Investment securities and fair value disclosure - Equity securities summary (Details) - CNY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Investment securities and fair value disclosure
Net unrealized gains (losses) recognized during the period for equity securities still held as of the end of the period	¥ (15,264)	¥ 598	¥ 11
Net gains recognized during the period from disposals of equity securities during the period	803	5,120	1
Net gains (losses) recognized during the period on equity securities	(14,461)	5,718	12
Upward adjustments	4,528	15,474
Impairments and downward adjustments	11,031	10,404
Investments in privately held companies recorded using measurement alternative	80,939	81,514
Realized gains or losses on disposal of debt investments	0	0	0
Impairment losses on debt investments	¥ 890	¥ 546	¥ 6

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in net income (trading). Excludes other-than-temporary impairment (OTTI).

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Amount of investment in equity security without readily determinable fair value.

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Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value.

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Amount of unrealized and realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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Amount of unrealized gain (loss) on investment in marketable security.

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Amount of other-than-temporary impairment (OTTI) on investment in debt security, recognized in earnings.

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