Commitments and Contingencies Health Benefit Plan Costs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Plan Costs	$ 7,441	$ 5,653	$ 20,319	$ 18,324

Amount represents health insurance plan costs such as paid claims, the change in the estimate of incurred but not reported claims, taxes related to health costs, and administrative fees.

No definition available.

Name:	itri_HealthBenefitPlanCosts
Namespace Prefix:	itri_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration