N-2 |
12 Months Ended |
|---|---|
Dec. 31, 2025 | |
| Cover [Abstract] | |
| Entity Central Index Key | 0000850027 |
| Amendment Flag | false |
| Entity Inv Company Type | N-2 |
| Document Type | N-CSR |
| Entity Registrant Name | Eagle Capital Growth Fund, Inc. |
| Document Period End Date | Dec. 31, 2025 |
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- Definition Boolean flag that is true when the XBRL content amends previously-filed or accepted submission. No definition available.
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- Definition Cover page. No definition available.
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- Definition For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD. No definition available.
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| X | ||||||||||
- Definition The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'. No definition available.
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- Definition A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition One of: N-1A (Mutual Fund), N-1 (Open-End Separate Account with No Variable Annuities), N-2 (Closed-End Investment Company), N-3 (Separate Account Registered as Open-End Management Investment Company), N-4 (Variable Annuity UIT Separate Account), N-5 (Small Business Investment Company), N-6 (Variable Life UIT Separate Account), S-1 or S-3 (Face Amount Certificate Company), S-6 (UIT, Non-Insurance Product). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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