Debt and Banking Arrangements (Tables)

3 Months Ended

Mar. 31, 2017

Debt Disclosure [Abstract]

Schedule of Line of Credit Facilities [Table Text Block]

Credit Facilities

	March 31, 2017
	Stated Capacity		Outstanding
	(Millions)
WMB
Long-term credit facility	$	1,500	$	595
Letters of credit under certain bilateral bank agreements			13
WPZ
Long-term credit facility (1)	3,500		—
Letters of credit under certain bilateral bank agreements			1

(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.