Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 71,617	$ 94,781
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	52,809	50,829
Regulatory debits	1,847	2,461
Regulatory charge resulting from tax rate change	12,152	0
Amortization of deferred charges and credits	450	683
Allowance for equity funds used during construction	(767)	(388)
Changes in current assets and liabilities:
Trade and other accounts receivable	4,330	4,533
Affiliated receivables	250	(184)
Exchange gas due from others	1,600	2,787
Materials and supplies	55	(56)
Other current assets	538	(1,022)
Trade accounts payable	(1,307)	(962)
Affiliated payables	(4,121)	(686)
Exchange gas due to others	(1,600)	(2,787)
Other accrued liabilities	(4,197)	5,691
Changes in noncurrent assets and liabilities:
Deferred charges and regulatory assets	(2,789)	298
Noncurrent liabilities	3,325	(1,055)
Net cash provided by operating activities	134,192	154,923
Cash flows from financing activities:
Proceeds from long-term debt	0	249,102
Retirement of long-term debt	(250,000)	(185,000)
Debt issuance costs	(177)	(2,082)
Advances from affiliates, net	(90,069)	0
Cash distributions to parent	(87,000)	(107,000)
Net cash used in financing activities	(247,108)	(44,980)
Property, plant and equipment:
Capital expenditures, net of equity AFUDC	(25,202)	(31,493)
Contributions and advances for construction costs	1,138	365
Disposal of property, plant and equipment, net	(686)	48
Advances to affiliates, net	137,666	(78,863)
Net cash used in investing activities	112,916	(109,943)
NET INCREASE (DECREASE) IN CASH	0	0
CASH AT BEGINNING OF PERIOD	0	0
CASH AT END OF PERIOD	0	0
Increases to property, plant and equipment	(30,806)	(33,894)
Changes in related in accounts payable and accrued liabilities	5,604	2,401
Capital expenditures, net of equity AFUDC	$ (25,202)	$ (31,493)