CONSOLIDATED BALANCE SHEETS - Entity [Domain] - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Current Assets:
Cash and Cash Equivalents	$ 16.1	$ 8.4	$ 12.0
Accounts Receivable, net	52.3	60.7	44.9
Accrued Revenue	28.6	48.5	33.4
Exchange Gas Receivable	7.2	15.0	8.3
Deferred Income Taxes	15.2		1.5
Gas Inventory	0.5	1.1	0.8
Materials and Supplies	6.7	6.3	6.1
Prepayments and Other	7.3	5.2	6.9
Total Current Assets	133.9	145.2	113.9
Utility Plant:
Gas	532.1	522.9	483.9
Electric	396.4	390.6	379.1
Common	35.0	32.7	32.3
Construction Work in Progress	57.4	42.6	34.3
Total Utility Plant	1,020.9	988.8	929.6
Less: Accumulated Depreciation	263.9	255.1	247.9
Net Utility Plant	757.0	733.7	681.7
Other Noncurrent Assets:
Regulatory Assets	104.3	107.6	88.1
Other Assets	16.2	13.7	16.9
Total Other Noncurrent Assets	120.5	121.3	105.0
TOTAL ASSETS	1,011.4	1,000.2	900.6
Current Liabilities:
Accounts Payable	19.0	44.2	20.5
Short-Term Debt		29.3	35.0
Long-Term Debt, Current Portion	4.1	4.0	2.5
Energy Supply Obligations	13.8	22.1	12.3
Deferred Income Taxes		3.1
Environmental Obligations	3.4	3.5	6.4
Interest Payable	3.5	3.5	3.1
Regulatory Liabilities	31.2	8.7	13.0
Taxes Payable	9.1	0.1	0.1
Other Current Liabilities	10.4	10.9	9.7
Total Current Liabilities	94.5	129.4	102.6
Noncurrent Liabilities:
Deferred Income Taxes	90.2	72.9	87.8
Cost of Removal Obligations	68.1	63.8	60.8
Retirement Benefit Obligations	123.5	118.6	80.8
Regulatory Liabilities	11.0	0.1
Capital Lease Obligations	9.5	7.5	5.6
Environmental Obligations	2.0	2.0	2.0
Other Noncurrent Liabilities	3.5	3.7	5.6
Total Noncurrent Liabilities	307.8	268.6	242.6
Capitalization:
Long-Term Debt, Less Current Portion	328.6	328.9	284.6
Stockholders' Equity:
Common Equity (Authorized: 25,000,000 and Outstanding: 13,974,576, 13,916,026 and 13,895,777 Shares)	236.4	234.7	233.6
Retained Earnings	43.9	38.4	37.0
Total Common Stock Equity	280.3	273.1	270.6
Preferred Stock	0.2	0.2	0.2
Total Stockholders' Equity	280.5	273.3	270.8
Total Capitalization	$ 609.1	$ 602.2	$ 555.4
Commitments and Contingencies (Notes 6 & 7)
TOTAL LIABILITIES AND CAPITALIZATION	$ 1,011.4	$ 1,000.2	$ 900.6

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.