CONDENSED STATEMENTS OF OPERATIONS (Parenthetical) - Over-allotment	Sep. 30, 2020 shares
Maximum shares subject to forfeiture	699,164
Class B common stock
Maximum shares subject to forfeiture	699,164

Represents the maximum number of common stock shares subject to forfeiture.

No definition available.

Name:	bft_MaximumCommonStockSharesSubjectToForfeiture
Namespace Prefix:	bft_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant