Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
Operating Activities:
Net Income	$ 9.2	$ 6.4
Adjustments to Reconcile Net Income to Cash Provided by Operating Activities:
Depreciation and Amortization	25.9	22.5
Deferred Tax Provision	4.9	2.5
Changes in Working Capital Items:
Accounts Receivable	13.5	6.5
Accrued Revenue	22.0	11.5
Gas Inventory	2.5	(5.0)
Accounts Payable	(9.3)	(10.5)
Taxes Refundable / Payable	(0.5)	8.1
Other Changes in Working Capital Items	(1.8)	4.3
Deferred Regulatory and Other Charges	3.6	8.8
Other, net	(8.1)	(5.3)
Cash Provided by Operating Activities	61.9	49.8
Investing Activities:
Property, Plant and Equipment Additions	(47.4)	(42.7)
Cash (Used in) Investing Activities	(47.4)	(42.7)
Financing Activities:
Repayment of Short-Term Debt, net	(63.8)	(1.4)
Repayment of Long-Term Debt, net	(0.3)	(0.3)
Net Increase (Decrease) in Gas Inventory Financing	(1.8)	5.1
Dividends Paid	(12.4)	(11.4)
Proceeds from Issuance of Common Stock, net	66.5	0.7
Other, net	(0.7)	(0.8)
Cash (Used in) Financing Activities	(12.5)	(8.1)
Net Increase (Decrease) in Cash	2.0	(1.0)
Cash at Beginning of Period	7.5	8.9
Cash at End of Period	9.5	7.9
Supplemental Cash Flow Information:
Interest Paid	13.5	13.8
Income Taxes Paid (Refunded)	$ 0.7	$ (7.3)

Name:	us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.