Common stock - Additional Information (Detail) - JPY (¥) ¥ in Millions			4 Months Ended
	Apr. 22, 2026	Feb. 02, 2026	Mar. 31, 2026
Cancellation of share treasury stock	47,016,600
Common Stock [Member]
Share repurchase period description		November 17, 2025 to March 31, 2026
Share repurchase			47,016,600
Share repurchase value			¥ 299,999,885,700
The Repurchase Plan [Member] \| Common Stock [Member]
Number of shares to be repurchased		65,000,000
Total amount of shares to be repurchased		¥ 300,000

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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