v2.4.1.9

COMPENSATION PLANS (Summary of Stock Option Activity) (Details) (Stock Options, USD $)	3 Months Ended
	Mar. 31, 2015
Stock Options
Stock Option Activity, Number of Shares
Outstanding non-qualified stock options, end of period (in shares)	319,972us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Vested or expected to vest, end of period (in shares)	319,972us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Exercisable non-qualified stock options, end of period (in shares)	319,972us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock Options, Weighted Average Exercise Price
Outstanding non-qualified stock options, end of period (in dollars per share)	$ 26.16us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Vested or expected to vest, end of period (in dollars per share)	$ 26.16us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Exercisable non-qualified stock options, end of period (in dollars per share)	$ 26.16us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock Options, Aggregate Intrinsic Value
Outstanding non-qualified stock options, end of period (in shares)	$ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Vested or expected to vest, end of period (in shares)	0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Exercisable non-qualified stock options, end of period (in shares)	$ 0us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock Options, Weighted Average Remaining Contractual Life
Outstanding non-qualified stock options, end of period (in years)	3 years 4 months 10 days
Vested or expected to vest, end of period (in years)	3 years 4 months 10 days
Exercisable non-qualified stock options, end of period (in years)	3 years 4 months 10 days
Stock Options, Weighted Average Grant Date Fair Value
Outstanding non-qualified stock options, end of period (in dollars per share)	$ 13.05ipi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Vested or expected to vest, end of period (in dollars per share)	$ 13.05ipi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Exercisable non-qualified stock options, end of period (in dollars per share)	$ 13.05ipi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember

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The weighted average grant-date fair value of options exercisable during the reporting period as calculated by applying the disclosed option pricing methodology.

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The weighted average grant-date fair value of options that are fully vested and expected to vest during the reporting period as calculated by applying the disclosed option pricing methodology.

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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 weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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