Callaway Energy Center (Insurance Disclosure) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Nuclear Waste Matters [Line Items]
Number Of Years The Limit Of Liability And The Maximum Potential Annual Payments Are Adjusted	five years
Number of weeks of coverage after the first twelve weeks of an outage	1
Number Of Additional Weeks After Initial Indemnity Coverage For Power Outage	1.365
Public Liability And Nuclear Worker Liability - American Nuclear Insurers
Nuclear Waste Matters [Line Items]
Maximum assessments for single incidents	$ 0.0
Maximum coverages	450.0
Public Liability And Nuclear Worker Liability - Pool Participation
Nuclear Waste Matters [Line Items]
Maximum assessments for single incidents	138.0
Threshold Amount For which a Retrospective Assessment For a Covered loss is necessary	450.0
Maximum Annual Payment Per Incident At Licensed Commercial Nuclear Reactor	21.0
Maximum coverages	13,486.0
Public Liability And Nuclear Worker Liability
Nuclear Waste Matters [Line Items]
Maximum assessments for single incidents	138.0
Maximum coverages	13,936.0
Property Damage - Nuclear Electric Insurance Ltd
Nuclear Waste Matters [Line Items]
Maximum assessments for single incidents	27.0
Maximum coverages	3,200.0
Replacement Power - Nuclear Electric Insurance Ltd
Nuclear Waste Matters [Line Items]
Maximum assessments for single incidents	7.0
Maximum coverages	490.0
Amount of Weekly Indemnity Coverage Commencing Twelve Weeks After Power Outage	4.5
Amount of additional weekly indemnity coverage commencing after initial indemnity coverage	3.6
Amount Of Weekly Indemnity Coverage Thereafter Not Exceeding Policy Limit	490.0
Sub-limit of for Non-Nuclear Events	328.0
Radiation Event
Nuclear Waste Matters [Line Items]
Maximum coverages	2,700.0
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period	3,200.0
Non-radiation event
Nuclear Waste Matters [Line Items]
Maximum coverages	2,300.0
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period	1,800.0
Property Damage European Mutual Association for Nuclear Insurance
Nuclear Waste Matters [Line Items]
Maximum coverages	$ 490.0