Commitments and Contingencies Health Benefit Plan Costs (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Plan Costs	$ 24,331	$ 20,548	$ 19,802

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