STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Document Fiscal Year Focus	2020
Operating activities
Net income	$ 91,677	$ 93,660
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,513	43,846
Deferred income taxes	6,856	4,828
Share-based compensation expense	2,261	1,954
Provision for doubtful accounts	3,077	2,263
Changes in assets and liabilities:
Accounts receivable	22,608	(44,924)
Materials and supplies	2,342	(2,562)
Natural gas in storage	56,227	55,820
Increase (Decrease) in Other Regulatory Assets	(9,888)	(11,169)
Accounts payable	(34,227)	(53,172)
Accrued taxes other than income	(1,182)	4,263
Customer deposits	285	1,218
Regulatory assets and liabilities	4,932	29,090
Other assets and liabilities	(9,748)	(2,824)
Cash provided by operating activities	182,733	122,291
Investing activities
Capital expenditures	(113,517)	(83,303)
Other	(314)	(3,351)
Proceeds from Sale of Other Assets, Investing Activities	650	311
Cash used in investing activities	(113,181)	(86,343)
Financing activities
Repayments of notes payable, net	(41,805)	(4,000)
Dividends paid	(28,543)	(26,343)
Tax withholdings related to net share settlements of stock compensation	(5,988)	(7,300)
Cash used in financing activities	(76,336)	(37,643)
Change in cash and cash equivalents	(6,784)	(1,695)
Cash and cash equivalents at beginning of period	17,853	21,323
Cash and cash equivalents at end of period	11,069	19,628
Common Stock [Member]
Operating activities
Net income	$ 0	$ 0