Restructuring Charges (Estimated Restructuring Costs) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
2020 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	$ 1
Restructuring costs incurred during period	1
Total expected costs remaining	0
2019 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	52
Restructuring costs incurred during period	1	$ 50
Total expected costs remaining	1
2017 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	23
Restructuring costs incurred during period	0	2	$ 4	$ 11
Total expected costs remaining	6
Operating Segments | Water Infrastructure | 2020 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	1
Restructuring costs incurred during period	1
Total expected costs remaining	0
Operating Segments | Water Infrastructure | 2019 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	20
Restructuring costs incurred during period	1	18
Total expected costs remaining	1
Operating Segments | Water Infrastructure | 2017 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	12
Restructuring costs incurred during period	0	1	2	5
Total expected costs remaining	4
Operating Segments | Applied Water | 2020 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	0
Restructuring costs incurred during period	0
Total expected costs remaining	0
Operating Segments | Applied Water | 2019 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	5
Restructuring costs incurred during period	0	5
Total expected costs remaining	0
Operating Segments | Applied Water | 2017 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	7
Restructuring costs incurred during period	0	0	1	4
Total expected costs remaining	2
Operating Segments | Measurement & Control Solutions | 2020 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	0
Restructuring costs incurred during period	0
Total expected costs remaining	0
Operating Segments | Measurement & Control Solutions | 2019 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	27
Restructuring costs incurred during period	0	27
Total expected costs remaining	0
Operating Segments | Measurement & Control Solutions | 2017 Plan
Restructuring Cost and Reserve [Line Items]
Total expected costs	4
Restructuring costs incurred during period	0	$ 1	$ 1	$ 2
Total expected costs remaining	$ 0