| Goodwill and Other Identifiable Intangible Assets The changes in the carrying amount of goodwill by reporting unit were as follows: | | | | | | | | | | | | | | | | | | In millions | December 31, 2024 | Acquisitions/
divestitures | | | Foreign currency
translation/other | December 31, 2025 | | Systems Protection | $ | 790.1 | | $ | 398.0 | | | | $ | 14.3 | | $ | 1,202.4 | | | Electrical Connections | 1,431.7 | | 43.9 | | | | — | | 1,475.6 | | | Total goodwill | $ | 2,221.8 | | $ | 441.9 | | | | $ | 14.3 | | $ | 2,678.0 | |
| | | | | | | | | | | | | | | | | In millions | December 31, 2023 | Acquisitions/
divestitures | | Foreign currency
translation/other | December 31, 2024 | | Systems Protection | $ | 430.4 | | $ | 365.9 | | | $ | (6.2) | | $ | 790.1 | | | Electrical Connections | 1,427.7 | | 4.0 | | | — | | 1,431.7 | | | Total goodwill | $ | 1,858.1 | | $ | 369.9 | | | $ | (6.2) | | $ | 2,221.8 | |
There was no impairment expense recorded in 2025, 2024 or 2023 related to goodwill. Identifiable intangible assets consisted of the following at December 31: | | | | | | | | | | | | | | | | | | | | | | | | | 2025 | | 2024 | | In millions | Cost | Accumulated
amortization | Net | | Cost | Accumulated
amortization | Net | | Definite-life intangibles | | | | | | | | | Customer relationships | $ | 1,904.0 | | $ | (551.5) | | $ | 1,352.5 | | | $ | 1,571.7 | | $ | (458.7) | | $ | 1,113.0 | | | | | | | | | | Proprietary technologies and patents | 111.8 | | (31.8) | | 80.0 | | | 78.2 | | (19.5) | | 58.7 | | | Other definite-life intangible assets | 139.5 | | (63.1) | | 76.4 | | | 63.7 | | (18.9) | | 44.8 | | | Total definite-life intangibles | 2,155.3 | | (646.4) | | 1,508.9 | | | 1,713.6 | | (497.1) | | 1,216.5 | | | Indefinite-life intangibles | | | | | | | | | Trade names | 367.6 | | — | | 367.6 | | | 370.5 | | — | | 370.5 | | | Total intangibles | $ | 2,522.9 | | $ | (646.4) | | $ | 1,876.5 | | | $ | 2,084.1 | | $ | (497.1) | | $ | 1,587.0 | |
Identifiable intangible asset amortization expense in 2025, 2024 and 2023 was $147.1 million, $94.7 million and $69.5 million, respectively. There was no impairment expense recorded in 2025, 2024 or 2023 related to identifiable intangible assets. Estimated future amortization expense for identifiable intangible assets during the next five years is as follows: | | | | | | | | | | | | | | | | | | | In millions | 2026 | 2027 | 2028 | 2029 | 2030 | | Estimated amortization expense | $ | 153.9 | | $ | 136.4 | | $ | 111.0 | | $ | 111.0 | | $ | 107.9 | |
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