Revenue Recognition - Additional Information (Detail)	9 Months Ended
Oct. 02, 2018
Revenue From Contract With Customer [Abstract]
Gift cards breakage, redemption period	24 months

Revenue recognition gift cards breakage redemption period.

No definition available.

Name:	bjri_RevenueRecognitionGiftCardsBreakageRedemptionPeriod
Namespace Prefix:	bjri_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration