v2.4.1.9
ASSET RETIREMENT OBLIGATION (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2013
Asset Retirement Obligation Disclosure [Abstract]    
Credit adjusted risk-free rates to discount abandonment liabilities, low end of range (as a percent) 6.90%ipi_AssetRetirementObligationCreditAdjustedRiskFreeRateToDiscountLiabilitiesLowEndOfRange  
Credit adjusted risk-free rates to discount abandonment liabilities, high end of range (as a percent) 8.50%ipi_AssetRetirementObligationCreditAdjustedRiskFreeRateToDiscountLiabilitiesHighEndOfRange  
Asset retirement obligation, current $ 1.6us-gaap_AssetRetirementObligationCurrent $ 1.6us-gaap_AssetRetirementObligationCurrent
Undiscounted amount of asset retirement obligation $ 57.7ipi_AssetRetirementObligationUndiscountedAmount