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Represents the cash and cash equivalents that have been issued by the entity but have not cleared through bank.

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Represents the percentage that unrecognized gains or losses as of the most recent measurement date must exceed the greater of the postretirement benefit obligation or fair value of plan assets for additional income or expense to be recognized.

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No definition available.

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Represents the amortization period of unrecognized gains or losses into actuarial expense.

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Represents the excess of fair value of the reporting unit over carrying value.

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Represents the number of approaches used for fair value measurement.

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Represents the percentage of changes in fuel and purchased power costs prudently incurred above or below the base cost which are permitted to be distributed to customers under a fuel adjustment clause.

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No definition available.

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Represents the maximum number of rate changes allowed throughout the year under a gas adjustment clause.

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Represents the number of assumptions whose negative charge will affect impairment.

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Represents number of SO2 allowances in inventory at the balance sheet date.

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Represents the amount of cash and cash equivalents, which are restricted as to withdrawal or usage for secured collateral.

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Represents the amount of cash and cash equivalents, which are restricted as to withdrawal or usage for construction costs.

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Represents the amount of cash and cash equivalents, which are restricted as to withdrawal or usage for operating costs.

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The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

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Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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Amount of valuation reserve for inventory.

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Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) (USD $)	0 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014 item	Dec. 31, 2013	Dec. 31, 2012	Oct. 31, 2014
Asset Retirement Obligation
Proportionate ownership interest (as a percent)	12.00%		12.00%
Change in asset retirement obligation
Opening balance of asset retirement obligation	$ 4,847,000us-gaap_AssetRetirementObligation	$ 4,190,000us-gaap_AssetRetirementObligation	$ 4,190,000us-gaap_AssetRetirementObligation	$ 4,711,000us-gaap_AssetRetirementObligation
Liabilities settled			(1,175,000)	(734,000)
Accretion			(172,000)	(213,000)
Cash Flow Revisions			1,660,000
Closing balance of asset retirement obligation	4,847,000us-gaap_AssetRetirementObligation	4,190,000us-gaap_AssetRetirementObligation	4,847,000us-gaap_AssetRetirementObligation	4,190,000us-gaap_AssetRetirementObligation	4,711,000us-gaap_AssetRetirementObligation
Allowance for Funds Used During Construction
Aggregate rates (on a before-tax basis)			6.60%	7.30%	5.60%
Asset Impairments (excluding goodwill)
Assets impaired	0	0
Goodwill
Number of assumptions whose negative charge will affect impairment			1
Number of approaches used to estimate the fair value			2
Fuel and Purchased Power
Inventory allowances	0us-gaap_InventoryValuationReserves		0us-gaap_InventoryValuationReserves
Pension and Other Postretirement Benefits
Percentage that unrecognized gains or losses must exceed postretirement benefit obligation or fair value of plan assets for recognition of additional income or expense			10.00%
Amortization period of unrecognized gains or losses into actuarial expense			10 years
Cash & Cash Equivalents
Checks and electronic fund transfers that have been issued but not cleared through bank	28,300,000	22,100,000	28,300,000	22,100,000
Restricted Cash
Amounts restricted for construction costs					2,500,000
Amounts restricted for operating costs	1,800,000	1,800,000	1,800,000	1,800,000
Electric
Fuel and Purchased Power
Number of SO2 allowances in inventory			872	1,834
Electric \| Missouri Public Service Commission (MPSC)
Fuel and Purchased Power
Percentage of changes in fuel and purchased power costs from the base cost permitted for distribution to customers under fuel adjustment clause			95.00%
Gas
Fuel and Purchased Power
Maximum number of rate changes allowed by PGA clause throughout the year			4
SPP
Restricted Cash
Amounts restricted for secured collateral	2,500,000	1,100,000	2,500,000	1,100,000
MISO
Restricted Cash
Amounts restricted for secured collateral	500,000	0	500,000	0
Low end of range
Asset Retirement Obligation
Credit adjusted risk-free rate (as a percent)	4.50%		4.50%
Low end of range \| Gas
Goodwill
Excess fair value of the reporting unit over carrying value						10,000,000
High end of range
Asset Retirement Obligation
Credit adjusted risk-free rate (as a percent)	5.52%		5.52%
High end of range \| Gas
Goodwill
Excess fair value of the reporting unit over carrying value						$ 14,000,000