Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Goodwill and Other Intangible Assets (Rollforward of Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in the carrying value of goodwill by operating segment
Beginning Balance			$ 2,839	$ 2,976
Goodwill acquired				19
Goodwill, Impairment Loss	$ (58)	$ (148)	(58)	(148)	$ 0
Foreign currency and other			73	(8)
Ending Balance			2,854	2,839	2,976
Water Infrastructure
Changes in the carrying value of goodwill by operating segment
Beginning Balance			651	653
Goodwill acquired				0
Goodwill, Impairment Loss			0	0
Foreign currency and other			17	(2)
Ending Balance			668	651	653
Applied Water
Changes in the carrying value of goodwill by operating segment
Beginning Balance			513	516
Goodwill acquired				0
Goodwill, Impairment Loss			0	0
Foreign currency and other			16	(3)
Ending Balance			529	513	516
Measurement & Control Solutions
Changes in the carrying value of goodwill by operating segment
Beginning Balance			1,675	1,807
Goodwill acquired				19
Goodwill, Impairment Loss	$ (58)		(58)	(148)
Foreign currency and other			40	(3)
Ending Balance			$ 1,657	$ 1,675	$ 1,807