Commitments And Contingencies (Callaway Nuclear Energy Center) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies [Line Items]
Threshold Amount For Retrospective Insurance Assessment For Covered Loss Under Public Liability And Nuclear Worker Liability Insurance Policy	$ 375,000,000
Insurance aggregate maximum coverage	13,616,000,000	[1]
Insurance maximum coverage per incident	128,000,000
Annual payment in the event of an incident at any licensed commercial reactor	19,000,000
Aggregate maximum assessment per incident under Price-Anderson liability provisions of Atomic Energy Act	128,000,000
Maximum annual payment to be paid in a calendar year per reactor incident under liability provisions of Atomic Energy Act	19,000,000
Amount of coverage in excess of primary property liability coverage	2,250,000,000.00
Amount of weekly indemnity coverage commencing eight weeks after power outage	4,500,000
Number of weeks of coverage after the first eight weeks of an outage	1 year
Amount of additional weekly indemnity coverage commencing after initial indemnity coverage	3,600,000
Number of additional weeks after initial indemnity coverage for power outage, minimum	1 year 4 months 10 days
Amount of weekly indemnity coverage thereafter not exceeding policy limit	490,000,000
Amount of secondary weekly indemnity coverage for prolonged nuclear plant outage in excess of primary indemnity coverage	900,000.0
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period	3,240,000,000
Public Liability And Nuclear Worker Liability - American Nuclear Insurers
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	375,000,000
Insurance maximum coverage per incident	0
Public Liability And Nuclear Worker Liability - Pool Participation
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	13,241,000,000	[2]
Insurance maximum coverage per incident	128,000,000	[3]
Property Damage - Nuclear Electric Insurance Ltd
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	2,250,000,000	[4]
Insurance maximum coverage per incident	23,000,000	[5]
Replacement Power - Nuclear Electric Insurance Ltd
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	490,000,000	[6]
Insurance maximum coverage per incident	9,000,000	[5]
Replacement Power - Energy Risk Assurance Company
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	64,000,000	[7]
Insurance maximum coverage per incident	0
Property Damage European Mutual Association for Nuclear Insurance
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	500,000,000	[8]
Amount of primary property liability coverage	500,000,000
Property Damage
Commitments and Contingencies [Line Items]
Insurance aggregate maximum coverage	2,750,000,000
Insurance maximum coverage per incident	23,000,000
Non-radiation event [Member]
Commitments and Contingencies [Line Items]
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period	$ 1,830,000,000

[1] Limit of liability for each incident under the Price-Anderson Act liability provisions of the Atomic Energy Act of 1954, as amended. A company could be assessed up to $128 million per incident for each licensed reactor it operates, with a maximum of $19 million per incident to be paid in a calendar year for each reactor. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.

[2] Provided through mandatory participation in an industrywide retrospective premium assessment program.

[3] Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $375 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.

[4] NEIL provides $2.25 billion in property damage, decontamination, and premature decommissioning insurance.

[5] NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.

[6] Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity is up to $4.5 million for 52 weeks, which commences after the first eight weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter, for a total not exceeding the policy limit of $490 million. Nonradiation events are sub-limited to $328 million.

[7] Provides replacement power cost insurance in the event of a prolonged accidental outage. The coverage commences after the first 52 weeks of insurance coverage from NEIL concludes; it is a weekly indemnity of up to $0.9 million for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate; it has reinsured this coverage with third-party insurance companies. See Note 14 – Related Party Transactions for more information on this affiliate transaction.

[8] European Mutual Association for Nuclear Insurance provides $500 million in excess of the $2.25 billion property coverage provided by NEIL.