CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
OPERATING ACTIVITIES:
Net Income	$ 73,623	$ 82,398
Items not affecting cash:
Depreciation and depletion	79,788	71,546
Amortization of debt issue costs, discount and deferred hedge gain	1,987	562
Stock-based compensation costs	3,361	2,331
Equity portion of allowance for funds used during construction	(1,608)	(3,971)
Loss (gain) on disposition of assets	1,054	(87)
Deferred income taxes	5,535	19,919
Changes in current assets and liabilities:
Restricted cash	46	(12)
Accounts receivable	38,577	40,591
Inventories	3,535	4,032
Other current assets	(7,365)	(1,040)
Accounts payable	(17,595)	(30,186)
Accrued expenses	786	(30,881)
Regulatory assets	10,865	20,579
Regulatory liabilities	(55,614)	4,389
Other noncurrent assets	(3,099)	(1,014)
Other noncurrent liabilities	7,118	11,182
Cash Provided by Operating Activities	140,994	190,338
INVESTING ACTIVITIES:
Property, plant, and equipment additions	(121,246)	(131,170)
Acquisitions	0	(492)
Proceeds from sale of assets	137	80
Change in restricted cash	0	9,153
Cash Used in Investing Activities	(121,109)	(122,429)
FINANCING ACTIVITIES:
Treasury stock activity	(1,614)	(1,008)
Dividends on common stock	(47,865)	(44,760)
Issuance of long-term debt	60,000	200,000
Repayments on long-term debt	(55,000)	(150,016)
Issuances (repayments) of short-term borrowings, net	26,932	(47,931)
Financing costs	(5,349)	(11,688)
Cash Used in Financing Activities	(22,896)	(55,403)
(Decrease) Increase in Cash and Cash Equivalents	(3,011)	12,506
Cash and Cash Equivalents, beginning of period	11,980	20,362
Cash and Cash Equivalents, end of period	8,969	32,868
Cash (received) paid during the period for:
Income taxes	(2,922)	27
Interest	42,861	44,611
Significant non-cash transactions:
Capital expenditures included in trade accounts payable	$ 11,054	$ 9,199