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PENSION PLANS AND POST-RETIREMENT BENEFITS - Fair Values of Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,799.1	$ 1,732.8	$ 1,603.4
Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	248.3	239.9	223.3
Evergy Kansas Central | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	887.0	842.1	804.6
Evergy Kansas Central | Pension Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	516.2	515.2
Evergy Kansas Central | Pension Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	370.8	326.9
Evergy Kansas Central | Pension Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	248.5	233.8
Evergy Kansas Central | Pension Benefits | Domestic equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	151.3	150.6
Evergy Kansas Central | Pension Benefits | Domestic equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Domestic equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Domestic equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	97.2	83.2
Evergy Kansas Central | Pension Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	171.2	162.4
Evergy Kansas Central | Pension Benefits | International equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	103.8	101.5
Evergy Kansas Central | Pension Benefits | International equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | International equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | International equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67.4	60.9
Evergy Kansas Central | Pension Benefits | Bond funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	281.2	281.7
Evergy Kansas Central | Pension Benefits | Bond funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	230.7	233.0
Evergy Kansas Central | Pension Benefits | Bond funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Bond funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Bond funds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50.5	48.7
Evergy Kansas Central | Pension Benefits | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46.7	46.5
Evergy Kansas Central | Pension Benefits | Real estate investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Real estate investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Real estate investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Real estate investments | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46.7	46.5
Evergy Kansas Central | Pension Benefits | Combination debt/equity/other fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.4	30.1
Evergy Kansas Central | Pension Benefits | Combination debt/equity/other fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.4	30.1
Evergy Kansas Central | Pension Benefits | Combination debt/equity/other fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Combination debt/equity/other fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Combination debt/equity/other fund | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Alternative investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	83.6	78.5
Evergy Kansas Central | Pension Benefits | Alternative investment funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Alternative investment funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Alternative investment funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Alternative investment funds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	83.6	78.5
Evergy Kansas Central | Pension Benefits | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25.4	9.1
Evergy Kansas Central | Pension Benefits | Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Short-term investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Pension Benefits | Short-term investments | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25.4	9.1
Evergy Kansas Central | Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125.8	120.5	109.7
Evergy Kansas Central | Post-Retirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.7	1.1
Evergy Kansas Central | Post-Retirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125.1	119.4
Evergy Kansas Central | Post-Retirement Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41.9	40.5
Evergy Kansas Central | Post-Retirement Benefits | Domestic equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Domestic equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Domestic equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Domestic equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41.9	40.5
Evergy Kansas Central | Post-Retirement Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27.7	26.0
Evergy Kansas Central | Post-Retirement Benefits | International equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | International equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | International equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | International equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27.7	26.0
Evergy Kansas Central | Post-Retirement Benefits | Bond funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55.5	52.9
Evergy Kansas Central | Post-Retirement Benefits | Bond funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Bond funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Bond funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Bond funds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55.5	52.9
Evergy Kansas Central | Post-Retirement Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.7	1.1
Evergy Kansas Central | Post-Retirement Benefits | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.7	1.1
Evergy Kansas Central | Post-Retirement Benefits | Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Cash and cash equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Kansas Central | Post-Retirement Benefits | Cash and cash equivalents | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	912.1	890.7	798.8
Evergy Metro | Pension Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	502.4	499.7
Evergy Metro | Pension Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	150.1	149.5
Evergy Metro | Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	259.6	241.5
Evergy Metro | Pension Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	247.4	244.8
Evergy Metro | Pension Benefits | Domestic equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	191.9	195.3
Evergy Metro | Pension Benefits | Domestic equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Domestic equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Domestic equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55.5	49.5
Evergy Metro | Pension Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	220.8	178.7
Evergy Metro | Pension Benefits | International equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	153.4	117.7
Evergy Metro | Pension Benefits | International equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | International equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | International equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67.4	61.0
Evergy Metro | Pension Benefits | Bond funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78.1	71.0
Evergy Metro | Pension Benefits | Bond funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21.1	15.6
Evergy Metro | Pension Benefits | Bond funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Bond funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Bond funds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.0	55.4
