| Document And Entity Information | 6 Months Ended |
| May 31, 2023 | |
| Document Information [Line Items] | |
| Entity Registrant Name | KAYNE ANDERSON ENERGY INFRASTRUCTURE FUND, INC. |
| Document Type | N-CSR |
| Amendment Flag | false |
| Entity Central Index Key | 0001293613 |
| Document Period End Date | May 31, 2023 |
| N-2 | 6 Months Ended |
| May 31, 2023 USD ($) $ / shares shares | |
| Cover [Abstract] | |
| Entity Central Index Key | 0001293613 |
| Amendment Flag | false |
| Document Type | N-CSR |
| Entity Registrant Name | KAYNE ANDERSON ENERGY INFRASTRUCTURE FUND, INC. |
| General Description of Registrant [Abstract] | |
| Investment Objectives and Practices [Text Block] | 1. Kayne Anderson Energy Infrastructure Fund, Inc. (the “Company” or “KYN”) was organized as a Maryland corporation on June 4, 2004, and is a non -diversified -end -tax KYN and Kayne Anderson NextGen Energy & Infrastructure, Inc. (“KMF”) have entered into a definitive agreement to combine the two funds (the “Merger”). The Merger and related transactions are subject to KYN and KMF stockholder approval. Additional information on the Merger is available in a preliminary joint proxy statement/prospectus (Form N -14 |
| Risk Factors [Table Text Block] | 4. The Company’s investments are concentrated in the energy sector. A downturn in one or more industries within the energy sector, material declines in energy -related At May Category Percent of Energy Companies 100.0% Equity securities 100.0% Energy Infrastructure Companies 99.1% Largest single issuer 11.9% Restricted securities 7.9% For more information about the principal risks of investing in the Company, see Investment Objective, Policies and Risks in the Company’s most recently filed annual report. |
| Share Price | $ / shares | $ 7.91 |
| NAV Per Share | $ / shares | $ 9.47 |
| Capital Stock, Long-Term Debt, and Other Securities [Abstract] | |
| Long Term Debt [Table Text Block] | The table below sets forth a summary of the redemptions and key terms of each series of Notes outstanding at May Series Principal Principal Principal Unamortized Estimated Fixed/Floating Maturity FF $ 16,571 $ (16,571) $ — $ — $ — 3.57% 4/16/23 GG 21,419 — 21,419 42 21,000 3.67% 4/16/25 KK 32,247 — 32,247 47 32,000 3.93% 7/30/24 NN 15,774 — 15,774 9 15,800 3.37% 10/29/23 OO 14,778 — 14,778 25 14,500 3.46% 10/29/24 PP 50,000 — 50,000 266 50,800 3-month LIBOR + 125 bps (1) 6/19/26 20,000 — 20,000 87 18,700 1.81% 6/19/25 RR 45,000 — 45,000 344 43,200 4.57% 5/18/32 SS 45,000 — 45,000 371 42,900 4.67% 8/2/34 $ 260,789 $ — $ 244,218 $ 1,191 $ 238,900 |
| Long Term Debt, Principal | $ | $ 244,218 |
| Long Term Debt, Structuring [Text Block] | 11. At May The table below sets forth a summary of the redemptions and key terms of each series of Notes outstanding at May Series Principal Principal Principal Unamortized Estimated Fixed/Floating Maturity FF $ 16,571 $ (16,571) $ — $ — $ — 3.57% 4/16/23 GG 21,419 — 21,419 42 21,000 3.67% 4/16/25 KK 32,247 — 32,247 47 32,000 3.93% 7/30/24 NN 15,774 — 15,774 9 15,800 3.37% 10/29/23 OO 14,778 — 14,778 25 14,500 3.46% 10/29/24 PP 50,000 — 50,000 266 50,800 3-month LIBOR + 125 bps (1) 6/19/26 20,000 — 20,000 87 18,700 1.81% 6/19/25 RR 45,000 — 45,000 344 43,200 4.57% 5/18/32 SS 45,000 — 45,000 371 42,900 4.67% 8/2/34 $ 260,789 $ — $ 244,218 $ 1,191 $ 238,900 (1) -month Holders of the fixed rate Notes are entitled to receive cash interest payments semi -annually As of May The Notes were issued in private placement offerings to institutional investors and are not listed on any exchange or automated quotation system. The Notes contain various covenants related to other indebtedness, liens and limits on the Company’s overall leverage. Under the 1940 Act and the terms of the Notes, the Company may not declare dividends or make other distributions on shares of its common stock or make purchases of such shares if, at any time of the declaration, distribution or purchase, asset coverage with respect to senior securities representing indebtedness (including the Notes) would be less than 300%. The Notes are redeemable in certain circumstances at the option of the Company. The Notes are also subject to a mandatory redemption to the extent needed to satisfy certain requirements if the Company fails to meet an asset coverage ratio required by law and is not able to cure the coverage deficiency by the applicable deadline. The Notes are unsecured obligations of the Company and, upon liquidation, dissolution or winding up of the Company, will rank: (1) senior to all of the Company’s outstanding preferred shares; (2) senior to all of the Company’s outstanding common shares; (3) on parity with any unsecured creditors of the Company and any unsecured senior securities representing indebtedness of the Company; and (4) junior to any secured creditors of the Company. At May |
