Debt and Interest Expense - Additional Information (Detail) (USD $)					3 Months Ended			3 Months Ended			3 Months Ended		3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 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]	Mar. 31, 2014 Senior Notes 1 [Member] Senior Notes [Member]	Mar. 31, 2014 Senior Notes Zero Coupon [Member] Senior Notes [Member]	Mar. 31, 2014 Senior Notes Zero Coupon [Member] Senior Notes [Member] Accreted Value At Next Potential Put Date [Member]	Mar. 31, 2014 Senior Notes 2 [Member] Senior Notes [Member] Western Gas Partners, LP [Member]	Mar. 31, 2014 Senior Notes 3 [Member] Senior Notes [Member] Western Gas Partners, LP [Member]	Mar. 31, 2014 Revolving Credit Facility [Member] Revolving Credit Facility 1 [Member]	Mar. 31, 2014 Revolving Credit Facility [Member] Revolving Credit Facility 2 [Member] Western Gas Partners, LP [Member]	Feb. 25, 2014 Revolving Credit Facility [Member] Revolving Credit Facility 2 [Member] Western Gas Partners, LP [Member]	Mar. 31, 2014 Revolving Credit Facility [Member] Revolving Credit Facility 2 [Member] Western Gas Partners, LP [Member] Minimum [Member] London Interbank Offered Rate (LIBOR) [Member]	Mar. 31, 2014 Revolving Credit Facility [Member] Revolving Credit Facility 2 [Member] Western Gas Partners, LP [Member] Maximum [Member] London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Line of credit, maximum capacity										$ 5,000,000,000	$ 1,200,000,000	$ 800,000,000
Debt instrument, principal amount	15,202,000,000	15,202,000,000			275,000,000			100,000,000	400,000,000
Debt instrument, stated interest rate					5.75%			2.60%	5.45%
Debt instrument, maturity date					Jun. 15, 2014	Oct. 10, 2036		Aug. 15, 2018	Apr. 01, 2044
Debt Instrument, earliest call date						Oct. 10, 2014
Debt instrument, accreted value	13,561,000,000	13,557,000,000					756,000,000
Estimated fair value of total borrowings			15,700,000,000	15,300,000,000
Line of credit, expandable maximum capacity											$ 1,500,000,000
Line of credit, expiration date											Feb. 26, 2019
Margin added to LIBOR													0.975%	1.45%