Schedule I Financial Statements of Parent Company Statements of Income & OCI (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Expenses
General and administrative									$ 3.0	$ 7.5	$ 5.9
General taxes									194.4	179.3	170.9
Operating Income (Loss)	67.8	271.7	143.6	86.1	62.9	277.0	150.0	49.0	569.2	538.9	479.8
Non-operating income									18.4	7.3	5.9
Interest charges									(198.4)	(220.8)	(218.4)
Income before income tax (expense) benefit and income (loss) from equity investments									379.6	304.9	259.1
Income tax (expense) benefit									(129.2)	(104.6)	(84.8)
Net income (loss)	17.5	143.1	63.6	26.0	4.7	146.4	58.1	(9.3)	250.2	199.9	174.2
Preferred stock dividend requirements									1.6	1.6	1.6
Earnings (loss) available for common shareholders									248.6	198.3	172.8
Weighted Average Number of Shares Outstanding, Basic									153.5	145.5	135.6
Weighted Average Number of Shares Outstanding, Diluted									153.7	147.2	138.7
Earnings Per Share, Basic									$ 1.62	$ 1.36	$ 1.27
Earnings Per Share, Diluted									$ 1.62	$ 1.35	$ 1.25
Common Stock, Dividends, Per Share, Declared									$ 0.8825	$ 0.855	$ 0.835
Comprehensive Income
Net income (loss)	17.5	143.1	63.6	26.0	4.7	146.4	58.1	(9.3)	250.2	199.9	174.2
Other comprehensive income
Gain (loss) on derivative hedging instruments									0	(0.1)	(5.9)
Income tax benefit (expense) on derivative hedging instruments									0	0	2.3
Net gain (loss) on derivative hedging instruments									0	(0.1)	(3.6)
Reclassification to expenses, net of tax									11.6	12.6	10.4
Derivative hedging activity, net of tax									11.6	12.5	6.8
Comprehensive income (loss) attributable to Great Plains Energy									263.3	211.3	180.7
Parent Company [Member]
Operating Expenses
General and administrative									1.0	3.3	0.8
General taxes									0.6	0.7	0.9
Operating Expenses									1.6	4.0	1.7
Operating Income (Loss)									(1.6)	(4.0)	(1.7)
Equity in earnings (loss) from Subsidiaries									256.5	219.2	200.8
Non-operating income									45.8	42.7	24.7
Interest charges									(54.7)	(69.6)	(66.5)
Income before income tax (expense) benefit and income (loss) from equity investments									246.0	188.3	157.3
Income tax (expense) benefit									4.2	11.6	17.1
Net income (loss)									250.2	199.9	174.4
Preferred stock dividend requirements									1.6	1.6	1.6
Earnings (loss) available for common shareholders									248.6	198.3	172.8
Weighted Average Number of Shares Outstanding, Basic									153.5	145.5	135.6
Weighted Average Number of Shares Outstanding, Diluted									153.7	147.2	138.7
Earnings Per Share, Basic									$ 1.62	$ 1.36	$ 1.27
Earnings Per Share, Diluted									$ 1.62	$ 1.35	$ 1.25
Common Stock, Dividends, Per Share, Declared									$ 0.8825	$ 0.855	$ 0.835
Comprehensive Income
Net income (loss)									250.2	199.9	174.4
Other comprehensive income
Gain (loss) on derivative hedging instruments									0	0	(5.3)
Income tax benefit (expense) on derivative hedging instruments									0	0	2.1
Net gain (loss) on derivative hedging instruments									0	0	(3.2)
Reclassification to expenses									9.9	11.5	8.2
Income tax (benefit) expense on reclassification to expenses									(3.9)	(4.6)	(3.2)
Reclassification to expenses, net of tax									6.0	6.9	5.0
Derivative hedging activity, net of tax									6.0	6.9	1.8
Other comprehensive income from subsidiaries, net of tax									7.1	4.5	4.5
Total other comprehensive income (loss)									13.1	11.4	6.3
Comprehensive income (loss) attributable to Great Plains Energy									$ 263.3	$ 211.3	$ 180.7