COMMITMENTS AND CONTINGENCIES, Business Combination Agreement (Details) $ in Millions		3 Months Ended
Sep. 14, 2020	Mar. 31, 2021 USD ($)
Business Combination Agreement [Abstract]
Stock conversion basis at time of business combination	1	1
Cash payment to option holders in lieu of assumption of a portion of vested options		$ 10

The amount of cash payment to option holders in lieu of assumption of a portion of their vested options.

No definition available.

Name:	sbg_CashPaymentToOptionHoldersInLieuOfAssumptionOfPortionOfVestedOptions
Namespace Prefix:	sbg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant