STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gross Margin
Revenues	$ 247,142	$ 232,191	$ 1,077,239	$ 986,479
Cost of natural gas	58,769	52,253	404,495	344,439
Net margin	188,373	179,938	672,744	642,040
Operating expenses
Operations and maintenance	95,371	99,402	305,969	302,652
Depreciation and amortization	38,423	36,241	113,293	106,490
General taxes	13,799	13,403	43,518	42,311
Total operating expenses	147,593	149,046	462,780	451,453
Operating income	40,780	30,892	209,964	190,587
Other income	1,042	911	3,163	1,345
Other expense	(444)	(357)	(1,246)	(1,126)
Interest expense, net	(11,495)	(10,809)	(34,281)	(32,504)
Income before income taxes	29,883	20,637	177,600	158,302
Income taxes	(11,086)	(7,900)	(61,724)	(60,521)
Net income	$ 18,797	$ 12,737	$ 115,876	$ 97,781
Earnings per share
Basic	$ 0.36	$ 0.24	$ 2.21	$ 1.86
Diluted	$ 0.36	$ 0.24	$ 2.19	$ 1.85
Average shares (thousands)
Basic	52,488	52,453	52,539	52,452
Diluted	52,926	52,942	52,984	52,962
Dividends declared per share of stock	$ 0.42	$ 0.35	$ 1.26	$ 1.05