CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 73.9	$ 326.2	$ 334.6
Other comprehensive income (loss):
Net foreign currency translation adjustment	28.5	(8.1)	(33.3)
Net change in postretirement benefit plans, net of tax impacts of $(18.7), $0.2, and $(1.6), respectively	77.4	(1.7)	6.0
Other comprehensive income (loss)	105.9	(9.8)	(27.3)
Comprehensive income	179.8	316.4	307.3
Less: Comprehensive income attributable to noncontrolling interests	1.4	1.1	0.9
Comprehensive income attributable to ITT Inc.	178.4	315.3	306.4
Disclosure of reclassification adjustments and other adjustments to postretirement benefit plans (See Note 16)
Amortization of prior service benefit, net of tax expense of $1.2, $1.0, and $1.1, respectively	(3.9)	(3.4)	(3.3)
Amortization of net actuarial loss, net of tax benefit of $(1.8), $(1.8), and $(2.4), respectively	7.1	5.6	7.4
Loss on plan settlement, net of tax benefit of $(25.7), $0.0, and $(0.4), respectively	111.3	0.0	1.3
Prior service cost, net of tax benefit (expense) of $0.0, $0.4, and $(0.1), respectively	0.0	(1.3)	0.0
Net actuarial loss, net of tax benefit of $7.6, $0.6, and $0.2, respectively	(34.2)	(2.9)	(0.4)
Unrealized change from foreign currency translation	(2.9)	0.3	1.0
Net change in postretirement benefit plans, net of tax impacts of $(18.7), $0.2, and $(1.6), respectively	$ 77.4	$ (1.7)	$ 6.0