v2.4.1.9
PROPERTY, PLANT, EQUIPMENT, AND MINERAL PROPERTIES (Schedule of Depreciation, Depletion, and Accretion) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Property, Plant and Equipment [Abstract]    
Depreciation $ 18,879us-gaap_Depreciation $ 18,260us-gaap_Depreciation
Depletion 1,973us-gaap_Depletion 983us-gaap_Depletion
Accretion 424us-gaap_AssetRetirementObligationAccretionExpense 406us-gaap_AssetRetirementObligationAccretionExpense
Total incurred $ 21,276ipi_DepreciationDepletionAmortizationAndAccretion $ 19,649ipi_DepreciationDepletionAmortizationAndAccretion