Postretirement Benefit Plans - Other Changes in Plan Assets and Net Periodic Postretirement Cost Recognized in Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Net periodic postretirement cost
Service cost	$ 6.3		$ 5.9
Interest cost	18.3		19.5
Amortization of prior service cost			0.0		$ 0.0
U.S. Pension Plans [Member]
Net periodic postretirement cost
Service cost	4.1		3.5		3.2
Interest cost	11.9		13.0		13.1
Expected return on plan assets	(20.1)		(20.8)		(20.0)
Amortization of net actuarial loss	7.1		7.5		5.8
Amortization of prior service cost	0.9		1.0		0.6
Net periodic postretirement cost	3.9		4.2		2.7
Effect of settlement, curtailment, or special termination benefit(a)	12.7	[1]	0.0		0.0
Total net periodic postretirement cost	16.6		4.2		2.7
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial loss (gain)	2.1		13.9		37.0
Prior service cost	0.0		0.0		4.5
Amortization of net actuarial (loss) gain	(19.8)		(7.5)		(5.8)
Amortization of prior service cost	(0.9)		(1.0)		(0.6)
Foreign currency translation	0.0		0.0		0.0
Total change recognized in other comprehensive loss	(18.6)		5.4		35.1
Total impact from net periodic postretirement cost and changes in other comprehensive loss	(2.0)		9.6		37.8
International Pension Plan [Member]
Net periodic postretirement cost
Service cost	1.3		1.5		1.6
Interest cost	1.5		1.5		2.4
Expected return on plan assets	0.0		0.0		(0.1)
Amortization of net actuarial loss	0.7		1.0		0.4
Amortization of prior service cost	0.0
Net periodic postretirement cost	3.5		4.0		4.3
Effect of settlement, curtailment, or special termination benefit(a)	0.0		0.1		0.4
Total net periodic postretirement cost	3.5		4.1		4.7
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial loss (gain)	4.0		(2.9)		13.7
Prior service cost	0.4		0.0		0.0
Amortization of net actuarial (loss) gain	(0.7)		(1.1)		(0.9)
Amortization of prior service cost	0.0		0.0		0.0
Foreign currency translation	(0.5)		(2.5)		(1.8)
Total change recognized in other comprehensive loss	3.2		(6.5)		11.0
Total impact from net periodic postretirement cost and changes in other comprehensive loss	6.7		(2.4)		15.7
Pension [Member]
Net periodic postretirement cost
Service cost	5.4		5.0		4.8
Interest cost	13.4		14.5		15.5
Expected return on plan assets	(20.1)		(20.8)		(20.1)
Amortization of net actuarial loss	7.8		8.5		6.2
Amortization of prior service cost	0.9		1.0		0.6
Net periodic postretirement cost	7.4		8.2		7.0
Effect of settlement, curtailment, or special termination benefit(a)	12.7		0.1		0.4
Total net periodic postretirement cost	20.1		8.3		7.4
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial loss (gain)	6.1		11.0		50.7
Prior service cost	0.4		0.0		4.5
Amortization of net actuarial (loss) gain	(20.5)		(8.6)		(6.7)
Amortization of prior service cost	(0.9)		(1.0)		(0.6)
Foreign currency translation	(0.5)		(2.5)		(1.8)
Total change recognized in other comprehensive loss	(15.4)		(1.1)		46.1
Total impact from net periodic postretirement cost and changes in other comprehensive loss	4.7		7.2		53.5
Other Postretirement Benefit Plan [Member]
Net periodic postretirement cost
Service cost	0.9		0.9		1.5
Interest cost	4.9		5.0		7.4
Expected return on plan assets	(0.5)		(0.9)		(0.7)
Amortization of net actuarial loss	4.6		4.6		2.7
Amortization of prior service cost	(6.5)		(11.0)		(6.6)
Net periodic postretirement cost	3.4		(1.4)		4.3
Effect of settlement, curtailment, or special termination benefit(a)	0.0		(4.2)	[2]	0.0
Total net periodic postretirement cost	3.4		(5.6)		4.3
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial loss (gain)	(1.9)		7.7		26.3
Prior service cost	0.0		0.0		(58.7)
Amortization of net actuarial (loss) gain	(4.6)		(4.6)		(2.7)
Amortization of prior service cost	6.5		11.0		6.6
Acceleration of prior service costs	0.0		6.2		0.0
Total change recognized in other comprehensive loss	0.0		20.3		(28.5)
Total impact from net periodic postretirement cost and changes in other comprehensive loss	$ 3.4		$ 14.7		$ (24.2)

[1] (a)During 2016, we recognized a non-cash pretax pension settlement charge of $12.7 as the result of a program offering certain former U.S. employees with a vested pension benefit an option to take a one-time lump sum distribution as part of ITT's overall plan to de-risk its pension plans. Approximately 1,100 participants accepted the offer, resulting in a payment of $28.0 from the plan and a reduction in the Company's projected benefit obligation of $26.6, including an actuarial loss of $1.4.

[2] (b)During 2015, we recognized a benefit of $4.2 from a curtailment gain related to a reduction in force in our ICS segment.