SUMMARY OF PRINCIPAL ACCOUNTING POLICIES - Product revenues and Service revenues (Details)	Dec. 31, 2025 item
Product revenues
Number of Medicine Marketplaces	1
Number of Pharmacy	1
Minimum percentage of surcharges and value added tax	0.00%
Maximum percentage of surcharges and value added tax	13.00%

Maximum range of surcharges and value added tax ("VAT").

No definition available.

Name:	yi_MaximumRangeOfSurchargesAndValueAddedTax
Namespace Prefix:	yi_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant