CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
OPERATING ACTIVITIES:
Net Income	$ 52,243	$ 43,481
Items not affecting cash:
Depreciation	56,632	52,859
Amortization of debt issue costs, discount and deferred hedge gain	193	180
Amortization of restricted stock	1,249	1,638
Equity portion of allowance for funds used during construction	(2,194)	(1,831)
Gain on disposition of assets	(705)	(122)
Deferred income taxes	32,393	27,067
Changes in current assets and liabilities:
Restricted cash	(1,368)	4,859
Accounts receivable	27,169	44,220
Inventories	6,551	16,520
Other current assets	(7,007)	(1,085)
Accounts payable	(23,617)	(17,217)
Accrued expenses	(8,632)	(14,729)
Regulatory assets	11,584	(1,026)
Regulatory liabilities	(73)	(4,696)
Other noncurrent assets	(25,336)	(13,298)
Other noncurrent liabilities	10,729	8,247
Cash provided by operating activities	129,811	145,067
INVESTING ACTIVITIES:
Property, plant, and equipment additions	(88,549)	(97,812)
Proceeds from sale of assets	747	149
Cash used in investing activities	(87,802)	(97,663)
FINANCING ACTIVITIES:
Treasury stock activity	(1,179)	(624)
Proceeds from issuance of common stock, net	43,781	23,876
Dividends on common stock	(28,627)	(26,927)
Repayments on long-term debt	(73)	(3,833)
Repayments of short-term borrowings, net	(57,940)	(36,965)
Financing costs	0	(754)
Cash used in financing activities	(44,038)	(45,227)
(Decrease) Increase in Cash and Cash Equivalents	(2,029)	2,177
Cash and Cash Equivalents, beginning of period	9,822	5,928
Cash and Cash Equivalents, end of period	7,793	8,105
Cash paid during the period for:
Income taxes	42	1,944
Interest	29,175	25,825
Significant non-cash transactions:
Capital expenditures included in accounts payable and accrued expenses	$ 9,081	$ 15,756