CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities:
Net Income	$ 29.0	$ 27.1	$ 26.3
Adjustments to Reconcile Net Income to Cash Provided by Operating Activities:
Depreciation and Amortization	46.9	46.6	45.7
Deferred Tax Provision	17.5	15.4	11.9
Changes in Working Capital Items:
Accounts Receivable	(14.5)	(5.4)	10.9
Accrued Revenue	(3.8)	(11.1)	10.1
Regulatory Liabilities	(1.2)	(5.2)	6.9
Exchange Gas Receivable	2.5	2.8	3.9
Accounts Payable	9.1	(0.9)	(10.9)
Other Changes in Working Capital Items	(1.8)	(1.0)	(2.4)
Deferred Regulatory and Other Charges	(6.1)	(5.0)	8.2
Other, net	8.6	5.0	4.5
Cash Provided by Operating Activities	86.2	68.3	115.1
Investing Activities:
Property, Plant and Equipment Additions	(119.3)	(98.1)	(103.9)
Cash Used In Investing Activities	(119.3)	(98.1)	(103.9)
Financing Activities:
(Repayment of) Proceeds from Short-Term Debt, net	(43.6)	39.9	12.7
Issuance of Long-Term Debt	89.3	30.0
Repayment of Long-Term Debt	(17.2)	(19.0)	(7.4)
(Decrease) Increase in Capital Lease Obligations	(2.5)	(2.8)	6.1
Net (Decrease) Increase in Exchange Gas Financing	(2.4)	(2.5)	(4.0)
Dividends Paid	(20.4)	(20.0)	(19.6)
Proceeds from Issuance of Common Stock	33.0	1.3	1.3
Cash Provided by (Used In) Financing Activities	36.2	26.9	(10.9)
Net Increase (Decrease) in Cash	3.1	(2.9)	0.3
Cash at Beginning of Year	5.8	8.7	8.4
Cash at End of Year	8.9	5.8	8.7
Supplemental Information:
Interest Paid	23.0	22.1	22.3
Income Taxes Paid		1.6	1.8
Payments on Capital Leases	3.3	3.4	1.1
Capital Expenditures Included in Accounts Payable	$ 1.1	0.3	$ 0.4
Non-Cash Additions to Property, Plant and Equipment		$ 3.5