CASH AND CASH EQUIVALENTS DISCONTINUED OPERATIONS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Significant noncash transactions
Net unrealized gains on energy contracts	$ (0.5)	$ (19.7)
Deferred income taxes and investment tax credits	45.2	90.3
Other	(10.9)	1.1
Discontinued operations
Significant noncash transactions
Net unrealized gains on energy contracts	0	19.6
Deferred income taxes and investment tax credits	0	11.5
Other	$ 1.3	$ 6.7

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

Amount of deferred income tax expense (benefit) and income tax credits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 20

-Section 55

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=32706628&loc=d3e11374-113907

+ Details

Name:	us-gaap_DeferredIncomeTaxesAndTaxCredits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Other cash or noncash adjustments to reconcile net income to cash provided by (used in) operating activities that are not separately disclosed in the statement of cash flows (for example, cash received or cash paid during the current period for miscellaneous operating activities, net change during the reporting period in other assets or other liabilities).

+ References

No definition available.

+ Details

Name:	us-gaap_OtherOperatingActivitiesCashFlowStatement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open agreements to purchase or sell energy at some future point, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

Name:	us-gaap_UnrealizedGainLossOnEnergyContracts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_StatementOperatingActivitiesSegmentAxis=us-gaap_SegmentDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: