Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 551,636	$ 440,856
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	264,176	239,368
Allowance for equity funds used during construction (equity AFUDC)	(78,337)	(53,867)
Regulatory credit resulting from Tax Reform (Note 1)	(20,867)	0
Equity in earnings of unconsolidated affiliates	(497)	(3,322)
Distribution from unconsolidated affiliates	1,751	6,261
Changes in operating assets and liabilities:
Receivables - affiliates	388	163
Receivables - trade and other	19,236	(2,156)
Transportation and exchange gas receivable	1,536	883
Inventories	(16,132)	7,524
Payables - affiliates	(1,235)	(5,972)
Payables - trade	(57,502)	(28,536)
Accrued liabilities	(8,867)	(41,137)
Asset retirement obligations - non-current	28,216	45,629
Asset retirement obligations - removal costs	(6,671)	(1,708)
Deferred revenue	(7,922)	(2,864)
Other, net	(1,387)	(4,179)
Net cash provided by operating activities	667,522	596,943
Cash flows from financing activities:
Proceeds from long-term debt	993,440	0
Proceeds from other financing obligations	29,188	0
Retirement of long-term debt	(250,000)	0
Payments on other financing obligation	(1,151)	(241)
Payments for debt issuance costs	(10,043)	(13)
Cash distributions to parent	(290,000)	(330,000)
Cash contributions from parent	340,000	110,000
Net cash provided by (used in) financing activities	811,434	(220,254)
Cash flows from investing activities:
Property, plant and equipment additions, net of equity AFUDC	(1,982,386)	(1,089,917)
Contributions and advances for construction costs	393,130	252,249
Disposal of property, plant and equipment, net	(21,284)	(33,281)
Advances to affiliate, net	150,431	512,634
Purchase of ARO Trust investments	(44,492)	(46,709)
Proceeds from sale of ARO Trust investments	25,964	27,520
Proceeds from insurance	0	3,200
Other, net	(319)	(2,385)
Net cash used in investing activities	(1,478,956)	(376,689)
Increase (decrease) in cash	0	0
Cash at beginning of period	0	0
Cash at end of period	0	0
Increase to property, plant and equipment, net of equity AFUDC	(1,803,610)	(1,154,317)
Changes in related accounts payable and accrued liabilities	(178,776)	64,400
Property, plant and equipment additions, net of equity AFUDC	$ (1,982,386)	$ (1,089,917)