Fair Value Measurement - Recurring and Non-recurring Basis (Details)
12 Months Ended
Dec. 31, 2021
USD ($)
item
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Reconciliation of the fair value measurements using significant unobservable inputs      
Equity securities, balance $ 223,385,000 $ 96,659,000  
Financial instruments measured on a recurring basis | Wealth management products      
Reconciliation of the fair value measurements using significant unobservable inputs      
Fair value changes, loss recognized 59,300,000    
Equity securities, balance 50,200,000    
Carrying value of impaired investments 109,500,000    
Non-recurring      
Reconciliation of the fair value measurements using significant unobservable inputs      
Impairment charge of goodwill recognized $ 0 0 $ 0
Significant Unobservable Inputs (Level 3)      
Reconciliation of the fair value measurements using significant unobservable inputs      
Valuation technique us-gaap:ValuationTechniqueDiscountedCashFlowMember    
Measurement input wb:MeasurementInputDiscountCurveOfMarketInterestRatesMember    
Significant Unobservable Inputs (Level 3) | Non-recurring | Minimum      
Reconciliation of the fair value measurements using significant unobservable inputs      
Discount rate (as a percent) | item 0.17    
Significant Unobservable Inputs (Level 3) | Non-recurring | Maximum      
Reconciliation of the fair value measurements using significant unobservable inputs      
Discount rate (as a percent) | item 0.23    
Significant Unobservable Inputs (Level 3) | Non-recurring | Certain investments under cost method and equity method were measured using significant unobservable inputs      
Reconciliation of the fair value measurements using significant unobservable inputs      
Impairment charge $ 106,800,000 126,800,000 $ 230,900,000
Carrying value of impaired investments $ 14,500,000 $ 89,500,000