Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									$ 4,681	$ 5,002	$ 4,963
Other									195	247	244
Total	$ 1,373	$ 1,220	$ 1,160	$ 1,123	$ 1,371	$ 1,296	$ 1,345	$ 1,237	4,876	5,249	5,207
United States
Disaggregation of Revenue [Line Items]
Total									2,297	2,554	2,424
Europe
Disaggregation of Revenue [Line Items]
Total									1,407	1,380	1,449
Water Infrastructure
Disaggregation of Revenue [Line Items]
Total									2,079	2,177	2,176
Water Infrastructure | United States
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									558	593	539
Water Infrastructure | Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									751	729	758
Water Infrastructure | Emerging Markets & Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									341	358	344
Water Infrastructure | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									234	250	291
Water Infrastructure | Transport
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									1,484	1,533	1,535
Water Infrastructure | Treatment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									400	397	397
Applied Water
Disaggregation of Revenue [Line Items]
Total									1,434	1,541	1,534
Applied Water | United States
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									754	816	797
Applied Water | Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									356	362	386
Applied Water | Emerging Markets & Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									152	164	153
Applied Water | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									172	199	198
Applied Water | Commercial Building Services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									804	848	828
Applied Water | Industrial Water
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									630	693	706
Measurement & Control Solutions | United States
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									856	972	913
Measurement & Control Solutions | Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									266	257	273
Measurement & Control Solutions | Emerging Markets & Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									109	118	144
Measurement & Control Solutions | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									132	184	167
Measurement & Control Solutions | Water
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									689	768	692
Measurement & Control Solutions | Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									276	337	338
Measurement & Control Solutions | Software and Services/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									92	99	123
Measurement & Control Solutions | Test
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									$ 306	$ 327	$ 344