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Redeemable Preferred Stock (Narrative) (Details) - IPL [Member] | 12 Months Ended
--- | ---
Dec. 31, 2017 Q board_member $ / shares shares | Dec. 31, 2016 shares
Temporary Equity [Line Items] |  |
Number of board members to be elected (in members) | board_member | 2 |
Number of quarterly dividend requirements (in quarters) | Q | 6 |
Redeemable Preferred Stock [Member] |  |
Temporary Equity [Line Items] |  |
Shares Authorized (in shares) | 16,000,000 |
Redeemable Preferred Stock [Member] | 5.1% [Member] |  |
Temporary Equity [Line Items] |  |
Shares Authorized (in shares) | 8,000,000 | 8,000,000
Cumulative preferred stock rate | 5.10% | 5.10%
Preferred stock redemption price per share (in dollars per share) | $ / shares | $ 25 |

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- Definition Number of board members to be elected if preferred dividends are in arrears for specified amount of time + References No definition available. + Details
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- Definition Number Of Quarterly Dividend Requirements + References No definition available. + Details
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- Definition The percentage rate used to calculate dividend payments on preferred stock. + References No definition available. + Details
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- Definition The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644 + Details
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- Definition The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws. + References Reference 1: 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- 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
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