Restricted Net Assets of Subsidiaries (Details 6) (USD $) In Billions, unless otherwise specified	Dec. 31, 2014
Debt Disclosure [Abstract]
Amount of restricted net assets for consolidated and unconsolidated subsidiaries	$ 15
Restricted net assets threshold	25.00%wmb_RestrictedNetAssetsThreshold

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(e)(3)(ii))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph e

-Subparagraph 3

-Article 4

Name:	us-gaap_AmountOfRestrictedNetAssetsForConsolidatedAndUnconsolidatedSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant