Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net income	$ 34,544	$ 30,620
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	63,924	61,435
Regulatory amortization of gas reserves	12,036	11,403
Deferred income taxes	17,287	17,810
Qualified defined benefit pension plan expense	3,923	3,989
Contributions to qualified defined benefit pension plans	(15,400)	(11,250)
Deferred environmental expenditures, net	(10,468)	(8,302)
Regulatory disallowance of prior environmental cost deferrals	0	3,287
Amortization of environmental remediation	10,920	8,113
Other	2,605	4,817
Changes in assets and liabilities:
Receivables, net	90,735	83,377
Inventories	(5,420)	3,226
Income taxes	146	7,170
Accounts payable	(29,726)	(17,612)
Interest accrued	3,888	3,798
Deferred gas costs	13,419	(10,470)
Other, net	443	14,988
Cash provided by operating activities	192,856	206,399
Investing activities:
Capital expenditures	(145,441)	(98,111)
Other	(1,131)	2,868
Cash used in investing activities	(146,572)	(95,243)
Financing activities:
Repurchases related to stock-based compensation	(2,034)	(1,042)
Proceeds from stock options exercised	3,711	5,874
Long-term debt issued	100,000	0
Long-term debt retired	40,000	0
Change in short-term debt	(53,300)	(75,135)
Cash dividend payments on common stock	(40,390)	(38,556)
Other	(2,012)	(278)
Cash used in financing activities	(34,025)	(109,137)
Increase in cash and cash equivalents	12,259	2,019
Cash and cash equivalents, beginning of period	3,521	4,211
Cash and cash equivalents, end of period	15,780	6,230
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	22,859	23,271
Income taxes paid (refunded)	$ 11,581	$ (6,900)