Debt and Banking Arrangements (Tables)

6 Months Ended

Jun. 30, 2016

Debt Disclosure [Abstract]

Schedule of Line of Credit Facilities [Table Text Block]

Credit Facilities

	June 30, 2016
	Stated Capacity		Outstanding
	(Millions)
WMB
Long-term credit facility	$	1,500	$	1,115
Letters of credit under certain bilateral bank agreements			14
Letters of credit under sublimit			9
WPZ
Long-term credit facility (1)	3,500		1,425
Letters of credit under certain bilateral bank agreements			2
Short-term credit facility (2)	150		—

(1) In managing our available liquidity, we do not expect a maximum outstanding amount in excess of the capacity of WPZ’s credit facility inclusive of any outstanding amounts under its commercial paper program.

(2) This facility expires August 24, 2016.