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Restructuring and Asset Impairment Charges (Components of Restructuring Charges and Segment Allocation) (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Severance and other charges					$ 36	$ 51	$ 19
Lease related charges					0	1	1
Asset impairment					18	0	0
Other restructuring charges					1	2	1
Reversal of restructuring accruals					(1)	(1)	(1)
Total restructuring charges					54	53	20
Asset impairment charges					21	10	2
Total restructuring and asset impairment charges					75	63	22
Water Infrastructure
Restructuring Cost and Reserve [Line Items]
Restructuring and asset impairment charges					20	20	11
Applied Water
Restructuring Cost and Reserve [Line Items]
Restructuring and asset impairment charges					4	5	2
Measurement & Control Solutions
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	$ 11	$ 10	$ 7	$ 3
Restructuring and asset impairment charges					$ 51	$ 38	$ 9