Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Jan. 02, 2010
Cash Flows from Operating Activities
Net income	$ 174.2	$ 211.9	$ 150.4
Adjustments to reconcile income to net cash from operating activities:
Depreciation and amortization	273.1	331.6	302.2
Amortization of:
Nuclear fuel	21.4	25.1	16.1
Other	12.7	(4.7)	(10.1)
Deferred income taxes, net	111.2	123.8	(3.6)
Investment tax credit amortization	(2.2)	(2.9)	(2.2)
Loss from equity investments, net of income taxes	0.1	1.0	0.4
Other operating activities (Note 2)	(147.5)	(133.7)	(117.8)
Net cash from operating activities	443.0	552.1	335.4
Cash Flows from Investing Activities
Utility capital expenditures	(456.6)	(618.0)	(841.1)
Allowance for borrowed funds used during construction	(5.8)	(28.5)	(37.7)
Payment to Black Hills for asset sale working capital adjustment	0	0	(7.7)
Purchases of nuclear decommissioning trust investments	(18.5)	(83.3)	(99.0)
Proceeds from nuclear decommissioning trust investments	15.1	79.6	95.3
Other investing activities	(19.9)	(7.5)	(7.4)
Net cash from investing activities	(485.7)	(657.7)	(897.6)
Cash Flows from Financing Activities
Issuance of common stock	5.9	6.2	219.9
Issuance of long-term debt	747.1	249.9	700.7
Issuance fees	(10.7)	(12.1)	(22.8)
Repayment of long-term debt	(598.5)	(1.3)	(70.7)
Net change in short-term borrowings	16.0	(165.6)	(145.6)
Net change in collateralized short-term borrowings	0	95.0	0
Dividends paid	(115.1)	(114.2)	(110.5)
Other financing activities	(6.6)	(7.4)	(4.0)
Net cash from financing activities	38.1	50.5	567.0
Net Change in Cash and Cash Equivalents	(4.6)	(55.1)	4.8
Cash and Cash Equivalents at Beginning of Year		65.9
Cash and Cash Equivalents at End of Year	6.2	10.8
Kansas City Power and Light Company [Member]
Cash Flows from Operating Activities
Net income	135.5	163.2	128.9
Adjustments to reconcile income to net cash from operating activities:
Depreciation and amortization	193.1	256.4	229.6
Amortization of:
Nuclear fuel	21.4	25.1	16.1
Other	29.5	24.2	19.0
Deferred income taxes, net	80.6	83.2	(38.2)
Investment tax credit amortization	(1.5)	(2.1)	(1.4)
Other operating activities (Note 2)	(118.3)	(127.8)	(66.1)
Net cash from operating activities	340.3	422.2	287.9
Cash Flows from Investing Activities
Utility capital expenditures	(336.5)	(463.1)	(626.5)
Allowance for borrowed funds used during construction	(2.9)	(22.4)	(31.1)
Purchases of nuclear decommissioning trust investments	(18.5)	(83.3)	(99.0)
Proceeds from nuclear decommissioning trust investments	15.1	79.6	95.3
Net money pool lending	(12.1)	6.1	6.0
Other investing activities	(9.7)	(13.4)	(0.6)
Net cash from investing activities	(340.4)	(508.7)	(667.9)
Cash Flows from Financing Activities
Issuance of long-term debt	397.4	0	413.2
Issuance fees	(6.1)	(5.1)	(4.0)
Repayment of long-term debt	(263.1)	(0.2)	0
Net change in short-term borrowings	(36.5)	76.9	(193.6)
Net change in collateralized short-term borrowings	0	95.0	0
Dividends paid	(100.0)	(95.0)	(72.0)
Net money pool borrowings	6.7	1.1	0.9
Equity contribution from Great Plains Energy			247.5
Net cash from financing activities	(1.6)	72.7	392.0
Net Change in Cash and Cash Equivalents	(1.7)	(13.8)	12.0
Cash and Cash Equivalents at Beginning of Year		17.4
Cash and Cash Equivalents at End of Year	$ 1.9	$ 3.6