Stock-Based Compensation Plans - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013 Stock_Plan Executives Directors	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued liabilities	$ 73.5	$ 72.1
Minimum out-performance of Innospec share price versus Russell 2000 Index for long-term incentive plan to be payable	10.00%
Long-term incentive plan term	5 years
Maximum bonus under long-term incentive plan	8
Stock Options Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of active stock option plans	5
Number of active stock option plans for employees	2
Number of active stock option plans for non-employee directors	1
Number of active stock option plans for key executives	1
Expiration term for stock granted	10 years
Aggregate number of shares of common stock reserved for issuance which can be granted	2,640,000
Number exercisable and fully vested	186,741
Fully vested stock options with performance conditions attached	77,001
Total compensation cost of SEUs	2.5	3.1	3.1
Total intrinsic value of options exercised	4.7	1.5	2.2
Total compensation cost related to non-vested stock options not yet recognized	2.7
Expected compensation cost recognized over the weighted average period	2 years 26 days
Cash tax benefit realized from stock option exercises	5.7	2.7	1.7
Excess tax benefit	3.8	2.2	1.1
Stock Options Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	24 months
Stock Options Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	6 years
Stock Equivalent Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term for stock granted	10 years
Fully vested stock options with performance conditions attached	57,677
Total compensation cost of SEUs	7.1	6.8	5.9
Total intrinsic value of options exercised	2.2	1.3	0.4
Expected compensation cost recognized over the weighted average period	9 months 18 days
Accrued liabilities	$ 12.1
Number of exercisable SEUs	64,019
Stock Equivalent Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	11 months
Stock Equivalent Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	4 years

Maximum bonus under long term incentive plan.

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Long term incentive plan minimum relative performance.

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Long term incentive plan term.

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Number of active stock option plans.

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Number of active stock option plans for employees.

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Number of active stock option plans for key executives.

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Number of active stock option plans for non-employee directors.

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Share based compensation arrangement by share based payment award options exercisable number performance conditions attached.

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Share-based compensation shares authorized under stock equivalent units exercise price range number of exercisable options.

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Amount of deferred tax expense from write-off of the deferred tax asset related to deductible stock options at exercise.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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