v2.4.1.9

Defined Benefit Pension Plans Significant Actuarial Weighted Assumptions (Discount Rate) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended |
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 2.36%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate | 3.76%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate | 3.36%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Percentage of Benefit Plans Denominated in Euro [Domain] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of benefit plans denominated in euro | 94% |  |
Euro Denominated Benefit Plans [Domain] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Support, Methodology and Source Data | we use two discount rates, with consideration of the duration of the plans, using a hypothetical yield curve developed from euro-denominated AA-rated corporate bond issues, partially weighted for market value, with minimum amounts outstanding of €500 million for bonds with less than 10 years to maturity and €50 million for bonds with 10 or more years to maturity, and excluding the highest and lowest yielding 10% of bonds within each maturity group. |  |
Shorter duration euro denominated defined benefit plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 1.50%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = itri_ShorterDurationEuroDenominatedDefinedBenefitPlansMember |  |
Longer duration euro denominated defined benefit plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 2.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = itri_LongerDurationEuroDenominatedDefinedBenefitPlansMember |  |
Defined Benefit Obligations [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Change in Discount Rate | 140 basis point |  |
Actuarial (gain) loss | 25,838 us-gaap_DefinedBenefitPlanActuarialGainLoss / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = itri_DefinedBenefitObligationsMember | $ (6,160)us-gaap_DefinedBenefitPlanActuarialGainLoss / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = itri_DefinedBenefitObligationsMember |

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- Definition Defined Benefit Plan, Change in Discount Rate assumption used to determine the benefit obligation + References No definition available. + Details
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- Definition Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Glossary Gain or Loss -URI http://asc.fasb.org/extlink&oid=6514294 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Glossary Gain or Loss -URI http://asc.fasb.org/extlink&oid=6749293 + Details
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- Definition The interest rate used to adjust for the time value of money for the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
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- Definition Disclosure of how the assumed discount rate was determined and the specific source data used to support the discount rate. + References No definition available. + Details
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- Definition Description of and general information regarding the types of plans utilized by the employer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2417-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2410-114920 + Details
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