Segment and Geographic Data (Summary of Operating Results by Segment) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) Segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | Segment									3
Financial information for each reportable segment
Revenue	$ 1,373	$ 1,220	$ 1,160	$ 1,123	$ 1,371	$ 1,296	$ 1,345	$ 1,237	$ 4,876	$ 5,249	$ 5,207
Operating income	$ 179	$ 73	$ 54	$ 61	$ 195	$ 11	$ 171	$ 109	367	486	654
Other non-operating (expense) income, net									(5)	(4)	13
Gain on sale of businesses									0	1	0
Interest Expense									77	67	82
Income before taxes									285	416	585
Depreciation and amortization									251	257	261
Capital expenditures									183	226	237
Water Infrastructure
Financial information for each reportable segment
Revenue									2,079	2,177	2,176
Operating income									318	365	359
Depreciation and amortization									57	61	66
Capital expenditures									48	79	84
Applied Water
Financial information for each reportable segment
Revenue									1,434	1,541	1,534
Operating income									205	241	236
Depreciation and amortization									24	24	22
Capital expenditures									18	19	28
Measurement & Control Solutions
Financial information for each reportable segment
Revenue									1,363	1,531	1,497
Operating income									(106)	(67)	118
Depreciation and amortization									142	144	144
Capital expenditures									90	100	101
Regional Selling Locations
Financial information for each reportable segment
Depreciation and amortization									20	18	20
Capital expenditures									22	19	16
Corporate and other
Financial information for each reportable segment
Operating income									(50)	(53)	(59)
Depreciation and amortization									8	10	9
Capital expenditures									$ 5	$ 9	$ 8