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Fair Value Measurements (Fair Value, Recurring and Nonrecurring, Valuation Techniques) (Details) (USD $)
 3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Discount Rate | Contingent Payments | Level 3    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques, Unobservable Inputs, Rate, Percentage 18.50%byd_FairValueMeasurementsRecurringAndNonrecurringValuationTechniquesUnobservableInputsRatePercentage
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/ us-gaap_FairValueByLiabilityClassAxis
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Discount Rate | Available-for-sale Securities | Level 3    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques, Unobservable Inputs, Rate, Percentage 9.90%byd_FairValueMeasurementsRecurringAndNonrecurringValuationTechniquesUnobservableInputsRatePercentage
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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Fair Value, Measurements, Recurring [Member] | Carrying Value    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Investment available for sale 21,700,000us-gaap_AvailableForSaleSecurities
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/ us-gaap_FairValueByMeasurementFrequencyAxis
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Debt Security, Interest Rate, Stated Percentage 7.50%byd_DebtSecurityInterestRateStatedPercentage
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Fair Value, Measurements, Recurring [Member] | Level 3    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Investment available for sale 18,658,000us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 18,357,000us-gaap_AvailableForSaleSecurities
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Peninsula Gaming    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Business Combination, Contingent Consideration, Liability for Payments to Option Holder, Noncurrent 2,900,000byd_BusinessCombinationContingentConsiderationLiabilityForPaymentsToOptionHolderNoncurrent
/ us-gaap_BusinessAcquisitionAxis
= byd_PeninsulaGamingMember		 2,900,000byd_BusinessCombinationContingentConsiderationLiabilityForPaymentsToOptionHolderNoncurrent
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= byd_PeninsulaGamingMember
Investment available for sale 18,300,000us-gaap_AvailableForSaleSecurities
/ us-gaap_BusinessAcquisitionAxis
= byd_PeninsulaGamingMember		 18,000,000us-gaap_AvailableForSaleSecurities
/ us-gaap_BusinessAcquisitionAxis
= byd_PeninsulaGamingMember
Available-for-sale Securities, Current   400,000us-gaap_AvailableForSaleSecuritiesCurrent
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Fair Value, Discount Amount, Available for sales securities   $ 3,300,000byd_FairValueDiscountAmountAvailableforsalessecurities
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= byd_PeninsulaGamingMember