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Commitments and Contingencies Commitments and Contingencies - Settlement Agreements (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2018 | Dec. 31, 2017
Guarantor Obligations [Line Items] |  |  |  |
Nontrade Receivables, Current | [1] |  | $ 124 | $ 94
Nontrade Receivables, Noncurrent | [2] |  | 15 | 15
Accounts Payable, Other, Current | [1],[3] |  | (17) | $ (11)
Exelon Generation Co L L C [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Spent Nuclear Fuel Storage Reimbursement | [4] |  | 1,274 |
Spent Nuclear Fuel Storage Reimbursement Net Co Owners | [4],[5] |  | $ 1,100 |
Exelon Generation Co L L C [Member] | Department of Energy [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Spent Nuclear Fuel Storage Reimbursement |  | $ 53 |  |
Spent Nuclear Fuel Storage Reimbursement Net Co Owners |  | $ 49 |  |
[1] | )Recorded in Accounts receivable, other.
[2] | )Recorded in Deferred debits and other assets, oth
[3] | )Non-CENG amounts owed to co-owners are recorded in Accounts receivable, other. CENG amounts owed to co-owners are recorded in Accounts payable. Represents amounts owed to the co-owners of Peach Bottom, Quad Cities, and Nine Mile Point Unit 2 generating facilities
[4] | )Includes $53 and $49, respectively, for amounts received since April 1, 2014, for costs incurred under the CENG DOE Settlement Agreements prior to the consolidation of CEN
[5] | )Total after considering amounts due to co-owners of certain nuclear stations and to the former owner of Oyster Cree

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- Definition Total of allowed cash reimbursements for received for costs incurred from the Department of Energy under the settlement agreement for spent nuclear fuel storage costs that have been incurred due to the delay in the Department of Energy accepting spent nuclear fuel. + References No definition available. + Details
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- Definition Total of allowed cash reimbursements received for cost incurred from the Department of Energy under the settlement agreement for spent nuclear fuel storage costs that have been incurred due to the delay in the Department of Energy accepting spent nuclear fuel after considering amounts due to co-owners. + References No definition available. + Details
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- Definition Amount of obligations incurred classified as other, payable within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6935-107765 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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