| Long Term Debt, Dividends and Covenants [Text Block] | (1) -month Holders of the fixed rate Notes are entitled to receive cash interest payments semi -annually As of May The Notes were issued in private placement offerings to institutional investors and are not listed on any exchange or automated quotation system. The Notes contain various covenants related to other indebtedness, liens and limits on the Company’s overall leverage. Under the 1940 Act and the terms of the Notes, the Company may not declare dividends or make other distributions on shares of its common stock or make purchases of such shares if, at any time of the declaration, distribution or purchase, asset coverage with respect to senior securities representing indebtedness (including the Notes) would be less than 300%. The Notes are redeemable in certain circumstances at the option of the Company. The Notes are also subject to a mandatory redemption to the extent needed to satisfy certain requirements if the Company fails to meet an asset coverage ratio required by law and is not able to cure the coverage deficiency by the applicable deadline. The Notes are unsecured obligations of the Company and, upon liquidation, dissolution or winding up of the Company, will rank: (1) senior to all of the Company’s outstanding preferred shares; (2) senior to all of the Company’s outstanding common shares; (3) on parity with any unsecured creditors of the Company and any unsecured senior securities representing indebtedness of the Company; and (4) junior to any secured creditors of the Company. At May |
| Outstanding Security, Title [Text Block] | Common stock |
| Outstanding Security, Authorized [Shares] | shares | 195,535,883 |
| Outstanding Security, Held [Shares] | shares | 136,131,530 |
| Preferred Stock [Member] | |
| Capital Stock, Long-Term Debt, and Other Securities [Abstract] | |
| Capital Stock [Table Text Block] | 12. At May The table below sets forth a summary of the key terms of each series of MRP Shares outstanding at May Series Liquidation May 31, 2023 Unamortized Estimated Rate Mandatory R 41,828 $ 323 $ 38,200 3.38% 2/11/27 S 49,775 620 43,400 3.60% 2/11/30 T 20,000 335 18,600 5.07% 8/2/32 $ 111,603 $ 1,278 $ 100,200 Holders of the MRP Shares are entitled to receive cumulative cash dividend payments on the first business day following each quarterly period (February 28, May 31, August 31 and November 30). As of May The MRP Shares rank senior to all of the Company’s outstanding common shares and on parity with any other preferred stock. The MRP Shares are redeemable in certain circumstances at the option of the Company and are also subject to a mandatory redemption if the Company fails to meet a total leverage (debt and preferred stock) asset coverage ratio of 225%. Under the terms of the MRP Shares, the Company may not declare dividends or pay other distributions on shares of its common stock or make purchases of such shares if, at any time of the declaration, distribution or purchase, asset coverage with respect to total leverage would be less than 225%. The holders of the MRP Shares have one vote per share and will vote together with the holders of common stock as a single class except on matters affecting only the holders of MRP Shares or the holders of common stock. The holders of the MRP Shares, voting separately as a single class, have the right to elect at least two directors of the Company. At May |
| Security Dividends [Text Block] | Under the terms of the MRP Shares, the Company may not declare dividends or pay other distributions on shares of its common stock or make purchases of such shares if, at any time of the declaration, distribution or purchase, asset coverage with respect to total leverage would be less than 225%. |
| Security Voting Rights [Text Block] | The holders of the MRP Shares have one vote per share and will vote together with the holders of common stock as a single class except on matters affecting only the holders of MRP Shares or the holders of common stock. The holders of the MRP Shares, voting separately as a single class, have the right to elect at least two directors of the Company. |
| Security Preemptive and Other Rights [Text Block] | The MRP Shares rank senior to all of the Company’s outstanding common shares and on parity with any other preferred stock. The MRP Shares are redeemable in certain circumstances at the option of the Company and are also subject to a mandatory redemption if the Company fails to meet a total leverage (debt and preferred stock) asset coverage ratio of 225%. |
| Common Stock [Member] | |
| Capital Stock, Long-Term Debt, and Other Securities [Abstract] | |
| Capital Stock [Table Text Block] | 13. At May During the six months ended May Shares outstanding at November 30, 2021 126,447,554 Shares issued in connection with merger of FMO 9,683,976 Shares outstanding at November 30, 2022 136,131,530 |
| Security Title [Text Block] | common stock |
