Segment Disclosures Reconciliation of Segment Assets to Consolidated (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Segment assets:
Total assets	$ 47,052	$ 46,352
Williams Partners [Member]
Segment assets:
Total assets	46,575	45,903
Other [Member]
Segment assets:
Total assets	541	589
Intersegment Elimination [Member]
Segment assets:
Total assets	$ (64)	$ (140)