LONG-TERM DEBT (Details) $ in Millions	Mar. 31, 2019 USD ($)
KCP&L \| Unsecured Debt \| Senior Notes due 2023 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 300.0
Interest rates (in hundredths)	3.15%
KCP&L \| Unsecured Debt \| Senior Notes due 2025 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 350.0
Interest rates (in hundredths)	3.65%
KCP&L \| Unsecured Debt \| Senior notes due 2035 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 250.0
Interest rates (in hundredths)	6.05%
KCP&L \| Unsecured Debt \| Senior Notes Due 2041 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 400.0
Interest rates (in hundredths)	5.30%
KCP&L \| Unsecured Debt \| Senior Notes Due 2047 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 300.0
Interest rates (in hundredths)	4.20%
KCP&L \| Unsecured Debt \| Senior Notes Due 2048 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 300.0
Interest rates (in hundredths)	4.20%
KCP&L \| Senior Notest \| Senior Notes Due 2049 KCPL
Debt Instrument [Line Items]
Long-term debt gross	$ 400.0
Interest rates (in hundredths)	4.125%
KCP&L \| Senior Notest \| Senior Notes Due 2019 KCPL
Debt Instrument [Line Items]
Interest rates (in hundredths)	7.15%
Repayments of long-term debt	$ 400.0
GMO \| Senior Notest \| Senior Notes Due 2022 GMO
Debt Instrument [Line Items]
Long-term debt gross	$ 100.0
Interest rates (in hundredths)	3.74%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=evrg_KCPLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2023KcplMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesdue2025KCPLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2035KcplMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2041KcplMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2047KCPLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2048KCPLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2049KCPLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2019KCPLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=evrg_KcplGreaterMissouriOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=evrg_SeniorNotesDue2022GMOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: