Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentInterestRateIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount (premium).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28567-108399

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

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

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Periodic Payment, Percentage

+ References

No definition available.

+ Details

Name:	wab_DebtInstrumentPeriodicPaymentPercentage
Namespace Prefix:	wab_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Restricted Covenants, Unrestricted Cash, Maximum

+ References

No definition available.

+ Details

Name:	wab_DebtInstrumentRestrictedCovenantsUnrestrictedCashMaximum
Namespace Prefix:	wab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line of Credit Uncommitted Accordion Feature

+ References

No definition available.

+ Details

Name:	wab_LineofCreditUncommittedAccordionFeature
Namespace Prefix:	wab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wab_TwoThousandandEighteenRefinancingAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=wab_FloatingRateNotesDue2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wab_A4.150PercentSeniorNotesDueTwentyThousandandTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wab_A4.70PercentSeniorNotesDueTwentyThousandandTwentySixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=wab_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_EurodollarMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=wab_DelayedDrawTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=wab_SwingLineSubFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LONG-TERM DEBT - Narrative (Details) - USD ($)			12 Months Ended
LONG-TERM DEBT - Narrative (Details) - USD ($)	Feb. 12, 2019	Sep. 14, 2018	Dec. 31, 2019	Dec. 31, 2018	Jun. 08, 2018
Debt Instrument [Line Items]
Total unamortized debt issuance costs			$ 21,300,000	$ 26,500,000
Maximum borrowing capacity			$ 1,200,000,000.0
Interest rate swap agreements
Debt Instrument [Line Items]
Interest rate on notional value (as a percent)			3.08%
2018 Refinancing Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Maximum unrestricted cash			$ 300,000,000.0
Senior Notes
Debt Instrument [Line Items]
Total unamortized debt issuance costs		$ 18,000,000.0
Par value		2,500,000,000.0
Discount at issuance		2,900,000
Debt issuance face value (as a percent)			101.00%
Interest rate increase	0.25%
Senior Notes \| Floating Rate Notes Due 2021
Debt Instrument [Line Items]
Par value		500,000,000.0
Discount at issuance		$ 0
Senior Notes \| Floating Rate Notes Due 2021 \| LIBOR
Debt Instrument [Line Items]
Debt instrument spread on variable rate		1.05%
Senior Notes \| 4.150 Percent Senior Notes Due Twenty Thousand and Twenty Four
Debt Instrument [Line Items]
Par value		$ 750,000,000.0
Discount at issuance		$ 1,500,000
Stated interest rate (as a percent)		4.15%	4.15%	4.15%
Senior Notes \| 4.70 Percent Senior Notes Due Twenty Thousand and Twenty Six
Debt Instrument [Line Items]
Par value		$ 1,250,000,000.0
Discount at issuance		$ 1,400,000
Stated interest rate (as a percent)		4.70%	4.70%	4.70%
Line of Credit \| 2018 Refinancing Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Debt instrument spread on variable rate			1.375%
Line of Credit \| 2018 Refinancing Credit Agreement \| Base Rate
Debt Instrument [Line Items]
Debt instrument spread on variable rate			0.375%
Line of Credit \| 2018 Refinancing Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 1,200,000,000.0
Commitment fee percentage			0.15%
Uncommitted accordion feature					600,000,000.0
Line of Credit \| 2018 Refinancing Credit Agreement \| Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Commitment fee percentage			0.10%
Line of Credit \| 2018 Refinancing Credit Agreement \| Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Commitment fee percentage			0.30%
Line of Credit \| 2018 Refinancing Credit Agreement \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity					350,000,000.0
Quarterly repayment amount (as a percent)			2.50%
Line of Credit \| 2018 Refinancing Credit Agreement \| Term Loan \| Base Rate
Debt Instrument [Line Items]
Debt instrument spread on variable rate			0.375%
Line of Credit \| 2018 Refinancing Credit Agreement \| Term Loan \| Eurodollar
Debt Instrument [Line Items]
Debt instrument spread on variable rate			1.375%
Line of Credit \| 2018 Refinancing Credit Agreement \| Delayed Draw Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity					400,000,000.0
Line of Credit \| 2018 Refinancing Credit Agreement \| Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					450,000,000.0
Line of Credit \| 2018 Refinancing Credit Agreement \| Swing Line Sub Facility
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 75,000,000.0