Postretirement Benefit Plans - Additional Information (Detail) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) Participant shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Company contributions to defined contribution plans	$ 17.6	$ 17.1	$ 16.7
Shares of ITT Stock Held in Defined Contribution Plan | shares	0.2
Active participants in numerous defined benefit pension plans | Participant	1,800
Accumulated benefit obligation	$ 406.3	379.1
Assumed rate of future decrease in per capita cost of health care for 2027	4.50%
Contributions to postretirement plans	$ 22.9	11.2	45.0
Employer contributions	22.9	11.2
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment or settlement charges	0.0	1.7	3.7
Contributions to postretirement plans	12.9	4.3
Discretionary Pension Contribution	9.0
Defined Benefit Plan, Expected Employer Contributions Next Fiscal Year	5.0
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Employer Contributions Next Fiscal Year	10.0
Employer contributions	$ 10.0	6.9
International Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation	24.00%
International Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment or settlement charges	$ 0.0	0.0	$ 0.0
Employer contributions	$ 3.0	$ 3.4
Pre Age Sixty Five [Member]
Defined Benefit Plan Disclosure [Line Items]
Assumed rate of future increase in per capita cost of health care for 2018	6.80%
Post-age 65 retirees [Member]
Defined Benefit Plan Disclosure [Line Items]
Assumed rate of future increase in per capita cost of health care for 2018	6.00%
Other Non Qualified Us Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation	76.00%