Stockholders' Equity and Share Based Compensation Plans (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
Jun. 30, 2012 Directors Employee Executives Stock_Plan	Jun. 30, 2011	Dec. 31, 2011
Stockholders Equity And Share Based Compensation Plans (Textual) [Abstract]
Number of shares of common stock authorized	40,000,000		40,000,000
Number of shares issued	29,554,500		29,554,500
Treasury stock, shares	6,339,772		6,507,081
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 options granted	10 years
Aggregate number of shares of common stock reserved for issuance which can be granted	2,640,000
Aggregate intrinsic value of fully vested stock options	$ 0.7
Fully vested stock options	150,310
Fully vested stock options with performance conditions attached	59,009
Total compensation cost	1.6	1.6
Total compensation cost related to non-vested stock options not yet recognized	3.9
Expected compensation cost recognized over the weighted average period	1 year 7 months 17 days
Total intrinsic value of options exercised	0.6	2.1
Cash received from the exercise of stock option awards	0.7	0.7
Total fair value of shares vested	0.7	2.9
Total options vested	242,880	290,363
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
Out-performance of Innospec share price versus Russell 2000 Index for maximum bonus under long-term incentive plan	30.00%
Maximum bonus under long term incentive plan	$ 8	$ 8
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock options vesting period	6 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock options vesting period	24 months

Maximum bonus under long term incentive plan.

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Long term incentive plan minimum relative performance.

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Out-performance of Innospec share price versus Russell 2000 Index for maximum bonus under long-term incentive plan.

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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 expiration period.

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

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Number of share options (or share units) vested during the current period.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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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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Aggregate unrecognized cost of option awards made to employees under a stock option plan or plans, that have yet to vest.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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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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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 difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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