Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

Acquisitions and Divestitures - Narrative (Details) $ in Millions								3 Months Ended		9 Months Ended
	Jul. 23, 2025 USD ($)	Apr. 01, 2025 USD ($)	Feb. 07, 2025 USD ($)	Jan. 31, 2025 USD ($) employee	Dec. 10, 2024 USD ($)	Dec. 05, 2024 USD ($) employee	Apr. 26, 2023 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 09, 2024 USD ($)
Business Combination [Line Items]
Payments to acquire productive assets										$ 248	$ 221
Payments for asset acquisition at closing										37	0
Goodwill								$ 8,280		8,280		$ 7,980
Proceeds from sale of businesses, net of cash disposed										48	11
Loss on sale of business								37	$ 2	47	6
Payments to acquire equity method investments										5	4
Acquisition of business, net of cash acquired										113	$ 5
Vacom Systems LLC
Business Combination [Line Items]
Payments to acquire productive assets		$ 42
Payments for asset acquisition at closing		$ 37
Royalty on revenue, percentage		5.00%
Royalty on revenue, period after acquisition		5 years
Royalty on revenue, maximum		$ 25
Vacom Systems LLC \| Minimum
Business Combination [Line Items]
Asset acquisition, remaining period to pay consideration		12 months
Vacom Systems LLC \| Maximum
Business Combination [Line Items]
Asset acquisition, remaining period to pay consideration		18 months
Vacom Systems LLC \| Developed Technology Rights
Business Combination [Line Items]
Fair Value (in millions)		$ 49
Useful life (in years)		15 years
Global Omnium Idrica S.L.
Business Combination [Line Items]
Ownership percentage, parent					61.00%
Global Omnium Idrica S.L.
Business Combination [Line Items]
Ownership percentage in equity method investment							25.10%
Payments to acquire equity method investments							$ 51
Equity securities, FV-NI													$ 193
Gain on remeasurement of previously held equity interest								$ 152
Equity securities, FV-NI, cost					$ 41
Disposed of by Sale \| Evoqua Magneto
Business Combination [Line Items]
Proceeds from sale of businesses			$ 61
Proceeds from sale of businesses, net of cash disposed			48
Loss on sale of business			$ 8
Discontinued Operations, Held-for-Sale \| International Metering Business
Business Combination [Line Items]
Loss on sale of business										$ 39
Simply Clean Air and Water, Inc
Business Combination [Line Items]
Cash paid				$ 7
Number of employees \| employee				20
Global Omnium Idrica S.L.
Business Combination [Line Items]
Fair Value (in millions)					$ 165
Useful life (in years)					10 years
Cash paid					$ 154
Percentage of ownership interest acquired					35.90%
Consideration transferred					$ 637
Goodwill					522
Acquisition of business, net of cash acquired					$ 150
Heusser Water Solutions AG
Business Combination [Line Items]
Number of employees \| employee						90
Consideration transferred						$ 40
Proceeds from sale of businesses, net of cash disposed						$ 35
EMX Holdings, Inc.
Business Combination [Line Items]
Fair Value (in millions)	$ 34
Useful life (in years)	8 years 1 month 6 days
Percentage of ownership interest acquired	100.00%
Consideration transferred	$ 106
Goodwill	76
Goodwill, expected tax deductible amount	$ 0