Long-Term Debt Subsequent Event (Details) - Subsequent Event [Member] $ in Millions	1 Months Ended
Jul. 31, 2017 USD ($)
Kansas City Power and Light Company [Member] \| Secured Debt [Member] \| General Mortgage Bonds EIRR due 2017-2023 [Member]
Subsequent Event [Line Items]
Repayments of Long-Term Debt	$ 31.0
Great Plains Energy [Member] \| Senior Notes [Member] \| GPE 4.3 Billion Senior Notes [Member]
Subsequent Event [Line Items]
Loss on Redemption of Debt	$ 83.0
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	101.00%
Total Redemption Cost	$ 4,400.1

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629

Reference 2: 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=66902209&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration