STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Gross Margin
Revenues from contracts with customers	$ 635,237	$ 536,160
Other revenue	3,227	14,248
Regulated Operating Revenue	638,464	550,408
Cost of natural gas	350,419	263,154
Net margin	288,045	287,254
Operating expenses
Operations and maintenance	102,665	105,044
Depreciation and amortization	38,890	37,019
General taxes	16,200	15,746
Total operating expenses	157,755	157,809
Operating income	130,290	129,445
Other expense, net	(2,164)	(3,407)
Interest expense, net	(12,352)	(11,481)
Income before income taxes	115,774	114,557
Income taxes	(24,939)	(38,101)
Net income	$ 90,835	$ 76,456
Earnings per share
Basic	$ 1.73	$ 1.45
Diluted	$ 1.72	$ 1.44
Average shares (thousands)
Basic	52,604	52,576
Diluted	52,897	53,056
Dividends declared per share of stock	$ 0.46	$ 0.42