Revenue from services provided to customers - Additional information (Detail) - JPY (¥) ¥ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue from performance obligations satisfied in previous periods	¥ 810	¥ 1,817	¥ 4,511	¥ 5,930
Remaining performance obligations, Transaction price	¥ 1,431		¥ 1,431		¥ 1,350
Estimated contract period			1 year		1 year

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details