Note 7 - Long-term Debt - Maximum Secured Leverage Ratio (Details)	Dec. 31, 2019
Four Fiscal Quarters Ended March 31, 2019 through December 31, 2019 [Member]
Maximum secured leverage ratio	3.75
Four Fiscal Quarters Ended March 31, 2020 and Thereafter [Member]
Maximum secured leverage ratio	3.50

The maximum secured leverage ratio allowed under line of credit facility covenant terms.

No definition available.

Name:	byd_LineOfCreditFacilityCovenantTermsMaximumSecuredLeverageRatioAllowed
Namespace Prefix:	byd_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant