Debt and Interest Expense - Outstanding Debt Table (Detail) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total borrowings at face value		$ 20,411	$ 17,312
Net unamortized discounts, premiums, and debt issuance costs (3)	[1]	(1,680)	(1,664)
Total borrowings		18,731	15,648
Capital lease obligation		20	20
Less short-term debt		3,025	32
Total long-term debt		15,726	15,636
Western Gas Partners, LP [Member]
Debt Instrument [Line Items]
Total borrowings at face value		3,050	2,720
Net unamortized discounts, premiums, and debt issuance costs (3)	[1]	(29)	(29)
Total borrowings		3,021	2,691
Capital lease obligation		0	0
Less short-term debt		0	0
Total long-term debt		3,021	2,691
Western Gas Equity Partners, LP excluding WES [Member]
Debt Instrument [Line Items]
Total borrowings at face value	[2]	28	0
Net unamortized discounts, premiums, and debt issuance costs (3)	[1],[2]	0	0
Total borrowings	[2]	28	0
Capital lease obligation	[2]	0	0
Less short-term debt	[2]	0	0
Total long-term debt	[2]	28	0
Anadarko Excluding WES and WGP [Member]
Debt Instrument [Line Items]
Total borrowings at face value	[3]	17,333	14,592
Net unamortized discounts, premiums, and debt issuance costs (3)	[1],[3]	(1,651)	(1,635)
Total borrowings	[3]	15,682	12,957
Capital lease obligation	[3]	20	20
Less short-term debt	[3]	3,025	32
Total long-term debt	[3]	$ 12,677	$ 12,945

[1] Unamortized discounts, premiums, and debt issuance costs are amortized over the term of the related debt. Debt issuance costs related to revolving credit facilities are included in other current assets and other assets on the Company’s Consolidated Balance Sheets.

[2] Excludes WES.

[3] Excludes WES and WGP.