Fair Value Measurements Concentration of Credit Risk (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Concentration Risk [Line Items]
Trade accounts and other receivables	$ 938	$ 1,041
NGLs, natural gas, and related products and services [Member]
Concentration Risk [Line Items]
Trade accounts and other receivables	736	823
Transportation of natural gas and related products [Member]
Concentration Risk [Line Items]
Trade accounts and other receivables	187	202
Other Receivable [Member]
Concentration Risk [Line Items]
Trade accounts and other receivables	15	16
Chesapeake Energy Corporation [Member] \| Customer Concentration Risk [Member] \| Accounts receivable [Member] \| Williams Partners [Member]
Concentration Risk [Line Items]
Trade accounts and other receivables	$ 133	$ 364
Chesapeake Energy Corporation [Member] \| Customer Concentration Risk [Member] \| Sales Revenue, Net [Member] \| Williams Partners [Member]
Concentration Risk [Line Items]
Consolidated revenue, major customer, percentage	14.00%	18.00%

The total amount due to the entity within one year of the balance sheet date (or one operating cycle, if longer) from outside sources, including trade accounts receivable, notes and loans receivable, as well as any other types of receivables, net of allowances established for the purpose of reducing such receivables to an amount that approximates their net realizable value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-06(3))
-URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e604059-122996

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(5))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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