Segment Information (Summary of Operations by Segment) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Financial information for each reportable segment
Revenues		$ 1,351	$ 1,160	$ 2,607	$ 2,283
Operating income		160	54	293	115
Interest Expense		21	18	42	34
Other Nonoperating Income (Expense)		(3)	(1)	(1)	(4)
Gain from sale of business		2	0	2	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		138	35	252	77
Depreciation and amortization		62	62	124	126
Capital expenditures		41	44	80	95
Water Infrastructure
Financial information for each reportable segment
Revenues		569	501	1,078	939
Operating income		93	73	164	112
Depreciation and amortization		13	16	26	31
Capital expenditures		13	8	24	18
Applied Water
Financial information for each reportable segment
Revenues		414	337	807	675
Operating income		64	41	130	88
Depreciation and amortization		6	5	12	11
Capital expenditures		3	3	7	12
Measurement & Control Solutions
Financial information for each reportable segment
Revenues		368	322	722	669
Operating income		13	(46)	22	(58)
Depreciation and amortization		37	34	73	70
Capital expenditures		20	24	41	51
Regional Selling Locations
Financial information for each reportable segment
Depreciation and amortization	[1]	4	7	9	11
Capital expenditures	[2]	5	8	8	12
Corporate and other
Financial information for each reportable segment
Operating income		(10)	(14)	(23)	(27)
Depreciation and amortization		2	0	4	3
Capital expenditures		$ 0	$ 1	$ 0	$ 2

[1] Depreciation and amortization expense incurred by the Regional selling locations was included in an overall allocation of Regional selling location costs to the segments; however, a certain portion of that expense was not specifically identified to a segment. That expense is captured in this Regional selling location line.

[2] Represents capital expenditures incurred by the Regional selling locations not allocated to the segments.