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v3.25.2

Segment Reporting - Summary of Segment Reporting related to Selling, General and Administrative Expense and Research and Development Expense (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Segment Reporting Information [Line Items] |  |  |  |
Total selling, general and administrative expenses and research and development expenses | $ 88.2 | $ 85.6 | $ 170.2 | $ 190.1
Operating Segments [Member] | Performance Chemicals [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total selling, general and administrative expenses and research and development expenses | 16.2 | 15.0 | 31.7 | 31.6
Operating Segments [Member] | Fuel Specialties [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total selling, general and administrative expenses and research and development expenses | 27.5 | 27.2 | 51.4 | 54.4
Operating Segments [Member] | Oilfield Services [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total selling, general and administrative expenses and research and development expenses | 23.6 | 25.8 | 48.5 | 66.3
Corporate, Non-Segment [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total selling, general and administrative expenses and research and development expenses | $ 20.9 | $ 17.6 | $ 38.6 | $ 37.8

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- Definition Selling, general and administrative expense and research and development expense. + References No definition available. + Details
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Namespace Prefix: | iosp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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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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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |