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Goodwill - Summary of Goodwill (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | Mar. 31, 2014 | Mar. 31, 2013
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Goodwill And Intangible Assets Disclosure [Abstract] |  |
Historical accumulated amortization | $ 298.5 | $ 298.5

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- Definition Goodwill historical accumulated amortization. + References No definition available. + Details
Name: | iosp_GoodwillHistoricalAccumulatedAmortization
Namespace Prefix: | iosp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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