Debt and Interest Expense - Additional Information (Details) - USD ($)				3 Months Ended
		Jan. 31, 2020	Jan. 13, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Jul. 01, 2019	Feb. 28, 2019	Dec. 31, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					$ 7,345,000		$ 0
Accrued liability on interest-rate swaps	[1]				166,738,000	$ 149,793,000
Gain (loss) on interest-rate swaps					0		(35,638,000)
Affiliates [Member]
Debt Instrument [Line Items]
Accrued liability on interest-rate swaps					2,500,000	3,100,000
WES [Member] | Revolving Credit Facility [Member] | WGP RCF [Member]
Debt Instrument [Line Items]
Facility, repayment of borrowings							28,000,000.0
WES Operating [Member]
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					7,345,000		0
Accrued liability on interest-rate swaps	[2]				160,175,000	149,639,000
Gain (loss) on interest-rate swaps					0		(35,638,000)
WES Operating [Member] | Interest-Rate Swap [Member]
Debt Instrument [Line Items]
Cash paid to settle interest-rate swaps						107,700,000
Gain (loss) on interest-rate swaps							35,600,000
WES Operating [Member] | Not Designated as Hedging Instrument [Member] | Interest-Rate Swap [Member]
Debt Instrument [Line Items]
Interest-rate swap, notional amount						1,125,000,000.0	$ 375,000,000.0			$ 750,000,000.0
Accrued liability on interest-rate swaps						25,600,000
WES Operating [Member] | Affiliates [Member]
Debt Instrument [Line Items]
Future lease payments					2,600,000
Accrued liability on interest-rate swaps					2,500,000	$ 3,100,000
WES Operating [Member] | Third Parties [Member]
Debt Instrument [Line Items]
Future lease payments					43,500,000
WES Operating [Member] | Revolving Credit Facility [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Facility, repayment of borrowings		$ 3,000,000,000.0			3,000,000,000
Gain (loss) on early extinguishment of debt					2,300,000
Facility, maximum borrowing capacity								$ 3,000,000,000.0
Facility, interest rate at period end							3.87%
WES Operating [Member] | Revolving Credit Facility [Member] | RCF [Member]
Debt Instrument [Line Items]
Facility, repayment of borrowings					380,000,000
Facility, expandable maximum borrowing capacity									$ 2,500,000,000
Facility, maximum borrowing capacity									$ 2,000,000,000.0
Facility, outstanding borrowings					125,000,000.0
Facility, outstanding letters of credit					6,500,000
Facility, available borrowing capacity					$ 1,900,000,000
Facility, interest rate at period end					2.13%		3.79%
Facility, fee rate					0.20%		0.20%
WES Operating [Member] | Revolving Credit Facility [Member] | RCF [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Facility, fee rate				0.25%
Facility, interest rate increase				0.20%
Facility, fee rate increase				0.05%
WES Operating [Member] | Revolving Credit Facility [Member] | RCF [Member] | Non-Extending Lender [Member]
Debt Instrument [Line Items]
Facility, borrowing capacity for non-extending lender					$ 100,000,000.0
WES Operating [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					$ 9,600,000
WES Operating [Member] | Senior Notes [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Borrowing costs increase				$ 17,500,000
WES Operating [Member] | Senior Notes [Member] | 3.100% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Senior note, interest rate			3.10%		3.10%
Senior note, offering percent			99.962%
Senior note, effective interest rate					3.287%
WES Operating [Member] | Senior Notes [Member] | 4.050% Senior Notes due 2030 [Member]
Debt Instrument [Line Items]
Senior note, interest rate			4.05%		4.05%
Senior note, offering percent			99.90%
Senior note, effective interest rate					4.168%
WES Operating [Member] | Senior Notes [Member] | 5.250% Senior Notes due 2050 [Member]
Debt Instrument [Line Items]
Senior note, interest rate			5.25%		5.25%
Senior note, offering percent			99.442%
Senior note, effective interest rate					5.362%
WES Operating [Member] | Senior Notes [Member] | Floating-Rate Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Senior note, effective interest rate					2.69%
WES Operating [Member] | Senior Notes [Member] | Floating-Rate Senior Notes due 2023 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Alternate Base Rate [Member]
Debt Instrument [Line Items]
Facility, applicable margin added			0.85%
WES Operating [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Senior note, interest rate					5.375%
Repayments of senior notes					$ 61,369,000
WES Operating [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior note, interest rate					4.00%
Repayments of senior notes					$ 38,631,000
Maximum [Member] | WES Operating [Member] | APCWH Note Payable [Member]
Debt Instrument [Line Items]
APCWH Note Payable, maximum borrowing											$ 500,000,000.0

[1] Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020, and December 31, 2019, respectively.

[2] Accrued liabilities includes related-party amounts of $2.5 million and $3.1 million as of March 31, 2020, and December 31, 2019, respectively.