Cash Dividends (Details) (USD $)	9 Months Ended
Jan. 31, 2013
Cash Dividends [Abstract]
Common Stock, Special Dividends, Per Share, Declared	$ 4.00

Common Stock, Special Dividends, Per Share, Declared

No definition available.

Name:	bfb_CommonStockSpecialDividendsPerShareDeclared
Namespace Prefix:	bfb_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration