| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 |
| | 10-K | 10-K | 10-K | 10-K |
| Net revenue | 635.7 | 627.9 | 592.3 | 785.5 |
| Net revenue growth | 1.2% | 6.0% | -24.6% | |
| Cost of services: | | | | |
| Salaries and related costs | 358.0 | 336.5 | 306.5 | 414.5 |
| Rent, clinic supplies, contract labor and other | 202.6 | 180.9 | 166.1 | 170.5 |
| Provision for doubtful accounts | 13.9 | 16.4 | 16.2 | 22.2 |
| Total cost of services | 1,533.4 | 1,944.4 | 488.8 | 607.2 |
| Selling, general and administrative expenses | 114.7 | 111.8 | 104.3 | 119.2 |
| Goodwill, intangible and other asset impairment charges | 486.3 | 962.3 | | |
| Operating loss | -539.7 | -980.0 | -0.9 | 59.0 |
| Operating margin | -84.9% | -156.1% | -0.2% | 7.5% |
| Change in fair value of warrant liability | -4.2 | -22.6 | | |
| Change in fair value of contingent common shares liability | -42.5 | -175.1 | | |
| Interest expense, net | 45.3 | 46.3 | 69.3 | 77.0 |
| Other expense, net | 3.3 | 0.2 | -91.0 | 0.8 |
| Loss before taxes | -541.6 | -853.0 | 1.8 | -34.3 |
| Income tax expense (benefit) | -48.5 | -71.0 | 2.1 | -44.0 |
| Net loss | -541.6 | -853.0 | 1.8 | -34.3 |
| Net income (loss) attributable to non-controlling interests | -0.7 | -3.7 | 5.1 | 4.4 |
| Net loss attributable to ATI Physical Therapy, Inc. | -492.4 | -778.3 | -5.4 | 5.3 |
| Loss available to common stockholders, basic | -540.9 | -849.3 | -3.3 | -38.7 |
| |
| Loss per share of Class A common stock: | | | | |
| Basic (in dollars per share) | ($2.51) | ($4.69) | ($0.04) | $0.04 |
| Diluted (in dollars per share) | ($2.51) | ($4.69) | ($0.04) | $0.04 |
| |
| Weighted average shares outstanding: | | | | |
| Basic (in shares) | 203.2 | 165.8 | 128.3 | 128.3 |
| Diluted (in shares) | 203.2 | 165.8 | 128.3 | 128.3 |