REGULATORY MATTERS (Details 3) (USD $)	1 Months Ended		12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended				12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended					12 Months Ended					1 Months Ended			1 Months Ended												12 Months Ended
	May 31, 2011 M	Dec. 31, 2011	Dec. 31, 2011 Missouri Public Service Commission (MPSC) Electric	Jun. 15, 2011 Missouri Public Service Commission (MPSC) Electric Missouri 2010 Rate Case Y	Sep. 28, 2010 Missouri Public Service Commission (MPSC) Electric Missouri 2010 Rate Case	Sep. 30, 2010 Missouri Public Service Commission (MPSC) Electric Missouri 2009 Rate Case	Mar. 31, 2010 Missouri Public Service Commission (MPSC) Electric Missouri 2009 Rate Case	Dec. 31, 2011 Missouri Public Service Commission (MPSC) Electric Missouri 2009 Rate Case Y	Sep. 10, 2010 Missouri Public Service Commission (MPSC) Electric Missouri 2009 Rate Case	May 12, 2010 Missouri Public Service Commission (MPSC) Electric Missouri 2009 Rate Case	Oct. 29, 2009 Missouri Public Service Commission (MPSC) Electric Missouri 2009 Rate Case	Dec. 31, 2011 Missouri Public Service Commission (MPSC) Electric Tornado Recovery Y	Jul. 31, 2008 Missouri Public Service Commission (MPSC) Electric Missouri 2007 Rate Case	Dec. 31, 2011 Missouri Public Service Commission (MPSC) Electric Missouri 2007 Rate Case modified	Jun. 30, 2009 Missouri Public Service Commission (MPSC) Gas Gas rate case	Apr. 02, 2010 Missouri Public Service Commission (MPSC) Gas Gas rate case	Jun. 05, 2009 Missouri Public Service Commission (MPSC) Gas Gas rate case mi	Jul. 02, 2010 Kansas Corporation Commission (KCC) Electric Kansas 2009 Rate Case	Nov. 04, 2009 Kansas Corporation Commission (KCC) Electric Kansas 2009 Rate Case	Jun. 17, 2011 Kansas Corporation Commission (KCC) Electric Kansas 2011 Rate Case Y	Dec. 01, 2012 Kansas Corporation Commission (KCC) Electric Kansas 2011 Rate Case	Dec. 21, 2011 Kansas Corporation Commission (KCC) Electric Kansas 2011 Rate Case	Jun. 15, 2011 Kansas Corporation Commission (KCC) Electric Kansas 2011 Rate Case	Sep. 01, 2011 Oklahoma Corporation Commission (OCC) First Phase Capital Reliability Rider (CRR)	Mar. 31, 2010 Oklahoma Corporation Commission (OCC) Electric Capital cost recovery rider (CCRR) step	Mar. 25, 2010 Oklahoma Corporation Commission (OCC) Electric Capital cost recovery rider (CCRR)	Jan. 04, 2012 Oklahoma Corporation Commission (OCC) Electric Oklahoma 2011 Rate Case	Jan. 31, 2012 Oklahoma Corporation Commission (OCC) Electric Capital Reliability Rider (CRR)	Mar. 31, 2011 Oklahoma Corporation Commission (OCC) Electric Capital Reliability Rider (CRR)	Aug. 31, 2010 Oklahoma Corporation Commission (OCC) Electric Capital Reliability Rider (CRR) phase	Jan. 04, 2012 Oklahoma Corporation Commission (OCC) Electric Capital Reliability Rider (CRR)	Jun. 30, 2011 Oklahoma Corporation Commission (OCC) Electric Capital Reliability Rider (CRR)	Sep. 01, 2011 Oklahoma Corporation Commission (OCC) Electric First Phase Capital Reliability Rider (CRR)	Mar. 02, 2011 Oklahoma Corporation Commission (OCC) Electric Phase 2 Capital Reliability Rider (CRR)	Jan. 28, 2011 Oklahoma Corporation Commission (OCC) Electric Phase 2 Capital Reliability Rider (CRR)	Apr. 13, 2011 Arkansas Public Service Commission (APSC) Electric Arkansas 2010 Rate Case	Feb. 02, 2011 Arkansas Public Service Commission (APSC) Electric Arkansas 2010 Rate Case	Aug. 19, 2010 Arkansas Public Service Commission (APSC) Electric Arkansas 2010 Rate Case	Dec. 31, 2011 Federal Energy Regulatory Commission (FERC) GFR rate case.	Dec. 31, 2010 Federal Energy Regulatory Commission (FERC) Electric GFR rate case.	Jun. 30, 2010 Federal Energy Regulatory Commission (FERC) Electric GFR rate case. customer
REGULATORY MATTERS
Test period for operating expense taken as a basis for increase in base rate (in months)	12
RATE MATTERS
Approved amount of annual increase in base rate				$ 18,700,000					$ 46,800,000							$ 2,600,000		$ 2,800,000			$ 1,250,000		$ 1,250,000	$ 1,456,979			$ 240,722						$ 2,600,000	$ 1,063,100		$ 2,104,321
Approved percentage of annual increase in base rate				4.70%					13.40%							4.37%		12.40%				5.20%		15.70%			1.66%				1.66%		27.67%	9.32%		19.00%
Requested amount of annual increase in electric base rate					36,500,000						68,200,000						2,900,000		5,200,000	1,500,000						3,000,000						600,000			1,100,000			3,200,000
Recover Iatan and Plum Poin cost deferrals (in years)																				3
Percentage of annual base rate increase requested					9.20%						19.60%						4.90%		24.60%	6.39%						33.00%						4.10%						27.30%
Annual regulatory amortization expense terminated as a result of rate case settlement				14,500,000
Stipulated annual base rate increase if in-service criteria met										46,800,000
Stipulated annual base rate increase if in-service criteria were not met										33,100,000
Base rate revenue included in authorized amount of increase in annual revenues						36,800,000							22,000,000															200,000
Percentage of base rate revenue included in authorized amount of increase in annual revenues													6.70%
Percentage of changes in fuel and purchased power costs from the base cost permitted for distribution to customers under fuel adjustment clause			95.00%											95.00%
Number of times rate of recovery will be modified														2
Regulatory amortization included in authorized amount of increase in annual revenues						10,000,000
Amortization period for deferred asset related to the tax benefits of cost of removal (in years)								18				10
Deferred depreciation, operations and maintenance, and carrying costs related to capital expenditure												1,600,000
Deferred expenses related to rate cases		2,000,000
Approximate tax benefits flowed through to customers								11,100,000
Regulatory assets recorded to recover tax benefits written off							1,200,000
Return on equity (as a percent)													10.80%		11.30%
Number of steps requested under the capital cost recovery rider preceding a general rate case																									3
Number of phases approved under the capital reliability rider preceding a general rate case																														2
Approximate total revenue requested under rate increase requests																													2,500,000
Percentage of general rate increase in electric base rate																																					19.00%
Amount subject to refund collected under GFR rate case																																								600,000
Number of on-system wholesale customers who were granted intervention																																									3
Accumulated provision - rate refunds																																							1,300,000
Area covered by gas distribution system (in miles)																	1,200
Period within which SWPA payment will be made to customers				10
Base rate increase request annual decrease to expenses				$ 1,400,000