Debt Schedule of Unamortized Prepaid Debt Fees (Details) (Credit Facilities [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011 2011 Senior Secured Credit Facility [Member]	Dec. 31, 2010 2007 Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Unamortized prepaid debt fees	$ 6,027	$ 4,483

Prepaid debt fees represent the capitalized direct costs incurred related to the issuance of debt. These costs are amortized to interest expense over the lives of the respective borrowings using the effective interest method. When debt is repaid early, or first becomes convertible the related portion of unamortized prepaid debt fees is written-off and included in interest expense.

No definition available.

Name:	itri_PrepaidDebtFeesNoncurrent
Namespace Prefix:	itri_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant