Carrying amount of reserve for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs, which is expected to be paid within one year of the date of the statement of financial position.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 55
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6396582&loc=d3e15243-108350

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Name:	us-gaap_LitigationReserveCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Risks and contingencies (Details) ¥ in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2019 CNY (¥)	Mar. 31, 2018 CNY (¥)	Mar. 31, 2017 CNY (¥)	Mar. 31, 2019 USD ($)	Mar. 31, 2019 CNY (¥)
Complaint about registration statement and prospectus
Risks and contingencies
Settlement provision				$ 250	¥ 1,679
Collectability of payments made relating to trade assurance program
Risks and contingencies
Provisions made in relation to the program	¥ 0	¥ 0	¥ 0