| In millions, except per share items | Jun-30-19 | Jun-30-18 | Jun-30-17 | Jun-30-16 | Jun-30-15 | Jun-30-14 | Jun-30-13 | Jun-30-12 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Revenues: | | | | | | | | |
| Revenue from contract with customer | 51.2 | 5.9 | 4.9 | -4.7 | | | 0.1 | 15.1 |
| Revenue from contract with customer growth | 762.3% | 20.5% | -204.5% | | | -100.0% | -99.2% | 274.5% |
| Rental income | 20.0 | 1.9 | | | | | | |
| Revenue | 51.2 | 5.9 | 4.9 | -4.7 | | | 0.1 | 15.1 |
| Revenue growth | 762.3% | 20.5% | -204.5% | | | -100.0% | -99.2% | 274.5% |
| Operating costs and expenses: | | | | | | | | |
| Total operating costs and expenses | | | | | | | | |
| Depreciation and amortization | 3.7 | 1.1 | 0.3 | 0.1 | | | | |
| Total operating costs and expenses | 55.5 | 16.4 | 9.5 | -9.8 | 8.0 | 5.7 | 39.6 | 24.0 |
| Operating loss | -4.3 | -10.5 | -4.6 | -9.8 | -8.0 | -5.7 | -39.5 | -9.0 |
| Operating margin | -8.4% | -176.4% | -93.5% | 208.6% | | | -32637.2% | -59.6% |
| Dividends and interest income | 2.6 | 2.6 | 1.3 | 0.0 | | | | |
| |
| Unrealized loss on investment in GECC | | | | | | | | |
| Interest expense | -6.3 | -1.1 | -6.3 | -4.9 | | | | |
| Other (expense) income, net | | | | | 0.3 | 0.6 | -0.3 | -0.4 |
| Loss from continuing operations, before income taxes | -9.1 | -11.7 | -18.7 | -14.5 | -12.0 | -8.7 | -39.6 | -9.4 |
| Income tax expense | 2.2 | 0.3 | 1.2 | 5.1 | -0.2 | 3.1 | 0.0 | 1.3 |
| Loss from continuing operations | -6.9 | -11.3 | -17.4 | -9.4 | | | -39.7 | |
| Net loss | -10.0 | -11.5 | -32.7 | 0.0 | | | -39.7 | |
| Less: net loss attributable to non-controlling interest | -0.2 | -0.4 | 0.0 | | | | | |
| Net loss attributable to Great Elm Capital Group | -2.9 | -11.1 | -15.2 | 9.4 | -41.8 | 0.4 | -47.6 | 14.6 |
| |
| Basic loss per share | | | | | | | | |
| Continuing operations | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| |
| Discontinued operations | | | | | | | | |
| Net loss | ($0.11) | ($0.46) | ($0.93) | $1.00 | ($4.48) | $0.05 | ($0.53) | $0.17 |
| |
| Diluted loss per share from: | | | | | | | | |
| Continuing operations | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| |
| Discontinued operations | | | | | | | | |
| Net loss | ($0.11) | ($0.46) | ($0.93) | $1.00 | ($4.48) | $0.05 | ($0.53) | $0.17 |
| |
| Weighted average shares outstanding | | | | | | | | |
| Basic | 0.0 | 0.0 | 0.0 | | | | 0.0 | 0.0 |
| |
| Diluted | 25.2 | 24.3 | 16.4 | 9.4 | 9.3 | 9.0 | 90.8 | 86.4 |