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

No definition available.

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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

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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Definition

Percent of offering price to public.

+ References

No definition available.

+ Details

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Namespace Prefix:	wes_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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Data Type:	na
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- Details

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- Details

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Namespace Prefix:
Data Type:	na
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Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Subsequent Events - Additional Information (Details) - WES Operating [Member] - USD ($)			12 Months Ended
	Jan. 31, 2020	Jan. 13, 2020	Dec. 31, 2019
Revolving Credit Facility [Member] \| Term Loan Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Alternate Base Rate [Member]
Subsequent Event [Line Items]
Senior note, applicable margin added			1.00%
Subsequent Event [Member] \| Revolving Credit Facility [Member] \| Term Loan Facility [Member]
Subsequent Event [Line Items]
Facility, repayment of borrowings	$ 3,000,000,000.0
Subsequent Event [Member] \| Senior Notes [Member] \| 3.100% Senior Notes due 2025 [Member]
Subsequent Event [Line Items]
Issuance of senior notes		$ 1,000,000,000.0
Senior note, interest rate		3.10%
Senior note, offering percent		99.962%
Subsequent Event [Member] \| Senior Notes [Member] \| 4.050% Senior Notes due 2030 [Member]
Subsequent Event [Line Items]
Issuance of senior notes		$ 1,200,000,000
Senior note, interest rate		4.05%
Senior note, offering percent		99.90%
Subsequent Event [Member] \| Senior Notes [Member] \| 5.250% Senior Notes due 2050 [Member]
Subsequent Event [Line Items]
Issuance of senior notes		$ 1,000,000,000.0
Senior note, interest rate		5.25%
Senior note, offering percent		99.442%
Subsequent Event [Member] \| Senior Notes [Member] \| Floating Rate Senior Notes due 2023 [Member]
Subsequent Event [Line Items]
Issuance of senior notes		$ 300,000,000.0
Subsequent Event [Member] \| Senior Notes [Member] \| Floating Rate Senior Notes due 2023 [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Alternate Base Rate [Member]
Subsequent Event [Line Items]
Senior note, applicable margin added		0.85%