Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Revenue
Natural gas transportation	$ 430,730	$ 460,934	$ 460,109
Natural gas storage	12,852	12,399	13,918
Other	36	73	2
Total operating revenues	443,618	473,406	474,029
OPERATING EXPENSES:
General and administrative	50,653	54,512	52,343
Operation and maintenance	75,237	78,085	79,514
Depreciation and amortization	106,073	102,084	101,672
Regulatory debits	2,334	4,857	3,510
Taxes, other than income taxes	17,507	17,889	17,835
Regulatory charge resulting from tax rate change	35,680	206,547	0
Other expenses, net	444	195	0
Total operating expenses	287,928	464,169	254,874
OPERATING INCOME	155,690	9,237	219,155
OTHER (INCOME) AND OTHER EXPENSES:
Interest expense	27,987	33,015	39,164
Allowance for equity and borrowed funds used during construction	(2,183)	(1,444)	(1,371)
Miscellaneous other (income) expenses, net	(1,575)	5,500	907
Total other (income) and other expenses	24,229	37,071	38,700
NET INCOME (LOSS)	131,461	(27,834)	180,455
CASH FLOW HEDGES:
Amortization of cash flow hedges into Interest expense	0	0	(28)
COMPREHENSIVE INCOME (LOSS)	$ 131,461	$ (27,834)	$ 180,427