Derivative Financial Instruments and Hedge Accounting - Schedule of Items Designated as Hedged Items (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disclosure of detailed information about financial instruments [line items]
Change in value used for calculating hedge ineffectiveness	¥ 283,388	¥ 12,187
Translating foreign operations reserve	1,169,467	886,080
USD foreign operations [member]
Disclosure of detailed information about financial instruments [line items]
Change in value used for calculating hedge ineffectiveness	92,106	(18,370)
Translating foreign operations reserve	469,405	377,299
EUR foreign operations [member]
Disclosure of detailed information about financial instruments [line items]
Change in value used for calculating hedge ineffectiveness	174,911	(9,731)
Translating foreign operations reserve	475,673	300,761
THB Foreign Operations [Member]
Disclosure of detailed information about financial instruments [line items]
Change in value used for calculating hedge ineffectiveness	45,372	25,100
Translating foreign operations reserve	149,753	104,381
Other foreign operations [member]
Disclosure of detailed information about financial instruments [line items]
Change in value used for calculating hedge ineffectiveness	(29,001)	15,188
Translating foreign operations reserve	¥ 74,636	¥ 103,639

The gain (loss) on the change in fair value of the hedged item used as a basis for recognising hedge ineffectiveness. Hedge ineffectiveness is the extent to which the changes in the fair value or the cash flows of the hedging instrument are greater or less than those on the hedged item.