CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities
Net income	$ 45,344	$ 41,588
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	48,481	45,067
Changes in value of life insurance contracts	(501)	(1,147)
Changes in operating assets and liabilities:
Receivables	(13,781)	(24,636)
Accounts payable	7,239	7,719
Other current assets	(6,859)	(751)
Other current liabilities	6,904	20,558
Other changes in noncurrent assets and liabilities	13,340	13,501
Net cash provided by operating activities	100,167	101,899
Investing activities:
Utility plant expenditures	(86,258)	(94,782)
Purchase of life insurance contracts	(3,207)	(3,204)
Changes in restricted cash and other changes	354	1,148
Net cash used in investing activities	(89,111)	(96,838)
Financing activities:
Short-term borrowings	99,900	35,315
Repayment of short-term borrowings	(85,000)	(113,275)
Proceeds from long-term debt		48
Repayment of long-term debt	(4,604)	(3,058)
Advances and contributions in aid of construction	8,780	7,577
Refunds of advances for construction	(4,858)	(5,230)
Issuance of common stock		110,688
Common stock issuance costs		(5,088)
Dividends paid	(23,295)	(21,981)
Net cash (used in) provided by financing activities	(9,077)	4,996
Change in cash and cash equivalents	1,979	10,057
Cash and cash equivalents at beginning of period	27,506	38,790
Cash and cash equivalents at end of period	29,485	48,847
Supplemental information
Cash paid for interest (net of amounts capitalized)	14,102	15,141
Income tax refunds	(6,000)
Supplemental disclosure of non-cash activities:
Accrued payables for investments in utility plant	16,308	11,739
Utility plant contribution by developers	$ 8,148	$ 10,196