Long-Term Debt	3 Months Ended
Mar. 31, 2025
Debt Disclosure [Abstract]
Long-Term Debt	Note 7: Long-Term Debt On February 27, 2025, American Water Capital Corp. (“AWCC”) completed the sale of $800 million aggregate principal amount of its 5.250% Senior Notes due 2035. At the closing of this offering, AWCC received, after deduction of underwriting discounts and before deduction of offering expenses, net proceeds of approximately $792 million. AWCC used the net proceeds of the offering (i) to lend funds to American Water and the Regulated Businesses; (ii) to repay at maturity AWCC’s 3.400% Senior Notes due 2025; (iii) to repay commercial paper obligations of AWCC; and (iv) for general corporate purposes. In addition to the notes issued by AWCC as described above, during the three months ended March 31, 2025, the Company’s regulated subsidiaries issued in the aggregate $13 million of private activity bonds and government funded debt in multiple transactions with no annual interest and maturity dates ranging from 2025 through 2028. The private activity bonds and government funded debt issued by the Company’s regulated subsidiaries during the three months ended March 31, 2025, were collateralized. During the three months ended March 31, 2025, AWCC and the Company’s regulated subsidiaries made sinking fund payments for, or repaid at maturity, $531 million in aggregate principal amount of outstanding long-term debt, with annual interest rates ranging from 0.00% to 8.58%, a weighted average interest rate of 3.41%, and maturity dates ranging from 2025 to 2061. As of March 31, 2025, the Company had three treasury lock agreements, with a term of 30 years and an aggregate notional amount totaling $130 million, to reduce interest rate exposure on any future debt issuances in 2025. These treasury lock agreements terminate in June 2025 and December 2025 and have an average fixed interest rate of 4.12%. The Company designated these treasury lock agreements as cash flow hedges, measured at fair value with the gain or loss recorded in accumulated other comprehensive income. In February 2025, the Company terminated 10 treasury lock agreements designated as cash flow hedges, with a term of 10 years and an aggregate notional amount totaling $500 million, realizing a pre-tax net gain of $3 million recorded in accumulated other comprehensive income. The gain will be amortized through Interest expense over a 10-year period, in accordance with the tenor of the notes issued on February 27, 2025. No ineffectiveness was recognized on hedging instruments for the three months ended March 31, 2025 or 2024. On June 29, 2023, AWCC issued $1,035 million aggregate principal amount of 3.625% Exchangeable Senior Notes due 2026 (the “Notes”). AWCC received net proceeds of approximately $1,022 million, after deduction of underwriting discounts and commissions but before deduction of offering expenses payable by AWCC. A portion of the net proceeds was used to repay AWCC’s commercial paper obligations and the remainder was used for general corporate purposes. The Notes will mature on June 15, 2026 (the “Maturity Date”), unless earlier exchanged or repurchased. The Notes are exchangeable at an initial exchange rate of 5.8213 shares of parent company's common stock per $1,000 principal amount of Notes (equivalent to an initial exchange price of approximately $171.78 per share of common stock). The initial exchange rate of the Notes is subject to adjustment as provided in the indenture pursuant to which the Notes were issued (the “Note Indenture”). Prior to the close of business on the business day immediately preceding March 15, 2026, the Notes are exchangeable at the option of the noteholders only upon the satisfaction of specified conditions and during certain periods described in the Note Indenture. On or after March 15, 2026, until the close of business on the business day immediately preceding the Maturity Date, the Notes will be exchangeable at the option of the noteholders at any time regardless of these conditions or periods. Upon any exchange of the Notes, AWCC will (i) pay cash up to the aggregate principal amount of the Notes and (ii) pay or deliver (or cause to be delivered), as the case may be, cash, shares of parent company's common stock, or a combination of cash and shares of such common stock, at AWCC's election, in respect of the remainder, if any, of AWCC’s exchange obligation in excess of the aggregate principal amount of the Notes being exchanged. AWCC may not redeem the Notes prior to the Maturity Date, and no sinking fund is provided for the Notes. Subject to certain conditions, holders of the Notes will have the right to require AWCC to repurchase all or a portion of their Notes upon the occurrence of a fundamental change, as defined in the Note Indenture, at a repurchase price of 100% of their principal amount plus any accrued and unpaid interest.

On February 27, 2025, American Water Capital Corp. (“AWCC”) completed the sale of $800 million aggregate principal amount of its 5.250% Senior Notes due 2035. At the closing of this offering, AWCC received, after deduction of underwriting discounts and before deduction of offering expenses, net proceeds of approximately $792 million. AWCC used the net proceeds of the offering (i) to lend funds to American Water and the Regulated Businesses; (ii) to repay at maturity AWCC’s 3.400% Senior Notes due 2025; (iii) to repay commercial paper obligations of AWCC; and (iv) for general corporate purposes.

In addition to the notes issued by AWCC as described above, during the three months ended March 31, 2025, the Company’s regulated subsidiaries issued in the aggregate $13 million of private activity bonds and government funded debt in multiple transactions with no annual interest and maturity dates ranging from 2025 through 2028. The private activity bonds and government funded debt issued by the Company’s regulated subsidiaries during the three months ended March 31, 2025, were collateralized. During the three months ended March 31, 2025, AWCC and the Company’s regulated subsidiaries made sinking fund payments for, or repaid at maturity, $531 million in aggregate principal amount of outstanding long-term debt, with annual interest rates ranging from 0.00% to 8.58%, a weighted average interest rate of 3.41%, and maturity dates ranging from 2025 to 2061.

As of March 31, 2025, the Company had three treasury lock agreements, with a term of 30 years and an aggregate notional amount totaling $130 million, to reduce interest rate exposure on any future debt issuances in 2025. These treasury lock agreements terminate in June 2025 and December 2025 and have an average fixed interest rate of 4.12%. The Company designated these treasury lock agreements as cash flow hedges, measured at fair value with the gain or loss recorded in accumulated other comprehensive income.

In February 2025, the Company terminated 10 treasury lock agreements designated as cash flow hedges, with a term of 10 years and an aggregate notional amount totaling $500 million, realizing a pre-tax net gain of $3 million recorded in accumulated other comprehensive income. The gain will be amortized through Interest expense over a 10-year period, in accordance with the tenor of the notes issued on February 27, 2025.

On June 29, 2023, AWCC issued $1,035 million aggregate principal amount of 3.625% Exchangeable Senior Notes due 2026 (the “Notes”). AWCC received net proceeds of approximately $1,022 million, after deduction of underwriting discounts and commissions but before deduction of offering expenses payable by AWCC. A portion of the net proceeds was used to repay AWCC’s commercial paper obligations and the remainder was used for general corporate purposes. The Notes will mature on June 15, 2026 (the “Maturity Date”), unless earlier exchanged or repurchased.

The Notes are exchangeable at an initial exchange rate of 5.8213 shares of parent company's common stock per $1,000 principal amount of Notes (equivalent to an initial exchange price of approximately $171.78 per share of common stock). The initial exchange rate of the Notes is subject to adjustment as provided in the indenture pursuant to which the Notes were issued (the “Note Indenture”). Prior to the close of business on the business day immediately preceding March 15, 2026, the Notes are exchangeable at the option of the noteholders only upon the satisfaction of specified conditions and during certain periods described in the Note Indenture. On or after March 15, 2026, until the close of business on the business day immediately preceding the Maturity Date, the Notes will be exchangeable at the option of the noteholders at any time regardless of these conditions or periods. Upon any exchange of the Notes, AWCC will (i) pay cash up to the aggregate principal amount of the Notes and (ii) pay or deliver (or cause to be delivered), as the case may be, cash, shares of parent company's common stock, or a combination of cash and shares of such common stock, at AWCC's election, in respect of the remainder, if any, of AWCC’s exchange obligation in excess of the aggregate principal amount of the Notes being exchanged.

AWCC may not redeem the Notes prior to the Maturity Date, and no sinking fund is provided for the Notes. Subject to certain conditions, holders of the Notes will have the right to require AWCC to repurchase all or a portion of their Notes upon the occurrence of a fundamental change, as defined in the Note Indenture, at a repurchase price of 100% of their principal amount plus any accrued and unpaid interest.