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.

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Details

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

LONG-TERM DEBT - Schedule of Line of Credit Facilities (Details) - USD ($)	Dec. 31, 2020	Apr. 10, 2020	Dec. 31, 2019	Jun. 08, 2018
Debt Instrument [Line Items]
Letters of Credit Under Credit Agreement	$ 736,600,000		$ 714,000,000.0
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum Availability	144,000,000.0
Current Availability	144,000,000.0
Revolving Credit Facility \| 2018 Refinancing Credit Agreement
Debt Instrument [Line Items]
Maximum Availability	1,200,000,000.0
Current Availability	1,180,900,000
Line of Credit
Debt Instrument [Line Items]
Maximum Availability		$ 600,000,000
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum Availability		$ 144,000,000.0
Letters of Credit Under Credit Agreement	0
Line of Credit \| Revolving Credit Facility \| 2018 Refinancing Credit Agreement
Debt Instrument [Line Items]
Maximum Availability				$ 1,200,000,000.0
Letters of Credit Under Credit Agreement	$ 19,100,000