v2.4.1.9

Shareholders' Equity Share Repurchase Plan Information (Details) (USD $) In Millions, except Share data, unless otherwise specified	2 Months Ended	10 Months Ended	2 Months Ended
	Mar. 07, 2014	Dec. 31, 2014	Feb. 20, 2015	Feb. 07, 2014	Dec. 31, 2013	Mar. 08, 2013	Feb. 19, 2015
Stock Repurchased and Retired During Period, Shares	75,203us-gaap_StockRepurchasedAndRetiredDuringPeriodShares	910,990us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Stock Repurchase Program, Authorized Amount				$ 50.0us-gaap_StockRepurchaseProgramAuthorizedAmount1		$ 50.0us-gaap_StockRepurchaseProgramAuthorizedAmount1
Stock Repurchased and Retired During Period, Value	2.9us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	36.7us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Stock Repurchase Program, Remaining Authorized Repurchase Amount		13.3us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Preferred stock, shares authorized		10,000,000us-gaap_PreferredStockSharesAuthorized			10,000,000us-gaap_PreferredStockSharesAuthorized
Subsequent Event [Member]
Stock Repurchased and Retired During Period, Shares			335,251us-gaap_StockRepurchasedAndRetiredDuringPeriodShares / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Stock Repurchased and Retired During Period, Average Price Per Share			$ 39.62itri_StockRepurchasedAndRetiredDuringPeriodAveragePricePerShare / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Stock Repurchase Program, Authorized Amount							$ 50.0us-gaap_StockRepurchaseProgramAuthorizedAmount1 / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember

X

- Definition

Stock Repurchased and Retired During Period, Average Price Per Share

+ References

No definition available.

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- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

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- Definition

Number of shares that have been repurchased and retired during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

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- Definition

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30, 31

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- Definition

Amount of stock repurchase plan authorized.

+ References

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- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

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