Restructuring Charges (Accrual Rollfoward) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Reserve [Roll Forward]
Restructuring accruals - January 1				$ 5	$ 7
Restructuring charges		$ 26	$ 4	48	19
Cash payments				(21)	(18)
Foreign currency and other				(2)	(1)
Restructuring accruals - September 30		30	7	30	7
Water Infrastructure
Restructuring Reserve [Roll Forward]
Restructuring charges		6	2	17	8
Restructuring accruals - September 30		1	1	1	1
Applied Water
Restructuring Reserve [Roll Forward]
Restructuring charges		2	1	4	2
Restructuring accruals - September 30		1	1	1	1
Measurement & Control Solutions
Restructuring Reserve [Roll Forward]
Restructuring charges		25	1	37	9
Restructuring accruals - September 30		21	3	21	3
Regional Selling Locations
Restructuring Reserve [Roll Forward]
Restructuring accruals - September 30	[1]	7	2	7	2
Corporate and other
Restructuring Reserve [Roll Forward]
Restructuring accruals - September 30		$ 0	$ 0	$ 0	$ 0

[1] (a) Regional selling locations consist primarily of selling and marketing organizations and related support services that incurred restructuring expense which was allocated to the segments. The liabilities associated with restructuring expense were not allocated to the segments.