| 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: | | | | | | | | |
| Total revenue | 720.2 | 713.3 | 700.7 | 696.2 | 680.8 | 638.1 | 602.7 | 538.8 |
| Total revenue growth | 5.8% | 11.8% | 16.3% | 29.2% | 40.7% | 36.0% | 32.3% | 21.4% |
| OPERATING EXPENSES (excluding depreciation and amortization unless otherwise indicated): | | | | | | | | |
| Cost of services | | | | | | | | |
| Stock-based compensation | 4.5 | 4.3 | | | 4.0 | 1.5 | | |
| Transaction-related charges | 4.3 | 4.3 | 4.8 | 6.8 | 9.1 | 10.0 | 10.2 | 9.3 |
| Restructuring expenses | 3.3 | 2.9 | | | | | | |
| Depreciation and amortization | 147.2 | 144.8 | 141.6 | 141.1 | 137.0 | 123.3 | 110.5 | 95.2 |
| (Gain) Loss on disposition of long-lived assets | 1.3 | 0.8 | 4.4 | 6.0 | 5.3 | 6.1 | 2.8 | 22.1 |
| Total operating expenses | 737.3 | 731.0 | 717.8 | 738.3 | 725.3 | 668.5 | 617.7 | 548.3 |
| Income from operations | 9.2 | 8.5 | 7.9 | -17.0 | -19.4 | -18.3 | -15.0 | -9.4 |
| Operating margin | 1.3% | 1.2% | 1.1% | -2.4% | -2.9% | -2.9% | -2.5% | -1.7% |
| |
| OTHER INCOME (EXPENSE) | | | | | | | | |
| Interest income | 0.4 | 0.4 | 0.2 | 0.1 | | 0.2 | 0.1 | 0.1 |
| Interest expense | -32.1 | -25.9 | -20.5 | -17.0 | -15.0 | -11.8 | -9.6 | -7.0 |
| Other income | 5.2 | 0.2 | 4.2 | 3.3 | 1.0 | 3.6 | 1.8 | 2.1 |
| Other income (expense) | -26.5 | -25.3 | -11.8 | -9.4 | -9.6 | -3.8 | -5.3 | -2.4 |
| LOSS BEFORE INCOME TAXES | -17.3 | -16.8 | -8.1 | -30.7 | -33.3 | -26.3 | -22.7 | -14.2 |
| Income tax (benefit) expense | -5.3 | -4.2 | -0.5 | -1.7 | -1.7 | 0.8 | -1.9 | 0.3 |
| NET LOSS | -12.0 | -12.7 | -7.6 | -28.9 | -31.6 | -27.0 | -20.8 | -14.5 |
| Net loss attributable to noncontrolling interests, net of tax (benefit) expense of $(0.7) million, $0 million, $(1.2) million and $(0.5) million respectively | 2.7 | 2.1 | 1.9 | 0.5 | 3.3 | 1.3 | -1.3 | -3.9 |
| NET INCOME (LOSS) ATTRIBUTABLE TO ATN INTERNATIONAL, INC. STOCKHOLDERS | -9.3 | -10.6 | -5.6 | -28.5 | -28.3 | -25.8 | -22.1 | -18.4 |
| |
| NET LOSS PER WEIGHTED AVERAGE SHARE ATTRIBUTABLE TO ATN INTERNATIONAL, INC. STOCKHOLDERS: | | | | | | | | |
| NET LOSS PER WEIGHTED AVERAGE SHARE ATTRIBUTABLE TO ATN INTERNATIONAL, INC. STOCKHOLDERS: | | | | | | | | |
| Basic (in dollars per share) | ($0.90) | ($0.98) | ($0.67) | ($2.09) | ($2.06) | ($1.82) | ($1.52) | ($1.21) |
| Diluted (in dollars per share) | ($0.90) | ($0.98) | ($0.67) | ($2.09) | ($2.06) | ($1.82) | ($1.52) | ($1.21) |
| |
| WEIGHTED AVERAGE COMMON SHARES OUTSTANDING: | | | | | | | | |
| Basic (in shares) | 11.8 | 15.8 | 15.7 | 15.8 | 15.8 | 15.8 | 15.9 | 15.9 |
| Diluted (in shares) | 11.8 | 15.8 | 15.7 | 15.8 | 15.8 | 15.8 | 15.9 | 15.9 |
| |
| DIVIDENDS PER SHARE APPLICABLE TO COMMON STOCK | $0.80 | $0.76 | $0.72 | $0.68 | $0.68 | $0.68 | $0.68 | $0.68 |