CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDER'S EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interest [Member]
Common stock, beginning balance at Dec. 31, 2014		91.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity from stock incentive plans		0.6
Share repurchases	(2.0)	(2.1)
Common stock, ending balance at Dec. 31, 2015		89.5
Common stock, beginning balance at Dec. 31, 2014		$ 91.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity from stock incentive plans		0.6	$ 24.5
Share repurchases	$ (80.0)	(2.1)	(81.9)
Common stock, ending balance at Dec. 31, 2015		89.5
Retained earnings, beginning balance at Dec. 31, 2014			1,445.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative adjustment for accounting change (See Note 2)			0.0
Net income attributable to ITT Inc.	351.8		351.8
Dividends declared			(42.8)
Activity from stock incentive plans		0.6	24.5
Share repurchases	(80.0)	$ (2.1)	(81.9)
Purchase of noncontrolling interest			0.0
Retained earnings, ending balance at Dec. 31, 2015			1,696.7
Postretirement benefit plans, beginning balance at Dec. 31, 2014				$ (144.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in postretirement benefit plans	(9.5)			(9.5)
Postretirement benefit plans, ending balance at Dec. 31, 2015				(153.7)
Cumulative translation adjustment, beginning balance at Dec. 31, 2014				(176.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net cumulative translation adjustment				(93.4)
Cumulative translation adjustments, ending balance at Dec. 31, 2015				(270.1)
Unrealized (loss) gain on investment securities, beginning balance at Dec. 31, 2014				(0.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in investment securities	0.0			0.0
Unrealized (loss) gain on investment securities, ending balance at Dec. 31, 2015				(0.3)
Noncontrolling interests, beginning balance at Dec. 31, 2014					$ 5.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income (loss) attributable to noncontrolling interests	0.2				(0.2)
Dividend to noncontrolling interest shareholders					(3.3)
Noncontrolling interest acquired					1.4
Other					0.0
Noncontrolling interests, ending balance at Dec. 31, 2015					3.3
Total shareholders’ equity, beginning balance at Dec. 31, 2014	1,220.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in common stock	(1.5)
Net change in retained earnings	251.6
Net change in accumulated other comprehensive loss	(102.9)
Net change in noncontrolling interests	(2.1)
Total shareholders’ equity, ending balance at Dec. 31, 2015	$ 1,365.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total accumulated other comprehensive loss				(424.1)
Activity from stock incentive plans		1.1
Share repurchases	(2.0)	(2.2)
Common stock, ending balance at Dec. 31, 2016	104.5	88.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity from stock incentive plans		$ 1.1	27.0
Share repurchases	$ (70.0)	(2.2)	(75.6)
Common stock, ending balance at Dec. 31, 2016	88.4	88.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative adjustment for accounting change (See Note 2)			0.0
Net income attributable to ITT Inc.	186.1		186.1
Dividends declared			(44.6)
Activity from stock incentive plans		1.1	27.0
Share repurchases	(70.0)	$ (2.2)	(75.6)
Purchase of noncontrolling interest			(0.4)
Retained earnings, ending balance at Dec. 31, 2016	1,789.2		1,789.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in postretirement benefit plans	8.5			8.5
Postretirement benefit plans, ending balance at Dec. 31, 2016	(145.2)			(145.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net cumulative translation adjustment				(35.9)
Cumulative translation adjustments, ending balance at Dec. 31, 2016	(306.0)			(306.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in investment securities	0.2			0.3
Unrealized (loss) gain on investment securities, ending balance at Dec. 31, 2016				0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income (loss) attributable to noncontrolling interests	(0.5)				0.5
Dividend to noncontrolling interest shareholders					(1.9)
Noncontrolling interest acquired					0.0
Other					0.1
Noncontrolling interests, ending balance at Dec. 31, 2016	2.0				2.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in common stock	(1.1)
Net change in retained earnings	92.5
Net change in accumulated other comprehensive loss	(27.1)
Net change in noncontrolling interests	(1.3)
Total shareholders’ equity, ending balance at Dec. 31, 2016	$ 1,428.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total accumulated other comprehensive loss				(451.2)
Activity from stock incentive plans		0.7
Share repurchases	(0.8)	(0.9)
Common stock, ending balance at Dec. 31, 2017	88.2	88.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity from stock incentive plans		$ 0.7	29.9
Share repurchases	$ (30.0)	(0.9)	(32.0)
Common stock, ending balance at Dec. 31, 2017	88.2	88.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative adjustment for accounting change (See Note 2)	1.0
Net income attributable to ITT Inc.	113.5
Dividends declared			(45.5)
Activity from stock incentive plans		0.7	29.9
Share repurchases	(30.0)	$ (0.9)	(32.0)
Purchase of noncontrolling interest			$ 0.0
Retained earnings, ending balance at Dec. 31, 2017	1,856.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in postretirement benefit plans	7.6			7.6
Postretirement benefit plans, ending balance at Dec. 31, 2017	(137.6)			(137.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net cumulative translation adjustment				95.4
Cumulative translation adjustments, ending balance at Dec. 31, 2017	(210.6)			(210.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in investment securities	0.0			0.0
Unrealized (loss) gain on investment securities, ending balance at Dec. 31, 2017				0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income (loss) attributable to noncontrolling interests	0.2				0.2
Dividend to noncontrolling interest shareholders					0.0
Noncontrolling interest acquired					0.0
Other					$ (0.1)
Noncontrolling interests, ending balance at Dec. 31, 2017	1.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net change in common stock	(0.2)
Net change in retained earnings	66.9
Net change in accumulated other comprehensive loss	103.0
Net change in noncontrolling interests	(0.3)
Total shareholders’ equity, ending balance at Dec. 31, 2017	$ 1,597.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total accumulated other comprehensive loss				$ (348.2)