Restructuring (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2017
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			$ 54
Restructuring expense	$ 21	$ 13	45	$ 31
Restructuring paid			42
Ending restructuring of operations liability	57		57
Severance and benefits [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			44
Restructuring expense			26
Restructuring paid			22
Ending restructuring of operations liability	48		48
Lease and other contract terminations [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			5
Restructuring expense			0
Restructuring paid			2
Ending restructuring of operations liability	3		3
Assets Write Downs [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			0
Restructuring expense			2
Restructuring paid			2
Ending restructuring of operations liability	0		0
Vacant facility and other shutdown costs [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			3
Restructuring expense			4
Restructuring paid			5
Ending restructuring of operations liability	2		2
Start-up and moving costs [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			2
Restructuring expense			13
Restructuring paid			11
Ending restructuring of operations liability	4		4
Automation Solutions [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	20	9	35	22
Commercial & Residential Solutions [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	1	1	9	6
Climate Technologies [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	1	1	8	4
Tools & Home Products [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	0	0	1	2
Corporate Segment [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	$ 0	$ 3	1	$ 3
Scenario, Forecast [Member]
Restructuring Reserve [Roll Forward]
Expected fiscal year restructuring expense					$ 85
Pentair's Valves & Controls [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense			$ 9
Pentair's Valves & Controls [Member] | Scenario, Forecast [Member]
Restructuring Reserve [Roll Forward]
Expected fiscal year restructuring expense					$ 35