Hedging Activities, Derivative Instruments and Fair Value Measurements - Gains (Losses), Net of Income Tax (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Gain, net of income tax, recorded through other comprehensive income	$ 12.2	$ 21.9	$ 25.4	$ 22.8

The gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that of income tax was recognized in other comprehensive income during the current period.

No definition available.

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Namespace Prefix:	iri_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration