v2.4.1.9
EARNINGS PER SHARE (Schedule of Calculation of Basic and Diluted Loss or Earnings Per Share) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Earnings Per Share [Abstract]    
Net (loss) income $ 6,529us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic $ (355)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
Basic weighted average common shares outstanding (in shares) 75,589,092us-gaap_WeightedAverageNumberOfSharesOutstandingBasic 75,444,953us-gaap_WeightedAverageNumberOfSharesOutstandingBasic
Add: Dilutive effect of non-vested restricted common stock (in shares) 110,000ipi_IncrementalCommonSharesAttributableToNonvestedRestrictedCommonStock 0ipi_IncrementalCommonSharesAttributableToNonvestedRestrictedCommonStock
Add: Dilutive effect of performance units (in shares) 8,000ipi_IncrementalCommonSharesAttributableToPerformanceAwards 0ipi_IncrementalCommonSharesAttributableToPerformanceAwards
Diluted weighted average common shares outstanding (in shares) 75,707,000us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding 75,444,953us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding
(Loss) Earnings per share:    
Basic (in dollars per share) $ 0.09us-gaap_EarningsPerShareBasic $ 0.00us-gaap_EarningsPerShareBasic
Diluted (in dollars per share) $ 0.09us-gaap_EarningsPerShareDiluted $ 0.00us-gaap_EarningsPerShareDiluted