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Defined Contribution 401(k) Plan - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]    
Defined contribution plan, employer discretionary contributions amount $ 0 $ 0
Defined Contribution Plan, Plan Name [Extensible List] bdsx:FourZeroOneKPlanMember bdsx:FourZeroOneKPlanMember