Business Combination, Contingent Consideration Arrangements, Payment to Option Holder, Percentage of EBITDA

No definition available.

Name:	byd_BusinessCombinationContingentConsiderationArrangementsPaymentToOptionHolderPercentageOfEbitda
Namespace Prefix:	byd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Business Combination, Contingent Consideration, Liability for Payments to Option Holder, Current

+ References

No definition available.

+ Details

Name:	byd_BusinessCombinationContingentConsiderationLiabilityForPaymentsToOptionHolderCurrent
Namespace Prefix:	byd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Contingent Consideration, Liability for Payments to Option Holder, Noncurrent

+ References

No definition available.

+ Details

Name:	byd_BusinessCombinationContingentConsiderationLiabilityForPaymentsToOptionHolderNoncurrent
Namespace Prefix:	byd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Security, Interest Rate, Stated Percentage

+ References

No definition available.

+ Details

Name:	byd_DebtSecurityInterestRateStatedPercentage
Namespace Prefix:	byd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair Value, Discount Amount, Available for sales securities

+ References

No definition available.

+ Details

Name:	byd_FairValueDiscountAmountAvailableforsalessecurities
Namespace Prefix:	byd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques, Unobservable Inputs, Rate, Percentage

+ References

No definition available.

+ Details

Name:	byd_FairValueMeasurementsRecurringAndNonrecurringValuationTechniquesUnobservableInputsRatePercentage
Namespace Prefix:	byd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period between issuance and maturity of long-term debt, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_LongTermDebtTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=byd_DiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=byd_KansasStarMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=byd_ContingentConsiderationLiabilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=byd_OtherLongTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Fair Value Measurements (Narrative-Balances Measured at Fair Value) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Dec. 20, 2011	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment available for sale		$ 15,900	$ 15,300
Available-for-sale Securities, Current		500	500
Fair Value, Discount Amount, Available for sales securities		2,800	2,800
Business Combination, Contingent Consideration, Liability for Payments to Option Holder, Current		900	800
Business Combination, Contingent Consideration, Liability for Payments to Option Holder, Noncurrent		1,400	1,600
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment available for sale		20,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment available for sale		$ 16,452	15,772
Debt Security, Interest Rate, Stated Percentage		7.50%
Fair Value, Measurements, Recurring [Member] \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment available for sale		$ 16,452	$ 15,772
Available-for-sale Securities [Member] \| Discount Rate [Member] \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques, Unobservable Inputs, Rate, Percentage		10.965%	11.22%
Kansas Star [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration Arrangements, Payment to Option Holder, Percentage of EBITDA	1.00%
Contingent Payments \| Discount Rate [Member] \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques, Unobservable Inputs, Rate, Percentage		6.90%	6.80%
Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Term		96 months