STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Gross Margin
Revenues from contracts with customers	$ 235,757	$ 244,402	$ 1,162,162	$ 1,054,595
Other revenue	2,523	2,740	7,103	22,644
Regulated Operating Revenue	238,280	247,142	1,169,265	1,077,239
Cost of natural gas	51,256	58,769	495,834	404,495
Net margin	187,024	188,373	673,431	672,744
Operating expenses
Operations and maintenance	96,443	91,058	302,103	293,030
Depreciation and amortization	40,344	38,423	118,991	113,293
General taxes	13,996	13,799	44,763	43,518
Total operating expenses	150,783	143,280	465,857	449,841
Operating income	36,241	45,093	207,574	222,903
Other expense, net	(1,929)	(3,715)	(6,287)	(11,022)
Interest expense, net	(12,365)	(11,495)	(36,720)	(34,281)
Income before income taxes	21,947	29,883	164,567	177,600
Income taxes	(5,671)	(11,086)	(37,037)	(61,724)
Net income	$ 16,276	$ 18,797	$ 127,530	$ 115,876
Earnings per share
Basic	$ 0.31	$ 0.36	$ 2.42	$ 2.21
Diluted	$ 0.31	$ 0.36	$ 2.41	$ 2.19
Average shares (thousands)
Basic	52,736	52,488	52,678	52,539
Diluted	53,112	52,926	52,969	52,984
Dividends declared per share of stock	$ 0.46	$ 0.42	$ 1.38	$ 1.26