 | 42.5 |
| Marketing and sales | 95.9 | 100.2 | 94.3 | 116.4 | 131.0 | 109.9 | 118.3 | 114.6 |
| General and administrative | 32.7 | 39.3 | 39.4 | 41.5 | 50.2 | 64.3 | 44.3 | 46.2 |
| Restructuring charges | 3.6 | 4.9 | 11.6 | 16.8 | 0.8 | | 5.4 | 1.3 |
| Impairment charges | 134.1 | | 79.5 | | 58.8 | | | |
| Total costs and expenses | 378.2 | 258.7 | 336.5 | 289.4 | 364.7 | 293.3 | 275.9 | 274.3 |
| Loss from operations | -156.1 | -20.2 | -104.2 | -48.0 | -111.4 | -49.7 | -43.5 | -37.1 |
| Operating margin | -70.3% | -8.5% | -44.9% | -19.9% | -44.0% | -20.4% | -18.7% | -15.6% |
| Interest income | 0.4 | 0.4 | 0.3 | 0.2 | 0.3 | 0.3 | 0.5 | 0.4 |
| Interest expense | -17.9 | -18.0 | -15.9 | -13.9 | -13.9 | -18.2 | -16.9 | -8.2 |
| Debt modification expense and loss on debt extinguishment | | -16.7 | | | | | | |
| Other income (expense), net | 0.2 | 0.6 | -1.8 | -1.4 | -1.0 | -0.4 | -0.4 | 24.1 |
| Loss before income taxes | -173.4 | -53.9 | -121.7 | -63.0 | -126.0 | -68.0 | -60.4 | -22.0 |
| Income tax (expense) benefit | -0.2 | -0.1 | 0.1 | 0.2 | 0.3 | 0.7 | 0.3 | 0.1 |
| Net loss | -173.7 | -54.1 | -121.7 | -62.9 | -125.8 | -67.3 | -60.1 | -21.8 |
| |
| Net loss per share, basic (in dollars per share) | ($2.16) | ($0.68) | ($1.57) | ($0.82) | ($1.65) | ($0.89) | ($0.80) | ($0.29) |
| Net loss per share, diluted (in dollars per share) | ($2.16) | ($0.68) | ($1.57) | ($0.82) | ($1.65) | ($0.89) | ($0.80) | ($0.29) |
| |
| Weighted-average shares of common stock outstanding, basic (in shares) | 80.6 | 79.3 | 77.7 | 77.1 | 76.3 | 74.6 | 74.7 | 74.4 |
| Weighted-average shares of common stock outstanding, diluted (in shares) | 80.6 | 79.3 | 77.7 | 77.1 | 76.3 | 74.6 | 74.7 | 74.4 |
| |
| Other comprehensive loss | | | | | | | | |
| Foreign currency translation adjustments, net of tax of $0 for all periods presented | -4.0 | -3.3 | -5.6 | -7.7 | 7.3 | -4.0 | -4.3 | 3.0 |
| Comprehensive loss | -177.7 | -57.4 | -127.3 | -70.5 | -118.5 | -71.3 | -64.4 | -18.9 |