SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fuel Inventory and Supplies (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Inventory [Line Items]
Fuel inventory	$ 146.4	$ 168.9
Supplies	335.2	342.1
Fuel inventory and supplies	481.6	511.0
Evergy Kansas Central
Inventory [Line Items]
Fuel inventory	80.2	87.8
Supplies	186.2	189.0
Fuel inventory and supplies	266.4	276.8
Evergy Metro
Inventory [Line Items]
Fuel inventory	46.1	57.8
Supplies	116.9	119.8
Fuel inventory and supplies	$ 163.0	$ 177.6

Energy Related Inventory, Supplies

No definition available.

Name:	evrg_EnergyRelatedInventorySupplies
Namespace Prefix:	evrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of merchandise, goods, commodities, or supplies relating to a source of usable power held for future sale or future use in manufacturing or production process.

+ 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 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EnergyRelatedInventory
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of coal, which is a combustible rock or minerals which are extracted from the ground and used as fuel.

+ References

+ Details

Name:	us-gaap_EnergyRelatedInventoryCoal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_InventoryLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

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