CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 113.3	$ 186.6	$ 351.6
Other comprehensive income (loss):
Net foreign currency translation adjustment	95.4	(35.9)	(93.4)
Net change in postretirement benefit plans, net of tax impacts of $(5.5), $(6.9), and $9.8, respectively	7.6	8.5	(9.5)
Net change investment securities, net of tax impacts of $0.0, $0.1, and $0.0, respectively	0.0	0.2	0.0
Other comprehensive income (loss)	103.0	(27.2)	(102.9)
Comprehensive income	216.3	159.4	248.7
Less: Comprehensive (loss) income attributable to noncontrolling interests	(0.2)	0.5	(0.2)
Comprehensive income attributable to ITT Inc.	216.5	158.9	248.9
Disclosure of reclassification adjustments and other adjustments to postretirement benefit plans (See Note 15)
Amortization of prior service benefit, net of tax expense of $1.8, $2.1, and $3.8, respectively	(3.0)	(3.5)	(6.2)
Amortization of net actuarial loss, net of tax benefit of $(4.1), $(4.4), and $(4.5), respectively	7.9	8.0	8.6
Loss (gain) on plan curtailment, net of tax (benefit) expense of $(1.4), $0.0, and $1.6, respectively	(2.3)	0.0	2.6
Loss on plan settlement, net of tax benefit of $0.0, $(4.7), and $0.0, respectively	0.0	8.0	0.0
Prior service cost, net of tax benefit of $0.8, $0.0, and $0.7, respectively	(1.3)	(0.4)	(1.3)
Net actuarial gain (loss), net of tax (expense) benefit of $(2.6), $0.1, and $8.2, respectively	4.6	(4.1)	(10.5)
Unrealized change from foreign currency translation	(2.9)	0.5	2.5
Net change in postretirement benefit plans, net of tax impacts of $(5.5), $(6.9), and $9.8, respectively	7.6	8.5	(9.5)
Disclosure of reclassification adjustments to investment securities
Realized loss on investing securities, net of tax benefit of $0.0, $0.1, and $0.0, respectively	$ 0.0	$ 0.2	$ 0.0