Additional Shares From Early ASR Settlement

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- Definition

Common Shareholders' Equity [Line Items]

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- Definition

Debt Instrument, Covenant, Debt to Capitalization Ratio

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- Definition

Partial Settlement Of Accelerated Share Repurchase Agreement, Shares

+ References

No definition available.

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- Definition

Restriction on Payment of Dividends, Minimum Ratio of Equity to Capitalization

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No definition available.

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- Definition

Equity impact of the value of stock that has been repurchased and retired during the period under the repurchase plan. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

+ References

No definition available.

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- Definition

Amount of cash receipt from (payment to) bank; or stock received from (issuance to) bank in the settlement of the accelerated share repurchase agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 25
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6405686&loc=d3e22802-112653

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- Definition

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e)(3)(ii))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

+ References

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- Definition

Disclosure of the amount of equity that is restricted to use by regulation or agreement.

+ References

No definition available.

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- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

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- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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- Definition

Number of shares that have been repurchased and retired during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Shareholders' Equity (Details) - USD ($) $ in Millions	9 Months Ended
Shareholders' Equity (Details) - USD ($) $ in Millions	Sep. 30, 2018	Oct. 01, 2018	Aug. 01, 2018	Jul. 31, 2018	Dec. 31, 2017
Common Shareholders' Equity [Line Items]
Common stock - shares authorized (in shares)	600,000,000				275,000,000
Preferred stock - shares authorized (in shares)	12,000,000
Number of shares authorized to be repurchased (in shares)				60,000,000
Stock Repurchased and Retired During Period, Value	$ 486.1
Stock repurchased and retired during period under repurchase plan, value	$ 486.0
Stock Repurchased and Retired During Period, Shares	6,900,000
Accelerated Share Repurchases, Settlement (Payment) or Receipt			$ (450.0)
Partial Settlement Of Accelerated Share Repurchase Agreement, Shares			6,300,000
Restriction on payment of dividends, minimum ratio of total capitalization	35.00%
Restricted net assets of subsidiaries	$ 5,200.0
Westar Energy Inc [Member]
Common Shareholders' Equity [Line Items]
Common stock - shares authorized (in shares)	1,000				275,000,000
Restriction on payment of dividends, minimum ratio of total capitalization	40.00%
KCPL [Member]
Common Shareholders' Equity [Line Items]
Common stock - shares authorized (in shares)	1,000				1,000
Restriction on payment of dividends, minimum ratio of total capitalization	40.00%
Retained earnings restrictions	$ 227.4
Subsequent Event [Member]
Common Shareholders' Equity [Line Items]
Additional Shares From Early ASR Settlement		848,226
Maximum [Member] \| Westar Energy Inc [Member] \| Master Credit Facility [Member]
Common Shareholders' Equity [Line Items]
Debt Instrument, debt to capitalization ratio	65.00%
Maximum [Member] \| KCPL [Member] \| Master Credit Facility [Member]
Common Shareholders' Equity [Line Items]
Debt Instrument, debt to capitalization ratio	65.00%
Maximum [Member] \| Evergy [Member] \| Master Credit Facility [Member]
Common Shareholders' Equity [Line Items]
Debt Instrument, debt to capitalization ratio	65.00%
Maximum [Member] \| Kcpl Greater Missouri Operations Member \| Master Credit Facility [Member]
Common Shareholders' Equity [Line Items]
Debt Instrument, debt to capitalization ratio	65.00%