Other comprehensive income (loss) - Changes in Accumulated other comprehensive income (loss) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	3 Months Ended	6 Months Ended
Sep. 30, 2018	Sep. 30, 2018
Reclassifications out of accumulated other comprehensive income (loss) [Member] \| Cumulative translation adjustments [Member]
Affected line items in consolidated statements of income [Line Items]
Reclassification adjustment for loss	¥ 6,956	¥ 6,956

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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