XML 94 R71.htm IDEA: XBRL DOCUMENT v3.21.1
Summary of significant accounting policies - Intangible assets (Details)
12 Months Ended
Dec. 31, 2020
Land use right [Member]  
Finite-Lived Intangible Assets [Line Items]  
Estimated useful lives 30 years
Acquired computer software [Member]  
Finite-Lived Intangible Assets [Line Items]  
Estimated useful lives 5 years
Audio visual licenses [Member]  
Finite-Lived Intangible Assets [Line Items]  
Estimated useful lives 9 years
Minimum | Online game licenses [Member]  
Finite-Lived Intangible Assets [Line Items]  
Estimated useful lives 1 year
Maximum | Online game licenses [Member]  
Finite-Lived Intangible Assets [Line Items]  
Estimated useful lives 3 years