Debt, Banking Arrangements, and Leases (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

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

Long-Term Debt

	December 31,
	2018			2017
	(Millions)
Transco:
6.05% Notes due 2018	$	—		$	250
7.08% Debentures due 2026	8			8
7.25% Debentures due 2026	200			200
7.85% Notes due 2026	1,000			1,000
4% Notes due 2028	400			—
5.4% Notes due 2041	375			375
4.45% Notes due 2042	400			400
4.6% Notes due 2048	600			—
Other financing obligations	1,067			231
Northwest Pipeline:
6.05% Notes due 2018	—			250
7.125% Debentures due 2025	85			85
4% Notes due 2027	500			250
WMB:
4.125% Notes due 2020	600			600
5.25% Notes due 2020	1,500			1,500
4% Notes due 2021	500			500
7.875% Notes due 2021	371			371
3.35% Notes due 2022	750			750
3.6% Notes due 2022	1,250			1,250
3.7% Notes due 2023	850			850
4.5% Notes due 2023	600			600
4.3% Notes due 2024	1,000			1,000
4.55% Notes due 2024	1,250			1,250
4.875% Notes due 2024	—			750
3.9% Notes due 2025	750			750
4% Notes due 2025	750			750
3.75% Notes due 2027	1,450			1,450
7.5% Debentures due 2031	339			339
7.75% Notes due 2031	252			252
8.75% Notes due 2032	445			445
6.3% Notes due 2040	1,250			1,250
5.8% Notes due 2043	400			400
5.4% Notes due 2044	500			500
5.75% Notes due 2044	650			650
4.9% Notes due 2045	500			500
5.1% Notes due 2045	1,000			1,000
4.85% Notes due 2048	800			—
Various — 7.625% to 10.25% Notes and Debentures due 2019 to 2027	55			55
Credit facility loans	160			270
Debt issuance costs	(131		)	(122		)
Net unamortized debt premium (discount)	(62		)	(24		)
Total long-term debt, including current portion	22,414			20,935
Long-term debt due within one year	(47		)	(501		)
Long-term debt	$	22,367		$	20,434

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

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

	December 31, 2018
	(Millions)
2019	$	47
2020	2,138
2021	890
2022	2,021
2023	1,633

Schedule of Line of Credit Facilities [Table Text Block]

Credit Facilities

	December 31, 2018
	Stated Capacity		Outstanding
	(Millions)
Long-term credit facility (1)	$	4,500	$	160
Letters of credit under certain bilateral bank agreements			14

________________

(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, 2018
	(Millions)
2019	$	32
2020	31
2021	28
2022	24
2023	15
Thereafter	86
Total	$	216