| Mar 31,
2013 | Mar 31,
2014 | Mar 31,
2015 | Mar 31,
2016 | Mar 31,
2017 | Mar 31,
2018 |
|---|
| Cash and deposits | - | 5 | 6 | 0 | 0 | 0 |
|---|
| Other | - | 21 | 20 | 11 | 80 | 5 |
|---|
| Allowance for doubtful accounts | - | -0 | -0 | -0 | -0 | -0 |
|---|
| Current assets | - | 2,756 | 4,314 | 4,591 | 164 | 26 |
|---|
| Other, net | - | 1 | 1 | - | - | 6 |
|---|
| Property, plant and equipment | - | 9 | 9 | - | - | - |
|---|
| Other | - | 2 | 1 | - | - | 13 |
|---|
| Intangible assets | - | 1 | 1 | - | - | 13 |
|---|
| Investment securities | - | 22 | 5 | 29 | 44 | - |
|---|
| Exploration And Development Investment Account | - | - | - | - | - | 5,542 |
|---|
| Other | - | 21 | 20 | 1 | 1 | 0 |
|---|
| Investments and other assets | - | 2,301 | 2,050 | 945 | 45 | 246 |
|---|
| Non-current assets | - | 2,311 | 2,059 | 945 | 45 | 246 |
|---|
| Assets | - | 5,067 | 6,373 | 5,536 | 209 | 271 |
|---|
| Short-term loans payable | - | 43 | 98 | 343 | 431 | 239 |
|---|
| Accounts payable - other | - | 90 | 70 | 149 | 108 | 156 |
|---|
| Income taxes payable | - | 19 | 10 | 29 | 27 | 49 |
|---|
| Current portion of long-term loans payable | - | 1 | 1,987 | 2,912 | - | 680 |
|---|
| Current portion of convertible bonds | - | - | - | - | - | 250 |
|---|
| Asset retirement obligations | - | - | - | - | - | 23 |
|---|
| Options | - | - | - | - | - | 308 |
|---|
| Other | - | 1,580 | 207 | - | 70 | 16 |
|---|
| Current liabilities | - | 2,193 | 3,330 | 3,585 | 651 | 476 |
|---|
| Net defined benefit liability | - | - | - | - | - | 5 |
|---|
| Asset retirement obligations | - | 2,752 | 3,451 | - | - | 109 |
|---|
| Non-current liabilities | - | 2,385 | 2,762 | 2,487 | - | 5 |
|---|
| Liabilities | - | 4,578 | 6,093 | 6,072 | 651 | 481 |
|---|
| Capital stock | - | 2,332 | 2,332 | 2,337 | 2,518 | 2,748 |
|---|
| Capital surplus | - | 1,249 | 1,249 | 1,254 | 1,434 | 1,664 |
|---|
| Retained earnings | - | -3,069 | -3,267 | -4,091 | -4,357 | -4,586 |
|---|
| Treasury shares | - | -36 | -36 | -36 | -36 | -36 |
|---|
| Shareholders' equity | - | 476 | 278 | -536 | -441 | -210 |
|---|
| Foreign currency translation adjustment | - | 415 | 914 | 951 | - | 339 |
|---|
| Valuation and translation adjustments | - | 13 | 2 | 951 | -1 | 339 |
|---|
| Non-controlling interests | - | - | - | - | - | 1,708 |
|---|
| Net assets | 452 | 489 | 280 | -536 | -442 | -210 |
|---|
| Liabilities and net assets | - | 5,067 | 6,373 | 5,536 | 209 | 271 |
|---|