CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
OPERATING REVENUES:
Total operating revenues	$ 137	$ 110	$ 420	$ 342
OPERATING EXPENSES:
Cost of natural gas and other energy	0	0	2	2
Operating and maintenance	57	52	158	149
General and administrative	10	10	28	27
Depreciation and amortization	31	32	91	95
Total operating expenses	98	94	279	273
OPERATING INCOME	39	16	141	69
OTHER INCOME (EXPENSE):
Interest expense, net	(5)	(11)	(23)	(34)
Interest Expense, Related Party	(5)	0	(8)	0
Interest income - affiliates	0	1	0	9
Other, net	2	0	4	1
INCOME BEFORE INCOME TAX EXPENSE	31	6	114	45
Income tax expense	8	2	35	19
NET INCOME	23	4	79	26
OTHER COMPREHENSIVE INCOME, NET OF TAX
Actuarial gain relating to postretirement benefit plans	1	5	0	5
COMPREHENSIVE INCOME	24	9	79	31
Natural Gas, US Regulated [Member]
OPERATING REVENUES:
Transportation and storage of natural gas	128	104	401	327
Product and Service, Other [Member]
OPERATING REVENUES:
Transportation and storage of natural gas	$ 9	$ 6	$ 19	$ 15