Public Utilities, Adjustment, Common Equity Ratio Percentage

No definition available.

Name:	awk_PublicUtilitiesAdjustmentCommonEquityRatioPercentage
Namespace Prefix:	awk_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Common Equity Ratio Percentage

+ References

No definition available.

+ Details

Name:	awk_PublicUtilitiesCommonEquityRatioPercentage
Namespace Prefix:	awk_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Debt Ratio Percentage

+ References

No definition available.

+ Details

Name:	awk_PublicUtilitiesDebtRatioPercentage
Namespace Prefix:	awk_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, General Rate Case Authorizations, Annualized Incremental Revenues, Approved Amount

+ References

No definition available.

+ Details

Name:	awk_PublicUtilitiesGeneralRateCaseAuthorizationsAnnualizedIncrementalRevenuesApprovedAmount
Namespace Prefix:	awk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Public Utilities, General Rate Case Authorizations, Annualized Incremental Revenues, Requested Rate Increase (Decrease), Amount

+ References

No definition available.

+ Details

Name:	awk_PublicUtilitiesGeneralRateCaseAuthorizationsAnnualizedIncrementalRevenuesRequestedRateIncreaseDecreaseAmount
Namespace Prefix:	awk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Public Utilities, General Rate Case Authorizations, Annualized Incremental Revenues, Requested Rate, Increase (Decrease) In Capital Investments

+ References

No definition available.

+ Details

Name:	awk_PublicUtilitiesGeneralRateCaseAuthorizationsAnnualizedIncrementalRevenuesRequestedRateIncreaseDecreaseInCapitalInvestments
Namespace Prefix:	awk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Public Utilities, Infrastructure Surcharge, Annualized Incremental Revenues, Requested Amount

+ References

No definition available.

+ Details

Name:	awk_PublicUtilitiesInfrastructureSurchargeAnnualizedIncrementalRevenuesRequestedAmount
Namespace Prefix:	awk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_StatementGeographicalAxis=stpr_HI
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_MO
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_IA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Regulatory Matters - Pending General Rate Case Filing Additional Information (Details) - USD ($) $ in Millions								1 Months Ended
	Apr. 25, 2025	Mar. 17, 2025	Feb. 28, 2025	Sep. 06, 2024	Aug. 02, 2024	Jul. 01, 2024	May 01, 2024	Feb. 28, 2025
Hawaii
Public Utilities, General Disclosures
General rate case authorizations, annualized incremental revenues, requested rate increase (decrease), amount					$ 2
Proposed return on equity, percentage					10.67%
Common equity, percentage					52.11%
Debt ratio, percentage					47.89%
General rate case authorizations, annualized incremental revenues, requested rate, increase in capital investments					$ 41
Hawaii \| Subsequent Event
Public Utilities, General Disclosures
Debt ratio, percentage	47.89%
General rate case authorizations, annualized incremental revenues, approved amount	$ 1
Authorized return on equity, percentage	9.75%
Common equity, adjustment, percentage	52.11%
Missouri
Public Utilities, General Disclosures
General rate case authorizations, annualized incremental revenues, requested rate increase (decrease), amount		$ 63		$ 123		$ 148		$ (107)
Proposed return on equity, percentage						10.75%
Common equity, percentage						50.54%
Debt ratio, percentage						49.46%
General rate case authorizations, annualized incremental revenues, requested rate, increase in capital investments				$ 1,100		$ 1,500
Infrastructure surcharge, annualized incremental revenues, requested amount			$ 63
IOWA
Public Utilities, General Disclosures
General rate case authorizations, annualized incremental revenues, requested rate increase (decrease), amount							$ 21
Proposed return on equity, percentage							10.75%
Common equity, percentage							52.57%
Debt ratio, percentage							47.43%
General rate case authorizations, annualized incremental revenues, requested rate, increase in capital investments							$ 157