Debt, Banking Arrangements, and Leases (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]

Long-Term Debt

	December 31,
	2017			2016
	(Millions)
Transco:
6.05% Notes due 2018	$	250		$	250
7.08% Debentures due 2026	8			8
7.25% Debentures due 2026	200			200
7.85% Notes due 2026	1,000			1,000
5.4% Notes due 2041	375			375
4.45% Notes due 2042	400			400
Other financing obligation	231			—
Northwest Pipeline:
5.95% Notes due 2017	—			185
6.05% Notes due 2018	250			250
7.125% Debentures due 2025	85			85
4% Notes due 2027	250			—
WPZ:
7.25% Notes due 2017	—			600
5.25% Notes due 2020	1,500			1,500
4.125% Notes due 2020	600			600
4% Notes due 2021	500			500
3.6% Notes due 2022	1,250			1,250
3.35% Notes due 2022	750			750
6.125% Notes due 2022	—			750
4.5% Notes due 2023	600			600
4.875% Notes due 2023	—			1,400
4.3% Notes due 2024	1,000			1,000
4.875% Notes due 2024	750			750
3.9% Notes due 2025	750			750
4% Notes due 2025	750			750
3.75% Notes due 2027	1,450			—
6.3% Notes due 2040	1,250			1,250
5.8% Notes due 2043	400			400
5.4% Notes due 2044	500			500
4.9% Notes due 2045	500			500
5.1% Notes due 2045	1,000			1,000
Term Loan, variable interest rate, due 2018	—			850
WMB:
7.875% Notes due 2021	371			371
3.7% Notes due 2023	850			850
4.55% Notes due 2024	1,250			1,250
7.5% Debentures due 2031	339			339
7.75% Notes due 2031	252			252
8.75% Notes due 2032	445			445
5.75% Notes due 2044	650			650
Various — 7.625% to 10.25% Notes and Debentures due 2019 to 2027	55			55
Credit facility loans	270			775
Debt issuance costs	(122		)	(119		)
Net unamortized debt premium (discount)	(24		)	88
Total long-term debt, including current portion	20,935			23,409
Long-term debt due within one year	(501		)	(785		)
Long-term debt	$	20,434		$	22,624

Schedule of Maturities of Long-term Debt [Table Text Block]

The following table presents aggregate minimum maturities of long-term debt, excluding net unamortized debt premium (discount) and debt issuance costs, for each of the next five years:

	December 31, 2017
	(Millions)
2018	$	502
2019	33
2020	2,123
2021	1,143
2022	2,003

Schedule of Line of Credit Facilities [Table Text Block]

Credit Facilities

	December 31, 2017
	Available		Outstanding
	(Millions)
WMB
Long-term credit facility	$	1,500	$	270
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 our credit facility inclusive of any outstanding amounts under our commercial paper program.

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

The future minimum annual rentals under noncancelable operating leases, are payable as follows:

	December 31, 2017
	(Millions)
2018	$	43
2019	41
2020	33
2021	33
2022	29
Thereafter	137
Total	$	316