v2.4.1.9

Income Taxes Unrecognized Tax Benefits (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 28,615us-gaap_UnrecognizedTaxBenefits	$ 26,433us-gaap_UnrecognizedTaxBenefits	$ 28,482us-gaap_UnrecognizedTaxBenefits
Gross increase to positions in prior years	2,749us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	2,154us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	299us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions
Gross decrease to positions in prior years	(1,641)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	(536)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	(51)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions
Gross increases to current period tax positions	3,008us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	1,670us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	3,347us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions
Audit settlements	0us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	(27)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities
Decrease related to lapsing of statute of limitations	(1,715)us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	(817)us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	(5,769)us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations
Effect of change in exchange rates	(2,870)itri_EffectOfChangeInExchangeRatesUnrecognizedTaxBenefit	(289)itri_EffectOfChangeInExchangeRatesUnrecognizedTaxBenefit	152itri_EffectOfChangeInExchangeRatesUnrecognizedTaxBenefit
The amount of unrecognized tax benefits that, if recognized, would affect our effective tax rate	26,980us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	27,694us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	25,852us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Net interest and penalties expense (benefit)	(76)us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	(898)us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	(414)us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense
Accrued interest	1,755us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	2,078us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued
Accrued penalties	2,671us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued	3,075us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued
Unrecognized tax benefits	$ 28,146us-gaap_UnrecognizedTaxBenefits	$ 28,615us-gaap_UnrecognizedTaxBenefits	$ 26,433us-gaap_UnrecognizedTaxBenefits

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