LIFO to FIFO Change in Accounting Principle - OCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2025	Sep. 28, 2024	Sep. 27, 2025	Sep. 28, 2024
Net income	$ 128.1	$ 162.2	$ 358.9	$ 395.7
Comprehensive income	125.4	219.5	461.2	402.1
Comprehensive income attributable to ITT Inc.	$ 124.2	218.9	$ 458.6	399.3
Previously Reported
Net income		161.7		394.1
Comprehensive income		219.0		400.5
Comprehensive income attributable to ITT Inc.		218.4		397.7
Revision of Prior Period, Adjustment
Net income		0.5		1.6
Comprehensive income		0.5		1.6
Comprehensive income attributable to ITT Inc.		$ 0.5		$ 1.6