Debt and Interest Expense - Additional Information (Detail) (USD $)					9 Months Ended		9 Months Ended					9 Months Ended								9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Market Approach Valuation Technique [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Market Approach Valuation Technique [Member]	Sep. 30, 2014 Zero-Coupon Senior Notes [Member] Senior Notes [Member]	Sep. 30, 2014 Zero-Coupon Senior Notes [Member] Senior Notes [Member] Accreted Value At Next Potential Put Date [Member]	Sep. 30, 2014 Senior Notes 3 [Member] Senior Notes [Member]	Sep. 30, 2014 Senior Notes 4 [Member] Senior Notes [Member]	Sep. 30, 2014 Senior Notes 1 [Member] Senior Notes [Member] Western Gas Partners, LP [Member]	Sep. 30, 2014 Senior Notes 2 [Member] Senior Notes [Member] Western Gas Partners, LP [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] $5.0 billion Facility [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] Five-Year Credit Facility [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] Five-Year Credit Facility [Member] Minimum [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] Five-Year Credit Facility [Member] Maximum [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] 364-Day Credit Facility [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] 364-Day Credit Facility [Member] Minimum [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] 364-Day Credit Facility [Member] Maximum [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] WES RCF [Member] Western Gas Partners, LP [Member]	Feb. 25, 2014 Revolving Credit Facility [Member] WES RCF [Member] Western Gas Partners, LP [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] WES RCF [Member] Minimum [Member] Western Gas Partners, LP [Member] London Interbank Offered Rate (LIBOR) [Member]	Sep. 30, 2014 Revolving Credit Facility [Member] WES RCF [Member] Maximum [Member] Western Gas Partners, LP [Member] London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Line of credit, maximum capacity											$ 5,000,000,000	$ 3,000,000,000			$ 2,000,000,000			$ 1,200,000,000	$ 800,000,000
Debt instrument, maturity date					Oct. 10, 2036		Jul. 15, 2024	Jul. 15, 2044	Aug. 15, 2018	Apr. 01, 2044
Debt instrument, accreted value	14,720,000,000	13,557,000,000				756,000,000
Debt Instrument, earliest call date					Oct. 10, 2014
Estimated fair value of total borrowings			17,300,000,000	15,300,000,000
Debt instrument, principal amount	16,347,000,000	15,202,000,000					625,000,000	625,000,000	100,000,000	400,000,000
Debt instrument, stated interest rate							3.45%	4.50%	2.60%	5.45%
Line of credit, outstanding borrowings											0							170,000,000
Debt instrument, term												5 years			364 days
Line of credit, expandable maximum capacity												4,000,000,000						1,500,000,000
Applicable margin added													0.00%	1.65%		0.00%	1.675%			0.975%	1.45%
Ratio of indebtedness to total capital														0.65			0.65
Line of credit, expiration date																		Feb. 26, 2019
Line of credit, interest rate																		1.46%
Line of credit, available borrowing capacity																		1,000,000,000
Outstanding letters of credit																		$ 13,000,000