Evergy Metro | Pension Benefits | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	133.6	123.9
Evergy Metro | Pension Benefits | Corporate bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	133.6	123.9
Evergy Metro | Pension Benefits | Corporate bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Corporate bonds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | U.S. Treasury and agency bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	73.8	70.9
Evergy Metro | Pension Benefits | U.S. Treasury and agency bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61.5	53.5
Evergy Metro | Pension Benefits | U.S. Treasury and agency bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12.3	17.4
Evergy Metro | Pension Benefits | U.S. Treasury and agency bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | U.S. Treasury and agency bonds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Mortgage and asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.0	5.7
Evergy Metro | Pension Benefits | Mortgage and asset backed securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Mortgage and asset backed securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.0	5.7
Evergy Metro | Pension Benefits | Mortgage and asset backed securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Mortgage and asset backed securities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40.2	50.8
Evergy Metro | Pension Benefits | Real estate investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.6	12.8
Evergy Metro | Pension Benefits | Real estate investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Real estate investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Real estate investments | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38.6	38.0
Evergy Metro | Pension Benefits | Combination debt/equity/other fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.6	11.9
Evergy Metro | Pension Benefits | Combination debt/equity/other fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.6	11.9
Evergy Metro | Pension Benefits | Combination debt/equity/other fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Combination debt/equity/other fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Combination debt/equity/other fund | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Alternative investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39.7	36.6
Evergy Metro | Pension Benefits | Alternative investment funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Alternative investment funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Alternative investment funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Alternative investment funds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39.7	36.6
Evergy Metro | Pension Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.3	92.9
Evergy Metro | Pension Benefits | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.3	92.9
Evergy Metro | Pension Benefits | Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Cash and cash equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Cash and cash equivalents | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.4	1.0
Evergy Metro | Pension Benefits | Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Short-term investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Short-term investments | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.4	1.0
Evergy Metro | Pension Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(0.8)	2.5
Evergy Metro | Pension Benefits | Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(0.8)	2.5
Evergy Metro | Pension Benefits | Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Pension Benefits | Other | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	122.5	119.4	$ 113.6
Evergy Metro | Post-Retirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.1	15.2
Evergy Metro | Post-Retirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26.6	26.8
Evergy Metro | Post-Retirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78.8	77.4
Evergy Metro | Post-Retirement Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	3.2
Evergy Metro | Post-Retirement Benefits | Domestic equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	3.2
Evergy Metro | Post-Retirement Benefits | Domestic equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Domestic equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Domestic equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.2	1.1
Evergy Metro | Post-Retirement Benefits | International equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.2	1.1
Evergy Metro | Post-Retirement Benefits | International equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | International equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | International equities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Bond funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	79.0	77.5
Evergy Metro | Post-Retirement Benefits | Bond funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.2	0.1
Evergy Metro | Post-Retirement Benefits | Bond funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Bond funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Bond funds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78.8	77.4
Evergy Metro | Post-Retirement Benefits | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.9	17.8
Evergy Metro | Post-Retirement Benefits | Corporate bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.9	17.8
Evergy Metro | Post-Retirement Benefits | Corporate bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Corporate bonds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | U.S. Treasury and agency bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13.6	11.5
Evergy Metro | Post-Retirement Benefits | U.S. Treasury and agency bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.7	4.1
Evergy Metro | Post-Retirement Benefits | U.S. Treasury and agency bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.9	7.4
Evergy Metro | Post-Retirement Benefits | U.S. Treasury and agency bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | U.S. Treasury and agency bonds | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Mortgage and asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.5	1.3
Evergy Metro | Post-Retirement Benefits | Mortgage and asset backed securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Mortgage and asset backed securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.5	1.3
Evergy Metro | Post-Retirement Benefits | Mortgage and asset backed securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Mortgage and asset backed securities | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.4	6.7
Evergy Metro | Post-Retirement Benefits | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.4	6.7
Evergy Metro | Post-Retirement Benefits | Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Cash and cash equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Cash and cash equivalents | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.3
Evergy Metro | Post-Retirement Benefits | Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.3
Evergy Metro | Post-Retirement Benefits | Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Evergy Metro | Post-Retirement Benefits | Other | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0.0	$ 0.0

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
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-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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