Restructuring and Asset Impairment Charges (Restructuring Reserve Rollforward) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Restructuring accruals		$ 27	$ 5
Severance and other		54	53	$ 20
Cash payments		(36)	(30)	(21)
Asset impairment		(18)	0	0
Foreign currency and other		2	(1)
Restructuring accruals		29	27	$ 5
Water Infrastructure
Restructuring Reserve [Roll Forward]
Restructuring accruals		1
Restructuring accruals		4	1
Applied Water
Restructuring Reserve [Roll Forward]
Restructuring accruals		0
Restructuring accruals		1	0
Measurement & Control Solutions
Restructuring Reserve [Roll Forward]
Restructuring accruals		19
Restructuring accruals		18	19
Regional Selling Locations
Restructuring Reserve [Roll Forward]
Restructuring accruals	[1]	7
Restructuring accruals	[1]	5	7
Corporate and other
Restructuring Reserve [Roll Forward]
Restructuring accruals		0
Restructuring accruals		$ 1	$ 0

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