Stockholders' Equity and Share Based Compensation Plans (Details 2) (USD $)	6 Months Ended
Jun. 30, 2012
Summary of information about options outstanding
Number Outstanding	1,116,642
Number Exercisable and Fully Vested	150,310
$ 0 - $ 5 [Member]
Summary of information about options outstanding
Range of Exercise Price, Lower Range Limit	$ 0
Range of Exercise Price, Upper Range Limit	$ 5
Number Outstanding	641,549
Weighted Average Remaining Life in Years	7 years 5 months 5 days
Weighted Average Exercise Price	$ 0.57
Number Exercisable and Fully Vested	102,855
Weighted Average Remaining Life in Years	6 years 3 months
Weighted Average Exercise Price	$ 1.21
$ 5 - $10 [Member]
Summary of information about options outstanding
Range of Exercise Price, Lower Range Limit	$ 5
Range of Exercise Price, Upper Range Limit	$ 10
Number Outstanding	22,654
Weighted Average Remaining Life in Years	3 years
Weighted Average Exercise Price	$ 9.66
Number Exercisable and Fully Vested	22,654
Weighted Average Remaining Life in Years	3 years
Weighted Average Exercise Price	$ 9.66
$10 - $15 [Member]
Summary of information about options outstanding
Range of Exercise Price, Lower Range Limit	$ 10
Range of Exercise Price, Upper Range Limit	$ 15
Number Outstanding	386,946
Weighted Average Remaining Life in Years	2 years 6 months 4 days
Weighted Average Exercise Price	$ 11.48
Weighted Average Remaining Life in Years	0 years
Weighted Average Exercise Price	$ 0.00
$20 - $25 [Member]
Summary of information about options outstanding
Range of Exercise Price, Lower Range Limit	$ 20
Range of Exercise Price, Upper Range Limit	$ 25
Number Outstanding	12,385
Weighted Average Remaining Life in Years	5 years 8 months 5 days
Weighted Average Exercise Price	$ 20.53
Number Exercisable and Fully Vested	12,385
Weighted Average Remaining Life in Years	5 years 8 months 5 days
Weighted Average Exercise Price	$ 20.53
$25 - $30 [Member]
Summary of information about options outstanding
Range of Exercise Price, Lower Range Limit	$ 25
Range of Exercise Price, Upper Range Limit	$ 30
Number Outstanding	51,728
Weighted Average Remaining Life in Years	8 years 3 months 15 days
Weighted Average Exercise Price	$ 28.57
Number Exercisable and Fully Vested	12,416
Weighted Average Remaining Life in Years	4 years 7 months 24 days
Weighted Average Exercise Price	$ 27.09
$30 - $35 [Member]
Summary of information about options outstanding
Range of Exercise Price, Lower Range Limit	$ 30
Range of Exercise Price, Upper Range Limit	$ 35
Number Outstanding	1,380
Weighted Average Remaining Life in Years	8 years 10 months 13 days
Weighted Average Exercise Price	$ 32.60
Weighted Average Remaining Life in Years	0 years
Weighted Average Exercise Price	$ 0.00

Name:	iosp_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAbstract
Namespace Prefix:	iosp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a, b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration