American Water Works (AWK) 10-K 24 Feb 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-34028
Entity Registrant Name	AMERICAN WATER WORKS COMPANY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	51-0063696
Entity Address, Address Line One	1 Water Street
Entity Address, City or Town	Camden
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08102-1658
City Area Code	856
Local Phone Number	955-4001
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	AWK
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 20,390.8
Entity Common Stock, Shares Outstanding (in shares)		181,439,255
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the American Water Works Company, Inc. definitive proxy statement for the 2021 Ann ual Meeting of Shareholders to be filed with the Securities and Exchange Commission within 120 days after December 31, 2020 are incorporated by reference into Part III of this report.
Entity Central Index Key	0001410636
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Property, plant and equipment	$ 25,614	$ 23,941
Accumulated depreciation	(5,904)	(5,709)
Property, plant and equipment, net	19,710	18,232
Current assets:
Cash and cash equivalents	547	60
Restricted funds	29	31
Accounts receivable, net of allowance for uncollectible accounts of $60 and $41, respectively	321	294
Unbilled revenues	206	172
Materials and supplies	47	44
Assets held for sale	629	566
Other	127	118
Total current assets	1,906	1,285
Regulatory and other long-term assets:
Regulatory assets	1,127	1,128
Operating lease right-of-use assets	95	103
Goodwill	1,504	1,501
Postretirement benefit assets	173	159
Intangible assets	55	67
Other	196	207
Total regulatory and other long-term assets	3,150	3,165
Total assets	24,766	22,682
Capitalization:
Common stock ($0.01 par value; 500,000,000 shares authorized; 186,466,707 and 185,903,727 shares issued, respectively)	2	2
Paid-in-capital	6,747	6,700
Retained earnings (accumulated deficit)	102	(207)
Accumulated other comprehensive loss	(49)	(36)
Treasury stock, at cost (5,168,215 and 5,090,855 shares, respectively)	(348)	(338)
Total common shareholders' equity	6,454	6,121
Long-term debt	9,329	8,639
Redeemable preferred stock at redemption value	4	5
Total long-term debt	9,333	8,644
Total capitalization	15,787	14,765
Current liabilities:
Short-term debt	1,282	786
Current portion of long-term debt	329	28
Accounts payable	189	203
Accrued liabilities	591	596
Accrued taxes	50	46
Accrued interest	88	84
Liabilities related to assets held for sale	137	128
Other	215	174
Total current liabilities	2,881	2,045
Regulatory and other long-term liabilities:
Advances for construction	270	240
Deferred income taxes and investment tax credits	2,113	1,893
Regulatory liabilities	1,770	1,806
Operating lease liabilities	81	89
Accrued pension expense	388	411
Other	83	78
Total regulatory and other long-term liabilities	4,705	4,517
Contributions in aid of construction	1,393	1,355
Commitments and contingencies
Total capitalization and liabilities	$ 24,766	$ 22,682

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for uncollectible accounts	$ 60	$ 41
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	186,466,707	185,903,727
Treasury Stock, shares (in shares)	5,168,215	5,090,855

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Operating revenues		$ 3,777	$ 3,610	$ 3,440
Operating expenses:
Operation and maintenance		1,622	1,544	1,479
Depreciation and amortization		604	582	545
General taxes		303	280	277
Loss (gain) on asset dispositions and purchases		0	34	(20)
Impairment charge		0	0	57
Total operating expenses, net		2,529	2,440	2,338
Operating income		1,248	1,170	1,102
Other income (expense):
Interest, net		(395)	(382)	(350)
Non-operating benefit costs, net		49	16	20
Other, net		22	29	15
Total other income (expense)		(324)	(337)	(315)
Income before income taxes		924	833	787
Provision for income taxes		215	212	222
Consolidated net income		709	621	565
Net loss attributable to noncontrolling interest		0	0	(2)
Net income attributable to common shareholders		$ 709	$ 621	$ 567
Basic earnings per share:
Net income attributable to common shareholders (USD per share)	[1]	$ 3.91	$ 3.44	$ 3.16
Diluted earnings per share:
Net income attributable to common shareholders (USD per share)	[1]	$ 3.91	$ 3.43	$ 3.15
Weighted average common shares outstanding:
Basic (in shares)		181	181	180
Diluted (in shares)		182	181	180
[1]	Amounts may not calculate due to rounding.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income attributable to common shareholders	$ 709	$ 621	$ 567
Other comprehensive income (loss), net of tax:
Change in employee benefit plan funded status, net of tax of $(4), $3 and $20 in 2020, 2019 and 2018, respectively	(12)	8	60
Defined benefit pension plan actuarial loss, net of tax of $1, $1 and $3 in 2020, 2019 and 2018, respectively	3	4	7
Pension reclassification from accumulated other comprehensive loss of tax effects resulting from the Tax Cuts and Jobs Act	0	0	(22)
Foreign currency translation adjustment	0	(1)	0
Unrealized loss on cash flow hedges, net of tax of $(1), $(5) and $0 in 2020, 2019 and 2018, respectively	(4)	(13)	(2)
Cash flow hedges reclassification from accumulated other comprehensive loss of tax effects resulting from the Tax Cuts and Jobs Act	0	0	2
Net other comprehensive income (loss)	(13)	(2)	45
Comprehensive income attributable to common shareholders	$ 696	$ 619	$ 612

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Employee benefit plan funded status, tax	$ (4)	$ 3	$ 20
Actuarial loss, tax	1	1	3
Unrealized loss on cash flow hedges, tax	$ (1)	$ (5)	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 709	$ 621	$ 565
Adjustments to reconcile to net cash flows provided by operating activities:
Depreciation and amortization	604	582	545
Deferred income taxes and amortization of investment tax credits	207	208	195
Provision for losses on accounts receivable	34	28	33
Loss (gain) on asset dispositions and purchases	0	34	(20)
Impairment charge	0	0	57
Pension and non-pension postretirement benefits	(14)	17	23
Other non-cash, net	(20)	(41)	20
Changes in assets and liabilities:
Receivables and unbilled revenues	(97)	(25)	(17)
Pension and non-pension postretirement benefit contributions	(39)	(31)	(22)
Accounts payable and accrued liabilities	(2)	66	25
Other assets and liabilities, net	44	(72)	22
Impact of Freedom Industries settlement activities	0	(4)	(40)
Net cash provided by operating activities	1,426	1,383	1,386
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,822)	(1,654)	(1,586)
Acquisitions, net of cash acquired	(135)	(235)	(398)
Proceeds from sale of assets	2	48	35
Removal costs from property, plant and equipment retirements, net	(106)	(104)	(87)
Net cash used in investing activities	(2,061)	(1,945)	(2,036)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	1,334	1,530	1,358
Repayments of long-term debt	(342)	(495)	(526)
Proceeds from term loan	500	0	0
Net short-term borrowings with maturities less than three months	(5)	(178)	60
Issuance of common stock	0	0	183
Proceeds from issuances of employee stock plans and direct stock purchase plan, net of taxes paid of $17, $11 and $8 in 2020, 2019 and 2018, respectively	9	15	16
Advances and contributions in aid of construction, net of refunds of $24, $30 and $22 in 2020, 2019 and 2018, respectively	28	26	21
Debt issuance costs and make-whole premium on early debt redemption	(15)	(15)	(22)
Dividends paid	(389)	(353)	(319)
Anti-dilutive share repurchases	0	(36)	(45)
Net cash provided by financing activities	1,120	494	726
Net increase (decrease) in cash, cash equivalents and restricted funds	485	(68)	76
Cash, cash equivalents and restricted funds at beginning of period	91	159	83
Cash, cash equivalents and restricted funds at end of period	576	91	159
Cash paid during the year for:
Interest, net of capitalized amount	382	383	332
Income taxes, net of refunds of $2, $4 and $0 in 2020, 2019 and 2018, respectively	7	12	38
Non-cash investing activity:
Capital expenditures acquired on account but unpaid as of year end	$ 221	$ 235	$ 181

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Cash Flows [Abstract]
Income taxes paid on proceeds from issuance of employee stock plans and direct stock purchase plan	$ 17	$ 11	$ 8
Advances and contributions for construction, refunds	24	30	22
Income taxes, refunds	$ 2	$ 4	$ 0

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions		Total	Cumulative effect of change in accounting principle	Common Stock	Paid-in Capital	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit)Cumulative effect of change in accounting principle	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2017				182,500,000					(4,100,000)
Beginning Balance at Dec. 31, 2017		$ 5,385	$ 20	$ 2	$ 6,432	$ (723)	$ 20	$ (79)	$ (247)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common shareholders		567				567
Common stock issuances (in shares)	[1]			2,900,000					(100,000)
Common stock issuances	[1]	219			225	(1)			$ (5)
Repurchases of common stock (in shares)									(500,000)
Repurchases of common stock		(45)							$ (45)
Net other comprehensive income		45						45
Dividends (declared per common share)		(327)				(327)
Ending Balance (in shares) at Dec. 31, 2018				185,400,000					(4,700,000)
Ending Balance at Dec. 31, 2018		5,864	$ (2)	$ 2	6,657	(464)	$ (2)	(34)	$ (297)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common shareholders		621				621
Common stock issuances (in shares)	[1]			500,000					(100,000)
Common stock issuances	[1]	$ 38			43				$ (5)
Repurchases of common stock (in shares)		(400,000)							(300,000)
Repurchases of common stock		$ (36)							$ (36)
Net other comprehensive income		(2)						(2)
Dividends (declared per common share)		(362)				(362)
Ending Balance (in shares) at Dec. 31, 2019				185,900,000					(5,100,000)
Ending Balance at Dec. 31, 2019		6,121		$ 2	6,700	(207)		(36)	$ (338)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common shareholders		709				709
Common stock issuances (in shares)	[1]			600,000					(100,000)
Common stock issuances	[1]	$ 37			47				$ (10)
Repurchases of common stock (in shares)		0
Net other comprehensive income		$ (13)						(13)
Dividends (declared per common share)		(400)				(400)
Ending Balance (in shares) at Dec. 31, 2020				186,500,000					(5,200,000)
Ending Balance at Dec. 31, 2020		$ 6,454		$ 2	$ 6,747	$ 102		$ (49)	$ (348)
[1]	Includes stock-based compensation, employee stock purchase plan and direct stock reinvestment and purchase plan activity, as well as the issuance of shares in order to fund to the purchase of Pivotal Home Solutions (“Pivotal”) in 2018.

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	Dec. 10, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (USD per share)	$ 0.55	$ 2.20	$ 2	$ 1.82

Allowance for Uncollectible Acc

Allowance for Uncollectible Accounts	12 Months Ended
	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for Uncollectible Accounts	Note 8: Allowance for Uncollectible Accounts Presented in the table below are the changes in the allowances for uncollectible accounts for the years ended December 31: 2020 2019 2018 Balance as of January 1 $ (41) $ (45) $ (42) Amounts charged to expense (34) (28) (33) Amounts written off 12 32 34 Recoveries of amounts written off — — (4) Less: Allowance for uncollectible accounts included in assets held for sale (a) 3 — — Balance as of December 31 $ (60) $ (41) $ (45) (a) This portion of the allowance for uncollectible accounts is related to the pending transactions contemplated by the Stock Purchase Agreement among the Company, the Company’s New York subsidiary and an affiliate of Liberty Utilities Co., and is included in assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information.

Organization and Operation

Organization and Operation	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Operation	Note 1: Organization and Operation American Water Works Company, Inc. (the “Company” or “American Water”) is a holding company for regulated and market-based subsidiaries throughout the United States. References to “parent company” mean American Water Works Company, Inc., without its subsidiaries. The Company’s primary business involves the ownership of regulated utilities that provide water and wastewater services in 16 states in the United States, collectively referred to as the “Regulated Businesses.” The Company also operates market-based businesses that provide water and wastewater services within non-reportable operating segments, collectively referred to as the “Market-Based Businesses.” The Company’s primary Market-Based Businesses include the Homeowner Services Group (“HOS”), which provides various warranty protection programs and other home services to residential customers; and the Military Services Group (“MSG”), which enters into long-term contracts with the U.S. government to provide water and wastewater services on various military installations.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Significant Accounting Policies	Note 2: Significant Accounting Policies Regulation The Company’s regulated utilities are subject to regulation by multiple state utility commissions or other entities engaged in utility regulation, collectively referred to as Public Utility Commissions (“PUCs”). As such, the Company follows authoritative accounting principles required for rate regulated utilities, which requires the effects of rate regulation to be reflected in the Company’s Consolidated Financial Statements. PUCs generally authorize revenue at levels intended to recover the estimated costs of providing service, plus a return on net investments, or rate base. Regulators may also approve accounting treatments, long-term financing programs and cost of capital, operation and maintenance (“O&M”) expenses, capital expenditures, taxes, affiliated transactions and relationships, reorganizations, mergers, acquisitions and dispositions, along with imposing certain penalties or granting certain incentives. Due to timing and other differences in the collection of a regulated utility’s revenues, these authoritative accounting principles allow a cost that would otherwise be charged as an expense by a non-regulated entity, to be deferred as a regulatory asset if it is probable that such cost is recoverable through future rates. Conversely, these principles also require the creation of a regulatory liability for amounts collected in rates to recover costs expected to be incurred in the future, or amounts collected in excess of costs incurred and are refundable to customers. See Note 4—Regulatory Matters for additional information. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires that management make estimates, assumptions and judgments that could affect the Company’s financial condition, results of operations and cash flows. Actual results could differ from these estimates, assumptions and judgments. The Company considers its critical accounting estimates to include (i) the application of regulatory accounting principles and the related determination and estimation of regulatory assets and liabilities, (ii) revenue recognition and the estimates used in the calculation of unbilled revenue, (iii) accounting for income taxes, (iv) benefit plan assumptions and (v) the estimates and judgments used in determining loss contingencies. The Company’s critical accounting estimates that are particularly sensitive to change in the near term are amounts reported for regulatory assets and liabilities, income taxes, benefit plan assumptions and contingency-related obligations. Principles of Consolidation The accompanying Consolidated Financial Statements include the accounts of American Water and all of its subsidiaries in which a controlling interest is maintained after the elimination of intercompany balances and transactions. Property, Plant and Equipment Property, plant and equipment consists primarily of utility plant utilized by the Company’s regulated utilities. Additions to utility plant and replacement of retirement units of utility plant are capitalized and include costs such as materials, direct labor, payroll taxes and benefits, indirect items such as engineering and supervision, transportation and an allowance for funds used during construction (“AFUDC”). Costs for repair, maintenance and minor replacements are charged to O&M expense as incurred. The cost of utility plant is depreciated using the straight-line average remaining life, group method. The Company’s regulated utilities record depreciation in conformity with amounts approved by PUCs, after regulatory review of the information the Company submits to support its estimates of the assets’ remaining useful lives. Nonutility property consists primarily of buildings and equipment utilized by the Company’s Market-Based Businesses and for internal operations. This property is stated at cost, net of accumulated depreciation, which is calculated using the straight-line method over the useful lives of the assets. When units of property, plant and equipment are replaced, retired or abandoned, the carrying value is credited against the asset and charged to accumulated depreciation. To the extent the Company recovers cost of removal or other retirement costs through rates after the retirement costs are incurred, a regulatory asset is recorded. In some cases, the Company recovers retirement costs through rates during the life of the associated asset and before the costs are incurred. These amounts result in a regulatory liability being reported based on the amounts previously recovered through customer rates, until the costs to retire those assets are incurred. The costs incurred to acquire and internally develop computer software for internal use are capitalized as a unit of property. The carrying value of these costs amounted to $360 million and $345 million as of December 31, 2020 and 2019, respectively. Cash and Cash Equivalents, and Restricted Funds Substantially all cash is invested in interest-bearing accounts. All highly liquid investments with a maturity of three months or less when purchased are considered to be cash equivalents. Restricted funds consist primarily of proceeds from financings for the construction and capital improvement of facilities, and deposits for future services under O&M projects. Proceeds are held in escrow or interest-bearing accounts until the designated expenditures are incurred. Restricted funds are classified on the Consolidated Balance Sheets as either current or long-term based upon the intended use of the funds. Presented in the table below is a reconciliation of the cash and cash equivalents and restricted funds amounts as presented on the Consolidated Balance Sheets to the sum of such amounts presented on the Consolidated Statements of Cash Flows for the years ended December 31: 2020 2019 Cash and cash equivalents $ 547 $ 60 Restricted funds 29 31 Cash and cash equivalents and restricted funds as presented on the Consolidated Statements of Cash Flows $ 576 $ 91 Accounts Receivable and Unbilled Revenues Accounts receivable include regulated utility customer accounts receivable, which represent amounts billed to water and wastewater customers generally on a monthly basis. Credit is extended based on the guidelines of the applicable PUCs and collateral is generally not required. Also included are market-based trade accounts receivable and nonutility customer receivables of the regulated subsidiaries. Unbilled revenues are accrued when service has been provided but has not been billed to customers and when costs exceed billings on market-based construction contracts. Allowance for Uncollectible Accounts Allowances for uncollectible accounts are maintained for estimated probable losses resulting from the Company’s inability to collect receivables from customers. Accounts that are outstanding longer than the payment terms are considered past due. A number of factors are considered in determining the allowance for uncollectible accounts, including the length of time receivables are past due, previous loss history, current economic and societal conditions and reasonable and supportable forecasts that affect the collectability of receivables from customers. The Company generally writes off accounts when they become uncollectible or are over a certain number of days outstanding. An increase in the allowance for uncollectible accounts for the period ending December 31, 2020 reflects the impacts from the current novel coronavirus (“COVID-19”) pandemic, including an increase in uncollectible accounts expense and a reduction in amounts written off due to shutoff moratoria in place across the Company’s subsidiaries. See Note 8—Allowance for Uncollectible Accounts for additional information. Materials and Supplies Materials and supplies are stated at the lower of cost or net realizable value. Cost is determined using the average cost method. Leases On January 1, 2019, the Company adopted Accounting Standards Update 2016-02, Leases (Topic 842) , and all related amendments (collectively, the “Standard”). The Company implemented the guidance in the Standard using the modified retrospective approach and applied the optional transition method, which allowed entities to apply the new Standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Under this approach, prior periods have not been restated and continue to be reported under the accounting standards in effect for those periods. The Standard includes practical expedients, which relate to the identification and classification of leases that commenced before the adoption date, initial direct costs for leases that commenced before the adoption date, the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset and the ability to carry forward accounting treatment for existing land easements. Adoption of the Standard resulted in the recognition of operating lease right-of-use (“ROU”) assets and operating lease liabilities as of January 1, 2019 of approximately $117 million and $115 million, respectively. The difference between the ROU assets and operating lease liabilities was recorded as an adjustment to retained earnings. The Standard did not materially impact the Company’s consolidated results of operations and had no impact on cash flows. The Company has operating and finance leases involving real property, including facilities, utility assets, vehicles, and equipment. The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease ROU assets, accrued liabilities and operating lease liabilities on the Consolidated Balance Sheets. Finance leases are included in property, plant and equipment, accrued liabilities and other long-term liabilities on the Consolidated Balance Sheets. The Company has made an accounting policy election not to include operating leases with a lease term of twelve months or less. ROU assets represent the right to use an underlying asset for the lease term and the lease liabilities represent the obligation to make lease payments arising from the lease. ROU assets and lease liabilities are generally recognized at the commencement date based on the present value of discounted lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of discounted lease payments. The implicit rate is used when readily determinable. ROU assets also include any upfront lease payments and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease components (e.g., fixed payments including rent, real estate taxes and insurance costs) and non-lease components (e.g., common-area maintenance costs), which are generally accounted for separately; however, the Company accounts for the lease and non-lease components as a single lease component for certain leases. Certain lease agreements include variable rental payments adjusted periodically for inflation. Additionally, the Company applies a portfolio approach to effectively account for the ROU assets and lease liabilities. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. Goodwill Goodwill represents the excess of the purchase price paid over the estimated fair value of the assets acquired and liabilities assumed in the acquisition of a business. Goodwill is not amortized and must be allocated at the reporting unit level, which is defined as an operating segment or one level below, and tested for impairment at least annually, or more frequently if an event occurs or circumstances change that would more likely than not, reduce the fair value of a reporting unit below its carrying value. The Company’s goodwill is primarily associated with (i) the acquisition of American Water by an affiliate of the Company’s previous owner in 2003, (ii) the acquisition of E’town Corporation by a predecessor to the Company’s previous owner in 2001, and (iii) the acquisition of Pivotal in 2018; and has been allocated to reporting units based on the fair values at the date of the acquisitions. For purposes of testing goodwill for impairment, the reporting units in the Regulated Businesses segment are aggregated into a single reporting unit. The Market-Based Businesses is comprised of the HOS and MSG reporting units. The Company’s annual impairment testing is performed as of November 30 of each year, in conjunction with the completion of the Company’s annual business plan. The Company assesses qualitative factors to determine whether quantitative testing is necessary. If it is determined, based upon qualitative factors, that the estimated fair value of a reporting unit is more likely than not, greater than its carrying value, no further testing is required. If the Company bypasses the qualitative assessment, or performs the qualitative assessment and determines that the estimated fair value of a reporting unit is more likely than not, less than its carrying value, a quantitative, fair value-based test is performed. This quantitative testing compares the estimated fair value of the reporting unit to its respective net carrying value, including goodwill, on the measurement date. An impairment loss will be recognized in the amount equal to the excess of the reporting unit’s carrying value compared to its estimated fair value, limited to the total amount of goodwill allocated to that reporting unit. Application of goodwill impairment testing requires management judgment, including the identification of reporting units and determining the fair value of reporting units. Management estimates fair value using a discounted cash flow analysis. Significant assumptions used in these fair value estimations include, but are not limited to, forecasts of future operating results, discount and growth rates. The Company believes the assumptions and other considerations used to value goodwill to be appropriate, however, if actual experience differs from the assumptions and considerations used in its analysis, the resulting change could have a material adverse impact on the Consolidated Financial Statements. See Note 9—Goodwill and Other Intangible Assets for additional information. Intangible Assets Intangible assets consist primarily of finite-lived customer relationships associated with the acquisition of Pivotal. Finite-lived intangible assets are initially measured at their estimated fair values, and are amortized over their estimated useful lives based on the pattern in which the economic benefits of the intangible assets are consumed or otherwise used. See Note 9—Goodwill and Other Intangible Assets for additional information. Impairment of Long-Lived Assets Long-lived assets include property, plant and equipment, goodwill, intangible assets and long-term investments. The Company evaluates long-lived assets for impairment when circumstances indicate the carrying value of those assets may not be recoverable. When such indicators arise, the Company estimates the fair value of the long-lived asset from future cash flows expected to result from its use and, if applicable, the eventual disposition of the asset, comparing the estimated fair value to the carrying value of the asset. An impairment loss will be recognized in the amount equal to the excess of the long-lived asset’s carrying value compared to its estimated fair value. The long-lived assets of the Company’s regulated utilities are grouped on a separate entity basis for impairment testing, as they are integrated state-wide operations that do not have the option to curtail service and generally have uniform tariffs. A regulatory asset is charged to earnings if and when future recovery in rates of that asset is no longer probable. The Company believes the assumptions and other considerations used to value long-lived assets to be appropriate, however, if actual experience differs from the assumptions and considerations used in its estimates, the resulting change could have a material adverse impact on the Consolidated Financial Statements. Advances for Construction and Contributions in Aid of Construction Regulated utility subsidiaries may receive advances for construction and contributions in aid of construction from customers, home builders and real estate developers to fund construction necessary to extend service to new areas. Advances are refundable for limited periods of time as new customers begin to receive service or other contractual obligations are fulfilled. Included in other current liabilities as of December 31, 2020 and 2019 on the Consolidated Balance Sheets are estimated refunds of $23 million and $25 million, respectively. Those amounts represent expected refunds during the next 12-month period. Advances that are no longer refundable are reclassified to contributions. Contributions are permanent collections of plant assets or cash for a particular construction project. For ratemaking purposes, the amount of such contributions generally serves as a rate base reduction since the contributions represent non-investor supplied funds. Generally, the Company depreciates utility plant funded by contributions and amortizes its contributions balance as a reduction to depreciation expense, producing a result which is functionally equivalent to reducing the original cost of the utility plant for the contributions. In accordance with applicable regulatory guidelines, some of the Company’s utility subsidiaries do not amortize contributions, and any contribution received remains on the balance sheet indefinitely. Amortization of contributions in aid of construction was $32 million, $29 million and $28 million for the years ended December 31, 2020, 2019 and 2018, respectively. Revenue Recognition On January 1, 2018, the Company adopted Accounting Standards Codification Topic 606, Revenue From Contracts With Customers, and all related amendments (collectively, “ASC 606”) , using the modified retrospective approach, applied to contracts which were not completed as of January 1, 2018. Under ASC 606, a performance obligation is a promise within a contract to transfer a distinct good or service, or a series of distinct goods and services, to a customer. Revenue is recognized when performance obligations are satisfied and the customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for goods or services. Under ASC 606, a contract’s transaction price is allocated to each distinct performance obligation. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identifies the contracts with a customer; (ii) identifies the performance obligations within the contract, including whether any performance obligations are distinct and capable of being distinct in the context of the contract; (iii) determines the transaction price; (iv) allocates the transaction price to the performance obligations in the contract; and (v) recognizes revenue when, or as, the Company satisfies each performance obligation. The Company’s revenues from contracts with customers are discussed below. Customer payments for contracts are generally due within 30 days of billing and none of the contracts with customers have payment terms that exceed one year; therefore, the Company elected to apply the significant financing component practical expedient and no amount of consideration has been allocated as a financing component. Regulated Businesses Revenue Revenue from the Company’s Regulated Businesses is generated primarily from water and wastewater services delivered to customers. These contracts contain a single performance obligation, the delivery of water and/or wastewater services, as the promise to transfer the individual good or service is not separately identifiable from other promises within the contracts and, therefore, is not distinct. Revenues are recognized over time, as services are provided. There are generally no significant financing components or variable consideration. Revenues include amounts billed to customers on a cycle basis and unbilled amounts calculated based on estimated usage from the date of the meter reading associated with the latest customer bill, to the end of the accounting period. The amounts that the Company has a right to invoice are determined by each customer’s actual usage, an indicator that the invoice amount corresponds directly to the value transferred to the customer. The Company also recognizes revenue when it is probable that future recovery of previously incurred costs or future refunds that are to be credited to customers will occur through the ratemaking process. Market-Based Businesses Revenue Through various warranty protection programs and other home services, the Company provides fixed fee services to residential customers for interior and exterior water and sewer lines, interior electric and gas lines, heating and cooling systems, water heaters and other home appliances, as well as power surge protection and other related services. Most of the contracts have a one-year term and each service is a separate performance obligation, satisfied over time, as the customers simultaneously receive and consume the benefits provided from the service. Customers are obligated to pay for the protection programs ratably over 12 months or via a one-time, annual fee, with revenues recognized ratably over time for these services. Advances from customers are deferred until the performance obligation is satisfied. The Company also has long-term, fixed fee contracts to operate and maintain water and wastewater systems for the U.S. government on various military installations and facilities owned by municipal customers. Billing and revenue recognition for the fixed fee revenues occurs ratably over the term of the contract, as customers simultaneously receive and consume the benefits provided by the Company. Additionally, these contracts allow the Company to make capital improvements to underlying infrastructure, which are initiated through separate modifications or amendments to the original contract, whereby stand-alone, fixed pricing is separately stated for each improvement. The Company has determined that these capital improvements are separate performance obligations, with revenue recognized over time based on performance completed at the end of each reporting period. Losses on contracts are recognized during the period in which the losses first become probable and estimable. Revenues recognized during the period in excess of billings on construction contracts are recorded as unbilled revenues, with billings in excess of revenues recorded as other current liabilities until the recognition criteria are met. Changes in contract performance and related estimated contract profitability may result in revisions to costs and revenues, and are recognized in the period in which revisions are determined. See Note 5—Revenue Recognition for additional information. Income Taxes The Company and its subsidiaries participate in a consolidated federal income tax return for U.S. tax purposes. Members of the consolidated group are charged with the amount of federal income tax expense determined as if they filed separate returns. Certain income and expense items are accounted for in different time periods for financial reporting than for income tax reporting purposes. The Company provides deferred income taxes on the difference between the tax basis of assets and liabilities and the amounts at which they are carried in the financial statements. These deferred income taxes are based on the enacted tax rates expected to be in effect when these temporary differences are projected to reverse. In addition, the regulated utility subsidiaries recognize regulatory assets and liabilities for the effect on revenues expected to be realized as the tax effects of temporary differences, previously flowed through to customers, reverse. Investment tax credits have been deferred by the regulated utility subsidiaries and are being amortized to income over the average estimated service lives of the related assets. The Company recognizes accrued interest and penalties related to tax positions as a component of income tax expense and accounts for sales tax collected from customers and remitted to taxing authorities on a net basis. See Note 15—Income Taxes for additional information. Allowance for Funds Used During Construction AFUDC is a non-cash credit to income with a corresponding charge to utility plant that represents the cost of borrowed funds or a return on equity funds devoted to plant under construction. The regulated utility subsidiaries record AFUDC to the extent permitted by the PUCs. The portion of AFUDC attributable to borrowed funds is shown as a reduction of interest, net on the Consolidated Statements of Operations. Any portion of AFUDC attributable to equity funds would be included in other, net on the Consolidated Statements of Operations. Presented in the table below is AFUDC for the years ended December 31: 2020 2019 2018 Allowance for other funds used during construction $ 30 $ 28 $ 24 Allowance for borrowed funds used during construction 13 13 13 Environmental Costs The Company’s water and wastewater operations and the operations of its Market-Based Businesses are subject to U.S. federal, state, local and foreign requirements relating to environmental protection, and as such, the Company periodically becomes subject to environmental claims in the normal course of business. Environmental expenditures that relate to current operations or provide a future benefit are expensed or capitalized as appropriate. Remediation costs that relate to an existing condition caused by past operations are accrued, on an undiscounted basis, when it is probable that these costs will be incurred and can be reasonably estimated. A conservation agreement entered into by a subsidiary of the Company with the National Oceanic and Atmospheric Administration in 2010 and amended in 2017 required the subsidiary to, among other provisions, implement certain measures to protect the steelhead trout and its habitat in the Carmel River watershed in the State of California. The subsidiary agreed to pay $1 million annually commencing in 2010 with the final payment being made in 2021. Remediation costs accrued amounted to $1 million and $2 million as of December 31, 2020 and 2019, respectively. Derivative Financial Instruments The Company uses derivative financial instruments for purposes of hedging exposures to fluctuations in interest rates. These derivative contracts are entered into for periods consistent with the related underlying exposures and do not constitute positions independent of those exposures. The Company does not enter into derivative contracts for speculative purposes and does not use leveraged instruments. All derivatives are recognized on the balance sheet at fair value. On the date the derivative contract is entered into, the Company may designate the derivative as a hedge of the fair value of a recognized asset or liability (fair-value hedge) or a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability (cash-flow hedge). Changes in the fair value of a fair-value hedge, along with the gain or loss on the underlying hedged item, are recorded in current-period earnings. The gains and losses on the effective portion of cash-flow hedges are recorded in other comprehensive income, until earnings are affected by the variability of cash flows. Any ineffective portion of designated cash-flow hedges is recognized in current-period earnings. Cash flows from derivative contracts are included in net cash provided by operating activities on the Consolidated Statements of Cash Flows. See Note 12—Long-Term Debt for additional information. New Accounting Standards Presented in the table below are new accounting standards that were adopted by the Company in 2020: Standard Description Date of Adoption Application Effect on the Consolidated Financial Statements Measurement of Credit Losses on Financial Instruments Updated the accounting guidance on reporting credit losses for financial assets held at amortized cost basis and available-for-sale debt securities. Under this guidance, expected credit losses are required to be measured based on historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of the reported amount of financial assets. Also, this guidance requires that credit losses on available-for-sale debt securities be presented as an allowance rather than as a direct write-down. January 1, 2020 Modified retrospective The standard did not have a material impact on the Consolidated Financial Statements. Changes to the Disclosure Requirements for Fair Value Measurement Updated the disclosure requirements for fair value measurement. The guidance removes the requirements to disclose transfers between Level 1 and Level 2 measurements, the timing of transfers between levels, and the valuation processes for Level 3 measurements. Disclosure of transfers into and out of Level 3 measurements will be required. The guidance adds disclosure requirements for the change in unrealized gains and losses in other comprehensive income for recurring Level 3 measurements, as well as the range and weighted average of significant unobservable inputs used to develop Level 3 measurements. January 1, 2020 Prospective for added disclosures and for the narrative description of measurement uncertainty; retrospective for all other amendments. The standard did not have a material impact on the Consolidated Financial Statements. Facilitation of the Effects of Reference Rate Reform on Financial Reporting Provided optional guidance for a limited time to ease the potential accounting burden associated with the transition from London Interbank Offered Rate (“LIBOR”). The guidance contains optional expedients and exceptions for contract modifications, hedging relationships, and other transactions that reference LIBOR or other reference rates expected to be discontinued. The expedients elected must be applied for all eligible contracts or transactions, with the exception of hedging relationships, which can be applied on an individual basis. March 12, 2020 through December 31, 2022 Prospective for contract modifications and hedging relationships; applied as of January 1, 2020. The standard did not have a material impact on the Consolidated Financial Statements. Presented in the table below are recently issued accounting standards that have not yet been adopted by the Company as of December 31, 2020: Standard Description Date of Adoption Application Estimated Effect on the Consolidated Financial Statements Simplifying the Accounting for Income Taxes The guidance removes exceptions related to the incremental approach for intraperiod tax allocation, the requirement to recognize a deferred tax liability for changes in ownership of a foreign subsidiary or equity method investment, and the general methodology for calculating income taxes in an interim period when the year-to-date loss exceeds the anticipated loss. The guidance adds requirements to reflect changes to tax laws or rates in the annual effective tax rate computation in the interim period in which the changes were enacted, to recognize franchise or other similar taxes that are partially based on income as an income-based tax and any incremental amounts as non-income-based tax, and to evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction. January 1, 2021; early adoption permitted Modified retrospective for amendments related to changes in ownership of a foreign subsidiary or equity method investment; The standard will not have a material impa

Impact of Novel Coronavirus (CO

Impact of Novel Coronavirus (COVID-19) Pandemic	12 Months Ended
	Dec. 31, 2020
Risks and Uncertainties [Abstract]
Impact of Novel Coronavirus (COVID-19) Pandemic	Note 3: Impact of Novel Coronavirus (COVID-19) Pandemic American Water has been monitoring the global outbreak of the COVID-19 pandemic. To date, the Company has experienced COVID-19 financial impacts, including an increase in uncollectible accounts expense, additional debt costs, and certain incremental O&M expenses. The Company has also experienced decreased revenues as a result of the suspension of late fees and foregone reconnect fees. These impacts are collectively referred to as “financial impacts.” As of February 24, 2021, American Water has commission orders authorizing deferred accounting for COVID-19 financial impacts in 11 of 14 jurisdictions, with proceedings in two jurisdictions pending. In addition to approving deferred accounting, to date, two regulatory jurisdictions have also approved cost recovery mechanisms for specified COVID-19 financial impacts. Regulatory actions to date are presented in the table below: Commission Actions Description States Orders issued Allows the Company to establish regulatory assets to record certain financial impacts related to the COVID-19 pandemic. CA, HI, IA, IL, IN, MD, MO, NJ, PA, VA, WV Cost recovery mechanisms California’s Catastrophic Event Memorandum Account allows the Company to track and recover certain financial impacts related to the COVID-19 pandemic. Illinois has authorized cost recovery of COVID-19 financial impacts through a special purpose rider over a 24-month period, which was implemented by the Company’s Illinois subsidiary effective October 1, 2020. Additionally, Illinois approved a bad debt rider tariff on December 16, 2020. This rider will allow the Company to collect actual bad debt expense over last authorized beginning March 2021 over a 24-month period. CA, IL Proceedings pending Pending proceedings considering deferred accounting authorization for the future recovery of COVID-19 financial impacts. NY, TN Consistent with these regulatory orders, the Company has recorded $30 million in regulatory assets and $4 million of regulatory liabilities for the financial impacts related to the COVID-19 pandemic on the Consolidated Balance Sheets as of December 31, 2020. On December 30, 2020, the Company’s Kentucky subsidiary received an order denying its request to defer to a regulatory asset the financial impacts related to the COVID-19 pandemic. As of February 24, 2021, six states have ordered active moratoria on the suspension of service disconnections due to non-payment. The moratoria on disconnects have expired in eight states.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2020
Regulated Operations [Abstract]
Regulatory Matters	Note 4: Regulatory Matters General Rate Cases Presented in the table below are annualized incremental revenues, assuming a constant water sales volume, resulting from general rate cases authorizations that became effective during 2018 through 2020: (In millions) 2020 2019 2018 General rate cases by state: New Jersey (a) $ 39 $ — $ 40 Indiana (b) 13 4 — California (c) 5 4 10 Virginia (d) (1) — — Kentucky (effective June 28, 2019) — 13 — New York (e) — 4 5 West Virginia (effective February 25, 2019) — 19 — Maryland (effective February 5, 2019) — 1 — Missouri (effective May 28, 2018) — — 33 Pennsylvania (effective January 1, 2018) — — 62 Total general rate case authorizations $ 56 $ 45 $ 150 (a) The $39 million base rate increase was effective on November 1, 2020, which is net of excess accumulated deferred income taxes (“EADIT”) of $15 million being returned to customers. The unprotected EADIT balance of $133 million is being returned to customers over 15 years. The $39 million rate increase was further reduced by a bill credit, for a 10-month period beginning November 1, 2020 for both the protected and unprotected catch up period EADIT of $32.5 million. The catch up period of January 1, 2018 through October 31, 2020 covers the period from when the lower federal tax rate went into effect until new base rates went into effect. The $40 million rate increase was effective on June 15, 2018. As part of the resolution of the general rate case in 2018, the Company’s New Jersey subsidiary’s customers received refunds for the amount of provisional rates implemented as of June 15, 2018 that exceeded the final rate increase plus interest. (b) The Company’s Indiana subsidiary received an order approving a joint settlement agreement with all major parties with respect to its general rate case filing, authorizing annualized incremental revenues of $4 million in the first rate year, effective July 1, 2019, and $13 million in the second rate year, effective May 1, 2020. (c) The Company’s California subsidiary received approval for the third year (2020) step increase associated with its most recent general rate case authorization, effective January 1, 2020. In 2019, the step increase was effective May 11, 2019. On December 13, 2018, a settlement in this subsidiary’s general rate case filing was approved, authorizing rates effective January 1, 2018. (d) The Company’s Virginia subsidiary received an order approving increased water revenues by $1 million, inclusive of Water & Wastewater Infrastructure Service Charge (“WWISC”) revenues of $1 million, and decreased wastewater revenue by $1 million, for a net zero award including WWISC, or an overall decrease of $1 million excluding WWISC. Unprotected EADIT is being returned to customers over eight years, and base rates include a reduction of $1 million for EADIT. (e) The Company’s New York subsidiary implemented its third step increase associated with its most recent general rate case authorization, effective April 1, 2019. Due in part to the COVID-19 pandemic, the New York State Public Service Commission (the “NYSPSC”) approved, through a series of orders, the Company’s New York subsidiary’s request to postpone the previously approved step increase, originally scheduled to go into effect April 1, 2020 until May 1, 2021. The orders provided a make whole provision to recover the delayed revenues with no earnings impact. These delays impact rates for all metered and fire customers, which the Company is authorized to recover in a make-whole surcharge beginning May 1, 2021. Pending General Rate Case Filings On August 28, 2020, the Company’s Iowa subsidiary filed a general rate case requesting $3 million in annualized incremental revenues. Office of Consumer Advocate (“OCA”) and intervenor direct testimony was filed on December 17, 2020 and cross-reply testimony was filed on December 31, 2020. The Company’s Iowa subsidiary reply testimony was filed on January 14, 2021, and OCA rebuttal testimony was filed on February 8, 2021. Evidentiary hearings are scheduled to start March 3, 2021. An order is anticipated by April 30, 2021 with new rates effective by July 1, 2021. On June 30, 2020, the Company’s Missouri subsidiary filed a general rate case requesting $78 million in annualized incremental revenues. On August 26, 2020, the Missouri Public Service Commission (the “MPSC”) issued an order setting the test year and adopting a procedural schedule. Revenue requirement direct testimony was submitted on November 24, 2020 for all non-Company parties, and a technical conference was held on December 3, 2020. Cost of service and rate design direct testimony was submitted on December 9, 2020 for all non-company parties. Rebuttal testimony was submitted on January 15, 2021 for revenue requirement and on January 22, 2021 for rate design, and true-up data was filed on January 29, 2021, which included known and measurable changes through December 31, 2020. Settlement conferences commenced on February 16, 2021. A Motion to Suspend Procedural Schedule was filed on February 23, 2021 with the MPSC by all parties to the proceeding. The MPSC issued an order effective February 24, 2021 suspending the procedural schedule to allow for either a stipulation and agreement or a status report to be filed no later than February 26, 2021. On April 29, 2020, the Company’s Pennsylvania subsidiary filed a general rate case requesting $92 million and $46 million in annualized incremental revenues for rate year 1 and rate year 2, respectively. On October 30, 2020, the Company’s Pennsylvania subsidiary and the Bureau of Investigation and Enforcement entered into a settlement agreement providing for a total annualized revenue increase of $71 million over a two On July 1, 2019, the Company’s California subsidiary filed a general rate case requesting $26 million in annualized incremental revenues for 2021, and increases of $10 million and $11 million in the escalation year of 2022 and the attrition year of 2023, respectively. On October 11, 2019, the Company filed its 100 day update for the same proceeding and updated the request to $27 million in annualized incremental revenues for 2021, and increases of $10 million and $10 million in the escalation year of 2022 and the attrition year of 2023, respectively. On September 10, 2020, the California Public Utilities Commission (the “CPUC”) approved the Company’s California subsidiary’s motion for interim rates, establishing a memorandum account to track the difference between interim and final rates adopted by the CPUC in this proceeding, which were effective on January 1, 2021. Following settlement discussions among all parties to the proceeding, on January 22, 2021 and January 25, 2021, the Company’s California subsidiary filed with the CPUC a comprehensive settlement entered into among the Company’s California subsidiary, the Public Advocates Office, and other intervenors. These settlement agreements resolved all matters in dispute among the parties to the settlements. These settlements as well as resolution of issues raised by non-settling parties are now before the CPUC for approval. On January 22, 2020, the Company’s California subsidiary submitted a request to delay by one year its cost of capital filing and maintain its current authorized cost of capital through 2021. On March 12, 2020, the CPUC granted the request for a one year extension of the cost of capital filing to May 1, 2021, to set its authorized cost of capital beginning January 1, 2022. On January 5, 2021, the Company’s California subsidiary submitted a request to further delay by one year its cost of capital filing and maintain the authorized cost of capital through 2022. On February 22, 2021, the CPUC denied the request to further delay the cost of capital filing. The Company’s California subsidiary will submit a cost of capital application by May 1, 2021, with a new authorized cost of capital beginning January 1, 2022. Infrastructure Surcharges A number of states have authorized the use of regulatory mechanisms that permit rates to be adjusted outside of a general rate case for certain costs and investments, such as infrastructure surcharge mechanisms that permit recovery of capital investments to replace aging infrastructure. Presented in the table below are annualized incremental revenues, assuming a constant water sales volume, resulting from infrastructure surcharge authorizations that became effective during 2018 through 2020: (In millions) 2020 2019 2018 Infrastructure surcharges by state: Missouri (a) $ 12 $ 14 $ 6 Pennsylvania (b) 27 11 — Kentucky (effective July 1, 2020) 1 — — New Jersey (c) 20 15 — Tennessee (effective January 1, 2020, September 1, 2019 and April 10, 2018) 2 1 1 Illinois (effective January 1, 2020, January 1, 2019 and January 1, 2018) 7 8 3 West Virginia (effective January 1, 2020, January 1, 2019 and January 1, 2018) 3 2 3 New York (effective August 1, 2019) — 2 — Indiana (effective March 14, 2018) — — 7 Virginia (effective March 1, 2018) — — 1 Total infrastructure surcharge authorizations $ 72 $ 53 $ 21 (a) In 2020, $2 million was effective December 14 and $10 million was effective June 27. In 2019, $5 million was effective December 21 and $9 million was effective June 24. In 2018, the effective date was December 15. (b) In 2020, $8 million was effective October 1, $4 million was effective July 1, $5 million was effective April 1 and $10 million was effective January 1. In 2019, $6 million was effective October 1, $3 million was effective July 1 and $2 million was effective April 1. (c) In 2020, $10 million was effective June 29 and $10 million was effective January 1. In 2019, the effective date was July 1. Presented in the table below are annualized incremental revenues, assuming a constant water sales volume, resulting from infrastructure surcharge authorizations that became effective after January 1, 2020: (In millions) Amount Infrastructure surcharge filings by state: Pennsylvania (effective January 1, 2021) $ 8 Illinois (effective January 1, 2021) 7 West Virginia (effective January 1, 2021) 5 Tennessee (effective January 1, 2021) 3 Total infrastructure surcharge filings $ 23 Pending Infrastructure Surcharge Filings On January 15, 2021, the Company’s Indiana subsidiary filed for an infrastructure surcharge requesting $8 million in additional annualized revenues. On May 29, 2020, the Company’s New York subsidiary filed for an infrastructure surcharge requesting $1 million in additional annualized revenues. New rates related to this infrastructure surcharge were first deferred until January 1, 2021. Thereafter, on December 30, 2020, the NYSPSC ordered the postponement of rate changes until May 1, 2021, which will be recoverable, with interest, through a separate, make-whole recovery mechanism commencing May 1, 2021 through March 31, 2022. Regulatory Assets Regulatory assets represent costs that are probable of recovery from customers in future rates. Approximately 50% of the Company’s total regulatory asset balance at December 31, 2020 earns a return. Presented in the table below is the composition of regulatory assets as of December 31: 2020 2019 Deferred pension expense $ 374 $ 384 Removal costs recoverable through rates 314 305 Regulatory balancing accounts 57 96 Other 446 398 Less: Regulatory assets included in assets held for sale (a) (64) (55) Total regulatory assets $ 1,127 $ 1,128 (a) These regulatory assets are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information. The Company’s deferred pension expense includes a portion of the underfunded status that is probable of recovery through rates in future periods of $366 million and $375 million as of December 31, 2020 and 2019, respectively. The remaining portion is the pension expense in excess of the amount contributed to the pension plans which is deferred by certain subsidiaries and will be recovered in future service rates as contributions are made to the pension plan. Removal costs recoverable through rates represent costs incurred for removal of property, plant and equipment or other retirement costs. Regulatory balancing accounts accumulate differences between revenues recognized and authorized revenue requirements until they are collected from customers or are refunded. Regulatory balancing accounts include low income programs and purchased power and water accounts. Other regulatory assets include the financial impacts relating to the COVID-19 pandemic, purchase premium recoverable through rates, tank painting costs, certain construction costs for treatment facilities, property tax stabilization, employee-related costs, business services project expenses, coastal water project costs, rate case expenditures and environmental remediation costs among others. These costs are deferred because the amounts are being recovered in rates or are probable of recovery through rates in future periods. Regulatory Liabilities Regulatory liabilities generally represent amounts that are probable of being credited or refunded to customers through the rate making process. Also, if costs expected to be incurred in the future are currently being recovered through rates, the Company records those expected future costs as regulatory liabilities. Presented in the table below is the composition of regulatory liabilities as of December 31: 2020 2019 Income taxes recovered through rates $ 1,230 $ 1,258 Removal costs recovered through rates 301 297 Postretirement benefit liability 170 186 Other 111 102 Less: Regulatory liabilities included in liabilities related to assets held for sale (a) (42) (37) Total regulatory liabilities $ 1,770 $ 1,806 (a) These regulatory liabilities are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in liabilities related to assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information. Income taxes recovered through rates relate to deferred taxes that will likely be refunded to the Company’s customers. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “TCJA”) was signed into law, which, among other things, enacted significant and complex changes to the Code, including a reduction in the federal corporate income tax rate from 35% to 21% as of January 1, 2018. The enactment of the TCJA required a re-measurement of the Company’s deferred income taxes. The portion of this re-measurement related to the Regulated Businesses was substantially offset by a regulatory liability as excess accumulated deferred income taxes (“EADIT”) will be used to benefit its regulated customers in future rates. Nine of the Company’s regulated subsidiaries are amortizing EADIT and crediting customers, including one which is using the EADIT to offset future infrastructure investments. The Company expects the timing of the amortization of EADIT credits by the five remaining regulated subsidiaries to be addressed in pending or future rate cases or other proceedings. Removal costs recovered through rates are estimated costs to retire assets at the end of their expected useful lives that are recovered through customer rates over the lives of the associated assets. On August 31, 2018, the Postretirement Medical Benefit Plan was remeasured to reflect an announced plan amendment which changed benefits for certain union and non-union plan participants. As a result of the remeasurement, the Company recorded a $227 million reduction to the net accumulated postretirement benefit obligation, with a corresponding regulatory liability. Other regulatory liabilities include the financial impacts relating to the COVID-19 pandemic, TCJA reserve on revenue, pension and other postretirement benefit balancing accounts, legal settlement proceeds, deferred gains and various regulatory balancing accounts.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Note 5: Revenue Recognition Disaggregated Revenues Presented in the table below are operating revenues disaggregated for the year ended December 31, 2020: Revenues from Contracts with Customers Other Revenues Not from Contracts with Customers (a) Total Operating Revenues Regulated Businesses: Water services: Residential $ 1,895 $ — $ 1,895 Commercial 627 — 627 Fire service 147 — 147 Industrial 133 — 133 Public and other 201 — 201 Total water services 3,003 — 3,003 Wastewater services: Residential 134 — 134 Commercial 34 — 34 Industrial 3 — 3 Public and other 14 — 14 Total wastewater services 185 — 185 Miscellaneous utility charges 32 — 32 Alternative revenue programs — 25 25 Lease contract revenue — 10 10 Total Regulated Businesses 3,220 35 3,255 Market-Based Businesses 540 — 540 Other (17) (1) (18) Total operating revenues $ 3,743 $ 34 $ 3,777 (a) Includes revenues associated with provisional rates, alternative revenue programs, lease contracts and intercompany rent, which are outside the scope of ASC 606, and accounted for under other existing GAAP. Contract Balances Contract assets and contract liabilities are the result of timing differences between revenue recognition, billings and cash collections. In the Company’s Market-Based Businesses, certain contracts are billed as work progresses in accordance with agreed-upon contractual terms, either at periodic intervals or upon achievement of contractual milestones. Contract assets are recorded when billing occurs subsequent to revenue recognition and are reclassified to accounts receivable when billed and the right to consideration becomes unconditional. Contract liabilities are recorded when the Company receives advances from customers prior to satisfying contractual performance obligations, particularly for construction contracts and home warranty protection program contracts, and are recognized as revenue when the associated performance obligations are satisfied. Contract assets of $39 million, $13 million and $14 million are included in unbilled revenues on the Consolidated Balance Sheets as of December 31, 2020, 2019 and 2018, respectively. There were $60 million of contract assets added during 2020, and $34 million of contract assets were transferred to accounts receivable during 2020. There were $27 million of contract assets added during 2019, and $28 million of contract assets were transferred to accounts receivable during 2019. Contract liabilities of $35 million, $27 million and $20 million are included in other current liabilities on the Consolidated Balance Sheets as of December 31, 2020, 2019 and 2018, respectively. There were $120 million of contract liabilities added during 2020, and $112 million of contract liabilities were recognized as revenue during 2020. There were $62 million of contract liabilities added during 2019, and $55 million of contract liabilities were recognized as revenue during 2019. Remaining Performance Obligations Remaining performance obligations (“RPOs”) represent revenues the Company expects to recognize in the future from contracts that are in progress. The Company enters into agreements for the provision of services to water and wastewater facilities for the U.S. military, municipalities and other customers. As of December 31, 2020, the Company’s O&M and capital improvement contracts in the Market-Based Businesses have RPOs. Contracts with the U.S. government for work on various military installations expire between 2051 and 2071 and have RPOs of $6.3 billion as of December 31, 2020, as measured by estimated remaining contract revenue. Such contracts are subject to customary termination provisions held by the U.S. government, prior to the agreed-upon contract expiration. Contracts with municipalities and commercial customers expire between 2021 and 2038 and have RPOs of $478 million as of December 31, 2020, as measured by estimated remaining contract revenue. Some of the Company’s long-term contracts to operate and maintain the federal government’s, a municipality’s or other party’s water or wastewater treatment and delivery facilities include responsibility for certain maintenance for some of those facilities, in exchange for an annual fee. Unless specifically required to perform certain maintenance activities, the maintenance costs are recognized when the maintenance is performed.

Acquisitions and Divestitures

Acquisitions and Divestitures	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Acquisitions and Divestitures	Note 6: Acquisitions and Divestitures Regulated Businesses Acquisitions During 2020, the Company closed on 23 acquisitions of various regulated water and wastewater systems for a total aggregate purchase price of $135 million. Assets acquired from these acquisitions, principally utility plant, totaled $159 million and liabilities assumed totaled $29 million, including $21 million of contributions in aid of construction and assumed debt of $7 million. The Company recorded additional goodwill of $5 million associated with two of its acquisitions, which is reported in its Regulated Businesses segment. Several of these acquisitions were accounted for as business combinations, as the Company continues to grow its business through regulated acquisitions. The preliminary purchase price allocations related to acquisitions accounted for as business combinations will be finalized once the valuation of assets acquired has been completed, no later than one year after their acquisition date. During 2019, the Company closed on 21 acquisitions of various regulated water and wastewater systems for a total aggregate purchase price of $235 million. Assets acquired from these acquisitions, principally utility plant, totaled $237 million and liabilities assumed, primarily contributions in aid of construction, totaled $5 million. The Company recorded additional goodwill of $3 million associated with three of its acquisitions, which is reported in its Regulated Businesses segment. During 2018, the Company closed on 15 acquisitions of various regulated water and wastewater systems for a total aggregate purchase price of $33 million. Assets acquired from these acquisitions, principally utility plant, totaled $32 million and liabilities assumed, primarily contributions in aid of construction, totaled $1 million. The Company recorded additional goodwill of $2 million associated with one of its acquisitions, which is reported in its Regulated Businesses segment. Assets Held for Sale On November 20, 2019, the Company and the Company’s New York subsidiary, entered into a Stock Purchase Agreement (the “Stock Purchase Agreement”) with Liberty Utilities Co., which it subsequently assigned to its indirect, wholly owned subsidiary Liberty Utilities (Eastern Water Holdings) Corp. (“Liberty”), pursuant to which Liberty will purchase all of the capital stock of the New York subsidiary (the “Stock Purchase”) for an aggregate purchase price of approximately $608 million in cash, subject to adjustment as provided in the Stock Purchase Agreement. The Company’s regulated New York operations have approximately 125,000 customers in the State of New York. Algonquin Power & Utilities Corp., Liberty’s ultimate parent company, executed and delivered an absolute and unconditional guaranty of the performance of all of the obligations of Liberty under the Stock Purchase Agreement. The Stock Purchase is subject to various conditions, including obtaining approvals and satisfying or waiving other closing conditions. The Stock Purchase Agreement has an initial termination date of June 30, 2021. Either party may extend the agreement beyond June 30, 2021, and the Company intends to extend the agreement, if necessary, provided all of the conditions to closing have been or are capable of being met, other than obtaining regulatory approvals. If not otherwise extended, the ultimate termination date is December 31, 2021. Liberty may also terminate the Stock Purchase Agreement if any governmental authority initiates a condemnation or eminent domain proceeding against a majority of the consolidated properties of the New York subsidiary, taken as a whole. The assets and related liabilities of the New York subsidiary were classified as held for sale on the Consolidated Balance Sheets as of December 31, 2020. Presented in the table below are the components of assets held for sale and liabilities related to assets held for sale of the New York subsidiary as of December 31, 2020: December 31, 2020 Property, plant and equipment $ 504 Current assets 12 Regulatory assets 64 Goodwill 39 Other assets 10 Assets held for sale $ 629 Current liabilities 14 Deferred income taxes 69 Regulatory liabilities 42 Other liabilities 12 Liabilities related to assets held for sale $ 137 Market-Based Businesses Pivotal Acquisition On June 4, 2018, the Company, through its wholly owned subsidiary American Water Enterprises, LLC, completed the acquisition of Pivotal for a total purchase price of $365 million, net of cash received. Pivotal is complementary to the Company’s HOS product offerings and enhances its presence in the home warranty solutions markets through utility partnerships. The results of Pivotal have been consolidated into the HOS non-reportable operating segment. Divestitures On December 12, 2019, American Industrial Water LLC, a wholly owned subsidiary of the Company (“AIW”), sold all of the outstanding membership interests in Water Solutions Holdings, LLC (“WSH”), which was a wholly owned subsidiary of AIW, to a natural gas and oil industry investment group, for total cash consideration of $31 million. WSH was the parent company of Keystone Clearwater Solutions, LLC (“Keystone”). Keystone provided water transportation services to shale natural gas exploration and production customers in the Appalachian Basin. As a result of the sale, the Company recorded a pre-tax loss on sale of $44 million, or $35 million after-tax, during the fourth quarter of 2019. The pro forma impact of the Company’s acquisitions was not material to the Consolidated Statements of Operations for the years ended December 31, 2020, 2019 and 2018.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Note 7: Property, Plant and Equipment Presented in the table below are the major classes of property, plant and equipment by category as of December 31: 2020 2019 Range of Remaining Useful Lives Weighted Average Useful Life Utility plant: Land and other non-depreciable assets $ 174 $ 166 Sources of supply 897 858 2 to 127 years 47 years Treatment and pumping facilities 3,984 3,750 3 to 111 years 41 years Transmission and distribution facilities 11,457 10,807 9 to 149 years 69 years Services, meters and fire hydrants 4,555 4,304 5 to 90 years 31 years General structures and equipment 2,003 1,748 1 to 109 years 16 years Waste collection 1,288 1,153 5 to 113 years 59 years Waste treatment, pumping and disposal 859 720 2 to 139 years 47 years Construction work in progress 837 801 Less: Utility plant included in assets held for sale (a) (646) (587) Total utility plant 25,408 23,720 Nonutility property 211 226 3 to 50 years 8 years Less: Nonutility plant included in assets held for sale (a) (5) (5) Total property, plant and equipment $ 25,614 $ 23,941 (a) This property, plant and equipment is related to the pending transactions contemplated by the Stock Purchase Agreement and is included in assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information. Property, plant and equipment depreciation expense amounted to $520 million , $508 million and $497 million for the years ended December 31, 2020, 2019 and 2018, respectively and was included in depreciation and amortization expense on the Consolidated Statements of Operations. The provision for depreciation expressed as a percentage of the aggregate average depreciable asset balances was 2.82%, 2.96% and 3.09% for years December 31, 2020, 2019 and 2018, respectively. Additionally, the Company had capital expenditures acquired on account but unpaid of $221 million and $235 million included in accrued liabilities on the Consolidated Balance Sheets as of December 31, 2020 and 2019, respectively. In 2019, the Company completed and submitted its project completion certification to the New Jersey Economic Development Authority (“NJEDA”) in connection with its capital investment in its corporate headquarters in Camden, New Jersey. The NJEDA has determined that the Company is qualified to receive $164 million in tax credits over a ten year period. The Company is required to meet various annual requirements in order to monetize one-tenth of the tax credits annually, and is subject to a claw-back period if the Company does not meet certain NJEDA requirements of the tax credit program in years 11 through 15. As a result, the Company had receivables of $33 million and $131 million in other current assets and other long-term assets, respectively, on the Consolidated Balance Sheets as of December 31, 2020. In March 2020, in connection with the COVID-19 pandemic, the NJEDA, pursuant to Executive Order 103 - State of Emergency and a Public Health Emergency effective immediately (“EO-103”), temporarily waived the requirement that a full-time employee must spend at least 80% of his or her time at the qualified business facility to meet the definition of eligible position or full-time job. The waiver remains in effect for the period of time that the EO-103 is in effect.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Note 9: Goodwill and Other Intangible Assets Goodwill Presented in the table below are the changes in the carrying value of goodwill for the years ended December 31, 2020 and 2019: Regulated Businesses Market-Based Businesses Consolidated Cost Accumulated Impairment Cost Accumulated Impairment Cost Accumulated Impairment Total Net Balance as of January 1, 2019 $ 3,494 $ (2,332) $ 574 $ (161) $ 4,068 $ (2,493) $ 1,575 Goodwill from acquisitions 3 — — — 3 — 3 Goodwill reduced through sale of Keystone operations — — (91) 53 (91) 53 (38) Less: Goodwill included in assets held for sale (a) (39) — — (39) — (39) Balance as of December 31, 2019 $ 3,458 $ (2,332) $ 483 $ (108) $ 3,941 $ (2,440) $ 1,501 Goodwill from acquisitions 5 — — — 5 — 5 Measurement period adjustments (2) — — — (2) — (2) Balance as of December 31, 2020 $ 3,461 $ (2,332) $ 483 $ (108) $ 3,944 $ (2,440) $ 1,504 (a) This goodwill is related to the pending transactions contemplated by the Stock Purchase Agreement and is included in assets held for sale on the Consolidated Balance Sheets as of December 31, 2020 and 2019. See Note 6—Acquisitions and Divestitures for additional information. In 2020, the Company acquired goodwill of $5 million associated with two of its acquisitions in the Regulated Businesses segment. See Note 6—Acquisitions and Divestitures for additional information. The Company completed its annual impairment testing of goodwill as of November 30, 2020, which included qualitative assessments of its Regulated Businesses, HOS and MSG reporting units. Based on these assessments, the Company determined that there were no factors present that would indicate that the fair value of these reporting units was less than their respective carrying values as of November 30, 2020. In 2019, the Company acquired goodwill of $3 million associated with three of its acquisitions in the Regulated Businesses segment. Additionally, as part of the sale of the Company’s Keystone operations on December 12, 2019, the Company reduced goodwill, net, by $38 million. Intangible Assets The Company held finite-lived intangible assets, including customer relationships and other intangible assets as of December 31, 2020. The gross carrying value of customer relationships and other intangible assets was $78 million and $13 million, respectively, as of December 31, 2020 and 2019. Accumulated amortization of customer relationships and other intangible assets was $20 million and $4 million, respectively, as of December 31, 2019. Amortization expense related to customer relationships and other intangible assets was $9 million and $3 million, respectively, for the year ended December 31, 2020. The net book value of customer relationships and other intangible assets was $49 million and $6 million, respectively, as of December 31, 2020. Intangible asset amortization expense amounted to $12 million, $14 million and $12 million for the years ended December 31, 2020, 2019 and 2018, respectively. Estimated amortization expense for the next five years subsequent to December 31, 2020 is as follows: Amount 2021 $ 10 2022 8 2023 6 2024 5 2025 4

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Shareholders' Equity	Note 10: Shareholders ’ Equity Common Stock Under the Company’s dividend reinvestment and direct stock purchase plan (the “DRIP”), shareholders may reinvest cash common stock dividends and purchase additional shares of Company common stock, up to certain limits, through the plan administrator without paying brokerage commissions. Shares purchased by participants through the DRIP may be newly issued shares, treasury shares, or at the Company’s election, shares purchased by the plan administrator in the open market or in privately negotiated transactions. Purchases generally will be made and credited to DRIP accounts once each week. As of December 31, 2020, there were approximately 4.2 million shares available for future issuance under the DRIP. Anti-dilutive Stock Repurchase Program In February 2015, the Company’s Board of Directors authorized an anti-dilutive stock repurchase program, which allows the Company to purchase up to 10 million shares of its outstanding common stock from time to time over an unrestricted period of time. The Company did not repurchase shares of common stock during the year ended December 31, 2020. The Company repurchased 0.4 million shares of common stock in the open market at an aggregate cost of $36 million under this program for the year ended December 31, 2019. As of December 31, 2020, there were 5.1 million shares of common stock available for purchase under the program. Accumulated Other Comprehensive Loss Presented in the table below are the changes in accumulated other comprehensive loss by component, net of tax, for the years ended December 31, 2020 and 2019: Defined Benefit Plans Foreign Currency Translation Gain (Loss) on Cash Flow Hedge Accumulated Other Comprehensive Loss Employee Benefit Plan Funded Status Amortization of Prior Service Cost Amortization of Actuarial Loss Beginning balance as of January 1, 2019 $ (102) $ 1 $ 56 $ 1 $ 10 $ (34) Other comprehensive income (loss) before reclassification 8 — — — (13) (5) Amounts reclassified from accumulated other comprehensive loss — — 4 (1) — 3 Net other comprehensive income 8 — 4 (1) (13) (2) Ending balance as of December 31, 2019 $ (94) $ 1 $ 60 $ — $ (3) $ (36) Other comprehensive income (loss) before reclassification (12) — — — (4) (16) Amounts reclassified from accumulated other comprehensive loss — — 3 — — 3 Net other comprehensive income (loss) (12) — 3 — (4) (13) Ending balance as of December 31, 2020 $ (106) $ 1 $ 63 $ — $ (7) $ (49) The Company does not reclassify the amortization of defined benefit pension cost components from accumulated other comprehensive loss directly to net income in its entirety, as a portion of these costs have been deferred as a regulatory asset. These accumulated other comprehensive loss components are included in the computation of net periodic pension cost. See Note 16—Employee Benefits for additional information. The amortization of the gain (loss) on cash flow hedges is reclassified to net income during the period incurred and is included in interest, net in the accompanying Consolidated Statements of Operations. Dividends and Distributions The Company’s Board of Directors authorizes the payment of dividends. The Company’s ability to pay dividends on its common stock is subject to having access to sufficient sources of liquidity, net income and cash flows of the Company’s subsidiaries, the receipt of dividends and direct and indirect distributions from, and repayments of indebtedness of, the Company’s subsidiaries, compliance with Delaware corporate and other laws, compliance with the contractual provisions of debt and other agreements and other factors. The Company’s dividend rate on its common stock is determined by the Board of Directors on a quarterly basis and takes into consideration, among other factors, current and possible future developments that may affect the Company’s income and cash flows. When dividends on common stock are declared, they are typically paid in March, June, September and December. Historically, dividends have been paid quarterly to holders of record less than 30 days prior to the distribution date. Since the dividends on the Company’s common stock are not cumulative, only declared dividends are paid. During 2020, 2019 and 2018, the Company paid $389 million, $353 million and $319 million in cash dividends, respectively. Presented in the table below is the per share cash dividends paid for the years ended December 31: 2020 2019 2018 December $ 0.55 $ 0.50 $ 0.455 September $ 0.55 $ 0.50 $ 0.455 June $ 0.55 $ 0.50 $ 0.455 March $ 0.50 $ 0.455 $ 0.415 On December 10, 2020, the Company’s Board of Directors declared a quarterly cash dividend payment of $0.55 per share payable on March 2, 2021, to shareholders of record as of February 8, 2021. Under applicable law, the Company’s subsidiaries may pay dividends on their capital stock or other equity only from retained, undistributed or current earnings. A significant loss recorded at a subsidiary may limit the amount of the dividend that the subsidiary can pay. The ability of the Company’s subsidiaries to pay upstream dividends, make other upstream distributions or repay indebtedness to parent company or American Water Capital Corp. (“AWCC”), the Company’s wholly owned financing subsidiary, as applicable, is subject to compliance with applicable corporate, tax and other laws, regulatory restrictions and financial and other contractual obligations, including, for example, (i) regulatory capital, surplus or net worth requirements, (ii) outstanding debt service obligations, (iii) requirements to make preferred and preference stock dividend payments, and (iv) other contractual agreements, covenants or obligations made or entered into by the Company and its subsidiaries. Regulatory Restrictions on Indebtedness The issuance of long-term debt or equity securities by the Company or long-term debt by AWCC does not require authorization of any state PUC if no guarantee or pledge of the regulated subsidiaries is utilized. Based on the needs of the Regulated Businesses and parent company, AWCC may borrow funds or issue its debt in the capital markets and then, through intercompany loans, provide these borrowings to the Regulated Businesses or parent company. PUC authorization is generally required for the regulated subsidiaries to incur long-term debt. The Company’s regulated subsidiaries normally obtain these required PUC authorizations on a periodic basis to cover their anticipated financing needs for a period of time, or, as necessary, in connection with a specific financing or refinancing of debt.

Stock Based Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock Based Compensation	Note 11: Stock Based Compensation The Company has granted stock options, stock units and dividend equivalents to non-employee directors, officers and other key employees of the Company pursuant to the terms of its 2007 Omnibus Equity Compensation Plan (the “2007 Plan”). Stock units under the 2007 Plan generally vest based on (i) continued employment with the Company (“RSUs”), or (ii) continued employment with the Company where distribution of the shares is subject to the satisfaction in whole or in part of stated performance-based goals (“PSUs”). The 2007 Plan has been replaced by the 2017 Omnibus Plan, as defined below, and no additional awards may be granted under the 2007 Plan. However, shares may still be issued under the 2007 Plan pursuant to the terms of awards previously issued under that plan prior to May 12, 2017. In May 2017, the Company’s shareholders approved the American Water Works Company, Inc. 2017 Omnibus Equity Compensation Plan (the “2017 Omnibus Plan”). The Company has granted stock units, including RSUs and PSUs, stock awards and dividend equivalents to non-employee directors, officers and employees under the 2017 Omnibus Plan. A total of 7.2 million shares of common stock may be issued under the 2017 Omnibus Plan. As of December 31, 2020, 6.7 million shares were available for grant under the 2017 Omnibus Plan. The 2017 Omnibus Plan provides that grants of awards may be in any of the following forms: incentive stock options, nonqualified stock options, stock appreciation rights, stock units, stock awards, other stock-based awards and dividend equivalents. Dividend equivalents may be granted only on stock units or other stock-based awards. The 2017 Omnibus Plan expires in 2027. The cost of services received from employees in exchange for the issuance of stock options and restricted stock awards is measured based on the grant date fair value of the awards issued. The value of stock options and stock unit awards at the date of the grant is amortized through expense over the requisite service period. All awards granted in 2020, 2019 and 2018 are classified as equity. The Company recognizes compensation expense for stock awards over the vesting period of the award. The Company stratified its grant populations and used historic employee turnover rates to estimate employee forfeitures. The estimated rate is compared to the actual forfeitures at the end of the reporting period and adjusted as necessary. There have been no significant adjustments to the forfeiture rates during 2020, 2019 and 2018. There were no grants of stock options to employees after 2016, and the remaining stock options outstanding as of December 31, 2020 were not material. Presented in the table below is the stock-based compensation expense recorded in O&M expense in the accompanying Consolidated Statements of Operations for the years ended December 31: 2020 2019 2018 RSUs and PSUs $ 19 $ 15 $ 15 Nonqualified employee stock purchase plan 2 2 1 Stock-based compensation 21 17 16 Income tax benefit (5) (4) (5) Stock-based compensation expense, net of tax $ 16 $ 13 $ 11 There were no significant stock-based compensation costs capitalized during the years ended December 31, 2020, 2019 and 2018. Subject to limitations on deductibility imposed by the Federal income tax code, the Company receives a tax deduction based on the intrinsic value of the award at the exercise date for stock options and the distribution date for stock units. For each award, throughout the requisite service period, the Company records the tax impacts related to compensation costs as deferred income tax assets. The tax deductions in excess of the deferred benefits recorded throughout the requisite service period are recorded to the Consolidated Statements of Operations and are presented in the financing section of the Consolidated Statements of Cash Flows. Stock Units During 2020, 2019 and 2018, the Company granted RSUs to certain employees under the 2017 Omnibus Plan. RSUs generally vest based on continued employment with the Company over periods ranging from one During 2020, 2019 and 2018, the Company granted stock units to non-employee directors under the 2017 Omnibus Plan. The stock units were vested in full on the date of grant; however, distribution of the shares will be made within 30 days of the earlier of (i) 15 months after the date of the last annual meeting of shareholders, subject to any deferral election by the director, or (ii) the participant’s separation from service. Because these stock units vested on the grant date, the total grant date fair value was recorded in operation and maintenance expense on the grant date. The RSUs are valued at the closing price of the Company’s common stock on the date of the grant and the majority vest ratably over a three Presented in the table below is RSU activity for the year ended December 31, 2020: Shares (in thousands) Weighted Average Grant Date Fair Value (per share) Non-vested total as of December 31, 2019 118 $ 85.41 Granted 55 129.39 Vested (71) 98.67 Forfeited (10) 97.24 Non-vested total as of December 31, 2020 92 $ 100.39 As of December 31, 2020, $4 million of total unrecognized compensation cost related to the nonvested RSUs is expected to be recognized over the weighted average remaining life of 1.34 years. The total fair value of stock units and RSUs vested was $5 million, $4 million and $4 million for the years ended December 31, 2020, 2019 and 2018, respectively. During 2020, 2019 and 2018, the Company granted PSUs to certain employees under the 2017 Omnibus Plan. The majority of PSUs vest ratably based on continued employment with the Company over the three Presented in the table below is PSU activity for the year ended December 31, 2020: Shares (in thousands) Weighted Average Grant Date Fair Value (per share) Non-vested total as of December 31, 2019 316 $ 83.89 Granted 149 116.27 Vested (160) 72.13 Forfeited (12) 108.36 Non-vested total as of December 31, 2020 293 $ 105.70 As of December 31, 2020, $4 million of total unrecognized compensation cost related to the nonvested PSUs is expected to be recognized over the weighted average remaining life of 0.92 years. The total fair value of PSUs vested was $18 million, $14 million and $12 million for the years ended December 31, 2020, 2019 and 2018, respectively. PSUs granted with one or more internal performance measures are valued at the market value of the closing price of the Company’s common stock on the date of grant. PSUs granted with a relative total shareholder return condition are valued using a Monte Carlo model. Expected volatility is based on historical volatilities of traded common stock of the Company and comparative companies using daily stock prices over the past three years. The expected term is three years and the risk-free interest rate is based on the three-year U.S. Treasury rate in effect as of the measurement date. Presented in the table below are the weighted average assumptions used in the Monte Carlo simulation and the weighted average grant date fair values of PSUs granted for the years ended December 31: 2020 2019 2018 Expected volatility 16.65% 16.80% 17.23% Risk-free interest rate 1.28% 2.47% 2.36% Expected life (years) 3.0 3.0 3.0 Grant date fair value per share $159.64 $110.37 $73.62 The grant date fair value of PSUs that vest ratably and have market and/or performance conditions are amortized through expense over the requisite service period using the graded-vesting method. Employee Stock Purchase Plan The Company maintains a nonqualified employee stock purchase plan (the “ESPP”) that expires in 2027 through which employee participants (other than the Company’s executive officers) may use payroll deductions to acquire Company common stock at a purchase price of 85% of the fair market value of the common stock at the end of a three-month purchase period. A total of 2.0 million shares may be issued under the ESPP, and as of December 31, 2020, there were 1.7 million shares of common stock reserved for issuance under the ESPP. The ESPP is considered compensatory. During the years ended December 31, 2020, 2019 and 2018, the Company issued 86 thousand, 88 thousand and 95 thousand shares, respectively, under the ESPP.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Long-Term Debt	Note 12: Long-Term Debt The Company obtains long-term debt through AWCC primarily to fund capital expenditures of the Regulated Businesses and to lend funds to parent company to refinance debt and for other purposes. Presented in the table below are the components of long-term debt as of December 31: Rate Weighted Average Rate Maturity 2020 2019 Long-term debt of AWCC: (a) Senior notes—fixed rate 2.80%-8.27% 4.05% 2021-2050 $ 8,191 $ 7,191 Private activity bonds and government funded debt—fixed rate 0.60%-2.90% 1.64% 2021-2031 191 191 Long-term debt of other American Water subsidiaries: Private activity bonds and government funded debt—fixed rate 0.00%-5.50% 1.74% 2021-2048 735 724 Mortgage bonds—fixed rate 6.35%-9.69% 7.48% 2021-2039 565 578 Mandatorily redeemable preferred stock 8.47%-9.75% 8.57% 2024-2036 5 7 Finance lease obligations 12.25% 12.25% 2026 1 1 Long-term debt 9,688 8,692 Unamortized debt (discount) premium, net (b) (4) 1 Unamortized debt issuance costs (22) (21) Less current portion of long-term debt (329) (28) Total long-term debt $ 9,333 $ 8,644 (a) This indebtedness is considered “debt” for purposes of a support agreement between parent company and AWCC, which serves as a functional equivalent of a guarantee by parent company of AWCC’s payment obligations under such indebtedness. (b) Includes debt discount, net of fair value adjustments previously recognized in acquisition purchase accounting. All mortgage bonds and $734 million of the private activity bonds and government funded debt held by the Company’s subsidiaries were collateralized as of December 31, 2020. Long-term debt indentures contain a number of covenants that, among other things, limit, subject to certain exceptions, AWCC from issuing debt secured by the Company’s consolidated assets. Certain long-term notes require the Company to maintain a ratio of consolidated total indebtedness to consolidated total capitalization of not more than 0.70 to 1.00. The ratio as of December 31, 2020 was 0.63 to 1.00. In addition, the Company has $868 million of notes which include the right to redeem the notes at par value, in whole or in part, from time to time, subject to certain restrictions, with a weighted average interest rate of 1.85%. Presented in the table below are future sinking fund payments and debt maturities: Amount 2021 $ 329 2022 14 2023 356 2024 474 2025 597 Thereafter 7,918 Presented in the table below are the issuances of long-term debt in 2020: Company Type Rate Weighted Average Rate Maturity Amount AWCC Senior notes—fixed rate 2.80%-3.45% 3.13% 2030-2050 $ 1,000 AWCC (a) Private activity bonds and government funded debt—fixed rate 0.60%-0.70% 0.42% 2023-2023 86 Other American Water subsidiaries Private Activity Mortgage Bonds 0.85%-1.20% 1.10% 2023-2027 225 Other American Water subsidiaries Private activity bonds and government funded debt—fixed rate 0.00%-5.00% 0.16% 2021-2048 23 Total issuances $ 1,334 (a) This indebtedness has a mandatory redemption provision callable in 2023. The Company incurred debt issuance costs of $15 million related to the above issuances. Presented in the table below are the retirements and redemptions of long-term debt in 2020 through sinking fund provisions, optional redemption or payment at maturity: Company Type Rate Weighted Average Rate Maturity Amount AWCC Private activity bonds and government funded debt—fixed rate 1.79%-5.38% 5.29% 2020-2031 $ 87 Other American Water subsidiaries Private activity mortgage bonds 4.45%-5.60% 5.19% 2020 225 Other American Water subsidiaries Private activity bonds and government funded debt—fixed rate 0.00%-5.60% 2.08% 2020-2048 15 Other American Water subsidiaries Mortgage bonds 3.92%-9.71% 7.83% 2020-2021 13 Other American Water subsidiaries Mandatory redeemable preferred stock 8.49%-9.18% 8.64% 2031-2036 2 Total retirements and redemptions $ 342 On April 14, 2020, AWCC completed a $1.0 billion debt offering which included the sale of $500 million aggregate principal amount of its 2.80% senior notes due 2030 and $500 million aggregate principal amount of its 3.45% senior notes due 2050. At the closing of the offering, AWCC received, after deduction of underwriting discounts and before deduction of offering expenses, net proceeds of $989 million. AWCC used the net proceeds of this offering: to (i) lend funds to parent company and its regulated subsidiaries; (ii) to fund sinking fund payments for, and to repay at maturity, $28 million in aggregate principal amount of outstanding long-term debt of AWCC and certain of the Company’s regulated subsidiaries; (iii) to repay AWCC’s commercial paper obligations and short-term indebtedness under AWCC’s $2.25 billion unsecured revolving credit facility; and (iv) for general corporate purposes. One of the principal market risks to which the Company is exposed is changes in interest rates. In order to manage the exposure, the Company follows risk management policies and procedures, including the use of derivative contracts such as swaps. The Company reduces exposure to interest rates by managing commercial paper and debt maturities. The Company also does not enter into derivative contracts for speculative purposes and does not use leveraged instruments. The derivative contracts entered into are for periods consistent with the related underlying exposures. The Company is exposed to the risk that counterparties to derivative contracts will fail to meet their contractual obligations and minimizes this risk by dealing only with leading, credit-worthy financial institutions having long-term credit ratings of “A” or better. During March 2020, the Company entered into four 10-year treasury lock agreements, each with a notional amount of $100 million, to reduce interest rate exposure on debt, which was subsequently issued on April 14, 2020. These treasury lock agreements had an average fixed rate of 0.94%. The Company designated these treasury lock agreements as cash flow hedges, with their fair value recorded in accumulated other comprehensive gain or loss. On April 8, 2020 the Company terminated these four treasury lock agreements with an aggregate notional amount of $400 million, realizing a net loss of $6 million, to be amortized through interest, net over a 10 year period, in accordance with the terms of the $1.0 billion new debt issued on April 14, 2020. No ineffectiveness was recognized on hedging instruments for the years ended December 31, 2020 and 2019.

Short-Term Debt

Short-Term Debt	12 Months Ended
	Dec. 31, 2020
Short-term Debt [Abstract]
Short-Term Debt	Note 13: Short-Term Debt To ensure adequate liquidity given the impacts of the COVID-19 pandemic on debt and capital markets, on March 20, 2020, AWCC entered into a Term Loan Credit Agreement, by and among parent company, AWCC and the lenders party thereto, which provided for a term loan facility of up to $750 million (the “Term Loan Facility”). On March 20, 2020, AWCC borrowed $500 million under the Term Loan Facility, the proceeds of which were used for general corporate purposes of AWCC and parent company, and to provide additional liquidity. The Term Loan Facility allowed for a single additional borrowing of up to $250 million, which expired unused on June 19, 2020. The Term Loan Facility commitments terminate on March 19, 2021. AWCC may prepay all or a portion of amounts due under the Term Loan Facility without any premium or penalty. Borrowings under the Term Loan Facility bear interest at a variable annual rate based on LIBOR, plus a margin of 0.80%. The credit agreement for the Term Loan Facility contains the same affirmative and negative covenants and events of default as under AWCC’s $2.25 billion revolving credit facility. As of December 31, 2020, $500 million of principal was outstanding under the Term Loan Facility. Short-term debt consists of commercial paper and credit facility borrowings totaling $786 million for both periods ending December 31, 2020 and 2019. The weighted average interest rate on AWCC short-term borrowings was approximately 1.16% and 2.54% for the year ended December 31, 2020 and 2019, respectively. As of December 31, 2020 there were no borrowings outstanding with maturities greater than three months. Liquidity needs for capital investment, working capital and other financial commitments are funded through cash flows from operations, public and private debt offerings, commercial paper markets and, if and to the extent necessary, borrowings under the AWCC revolving credit facility and, in the future, issuances of equity. The revolving credit facility provides $2.25 billion in aggregate total commitments from a diversified group of financial institutions. On April 1, 2020, the termination date of the credit agreement with respect to AWCC’s revolving credit facility was extended, pursuant to the terms of the credit agreement, from March 21, 2024 to March 21, 2025. The facility is used principally to support AWCC’s commercial paper program and to provide a sub-limit of up to $150 million for letters of credit. Letters of credit are non-debt instruments maintained to provide credit support for certain transactions as requested by third parties. Subject to satisfying certain conditions, the credit agreement also permits AWCC to increase the maximum commitment under the facility by up to an aggregate of $500 million. As of December 31, 2020, AWCC had no outstanding borrowings and $76 million of outstanding letters of credit under the revolving credit facility, with $1.39 billion available to fulfill the Company’s short-term liquidity needs and to issue letters of credit. During 2020, the Company borrowed and subsequently repaid $650 million under the revolving credit facility. The Company regularly evaluates the capital markets and closely monitors the financial condition of the financial institutions with contractual commitments in its revolving credit facility. Interest rates on advances under the facility are based on a credit spread to the LIBOR rate (or applicable market replacement rate) or base rate in accordance with Moody Investors Service’s and Standard & Poor’s Financial Services’ then applicable credit rating on AWCC’s senior unsecured, non-credit enhanced debt. Presented in the tables below are the aggregate credit facility commitments, commercial paper limit and letter of credit availability under the revolving credit facility, as well as the available capacity for each, as of December 31: 2020 Commercial Paper Limit Letters of Credit Total (a) (In millions) Total availability $ 2,100 $ 150 $ 2,250 Outstanding debt (786) (76) (862) Remaining availability as of December 31, 2020 $ 1,314 $ 74 $ 1,388 (a) Total remaining availability of $1.39 billion as of December 31, 2020 may be accessed through revolver draws. 2019 Commercial Paper Limit Letters of Credit Total (a) (In millions) Total availability $ 2,100 $ 150 $ 2,250 Outstanding debt (786) (76) (862) Remaining availability as of December 31, 2019 $ 1,314 $ 74 $ 1,388 (a) Total remaining availability of $1.39 billion as of December 31, 2019 may be accessed through revolver draws. Presented in the table below is the Company’s total available liquidity as of December 31, 2020 and 2019: Cash and Cash Equivalents Availability on Revolving Credit Facility Total Available Liquidity (In millions) Available liquidity as of December 31, 2020 $ 547 $ 1,388 $ 1,935 Available liquidity as of December 31, 2019 $ 60 $ 1,388 $ 1,448 Presented in the table below is the short-term borrowing activity for AWCC for the years ended December 31: 2020 2019 Average borrowings $ 1,047 $ 726 Maximum borrowings outstanding 2,172 1,271 Weighted average interest rates, computed on daily basis 1.16 % 2.54 % Weighted average interest rates, as of December 31 0.53 % 1.86 % The changes in average borrowings between periods were mainly attributable to the $500 million borrowed under the Term Loan Facility during 2020, which is scheduled to terminate on March 19, 2021. The credit facility requires the Company to maintain a ratio of consolidated debt to consolidated capitalization of not more than 0.70 to 1.00. The ratio as of December 31, 2020 was 0.63 to 1.00. None of the Company’s borrowings are subject to default or prepayment as a result of a downgrading of securities, although such a downgrading could increase fees and interest charges under AWCC’s revolving credit facility.

General Taxes

General Taxes	12 Months Ended
	Dec. 31, 2020
General Taxes [Abstract]
General Taxes	Note 14: General Taxes Presented in the table below is the components of general tax expense for the years ended December 31: 2020 2019 2018 Property and capital stock $ 140 $ 124 $ 120 Gross receipts and franchise 116 110 112 Payroll 36 35 33 Other general 11 11 12 Total general taxes $ 303 $ 280 $ 277

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 15: Income Taxes Presented in the table below is the components of income tax expense for the years ended December 31: 2020 2019 2018 Current income taxes: State $ 8 $ 4 $ 26 Federal — — 1 Total current income taxes $ 8 $ 4 $ 27 Deferred income taxes: State $ 49 $ 54 $ 33 Federal 159 155 163 Amortization of deferred investment tax credits (1) (1) (1) Total deferred income taxes 207 208 195 Provision for income taxes $ 215 $ 212 $ 222 Presented in the table below is a reconciliation between the statutory federal income tax rate and the Company’s effective tax rate for the years ended December 31: 2020 2019 2018 Income tax at statutory rate 21.0 % 21.0 % 21.0 % Increases (decreases) resulting from: State taxes, net of federal taxes 4.8 % 5.4 % 5.5 % EADIT (2.1) % (0.9) % 1.5 % Other, net (0.4) % (0.1) % 0.2 % Effective tax rate 23.3 % 25.4 % 28.2 % Presented in the table below are the components of the net deferred tax liability as of December 31: 2020 2019 Deferred tax assets: Advances and contributions $ 424 $ 410 Tax losses and credits 65 136 Regulatory income tax assets 329 335 Pension and other postretirement benefits 100 94 Other 165 151 Total deferred tax assets 1,083 1,126 Valuation allowance (19) (21) Total deferred tax assets, net of allowance $ 1,064 $ 1,105 Deferred tax liabilities: Property, plant and equipment $ 2,913 $ 2,760 Deferred pension and other postretirement benefits 97 77 Other 216 207 Total deferred tax liabilities 3,226 3,044 Less: Deferred tax liabilities included in liabilities related to assets held for sale (a) 69 67 Total deferred tax liabilities, net of deferred tax assets $ (2,093) $ (1,872) (a) These deferred tax liabilities are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in liabilities related to assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information. As of December 31, 2020 and 2019, the Company recognized federal net operating loss (“NOL”) carryforwards of $366 million and $673 million, respectively. The Company’s federal NOL carryforwards begin to expire in 2029, however, the Company expects to fully utilize its federal NOL carryforwards in 2021, and therefore, no valuation allowance is required. As of December 31, 2020 and 2019, the Company had state NOLs of $357 million and $453 million, respectively, a portion of which are offset by a valuation allowance because the Company does not believe these NOLs are more likely than not to be realized. The state NOL carryforwards began to expire in 2020 and will continue through 2040. The Company files income tax returns in the United States federal jurisdiction and various state and foreign jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal, state or local or non-U.S. income tax examinations by tax authorities for years on or before 2012. The Company has state income tax examinations in progress and does not expect material adjustments to result. Presented in the table below are the changes in gross liability, excluding interest and penalties, for unrecognized tax benefits: Amount Balance as of January 1, 2019 $ 97 Increases in current period tax positions 17 Decreases in prior period measurement of tax positions (4) Balance as of December 31, 2019 $ 110 Increases in current period tax positions 18 Decreases in prior period measurement of tax positions (6) Balance as of December 31, 2020 $ 122 The Company’s tax positions relate primarily to the deductions claimed for repair and maintenance costs on its utility plant. The Company does not anticipate material changes to its unrecognized tax benefits within the next year. As discussed above, the Company expects to utilize its remaining federal NOLs in 2021, and therefore this federal tax attribute will not be available to reduce the federal liabilities for uncertain tax positions or interest accrued as presented on the Company’s Consolidated Financial Statements. If the Company sustains all of its positions as of December 31, 2020, an unrecognized tax benefit of $12 million, excluding interest and penalties, would impact the Company’s effective tax rate. The Company had an insignificant amount of interest and penalties related to its tax positions as of December 31, 2020 and 2019. Presented in the table below are the changes in the valuation allowance: Amount Balance as of January 1, 2018 $ 13 Increases in current period tax positions 1 Balance as of December 31, 2018 $ 14 Increases in current period tax positions 7 Balance as of December 31, 2019 $ 21 Decreases in current period tax positions (2) Balance as of December 31, 2020 $ 19

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefits	Note 16: Employee Benefits Pension and Other Postretirement Benefits The Company maintains noncontributory defined benefit pension plans covering eligible employees of its regulated utility and shared services operations. Benefits under the plans are based on the employee’s years of service and compensation. The pension plans have been closed for all new employees. The pension plans were closed for most employees hired on or after January 1, 2006. Union employees hired on or after January 1, 2001, except for specific eligible groups specified in the plan, had their accrued benefit frozen and will be able to receive this benefit as a lump sum upon termination or retirement. Union employees hired on or after January 1, 2001 and non-union employees hired on or after January 1, 2006 are provided with a 5.25% of base pay defined contribution plan. The Company does not participate in a multi-employer plan. The Company also has unfunded noncontributory supplemental nonqualified pension plans that provide additional retirement benefits to certain employees. The Company’s pension funding practice is to contribute at least the greater of the minimum amount required by the Employee Retirement Income Security Act of 1974 or the normal cost. Further, the Company will consider additional cash contributions and/or available prefunding balances if needed to avoid “at risk” status and benefit restrictions under the Pension Protection Act of 2006 (“PPA”). The Company may also consider increased contributions, based on other financial requirements and the plans’ funded position. Pension expense in excess of the amount contributed to the pension plans is deferred by certain regulated subsidiaries pending future recovery in rates charged for utility services as contributions are made to the plans. See Note 4—Regulatory Matters for additional information. Pension plan assets are invested in a number of actively managed, commingled funds, and limited partnerships including equities, fixed income securities, guaranteed annuity contracts with insurance companies, real estate funds and real estate investment trusts (“REITs”). The Company maintains other postretirement benefit plans providing varying levels of medical and life insurance to eligible retirees. The retiree welfare plans are closed for union employees hired on or after January 1, 2006. The plans had previously closed for non-union employees hired on or after January 1, 2002. The Company’s policy is to fund other postretirement benefit costs up to the amount recoverable through rates. Assets of the plans are invested in a number of actively managed funds in the form of separate accounts, commingled funds and limited partnerships, including equities and fixed income securities. The investment policy guideline of the pension plan is focused on diversification, improving returns and reducing the volatility of the funded status over a long-term horizon. The investment policy guidelines of the postretirement plans focus on the appropriate strategy given the funded status of the plans. None of the Company’s securities are included in pension or other postretirement benefit plan assets. The Company uses fair value for all classes of assets in the calculation of market-related value of plan assets. As of 2018, the fair values and asset allocations of the pension plan assets include the American Water Pension Plan, the New York Water Service Corporation Pension Plan, and the Shorelands Water Company, Inc. Pension Plan. Upon completion of the pending transactions contemplated by the Stock Purchase Agreement among the Company, the Company’s New York subsidiary and Liberty, there will be a transfer of assets from two pension plans and two other postretirement benefit plans from the Company to Liberty. The Company does not expect the assets to be transferred to be a significant percentage of the Company’s overall pension and other postretirement benefit plans. Presented in the tables below are the fair values and asset allocations of the pension plan assets as of December 31, 2020 and 2019, respectively, by asset category: Asset Category 2021 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of December 31, 2020 Cash $ 78 $ 78 $ — $ — 4 % Equity securities: 50 % U.S. large cap 420 420 — — 21 % U.S. small cap 124 124 — — 6 % International 367 8 169 190 18 % Real estate fund 120 — — 120 6 % REITs 7 — 7 — — % Fixed income securities: 50 % U.S. Treasury securities and government bonds 171 163 8 — 9 % Corporate bonds 594 — 594 — 30 % Mortgage-backed securities 9 — 9 — — % Municipal bonds 34 — 34 — 2 % Treasury futures 10 10 — — 1 % Long duration bond fund 10 7 3 — 1 % Guarantee annuity contracts 46 — — 46 2 % Total 100 % $ 1,990 $ 810 $ 824 $ 356 100 % Asset Category 2020 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of December 31, 2019 Cash $ 39 $ 39 $ — $ — 2 % Equity securities: 50 % U.S. large cap 358 358 — — 20 % U.S. small cap 84 78 6 — 5 % International 320 6 137 177 18 % Real estate fund 127 — — 127 7 % REITs 7 — 7 — — % Fixed income securities: 50 % U.S. Treasury securities and government bonds 169 158 11 — 10 % Corporate bonds 542 — 542 — 31 % Mortgage-backed securities 14 — 14 — 1 % Municipal bonds 26 — 26 — 1 % Treasury futures 8 8 — — 1 % Long duration bond fund 8 8 — — 1 % Guarantee annuity contracts 45 — — 45 3 % Total 100 % $ 1,747 $ 655 $ 743 $ 349 100 % Presented in the tables below are a reconciliation of the beginning and ending balances of the fair value measurements using significant unobservable inputs (Level 3) for 2020 and 2019, respectively: Level 3 Balance as of January 1, 2020 $ 349 Actual return on assets 3 Purchases, issuances and settlements, net 4 Balance as of December 31, 2020 $ 356 Level 3 Balance as of January 1, 2019 $ 230 Actual return on assets 25 Purchases, issuances and settlements, net 94 Balance as of December 31, 2019 $ 349 The Company’s postretirement benefit plans have different levels of funded status and the assets are held under various trusts. The investments and risk mitigation strategies for the plans are tailored specifically for each trust. In setting new strategic asset mixes, consideration is given to the likelihood that the selected asset allocation will effectively fund the projected plan liabilities and meet the risk tolerance criteria of the Company. The Company periodically updates the long-term, strategic asset allocations for these plans through asset liability studies and uses various analytics to determine the optimal asset allocation. Considerations include plan liability characteristics, liquidity needs, funding requirements, expected rates of return and the distribution of returns. In 2018, the Company announced plan design changes to the medical bargaining benefit plan, which resulted in a cap on future benefits and an over funded postretirement medical benefits bargaining plan. As a result of the change in funded status, the Company decreased the investment risk in the plan and reduced its exposure to changes in interest rates by matching the assets of the plan to the projected cash flows for future benefit payments of the liability. The Company engages third-party investment managers for all invested assets. Managers are not permitted to invest outside of the asset class (e.g. fixed income, equity, alternatives) or strategy for which they have been appointed. Investment management agreements and recurring performance and attribution analysis are used as tools to ensure investment managers invest solely within the investment strategy they have been provided. Futures and options may be used to adjust portfolio duration to align with a plan’s targeted investment policy. In order to minimize asset volatility relative to the liabilities, a portion of plan assets is allocated to long duration fixed income investments that are exposed to interest rate risk. Increases in interest rates generally will result in a decline in the value of fixed income assets while reducing the present value of the liabilities. Conversely, rate decreases will increase fixed income assets, partially offsetting the related increase in the liabilities. Within equities, risk is mitigated by constructing a portfolio that is broadly diversified by geography, market capitalization, manager mandate size, investment style and process. For the postretirement medical bargaining plan, its asset structure is designed to meet the cash flows of the liabilities. This design reduces the plan’s exposure to changes in interest rates. Actual allocations to each asset class vary from target allocations due to periodic investment strategy updates, market value fluctuations, the length of time it takes to fully implement investment allocations, and the timing of benefit payments and contributions. The asset allocation is rebalanced on a quarterly basis, if necessary. Voluntary Employees’ Beneficiary Association (“VEBA”) Trust assets include the American Water Postretirement Medical Benefits Bargaining Plan, the New York Water Service Corporation Postretirement Medical Benefits Bargaining Plan, the American Water Postretirement Medical Benefits Non-Bargaining Plan, and the American Water Life Insurance Trust. Presented in the tables below are the fair values and asset allocations of the postretirement benefit plan assets as of December 31, 2020 and 2019, respectively, by asset category: Asset Category 2021 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of December 31, 2020 Bargain VEBA: Cash $ 12 $ 12 $ — $ — 3 % Equity securities: 4 % U.S. large cap 14 14 — — 3 % Fixed income securities: 96 % U.S. Treasury securities and government bonds 389 308 81 — 93 % Long duration bond fund 5 5 — — 1 % Total bargain VEBA 100 % $ 420 $ 339 $ 81 $ — 100 % Non-bargain VEBA: Cash $ 1 $ 1 $ — $ — — Equity securities: 60 % U.S. large cap 51 51 — — 38 % International 33 33 — — 24 % Fixed income securities: 40 % Core fixed income bond fund (a) 50 — 50 — 38 % Total non-bargain VEBA 100 % $ 135 $ 85 $ 50 $ — 100 % Life VEBA: Equity securities: 70 % U.S. large cap $ — $ — $ — $ — — % Fixed income securities: 30 % Core fixed income bond fund (a) 1 1 — — 100 % Total life VEBA 100 % $ 1 $ 1 $ — $ — 100 % Total 100 % $ 556 $ 425 $ 131 $ — 100 % (a) Includes cash for margin requirements. Asset Category 2020 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of 12/31/2019 Bargain VEBA: Cash $ 6 $ 6 $ — $ — 2 % Equity securities: 4 % U.S. large cap 13 13 — — 3 % Fixed income securities: 96 % U.S. Treasury securities and government bonds 373 298 75 — 94 % Long duration bond fund 4 4 — — 1 % Total bargain VEBA 100 % $ 396 $ 321 $ 75 $ — 100 % Non-bargain VEBA: Cash $ 4 $ 4 $ — $ — — Equity securities: 60 % U.S. large cap 48 48 — — 36 % International 30 30 — — 23 % Fixed income securities: 40 % Core fixed income bond fund (a) 50 — 50 — 41 % Total non-bargain VEBA 100 % $ 132 $ 82 $ 50 $ — 100 % Life VEBA: Equity securities: 70 % U.S. large cap $ 2 $ 2 $ — $ — 50 % Fixed income securities: 30 % Core fixed income bond fund (a) 2 2 — — 50 % Total life VEBA 100 % $ 4 $ 4 $ — $ — 100 % Total 100 % $ 532 $ 407 $ 125 $ — 100 % (a) Includes cash for margin requirements. Valuation Techniques Used to Determine Fair Value Cash—Cash and investments with maturities of three months or less when purchased, including certain short-term fixed-income securities, are considered cash and are included in the recurring fair value measurements hierarchy as Level 1. Equity securities—For equity securities, the trustees obtain prices from pricing services, whose prices are obtained from direct feeds from market exchanges, that the Company is able to independently corroborate. Certain equity securities are valued based on quoted prices in active markets and categorized as Level 1. Other equities, such as international securities held in the pension plan, are invested in commingled funds and/or limited partnerships. These funds are valued to reflect the plan fund’s interest in the fund based on the reported year-end net asset value. Since net asset value is not directly observable or not available on a nationally recognized securities exchange for the commingled funds, they are categorized as Level 2. For limited partnerships, the assets as a whole are categorized as Level 3 due to the fact that the partnership provides the pricing and the pricing inputs are less readily observable. In addition, the limited partnership vehicle cannot be readily traded. Fixed-income securities—The majority of U.S. Treasury securities and government bonds have been categorized as Level 1 because they trade in highly-liquid and transparent markets and their prices can be corroborated. The fair values of corporate bonds, mortgage backed securities, and certain government bonds are based on prices that reflect observable market information, such as actual trade information of similar securities. They are categorized as Level 2 because the valuations are calculated using models which utilize actively traded market data that the Company can corroborate. Exchange-traded options and futures, for which market quotations are readily available, are valued at the last reported sale price or official closing price on the primary market or exchange on which they are traded and are classified as Level 1. Real estate fund—Real estate fund is categorized as Level 3 as the fund uses significant unobservable inputs for fair value measurement and the vehicle is in the form of a limited partnership. REITs—REITs are invested in commingled funds. Commingled funds are valued to reflect the plan fund’s interest in the fund based on the reported year-end net asset value. Since the net asset value is not directly observable for the commingled funds, they are categorized as Level 2. Guaranteed annuity contracts—Guaranteed annuity contracts are categorized as Level 3 because the investments are not publicly quoted. Since these market values are determined by the provider, they are not highly observable and have been categorized as Level 3. Exchange-traded future and option positions are reported in accordance with changes in variation margins that are settled daily. Presented in the table below is a rollforward of the changes in the benefit obligation and plan assets for the two most recent years, for all plans combined: Pension Benefits Other Benefits 2020 2019 2020 2019 Change in benefit obligation: Benefit obligation as of January 1, $ 2,161 $ 1,892 $ 374 $ 353 Service cost 31 28 4 4 Interest cost 73 82 12 15 Plan participants' contributions — — 2 2 Plan amendments — — 5 (1) Actuarial loss (gain) 233 264 13 25 Settlements (a) (3) — — — Gross benefits paid (109) (105) (29) (25) Federal subsidy — — 1 1 Benefit obligation as of December 31, $ 2,386 $ 2,161 $ 382 $ 374 Change in plan assets: Fair value of plan assets as of January 1, $ 1,747 $ 1,499 $ 532 $ 507 Actual return on plan assets 314 319 53 51 Employer contributions 41 33 (2) (2) Plan participants' contributions — — 2 2 Settlements (a) (3) — — — Benefits paid (109) (104) (29) (26) Fair value of plan assets as of December 31, $ 1,990 $ 1,747 $ 556 $ 532 Funded value as of December 31, $ (396) $ (414) $ 174 $ 158 Amounts recognized on the balance sheet: Noncurrent asset $ — $ — $ 173 $ 159 Current liability (2) (3) — — Noncurrent liability (388) (411) (1) (1) (Liabilities) assets related to assets held for sale (b) (6) — 2 — Net amount recognized $ (396) $ (414) $ 174 $ 158 (a) The Company paid $3 million of lump sum payment distributions from the Company’s New York Water Service Corporation Pension Plan for the year ended December 31, 2020. There were no lump sum payments made for the year ended December 31, 2019. (b) These balances are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in assets held for sale and liabilities related to assets held for sale on the Consolidated Balance Sheets as of December 31, 2020. See Note 6—Acquisitions and Divestitures for additional information. Presented in the table below are the components of accumulated other comprehensive income and regulatory assets that have not been recognized as components of periodic benefit costs as of December 31: Pension Benefits Other Benefits 2020 2019 2020 2019 Net actuarial loss $ 436 $ 435 $ 49 $ 72 Prior service credit (16) (19) (217) (257) Net amount recognized $ 420 $ 416 $ (168) $ (185) Regulatory assets (liabilities) $ 366 $ 375 $ (168) $ (185) Accumulated other comprehensive income 54 41 — — Total $ 420 $ 416 $ (168) $ (185) Presented in the tables below are the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for pension plans with a projected obligation in excess of plan assets as of December 31, 2020 and 2019: Projected Benefit Obligation Exceeds the Fair Value of Plans' Assets 2020 2019 Projected benefit obligation $ 2,386 $ 2,161 Fair value of plan assets 1,990 1,748 Accumulated Benefit Obligation Exceeds the Fair Value of Plans' Assets 2020 2019 Accumulated benefit obligation $ 2,188 $ 2,018 Fair value of plan assets 1,990 1,748 The accumulated postretirement plan assets exceed benefit obligations for all of the Company’s other postretirement benefit plans, except for the Northern Illinois Retiree Welfare Plan. In 2006, the PPA replaced the funding requirements for defined benefit pension plans by requiring that defined benefit plans contribute to 100% of the current liability funding target over seven years. Defined benefit plans with a funding status of less than 80% of the current liability are defined as being “at risk” and additional funding requirements and benefit restrictions may apply. The PPA was effective for the 2008 plan year with short-term phase-in provisions for both the funding target and at-risk determination. The Company’s qualified defined benefit plan is currently funded above the at-risk threshold, and therefore the Company expects that the plans will not be subject to the “at risk” funding requirements of the PPA. The Company is proactively monitoring the plan’s funded status and projected contributions under the law to appropriately manage the potential impact on cash requirements. Minimum funding requirements for the qualified defined benefit pension plan are determined by government regulations and not by accounting pronouncements. The Company plans to contribute amounts at least equal to or greater than the minimum required contributions or the normal cost in 2021 to the qualified pension plans. Contributions may be in the form of cash contributions as well as available prefunding balances. Presented in the table below is information about the expected cash flows for the pension and postretirement benefit plans: Pension Benefits Other Benefits 2021 expected employer contributions: To plan trusts $ 37 $ — To plan participants 2 — Presented in the table below are the net benefits expected to be paid from the plan assets or the Company’s assets: Pension Benefits Other Benefits Expected Benefit Payments Expected Benefit Payments Expected Federal Subsidy Payments 2021 $ 127 $ 27 $ 1 2022 128 27 1 2023 133 27 1 2024 135 27 1 2025 137 26 1 2026-2030 692 123 4 Because the above amounts are net benefits, plan participants’ contributions have been excluded from the expected benefits. Accounting for pensions and other postretirement benefits requires an extensive use of assumptions about the discount rate, expected return on plan assets, the rate of future compensation increases received by the Company’s employees, mortality, turnover and medical costs. Each assumption is reviewed annually. The assumptions are selected to represent the average expected experience over time and may differ in any one year from actual experience due to changes in capital markets and the overall economy. These differences will impact the amount of pension and other postretirement benefit expense that the Company recognizes. Presented in the table below are the significant assumptions related to the pension and other postretirement benefit plans: Pension Benefits Other Benefits 2020 2019 2018 2020 2019 2018 Weighted average assumptions used to determine December 31 benefit obligations: Discount rate 2.74% 3.44% 4.38% 2.56% 3.36% 4.32% Rate of compensation increase 3.51% 2.97% 3.00% N/A N/A N/A Medical trend N/A N/A N/A graded from graded from graded from 6.25% in 2021 6.50% in 2020 6.75% in 2019 to 5.00% in 2026+ to 5.00% in 2026+ to 5.00% in 2026+ Weighted average assumptions used to determine net periodic cost: Discount rate 3.44% 4.38% 3.75% 3.36% 4.32% 4.23% Expected return on plan assets 6.50% 6.20% 5.95% 3.68% 3.56% 4.77% Rate of compensation increase 2.97% 3.00% 3.02% N/A N/A N/A Medical trend N/A N/A N/A graded from graded from graded from 6.50% in 2020 6.75% in 2019 7.00% in 2018 to 5.00% in 2026+ to 5.00% in 2026+ to 4.50% in 2026+ NOTE “N/A” in the table above means assumption is not applicable. The discount rate assumption was determined for the pension and postretirement benefit plans independently. The Company uses an approach that approximates the process of settlement of obligations tailored to the plans’ expected cash flows by matching the plans’ cash flows to the coupons and expected maturity values of individually selected bonds. Historically, for each plan, the discount rate was developed at the level equivalent rate that would produce the same present value as that using spot rates aligned with the projected benefit payments. The expected long-term rate of return on plan assets is based on historical and projected rates of return, prior to administrative and investment management fees, for current and planned asset classes in the plans’ investment portfolios. Assumed projected rates of return for each of the plans’ projected asset classes were selected after analyzing historical experience and future expectations of the returns and volatility of the various asset classes. Based on the target asset allocation for each asset class, the overall expected rate of return for the portfolio was developed, adjusted for historical and expected experience of active portfolio management results compared to the benchmark returns. The Company’s pension expense increases as the expected return on assets decreases. The Company used an expected return on plan assets of 6.50% to estimate its 2020 pension benefit costs, and an expected blended return based on weighted assets of 3.68% to estimate its 2020 other postretirement benefit costs. The Company had previously adopted a mortality table based on the Society of Actuaries RP 2014 mortality table including a generational MP-2018 projection scale. In 2020, the Company adopted the Pri-2012 base mortality table and the new MP-2020 mortality improvement scale to replace the previous assumption. Presented in the table below are the components of net periodic benefit costs for the years ended December 31: 2020 2019 2018 Components of net periodic pension benefit cost: Service cost $ 31 $ 28 $ 34 Interest cost 73 82 76 Expected return on plan assets (111) (91) (97) Amortization of prior service (credit) cost (3) (3) 1 Amortization of actuarial loss 30 32 27 Settlements (a) 1 — — Net periodic pension benefit cost $ 21 $ 48 $ 41 Other changes in plan assets and benefit obligations recognized in other comprehensive income: Current year actuarial (gain) loss $ 12 $ (8) $ (60) Amortization of actuarial loss (3) (4) (7) Total recognized in other comprehensive income 9 (12) (67) Total recognized in net periodic benefit cost and other comprehensive income $ 30 $ 36 $ (26) Components of net periodic other postretirement benefit (credit) cost: Service cost $ 4 $ 4 $ 8 Interest cost 12 15 20 Expected return on plan assets (19) (18) (26) Amortization of prior service credit (34) (35) (23) Amortization of actuarial loss 2 3 3 Net periodic other postretirement benefit (credit) cost $ (35) $ (31) $ (18) (a) Due to the amount of lump sum payment distributions from the Company’s New York Water Service Corporation Pension Plan, settlement charges of less than $1 million were recorded for the year ended December 31, 2020. There were no settlement charges recorded for the year ended December 31, 2019. In accordance with existing regulatory accounting treatment, the Company has maintained the settlement charges in regulatory assets on the Consolidated Balance Sheets. The amount is being amortized in accordance with existing regulatory practice. The Company’s policy is to recognize curtailments when the total expected future service of plan participants is reduced by greater than 10% due to an event that results in terminations and/or retirements. Cumulative gains and losses that are in excess of 10% of the greater of either the projected benefit obligation or the fair value of plan assets are amortized over the expected average remaining future service of the current active membership for the plans. Savings Plans for Employees The Company maintains 401(k) savings plans that allow employees to save for retirement on a tax-deferred basis. Employees can make contributions that are invested at their direction in one or more funds. The Company makes matching contributions based on a percentage of an employee’s contribution, subject to certain limitations. Due to the Company’s discontinuing new entrants into the defined benefit pension plan, on January 1, 2006, the Company began providing an additional 5.25% of base pay defined contribution benefit for union employees hired on or after January 1, 2001 and non-union employees hired on or after January 1, 2006. The Company’s 401(k) savings plan expenses totaled $12 million, $12 million and $12 million for 2020, 2019 and 2018, respectively. Additionally, the Company’s 5.25% of base pay defined contribution benefit expenses totaled $15 million, $13 million and $11 million for 2020, 2019 and 2018, respectively. All of the Company’s contributions are invested in one or more funds at the direction of the employees.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 17: Commitments and Contingencies Commitments have been made in connection with certain construction programs. The estimated capital expenditures required under legal and binding contractual obligations amounted to $484 million as of December 31, 2020. The Company’s regulated subsidiaries maintain agreements with other water purveyors for the purchase of water to supplement their water supply. Presented in the table below are the future annual commitments related to minimum quantities of purchased water having non-cancelable contracts: Amount 2021 $ 66 2022 67 2023 66 2024 52 2025 52 Thereafter 618 The Company enters into agreements for the provision of services to water and wastewater facilities for the U.S. military, municipalities and other customers. See Note 5—Revenue Recognition for additional information regarding the Company’s performance obligations. Contingencies The Company is routinely involved in legal actions incident to the normal conduct of its business. As of December 31, 2020, the Company has accrued approximately $10 million of probable loss contingencies and has estimated that the maximum amount of losses associated with reasonably possible loss contingencies that can be reasonably estimated is $4 million. For certain matters, claims and actions, the Company is unable to estimate possible losses. The Company believes that damages or settlements, if any, recovered by plaintiffs in such matters, claims or actions, other than as described in this Note 17—Commitments and Contingencies, will not have a material adverse effect on the Company. West Virginia Elk River Freedom Industries Chemical Spill On June 8, 2018, the U.S. District Court for the Southern District of West Virginia granted final approval of a settlement class and global class action settlement (the “Settlement”) for all claims and potential claims by all class members (collectively, the “West Virginia Plaintiffs”) arising out of the January 2014 Freedom Industries, Inc. chemical spill in West Virginia. The effective date of the Settlement was July 16, 2018. Under the terms and conditions of the Settlement, the Company’s West Virginia subsidiary (“WVAWC”) and certain other Company affiliated entities (collectively, the “West Virginia-American Water Defendants”) did not admit, and will not admit, any fault or liability for any of the allegations made by the West Virginia Plaintiffs in any of the actions that were resolved. The aggregate pre-tax amount contributed by WVAWC of the $126 million portion of the Settlement with respect to the Company, net of insurance recoveries, is $19 million. As of December 31, 2020, $0.5 million of the aggregate Settlement amount of $126 million has been reflected in accrued liabilities, and $0.5 million in offsetting insurance receivables have been reflected in other current assets on the Consolidated Balance Sheets. The amount reflected in accrued liabilities as of December 31, 2020 reflects reductions in the liability and appropriate reductions to the offsetting insurance receivable reflected in other current assets, associated with payments made to the Settlement fund, the receipt of a determination by the Settlement fund’s appeal adjudicator on all remaining medical claims and the calculation of remaining attorneys’ fees and claims administration costs. The Company funded WVAWC’s contributions to the Settlement through existing sources of liquidity. Dunbar, West Virginia Water Main Break Class Action Litigation On the evening of June 23, 2015, a 36-inch pre-stressed concrete transmission water main, installed in the early 1970s, failed. The water main is part of the West Relay pumping station located in the City of Dunbar, West Virginia and owned by WVAWC. The failure of the main caused water outages and low pressure for up to approximately 25,000 WVAWC customers. In the early morning hours of June 25, 2015, crews completed a repair, but that same day, the repair developed a leak. On June 26, 2015, a second repair was completed and service was restored that day to approximately 80% of the impacted customers, and to the remaining approximately 20% by the next morning. The second repair showed signs of leaking but the water main was usable until June 29, 2015 to allow tanks to refill. The system was reconfigured to maintain service to all but approximately 3,000 customers while a final repair was completed safely on June 30, 2015. Water service was fully restored by July 1, 2015 to all customers affected by this event. On June 2, 2017, a complaint captioned Jeffries, et al. v. West Virginia-American Water Company was filed in West Virginia Circuit Court in Kanawha County on behalf of an alleged class of residents and business owners who lost water service or pressure as a result of the Dunbar main break. The complaint alleges breach of contract by WVAWC for failure to supply water, violation of West Virginia law regarding the sufficiency of WVAWC’s facilities and negligence by WVAWC in the design, maintenance and operation of the water system. The Jeffries plaintiffs seek unspecified alleged damages on behalf of the class for lost profits, annoyance and inconvenience, and loss of use, as well as punitive damages for willful, reckless and wanton behavior in not addressing the risk of pipe failure and a large outage. On February 4, 2020, the Jeffries plaintiffs filed a motion seeking class certification on the issues of breach of contract and negligence, and to determine the applicability of punitive damages and a multiplier for those damages if imposed. On July 14, 2020, the Circuit Court entered an order granting the Jeffries plaintiffs’ motion for certification of a class regarding certain liability issues but denying certification of a class to determine a punitive damages multiplier. On August 31, 2020, WVAWC filed a Petition for Writ of Prohibition in the Supreme Court of Appeals of West Virginia seeking to vacate or remand the Circuit Court’s order certifying the issues class. At the request of the parties, on September 10, 2020, the Circuit Court ordered the stay of all matters in the class proceeding pending consideration of this petition. On December 3, 2020, the Supreme Court of Appeals issued an order to show cause stating that there are sufficient grounds for oral argument to consider prohibiting the class certification order. On January 28, 2021, the Supreme Court of Appeals granted a motion by the Jeffries plaintiffs to remand the case back to the Circuit Court for further consideration in light of a recent Supreme Court of Appeals decision issued in another case relating to the class certification issues raised. The Company and WVAWC believe that WVAWC has valid, meritorious defenses to the claims raised in this class action complaint. WVAWC is vigorously defending itself against these allegations. The Company cannot currently determine the likelihood of a loss, if any, or estimate the amount of any loss or a range of such losses related to this proceeding. Chattanooga, Tennessee Water Main Break Class Action Litigation On September 12, 2019, the Company’s Tennessee subsidiary (“TAWC”), experienced a leak in a 36-inch water transmission main, which caused service fluctuations or interruptions to TAWC customers and the issuance of a boil water notice. TAWC repaired the main by early morning on September 14, 2019, and restored full water service by the afternoon of September 15, 2019, with the boil water notice lifted for all customers on September 16, 2019. On September 17, 2019, a complaint captioned Bruce, et al. v. American Water Works Company, Inc., et al. was filed in the Circuit Court of Hamilton County, Tennessee against TAWC, the Company and American Water Works Service Company, Inc. (“Service Company,” and together with TAWC and the Company, collectively, the “Tennessee-American Water Defendants”), on behalf of a proposed class of individuals or entities who lost water service or suffered monetary losses as a result of the Chattanooga incident (the “Tennessee Plaintiffs”). The complaint alleged breach of contract and negligence against the Tennessee-American Water Defendants, as well as an equitable remedy of piercing the corporate veil. In the complaint as filed, the Tennessee Plaintiffs were seeking an award of unspecified alleged damages for wage losses, business and economic losses, out-of-pocket expenses, loss of use and enjoyment of property and annoyance and inconvenience, as well as punitive damages, attorneys’ fees and pre- and post-judgment interest. On November 22, 2019, the Tennessee-American Water Defendants filed a motion to dismiss the complaint for failure to state a claim upon which relief may be granted, and, with respect to the Company, for lack of personal jurisdiction. Oral argument on the motion to dismiss took place on September 9, 2020. On September 18, 2020, the court (i) granted the motion to dismiss the Tennessee Plaintiffs’ negligence claim against all Tennessee-American Water Defendants, (ii) denied the motion to dismiss the breach of contract claim against TAWC, (iii) held in abeyance the motion to dismiss the breach of contract claims against the Company and Service Company pending a further hearing and (iv) held in abeyance the Company’s motion to dismiss the complaint for lack of personal jurisdiction. On September 24, 2020, at the request of the Tennessee Plaintiffs, the court dismissed without prejudice all claims in the Bruce complaint against the Company and Service Company. The impact of the September 2020 court orders was that all of the Tennessee Plaintiffs’ claims in this complaint were dismissed, other than the breach of contract claims against TAWC. On October 16, 2020, TAWC answered the complaint, and the parties are commencing with discovery. TAWC and the Company believe that TAWC has meritorious defenses to the claims raised in this class action complaint, and TAWC is vigorously defending itself against these allegations. The Company cannot currently determine the likelihood of a loss, if any, or estimate the amount of any loss or a range of such losses related to this proceeding.. Alternative Water Supply in Lieu of Carmel River Diversions Compliance with Orders to Reduce Carmel River Diversions—Monterey Peninsula Water Supply Project Under a 2009 order (the “2009 Order”) of the State Water Resources Control Board (the “SWRCB”), the Company’s California subsidiary (“Cal Am”) is required to decrease significantly its yearly diversions of water from the Carmel River according to a set reduction schedule. In 2016, the SWRCB issued an order (the “2016 Order”) approving a deadline of December 31, 2021 for Cal Am’s compliance with these prior orders (the “2021 Deadline”). Cal Am is currently involved in developing the Monterey Peninsula Water Supply Project (the “Water Supply Project”), which includes the construction of a desalination plant, to be owned by Cal Am, and the construction of wells that would supply water to the desalination plant. In addition, the Water Supply Project also includes Cal Am’s purchase of water from a groundwater replenishment project (the “GWR Project”) between Monterey One Water and the Monterey Peninsula Water Management District (the “MPWMD”). The Water Supply Project is intended, among other things, to fulfill Cal Am’s obligations under the 2009 Order and the 2016 Order. Cal Am’s ability to move forward on the Water Supply Project is subject to administrative review by the California Public Utilities Commission (the “CPUC”) and other government agencies, obtaining necessary permits, and intervention from other parties. In September 2016, the CPUC unanimously approved a final decision to authorize Cal Am to enter into a water purchase agreement for the GWR Project and to construct a pipeline and pump station facilities and recover up to the incurred $50 million in associated costs plus AFUDC, subject to meeting certain criteria. In September 2018, the CPUC unanimously approved another final decision finding that (i) the Water Supply Project meets the CPUC’s requirements for a certificate of public convenience and necessity, (ii) the issuance of the final decision should not be delayed, and (iii) an additional procedural phase was not necessary to consider alternative projects. The CPUC’s 2018 decision concludes that the Water Supply Project is the best project to address estimated future water demands in Monterey, and, in addition to the cost recovery approved in its 2016 decision, adopts Cal Am’s cost estimates for the Water Supply Project, which amounted to an aggregate of $279 million plus AFUDC at a rate representative of Cal Am’s actual financing costs. The 2018 final decision specifies the procedures for recovery of all of Cal Am’s prudently incurred costs associated with the Water Supply Project upon its completion, subject to the frameworks included in the final decision related to cost caps, operation and maintenance costs, financing, ratemaking and contingency matters. The reasonableness of the Water Supply Project costs will be reviewed in the first general rate case filed by Cal Am after it becomes operational. Cal Am has incurred $154 million in aggregate costs as of December 31, 2020 related to the Water Supply Project, which includes $36 million in AFUDC. While Cal Am believes that its expenditures to date have been prudent and necessary to comply with the 2009 Order and the 2016 Order, as well as the CPUC’s 2016 and 2018 final decisions, Cal Am cannot currently predict its ability to recover all of its costs and expenses associated with the Water Supply Project and there can be no assurance that Cal Am will be able to recover all of such costs and expenses in excess of the $50 million in construction costs previously approved by the CPUC in its 2016 final decision. Coastal Development Permit Application In June 2018, Cal Am submitted a coastal development permit application to the City of Marina (the “City”) for those project components of the Water Supply Project located within the City’s coastal zone. Members of the City’s Planning Commission, as well as City councilpersons, have publicly expressed opposition to the Water Supply Project. In May 2019, the City issued a notice of final local action based upon the denial by the Planning Commission of Cal Am’s coastal development permit application. Thereafter, Cal Am appealed this decision to the California Coastal Commission (the “Coastal Commission”), as permitted under the City’s code and the California Coastal Act. At the same time, Cal Am submitted an application to the Coastal Commission for a coastal development permit for those project components located within the Coastal Commission’s original jurisdiction. In October 2019, staff of the Coastal Commission issued a report recommending a denial of Cal Am’s application for a coastal development permit with respect to the Water Supply Project, largely based on a memorandum prepared by the general manager of the MPWMD that contradicted findings made by the CPUC in its final decision approving the Water Supply Project. In November 2019, discussions between staffs of the Coastal Commission and the CPUC took place regarding the Coastal Commission staff recommendation, at which time the CPUC raised questions about the Coastal Commission staff’s findings on water supply and demand, groundwater impacts and the viability of a project that the Coastal Commission staff believes may be a possible alternative to the Water Supply Project. On August 25, 2020, the staff of the Coastal Commission released a report again recommending denial of Cal Am’s application for a coastal development permit. Although the report concluded that the Water Supply Project would have a negligible impact on groundwater resources, the report also concluded it would impact other coastal resources, such as environmentally sensitive habitat areas and wetlands, and that the Coastal Commission staff believes that a feasible alternative project exists that would avoid those impacts. The staff’s report also noted disproportionate impacts to communities of concern. On September 16, 2020, Cal Am withdrew its original jurisdiction application to allow additional time to address the Coastal Commission staff’s environmental justice concerns. The withdrawal of the original jurisdiction application did not impact Cal Am’s appeal of the City’s denial, which remains pending before the Coastal Commission. Cal Am refiled the original jurisdiction application on November 6, 2020. On December 3, 2020, the Coastal Commission sent to Cal Am a notice of incomplete application, identifying certain additional information needed to consider the application complete. Cal Am is preparing a response to the Coastal Commission’s notice. Cal Am continues to work constructively with all appropriate agencies to provide necessary information in connection with obtaining required approvals for the Water Supply Project. However, based on the foregoing, there can be no assurance that the Water Supply Project in its current configuration will be completed on a timely basis, if ever. Due to the delay in the approval schedule, Cal Am currently does not believe that it will be able to fully comply with the diversion reduction requirements and other remaining requirements under the 2009 Order and the 2016 Order, including the 2021 Deadline. While the Company cannot currently predict the likelihood or result of any adverse outcome associated with these matters, further attempts to comply with the 2009 Order and the 2016 Order, or the 2021 Deadline, may result in material additional costs and obligations to Cal Am, including fines and penalties against Cal Am in the event of noncompliance with the 2009 Order and the 2016 Order.

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Common Share	Note 18: Earnings per Common Share Presented in the table below is a reconciliation of the numerator and denominator for the basic and diluted earnings per share (“EPS”) calculations for the years ended December 31: 2020 2019 2018 Numerator: Net income attributable to common shareholders $ 709 $ 621 $ 567 Denominator: Weighted average common shares outstanding—Basic 181 181 180 Effect of dilutive common stock equivalents 1 — — Weighted average common shares outstanding—Diluted 182 181 180 The effect of dilutive common stock equivalents is related to outstanding stock options, RSUs and PSUs granted under the Company’s 2007 Plan and outstanding RSUs and PSUs granted under the Company’s 2017 Omnibus Equity Compensation Plan, as well as estimated shares to be purchased under the Company’s 2017 Nonqualified Employee Stock Purchase Plan. Less than one million share-based awards were excluded from the computation of diluted EPS for the years ended December 31, 2020, 2019 and 2018, because their effect would have been anti-dilutive under the treasury stock method.

Fair Values of Financial Instru

Fair Values of Financial Instruments	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Values of Financial Instruments	Note 19: Fair Value of Financial Information The following methods and assumptions were used by the Company in estimating its fair value disclosures for financial instruments: Current assets and current liabilities—The carrying amounts reported on the Consolidated Balance Sheets for current assets and current liabilities, including revolving credit debt, due to the short-term maturities and variable interest rates, approximate their fair values. Preferred stock with mandatory redemption requirements and long-term debt—The fair values of preferred stock with mandatory redemption requirements and long-term debt are categorized within the fair value hierarchy based on the inputs that are used to value each instrument. The fair value of long-term debt classified as Level 1 is calculated using quoted prices in active markets. Level 2 instruments are valued using observable inputs and Level 3 instruments are valued using observable and unobservable inputs.. Presented in the tables below are the carrying amounts, including fair value adjustments previously recognized in acquisition purchase accounting, and the fair values of the Company’s financial instruments: Carrying Amount December 31, 2020 L e vel 1 Level 2 Level 3 Total Preferred stock with mandatory redemption requirements $ 5 $ — $ — $ 7 $ 7 Long-term debt (excluding finance lease obligations) 9,656 9,639 415 1,753 11,807 Carrying Amount December 31, 2019 L e vel 1 Level 2 Level 3 Total Preferred stock with mandatory redemption requirements $ 7 $ — $ — $ 9 $ 9 Long-term debt (excluding finance lease obligations) 8,664 7,689 417 1,664 9,770 Fair Value Measurements To increase consistency and comparability in fair value measurements, GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels as follows: Level 1—Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access as of the reporting date. Financial assets and liabilities utilizing Level 1 inputs include active exchange-traded equity securities, exchange-based derivatives, mutual funds and money market funds. Level 2—Inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. Financial assets and liabilities utilizing Level 2 inputs include fixed income securities, non-exchange-based derivatives, commingled investment funds not subject to purchase and sale restrictions and fair-value hedges. Level 3—Unobservable inputs, such as internally-developed pricing models for the asset or liability due to little or no market activity for the asset or liability. Financial assets and liabilities utilizing Level 3 inputs include infrequently-traded non-exchange-based derivatives and commingled investment funds subject to purchase and sale restrictions. Recurring Fair Value Measurements Presented in the tables below are assets and liabilities measured and recorded at fair value on a recurring basis and their level within the fair value hierarchy: At Fair Value as of December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Restricted funds $ 29 $ — $ — $ 29 Rabbi trust investments 19 — — 19 Deposits 4 — — 4 Other investments 11 — — 11 Total assets 63 — — 63 Liabilities: Deferred compensation obligations 24 — — 24 Total liabilities 24 — — 24 Total assets $ 39 $ — $ — $ 39 At Fair Value as of December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Restricted funds $ 31 $ — $ — $ 31 Rabbi trust investments 17 — — 17 Deposits 3 — — 3 Other investments 8 — — 8 Total assets 59 — — 59 Liabilities: Deferred compensation obligations 21 — — 21 Total liabilities 21 — — 21 Total assets (liabilities) $ 38 $ — $ — $ 38 Restricted funds—The Company’s restricted funds primarily represent proceeds received from financings for the construction and capital improvement of facilities and from customers for future services under operation, maintenance and repair projects. Rabbi trust investments—The Company’s rabbi trust investments consist of equity and index funds from which supplemental executive retirement plan benefits and deferred compensation obligations can be paid. The Company includes these assets in other long-term assets on the Consolidated Balance Sheets. Deposits—Deposits include escrow funds and certain other deposits held in trust. The Company includes cash deposits in other current assets on the Consolidated Balance Sheets. Deferred compensation obligations—The Company’s deferred compensation plans allow participants to defer certain cash compensation into notional investment accounts. The Company includes such plans in other long-term liabilities on the Consolidated Balance Sheets. The value of the Company’s deferred compensation obligations is based on the market value of the participants’ notional investment accounts. The notional investments are comprised primarily of mutual funds, which are based on observable market prices. Mark-to-market derivative assets and liabilities— The Company employs derivative financial instruments in the form of variable-to-fixed interest rate swaps and treasury lock agreements, classified as economic hedges and cash flow hedges, respectively, in order to fix the interest cost on existing or forecasted debt. The Company may use fixed-to-floating interest rate swaps, typically designated as fair-value hedges, to achieve a targeted level of variable-rate debt as a percentage of total debt. The Company uses a calculation of future cash inflows and estimated future outflows, which are discounted, to determine the current fair value. Additional inputs to the present value calculation include the contract terms, counterparty credit risk, interest rates and market volatility. The Company had no significant mark-to-market derivatives outstanding as of December 31, 2020. Other investments—Other investments primarily represent money market funds used for active employee benefits. The Company includes other investments in other current assets on the Consolidated Balance Sheets.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Note 20: Leases The Company has operating and finance leases involving real property, including facilities, utility assets, vehicles, and equipment. Certain operating leases have renewal options ranging from one The Company participates in a number of arrangements with various public entities (“Partners”) in West Virginia. Under these arrangements, the Company transferred a portion of its utility plant to the Partners in exchange for an equal principal amount of Industrial Development Bonds (“IDBs”) issued by the Partners under the Industrial Development and Commercial Development Bond Act. The Company leased back the utility plant under agreements for a period of 30 to 40 years. The Company has recorded these agreements as finance leases in property, plant and equipment, as ownership of the assets will revert back to the Company at the end of the lease term. The carrying value of the finance lease assets was $147 million and $147 million as of December 31, 2020 and 2019, respectively. The Company determined that the finance lease obligations and the investments in IDBs meet the conditions for offsetting, and as such, are reported net on the Consolidated Balance Sheets and excluded from the finance lease disclosure presented below. The Company also enters into O&M agreements with the Partners. The Company pays an annual fee for use of the Partners’ assets in performing under the O&M agreements. The O&M agreements are recorded as operating leases, and future annual use fees of $4 million in 2021 through 2025, and $52 million thereafter, are included in operating lease ROU assets and operating lease liabilities on the Consolidated Balance Sheets. Rental expenses under operating and finance leases presented on the Consolidated Balance Sheets were $14 million and $16 million for the years ended December 31, 2020 and 2019, respectively. Rental expenses under operating leases which included variable and short-term lease costs were $35 million for the year ended December 31, 2018. For the year ended December 31, 2020, cash paid for amounts in lease liabilities, which includes operating and financing cash flows from operating and finance leases, was $14 million. For the year ended December 31, 2020, ROU assets obtained in exchange for new operating lease liabilities was $2 million. As of December 31, 2020, the weighted-average remaining lease term of the finance lease and operating leases were five years and 19 years, respectively, and the weighted-average discount rate of the finance lease and operating leases were 12% and 4%, respectively. The future maturities of lease liabilities at December 31, 2020 are $13 million in 2021, $12 million in 2022, $8 million in 2023, $7 million in 2024, $7 million in 2025 and $94 million thereafter. At December 31, 2020 imputed interest was $49 million.
Leases	Note 20: Leases The Company has operating and finance leases involving real property, including facilities, utility assets, vehicles, and equipment. Certain operating leases have renewal options ranging from one The Company participates in a number of arrangements with various public entities (“Partners”) in West Virginia. Under these arrangements, the Company transferred a portion of its utility plant to the Partners in exchange for an equal principal amount of Industrial Development Bonds (“IDBs”) issued by the Partners under the Industrial Development and Commercial Development Bond Act. The Company leased back the utility plant under agreements for a period of 30 to 40 years. The Company has recorded these agreements as finance leases in property, plant and equipment, as ownership of the assets will revert back to the Company at the end of the lease term. The carrying value of the finance lease assets was $147 million and $147 million as of December 31, 2020 and 2019, respectively. The Company determined that the finance lease obligations and the investments in IDBs meet the conditions for offsetting, and as such, are reported net on the Consolidated Balance Sheets and excluded from the finance lease disclosure presented below. The Company also enters into O&M agreements with the Partners. The Company pays an annual fee for use of the Partners’ assets in performing under the O&M agreements. The O&M agreements are recorded as operating leases, and future annual use fees of $4 million in 2021 through 2025, and $52 million thereafter, are included in operating lease ROU assets and operating lease liabilities on the Consolidated Balance Sheets. Rental expenses under operating and finance leases presented on the Consolidated Balance Sheets were $14 million and $16 million for the years ended December 31, 2020 and 2019, respectively. Rental expenses under operating leases which included variable and short-term lease costs were $35 million for the year ended December 31, 2018. For the year ended December 31, 2020, cash paid for amounts in lease liabilities, which includes operating and financing cash flows from operating and finance leases, was $14 million. For the year ended December 31, 2020, ROU assets obtained in exchange for new operating lease liabilities was $2 million. As of December 31, 2020, the weighted-average remaining lease term of the finance lease and operating leases were five years and 19 years, respectively, and the weighted-average discount rate of the finance lease and operating leases were 12% and 4%, respectively. The future maturities of lease liabilities at December 31, 2020 are $13 million in 2021, $12 million in 2022, $8 million in 2023, $7 million in 2024, $7 million in 2025 and $94 million thereafter. At December 31, 2020 imputed interest was $49 million.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information	Note 21: Segment Information The Company’s operating segments are comprised of the revenue-generating components of its businesses for which separate financial information is internally produced and regularly used by management to make operating decisions, assess performance and allocate resources. The Company operates its businesses primarily through one reportable segment, the Regulated Businesses segment. The Company also operates market-based businesses that, individually, do not meet the criteria of a reportable segment in accordance with GAAP, and are collectively presented as the Market-Based Businesses. The Regulated Businesses segment is the largest component of the Company’s business and includes subsidiaries that provide water and wastewater services to customers in 16 states. The Company’s primary Market-Based Businesses include HOS, which provides various warranty protection programs and other home services to residential customers, and MSG, which enters into long-term contracts with the U.S. government to provide water and wastewater services on various military installations. The accounting policies of the segments are the same as those described in Note 2—Significant Accounting Policies. The Regulated Businesses segment and Market-Based Businesses include intercompany costs that are allocated by Service Company and intercompany interest that is charged by AWCC, both of which are eliminated to reconcile to the Consolidated Statements of Operations. Inter-segment revenues include the sale of water from a regulated subsidiary to market-based subsidiaries, leased office space, and furniture and equipment provided by the market-based subsidiaries to regulated subsidiaries. “Other” includes corporate costs that are not allocated to the Company’s operating segments, eliminations of inter-segment transactions, fair value adjustments, and associated income and deductions related to the acquisitions that have not been allocated to the operating segments for evaluation of performance and allocation of resource purposes. The adjustments related to the acquisitions are reported in Other as they are excluded from segment performance measures evaluated by management. Presented in the tables below is summarized segment information as of and for the years ended December 31: 2020 Regulated Market-Based Other Consolidated Operating revenues $ 3,255 $ 540 $ (18) $ 3,777 Depreciation and amortization 562 26 16 604 Total operating expenses, net 2,102 421 6 2,529 Interest, net (291) 1 (105) (395) Income before income taxes 932 120 (128) 924 Provision for income taxes 217 29 (31) 215 Net income attributable to common shareholders 715 91 (97) 709 Total assets 22,357 891 1,518 24,766 Cash paid for capital expenditures 1,804 10 8 1,822 2019 Regulated Market-Based Other Consolidated Operating revenues $ 3,094 $ 539 $ (23) $ 3,610 Depreciation and amortization 529 37 16 582 Total operating expenses, net 1,964 480 (4) 2,440 Interest, net (295) 5 (92) (382) Income before income taxes 869 66 (102) 833 Provision for income taxes 215 20 (23) 212 Net income attributable to common shareholders 654 46 (79) 621 Total assets 20,318 1,008 1,356 22,682 Cash paid for capital expenditures 1,627 13 14 1,654 2018 Regulated Market-Based Other Consolidated Operating revenues $ 2,984 $ 476 $ (20) $ 3,440 Depreciation and amortization 500 29 16 545 Impairment charge — 57 — 57 Total operating expenses, net 1,912 441 (15) 2,338 Interest, net (280) 4 (74) (350) Income before income taxes 826 41 (80) 787 Provision for income taxes 224 11 (13) 222 Net income attributable to common shareholders 602 32 (67) 567 Total assets 18,680 999 1,544 21,223 Cash paid for capital expenditures 1,477 13 96 1,586

Unaudited Quarterly Data

Unaudited Quarterly Data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Data [Abstract]
Unaudited Quarterly Data	Note 22: Unaudited Quarterly Data Presented in the tables below are supplemental, unaudited, consolidated, quarterly financial data for each of the four quarters in the years ended December 31, 2020 and 2019, respectively. The operating results for any quarter are not indicative of results that may be expected for a full year or any future periods. 2020 First Quarter Second Quarter Third Quarter Fourth Quarter Operating revenues $ 844 $ 931 $ 1,079 $ 923 Operating income 239 313 433 263 Net income attributable to common shareholders 124 176 264 145 Basic earnings per share: (a) Net income attributable to common shareholders $ 0.69 $ 0.97 $ 1.46 $ 0.80 Diluted earnings per share: Net income attributable to common shareholders 0.68 0.97 1.46 0.80 (a) Amounts may not sum due to rounding. 2019 First Quarter Second Quarter Third Quarter Fourth Quarter Operating revenues $ 813 $ 882 $ 1,013 $ 902 Operating income 238 302 406 224 Net income attributable to common shareholders 113 170 240 98 Basic earnings per share: (a) Net income attributable to common shareholders $ 0.62 $ 0.94 $ 1.33 $ 0.54 Diluted earnings per share: Net income attributable to common shareholders 0.62 0.94 1.33 0.54 (a) Amounts may not sum due to rounding.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Regulation	RegulationThe Company’s regulated utilities are subject to regulation by multiple state utility commissions or other entities engaged in utility regulation, collectively referred to as Public Utility Commissions (“PUCs”). As such, the Company follows authoritative accounting principles required for rate regulated utilities, which requires the effects of rate regulation to be reflected in the Company’s Consolidated Financial Statements. PUCs generally authorize revenue at levels intended to recover the estimated costs of providing service, plus a return on net investments, or rate base. Regulators may also approve accounting treatments, long-term financing programs and cost of capital, operation and maintenance (“O&M”) expenses, capital expenditures, taxes, affiliated transactions and relationships, reorganizations, mergers, acquisitions and dispositions, along with imposing certain penalties or granting certain incentives. Due to timing and other differences in the collection of a regulated utility’s revenues, these authoritative accounting principles allow a cost that would otherwise be charged as an expense by a non-regulated entity, to be deferred as a regulatory asset if it is probable that such cost is recoverable through future rates. Conversely, these principles also require the creation of a regulatory liability for amounts collected in rates to recover costs expected to be incurred in the future, or amounts collected in excess of costs incurred and are refundable to customers.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires that management make estimates, assumptions and judgments that could affect the Company’s financial condition, results of operations and cash flows. Actual results could differ from these estimates, assumptions and judgments. The Company considers its critical accounting estimates to include (i) the application of regulatory accounting principles and the related determination and estimation of regulatory assets and liabilities, (ii) revenue recognition and the estimates used in the calculation of unbilled revenue, (iii) accounting for income taxes, (iv) benefit plan assumptions and (v) the estimates and judgments used in determining loss contingencies. The Company’s critical accounting estimates that are particularly sensitive to change in the near term are amounts reported for regulatory assets and liabilities, income taxes, benefit plan assumptions and contingency-related obligations.
Principles of Consolidation	Principles of Consolidation The accompanying Consolidated Financial Statements include the accounts of American Water and all of its subsidiaries in which a controlling interest is maintained after the elimination of intercompany balances and transactions.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consists primarily of utility plant utilized by the Company’s regulated utilities. Additions to utility plant and replacement of retirement units of utility plant are capitalized and include costs such as materials, direct labor, payroll taxes and benefits, indirect items such as engineering and supervision, transportation and an allowance for funds used during construction (“AFUDC”). Costs for repair, maintenance and minor replacements are charged to O&M expense as incurred. The cost of utility plant is depreciated using the straight-line average remaining life, group method. The Company’s regulated utilities record depreciation in conformity with amounts approved by PUCs, after regulatory review of the information the Company submits to support its estimates of the assets’ remaining useful lives. Nonutility property consists primarily of buildings and equipment utilized by the Company’s Market-Based Businesses and for internal operations. This property is stated at cost, net of accumulated depreciation, which is calculated using the straight-line method over the useful lives of the assets. When units of property, plant and equipment are replaced, retired or abandoned, the carrying value is credited against the asset and charged to accumulated depreciation. To the extent the Company recovers cost of removal or other retirement costs through rates after the retirement costs are incurred, a regulatory asset is recorded. In some cases, the Company recovers retirement costs through rates during the life of the associated asset and before the costs are incurred. These amounts result in a regulatory liability being reported based on the amounts previously recovered through customer rates, until the costs to retire those assets are incurred.
Cash and Cash Equivalents, and Restricted Funds	Cash and Cash Equivalents, and Restricted Funds Substantially all cash is invested in interest-bearing accounts. All highly liquid investments with a maturity of three months or less when purchased are considered to be cash equivalents. Restricted funds consist primarily of proceeds from financings for the construction and capital improvement of facilities, and deposits for future services under O&M projects. Proceeds are held in escrow or interest-bearing accounts until the designated expenditures are incurred. Restricted funds are classified on the Consolidated Balance Sheets as either current or long-term based upon the intended use of the funds.
Accounts Receivable and Unbilled Revenues	Accounts Receivable and Unbilled Revenues Accounts receivable include regulated utility customer accounts receivable, which represent amounts billed to water and wastewater customers generally on a monthly basis. Credit is extended based on the guidelines of the applicable PUCs and collateral is generally not required. Also included are market-based trade accounts receivable and nonutility customer receivables of the regulated subsidiaries. Unbilled revenues are accrued when service has been provided but has not been billed to customers and when costs exceed billings on market-based construction contracts.
Allowance for Uncollectible Accounts	Allowance for Uncollectible AccountsAllowances for uncollectible accounts are maintained for estimated probable losses resulting from the Company’s inability to collect receivables from customers. Accounts that are outstanding longer than the payment terms are considered past due. A number of factors are considered in determining the allowance for uncollectible accounts, including the length of time receivables are past due, previous loss history, current economic and societal conditions and reasonable and supportable forecasts that affect the collectability of receivables from customers. The Company generally writes off accounts when they become uncollectible or are over a certain number of days outstanding. An increase in the allowance for uncollectible accounts for the period ending December 31, 2020 reflects the impacts from the current novel coronavirus (“COVID-19”) pandemic, including an increase in uncollectible accounts expense and a reduction in amounts written off due to shutoff moratoria in place across the Company’s subsidiaries.
Materials and Supplies	Materials and Supplies Materials and supplies are stated at the lower of cost or net realizable value. Cost is determined using the average cost method.
Leases	Leases On January 1, 2019, the Company adopted Accounting Standards Update 2016-02, Leases (Topic 842) , and all related amendments (collectively, the “Standard”). The Company implemented the guidance in the Standard using the modified retrospective approach and applied the optional transition method, which allowed entities to apply the new Standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Under this approach, prior periods have not been restated and continue to be reported under the accounting standards in effect for those periods. The Standard includes practical expedients, which relate to the identification and classification of leases that commenced before the adoption date, initial direct costs for leases that commenced before the adoption date, the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset and the ability to carry forward accounting treatment for existing land easements. Adoption of the Standard resulted in the recognition of operating lease right-of-use (“ROU”) assets and operating lease liabilities as of January 1, 2019 of approximately $117 million and $115 million, respectively. The difference between the ROU assets and operating lease liabilities was recorded as an adjustment to retained earnings. The Standard did not materially impact the Company’s consolidated results of operations and had no impact on cash flows. The Company has operating and finance leases involving real property, including facilities, utility assets, vehicles, and equipment. The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease ROU assets, accrued liabilities and operating lease liabilities on the Consolidated Balance Sheets. Finance leases are included in property, plant and equipment, accrued liabilities and other long-term liabilities on the Consolidated Balance Sheets. The Company has made an accounting policy election not to include operating leases with a lease term of twelve months or less. ROU assets represent the right to use an underlying asset for the lease term and the lease liabilities represent the obligation to make lease payments arising from the lease. ROU assets and lease liabilities are generally recognized at the commencement date based on the present value of discounted lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of discounted lease payments. The implicit rate is used when readily determinable. ROU assets also include any upfront lease payments and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease components (e.g., fixed payments including rent, real estate taxes and insurance costs) and non-lease components (e.g., common-area maintenance costs), which are generally accounted for separately; however, the Company accounts for the lease and non-lease components as a single lease component for certain leases. Certain lease agreements include variable rental payments adjusted periodically for inflation. Additionally, the Company applies a portfolio approach to effectively account for the ROU assets and lease liabilities. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants.
Leases	Leases On January 1, 2019, the Company adopted Accounting Standards Update 2016-02, Leases (Topic 842) , and all related amendments (collectively, the “Standard”). The Company implemented the guidance in the Standard using the modified retrospective approach and applied the optional transition method, which allowed entities to apply the new Standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Under this approach, prior periods have not been restated and continue to be reported under the accounting standards in effect for those periods. The Standard includes practical expedients, which relate to the identification and classification of leases that commenced before the adoption date, initial direct costs for leases that commenced before the adoption date, the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset and the ability to carry forward accounting treatment for existing land easements. Adoption of the Standard resulted in the recognition of operating lease right-of-use (“ROU”) assets and operating lease liabilities as of January 1, 2019 of approximately $117 million and $115 million, respectively. The difference between the ROU assets and operating lease liabilities was recorded as an adjustment to retained earnings. The Standard did not materially impact the Company’s consolidated results of operations and had no impact on cash flows. The Company has operating and finance leases involving real property, including facilities, utility assets, vehicles, and equipment. The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease ROU assets, accrued liabilities and operating lease liabilities on the Consolidated Balance Sheets. Finance leases are included in property, plant and equipment, accrued liabilities and other long-term liabilities on the Consolidated Balance Sheets. The Company has made an accounting policy election not to include operating leases with a lease term of twelve months or less. ROU assets represent the right to use an underlying asset for the lease term and the lease liabilities represent the obligation to make lease payments arising from the lease. ROU assets and lease liabilities are generally recognized at the commencement date based on the present value of discounted lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of discounted lease payments. The implicit rate is used when readily determinable. ROU assets also include any upfront lease payments and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease components (e.g., fixed payments including rent, real estate taxes and insurance costs) and non-lease components (e.g., common-area maintenance costs), which are generally accounted for separately; however, the Company accounts for the lease and non-lease components as a single lease component for certain leases. Certain lease agreements include variable rental payments adjusted periodically for inflation. Additionally, the Company applies a portfolio approach to effectively account for the ROU assets and lease liabilities. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants.
Goodwill	Goodwill Goodwill represents the excess of the purchase price paid over the estimated fair value of the assets acquired and liabilities assumed in the acquisition of a business. Goodwill is not amortized and must be allocated at the reporting unit level, which is defined as an operating segment or one level below, and tested for impairment at least annually, or more frequently if an event occurs or circumstances change that would more likely than not, reduce the fair value of a reporting unit below its carrying value. The Company’s goodwill is primarily associated with (i) the acquisition of American Water by an affiliate of the Company’s previous owner in 2003, (ii) the acquisition of E’town Corporation by a predecessor to the Company’s previous owner in 2001, and (iii) the acquisition of Pivotal in 2018; and has been allocated to reporting units based on the fair values at the date of the acquisitions. For purposes of testing goodwill for impairment, the reporting units in the Regulated Businesses segment are aggregated into a single reporting unit. The Market-Based Businesses is comprised of the HOS and MSG reporting units. The Company’s annual impairment testing is performed as of November 30 of each year, in conjunction with the completion of the Company’s annual business plan. The Company assesses qualitative factors to determine whether quantitative testing is necessary. If it is determined, based upon qualitative factors, that the estimated fair value of a reporting unit is more likely than not, greater than its carrying value, no further testing is required. If the Company bypasses the qualitative assessment, or performs the qualitative assessment and determines that the estimated fair value of a reporting unit is more likely than not, less than its carrying value, a quantitative, fair value-based test is performed. This quantitative testing compares the estimated fair value of the reporting unit to its respective net carrying value, including goodwill, on the measurement date. An impairment loss will be recognized in the amount equal to the excess of the reporting unit’s carrying value compared to its estimated fair value, limited to the total amount of goodwill allocated to that reporting unit.
Intangible Assets	Intangible AssetsIntangible assets consist primarily of finite-lived customer relationships associated with the acquisition of Pivotal. Finite-lived intangible assets are initially measured at their estimated fair values, and are amortized over their estimated useful lives based on the pattern in which the economic benefits of the intangible assets are consumed or otherwise used.
Impairments of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets include property, plant and equipment, goodwill, intangible assets and long-term investments. The Company evaluates long-lived assets for impairment when circumstances indicate the carrying value of those assets may not be recoverable. When such indicators arise, the Company estimates the fair value of the long-lived asset from future cash flows expected to result from its use and, if applicable, the eventual disposition of the asset, comparing the estimated fair value to the carrying value of the asset. An impairment loss will be recognized in the amount equal to the excess of the long-lived asset’s carrying value compared to its estimated fair value. The long-lived assets of the Company’s regulated utilities are grouped on a separate entity basis for impairment testing, as they are integrated state-wide operations that do not have the option to curtail service and generally have uniform tariffs. A regulatory asset is charged to earnings if and when future recovery in rates of that asset is no longer probable. The Company believes the assumptions and other considerations used to value long-lived assets to be appropriate, however, if actual experience differs from the assumptions and considerations used in its estimates, the resulting change could have a material adverse impact on the Consolidated Financial Statements.
Advances for Construction and Contributions in Aid of Construction	Advances for Construction and Contributions in Aid of Construction Regulated utility subsidiaries may receive advances for construction and contributions in aid of construction from customers, home builders and real estate developers to fund construction necessary to extend service to new areas. Advances are refundable for limited periods of time as new customers begin to receive service or other contractual obligations are fulfilled. Included in other current liabilities as of December 31, 2020 and 2019 on the Consolidated Balance Sheets are estimated refunds of $23 million and $25 million, respectively. Those amounts represent expected refunds during the next 12-month period. Advances that are no longer refundable are reclassified to contributions. Contributions are permanent collections of plant assets or cash for a particular construction project. For ratemaking purposes, the amount of such contributions generally serves as a rate base reduction since the contributions represent non-investor supplied funds.
Revenues Recognition	Revenue Recognition On January 1, 2018, the Company adopted Accounting Standards Codification Topic 606, Revenue From Contracts With Customers, and all related amendments (collectively, “ASC 606”) , using the modified retrospective approach, applied to contracts which were not completed as of January 1, 2018. Under ASC 606, a performance obligation is a promise within a contract to transfer a distinct good or service, or a series of distinct goods and services, to a customer. Revenue is recognized when performance obligations are satisfied and the customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for goods or services. Under ASC 606, a contract’s transaction price is allocated to each distinct performance obligation. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identifies the contracts with a customer; (ii) identifies the performance obligations within the contract, including whether any performance obligations are distinct and capable of being distinct in the context of the contract; (iii) determines the transaction price; (iv) allocates the transaction price to the performance obligations in the contract; and (v) recognizes revenue when, or as, the Company satisfies each performance obligation. The Company’s revenues from contracts with customers are discussed below. Customer payments for contracts are generally due within 30 days of billing and none of the contracts with customers have payment terms that exceed one year; therefore, the Company elected to apply the significant financing component practical expedient and no amount of consideration has been allocated as a financing component. Regulated Businesses Revenue Revenue from the Company’s Regulated Businesses is generated primarily from water and wastewater services delivered to customers. These contracts contain a single performance obligation, the delivery of water and/or wastewater services, as the promise to transfer the individual good or service is not separately identifiable from other promises within the contracts and, therefore, is not distinct. Revenues are recognized over time, as services are provided. There are generally no significant financing components or variable consideration. Revenues include amounts billed to customers on a cycle basis and unbilled amounts calculated based on estimated usage from the date of the meter reading associated with the latest customer bill, to the end of the accounting period. The amounts that the Company has a right to invoice are determined by each customer’s actual usage, an indicator that the invoice amount corresponds directly to the value transferred to the customer. The Company also recognizes revenue when it is probable that future recovery of previously incurred costs or future refunds that are to be credited to customers will occur through the ratemaking process. Market-Based Businesses Revenue Through various warranty protection programs and other home services, the Company provides fixed fee services to residential customers for interior and exterior water and sewer lines, interior electric and gas lines, heating and cooling systems, water heaters and other home appliances, as well as power surge protection and other related services. Most of the contracts have a one-year term and each service is a separate performance obligation, satisfied over time, as the customers simultaneously receive and consume the benefits provided from the service. Customers are obligated to pay for the protection programs ratably over 12 months or via a one-time, annual fee, with revenues recognized ratably over time for these services. Advances from customers are deferred until the performance obligation is satisfied.
Income Taxes	Income Taxes The Company and its subsidiaries participate in a consolidated federal income tax return for U.S. tax purposes. Members of the consolidated group are charged with the amount of federal income tax expense determined as if they filed separate returns. Certain income and expense items are accounted for in different time periods for financial reporting than for income tax reporting purposes. The Company provides deferred income taxes on the difference between the tax basis of assets and liabilities and the amounts at which they are carried in the financial statements. These deferred income taxes are based on the enacted tax rates expected to be in effect when these temporary differences are projected to reverse. In addition, the regulated utility subsidiaries recognize regulatory assets and liabilities for the effect on revenues expected to be realized as the tax effects of temporary differences, previously flowed through to customers, reverse. Investment tax credits have been deferred by the regulated utility subsidiaries and are being amortized to income over the average estimated service lives of the related assets.
Allowance for Funds Used During Construction	Allowance for Funds Used During ConstructionAFUDC is a non-cash credit to income with a corresponding charge to utility plant that represents the cost of borrowed funds or a return on equity funds devoted to plant under construction. The regulated utility subsidiaries record AFUDC to the extent permitted by the PUCs. The portion of AFUDC attributable to borrowed funds is shown as a reduction of interest, net on the Consolidated Statements of Operations. Any portion of AFUDC attributable to equity funds would be included in other, net on the Consolidated Statements of Operations.
Environmental Costs	Environmental CostsThe Company’s water and wastewater operations and the operations of its Market-Based Businesses are subject to U.S. federal, state, local and foreign requirements relating to environmental protection, and as such, the Company periodically becomes subject to environmental claims in the normal course of business. Environmental expenditures that relate to current operations or provide a future benefit are expensed or capitalized as appropriate. Remediation costs that relate to an existing condition caused by past operations are accrued, on an undiscounted basis, when it is probable that these costs will be incurred and can be reasonably estimated. A conservation agreement entered into by a subsidiary of the Company with the National Oceanic and Atmospheric Administration in 2010 and amended in 2017 required the subsidiary to, among other provisions, implement certain measures to protect the steelhead trout and its habitat in the Carmel River watershed in the State of California.
Derivative Financial Instruments	Derivative Financial Instruments The Company uses derivative financial instruments for purposes of hedging exposures to fluctuations in interest rates. These derivative contracts are entered into for periods consistent with the related underlying exposures and do not constitute positions independent of those exposures. The Company does not enter into derivative contracts for speculative purposes and does not use leveraged instruments. All derivatives are recognized on the balance sheet at fair value. On the date the derivative contract is entered into, the Company may designate the derivative as a hedge of the fair value of a recognized asset or liability (fair-value hedge) or a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability (cash-flow hedge). Changes in the fair value of a fair-value hedge, along with the gain or loss on the underlying hedged item, are recorded in current-period earnings. The gains and losses on the effective portion of cash-flow hedges are recorded in other comprehensive income, until earnings are affected by the variability of cash flows. Any ineffective portion of designated cash-flow hedges is recognized in current-period earnings.
New Accounting Standards	New Accounting Standards Presented in the table below are new accounting standards that were adopted by the Company in 2020: Standard Description Date of Adoption Application Effect on the Consolidated Financial Statements Measurement of Credit Losses on Financial Instruments Updated the accounting guidance on reporting credit losses for financial assets held at amortized cost basis and available-for-sale debt securities. Under this guidance, expected credit losses are required to be measured based on historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of the reported amount of financial assets. Also, this guidance requires that credit losses on available-for-sale debt securities be presented as an allowance rather than as a direct write-down. January 1, 2020 Modified retrospective The standard did not have a material impact on the Consolidated Financial Statements. Changes to the Disclosure Requirements for Fair Value Measurement Updated the disclosure requirements for fair value measurement. The guidance removes the requirements to disclose transfers between Level 1 and Level 2 measurements, the timing of transfers between levels, and the valuation processes for Level 3 measurements. Disclosure of transfers into and out of Level 3 measurements will be required. The guidance adds disclosure requirements for the change in unrealized gains and losses in other comprehensive income for recurring Level 3 measurements, as well as the range and weighted average of significant unobservable inputs used to develop Level 3 measurements. January 1, 2020 Prospective for added disclosures and for the narrative description of measurement uncertainty; retrospective for all other amendments. The standard did not have a material impact on the Consolidated Financial Statements. Facilitation of the Effects of Reference Rate Reform on Financial Reporting Provided optional guidance for a limited time to ease the potential accounting burden associated with the transition from London Interbank Offered Rate (“LIBOR”). The guidance contains optional expedients and exceptions for contract modifications, hedging relationships, and other transactions that reference LIBOR or other reference rates expected to be discontinued. The expedients elected must be applied for all eligible contracts or transactions, with the exception of hedging relationships, which can be applied on an individual basis. March 12, 2020 through December 31, 2022 Prospective for contract modifications and hedging relationships; applied as of January 1, 2020. The standard did not have a material impact on the Consolidated Financial Statements. Presented in the table below are recently issued accounting standards that have not yet been adopted by the Company as of December 31, 2020: Standard Description Date of Adoption Application Estimated Effect on the Consolidated Financial Statements Simplifying the Accounting for Income Taxes The guidance removes exceptions related to the incremental approach for intraperiod tax allocation, the requirement to recognize a deferred tax liability for changes in ownership of a foreign subsidiary or equity method investment, and the general methodology for calculating income taxes in an interim period when the year-to-date loss exceeds the anticipated loss. The guidance adds requirements to reflect changes to tax laws or rates in the annual effective tax rate computation in the interim period in which the changes were enacted, to recognize franchise or other similar taxes that are partially based on income as an income-based tax and any incremental amounts as non-income-based tax, and to evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction. January 1, 2021; early adoption permitted Modified retrospective for amendments related to changes in ownership of a foreign subsidiary or equity method investment; The standard will not have a material impact on the Consolidated Financial Statements. Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity Simplification of financial reporting associated with accounting for convertible instruments and contracts in an entity’s own equity. The standard reduced the number of accounting models for convertible debt instruments and convertible preferred stock. This will result in fewer embedded conversion features being separately recognized from the host contract. Earnings per share (“EPS”) calculations have been simplified for certain instruments. January 1, 2022; early adoption permitted but not before fiscal years beginning after December 15, 2020 Either modified retrospective or fully retrospective The Company is evaluating any impact on its Consolidated Financial Statements, as well as the timing of adoption.
Reclassifications	ReclassificationsCertain reclassifications have been made to prior periods in the Consolidated Financial Statements and Notes to conform to the current presentation.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Reconciliation Of Cash And Cash Equivalents, And Restricted Cash Reported	Presented in the table below is a reconciliation of the cash and cash equivalents and restricted funds amounts as presented on the Consolidated Balance Sheets to the sum of such amounts presented on the Consolidated Statements of Cash Flows for the years ended December 31: 2020 2019 Cash and cash equivalents $ 547 $ 60 Restricted funds 29 31 Cash and cash equivalents and restricted funds as presented on the Consolidated Statements of Cash Flows $ 576 $ 91
Schedule of Allowance for Funds Used During Construction	Presented in the table below is AFUDC for the years ended December 31: 2020 2019 2018 Allowance for other funds used during construction $ 30 $ 28 $ 24 Allowance for borrowed funds used during construction 13 13 13
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	New Accounting Standards Presented in the table below are new accounting standards that were adopted by the Company in 2020: Standard Description Date of Adoption Application Effect on the Consolidated Financial Statements Measurement of Credit Losses on Financial Instruments Updated the accounting guidance on reporting credit losses for financial assets held at amortized cost basis and available-for-sale debt securities. Under this guidance, expected credit losses are required to be measured based on historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of the reported amount of financial assets. Also, this guidance requires that credit losses on available-for-sale debt securities be presented as an allowance rather than as a direct write-down. January 1, 2020 Modified retrospective The standard did not have a material impact on the Consolidated Financial Statements. Changes to the Disclosure Requirements for Fair Value Measurement Updated the disclosure requirements for fair value measurement. The guidance removes the requirements to disclose transfers between Level 1 and Level 2 measurements, the timing of transfers between levels, and the valuation processes for Level 3 measurements. Disclosure of transfers into and out of Level 3 measurements will be required. The guidance adds disclosure requirements for the change in unrealized gains and losses in other comprehensive income for recurring Level 3 measurements, as well as the range and weighted average of significant unobservable inputs used to develop Level 3 measurements. January 1, 2020 Prospective for added disclosures and for the narrative description of measurement uncertainty; retrospective for all other amendments. The standard did not have a material impact on the Consolidated Financial Statements. Facilitation of the Effects of Reference Rate Reform on Financial Reporting Provided optional guidance for a limited time to ease the potential accounting burden associated with the transition from London Interbank Offered Rate (“LIBOR”). The guidance contains optional expedients and exceptions for contract modifications, hedging relationships, and other transactions that reference LIBOR or other reference rates expected to be discontinued. The expedients elected must be applied for all eligible contracts or transactions, with the exception of hedging relationships, which can be applied on an individual basis. March 12, 2020 through December 31, 2022 Prospective for contract modifications and hedging relationships; applied as of January 1, 2020. The standard did not have a material impact on the Consolidated Financial Statements. Presented in the table below are recently issued accounting standards that have not yet been adopted by the Company as of December 31, 2020: Standard Description Date of Adoption Application Estimated Effect on the Consolidated Financial Statements Simplifying the Accounting for Income Taxes The guidance removes exceptions related to the incremental approach for intraperiod tax allocation, the requirement to recognize a deferred tax liability for changes in ownership of a foreign subsidiary or equity method investment, and the general methodology for calculating income taxes in an interim period when the year-to-date loss exceeds the anticipated loss. The guidance adds requirements to reflect changes to tax laws or rates in the annual effective tax rate computation in the interim period in which the changes were enacted, to recognize franchise or other similar taxes that are partially based on income as an income-based tax and any incremental amounts as non-income-based tax, and to evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction. January 1, 2021; early adoption permitted Modified retrospective for amendments related to changes in ownership of a foreign subsidiary or equity method investment; The standard will not have a material impact on the Consolidated Financial Statements. Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity Simplification of financial reporting associated with accounting for convertible instruments and contracts in an entity’s own equity. The standard reduced the number of accounting models for convertible debt instruments and convertible preferred stock. This will result in fewer embedded conversion features being separately recognized from the host contract. Earnings per share (“EPS”) calculations have been simplified for certain instruments. January 1, 2022; early adoption permitted but not before fiscal years beginning after December 15, 2020 Either modified retrospective or fully retrospective The Company is evaluating any impact on its Consolidated Financial Statements, as well as the timing of adoption.

Impact of Novel Coronavirus (_2

Impact of Novel Coronavirus (COVID-19) Pandemic (Tables)	12 Months Ended
	Dec. 31, 2020
Risks and Uncertainties [Abstract]
Schedule Related To Approved Cost Recovery Mechanisms Related To Certain Incremental Costs From The COVID-19 Pandemic	Regulatory actions to date are presented in the table below: Commission Actions Description States Orders issued Allows the Company to establish regulatory assets to record certain financial impacts related to the COVID-19 pandemic. CA, HI, IA, IL, IN, MD, MO, NJ, PA, VA, WV Cost recovery mechanisms California’s Catastrophic Event Memorandum Account allows the Company to track and recover certain financial impacts related to the COVID-19 pandemic. Illinois has authorized cost recovery of COVID-19 financial impacts through a special purpose rider over a 24-month period, which was implemented by the Company’s Illinois subsidiary effective October 1, 2020. Additionally, Illinois approved a bad debt rider tariff on December 16, 2020. This rider will allow the Company to collect actual bad debt expense over last authorized beginning March 2021 over a 24-month period. CA, IL Proceedings pending Pending proceedings considering deferred accounting authorization for the future recovery of COVID-19 financial impacts. NY, TN

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2020
Regulated Operations [Abstract]
Schedule of Generate Rate Cases	Presented in the table below are annualized incremental revenues, assuming a constant water sales volume, resulting from general rate cases authorizations that became effective during 2018 through 2020: (In millions) 2020 2019 2018 General rate cases by state: New Jersey (a) $ 39 $ — $ 40 Indiana (b) 13 4 — California (c) 5 4 10 Virginia (d) (1) — — Kentucky (effective June 28, 2019) — 13 — New York (e) — 4 5 West Virginia (effective February 25, 2019) — 19 — Maryland (effective February 5, 2019) — 1 — Missouri (effective May 28, 2018) — — 33 Pennsylvania (effective January 1, 2018) — — 62 Total general rate case authorizations $ 56 $ 45 $ 150 (a) The $39 million base rate increase was effective on November 1, 2020, which is net of excess accumulated deferred income taxes (“EADIT”) of $15 million being returned to customers. The unprotected EADIT balance of $133 million is being returned to customers over 15 years. The $39 million rate increase was further reduced by a bill credit, for a 10-month period beginning November 1, 2020 for both the protected and unprotected catch up period EADIT of $32.5 million. The catch up period of January 1, 2018 through October 31, 2020 covers the period from when the lower federal tax rate went into effect until new base rates went into effect. The $40 million rate increase was effective on June 15, 2018. As part of the resolution of the general rate case in 2018, the Company’s New Jersey subsidiary’s customers received refunds for the amount of provisional rates implemented as of June 15, 2018 that exceeded the final rate increase plus interest. (b) The Company’s Indiana subsidiary received an order approving a joint settlement agreement with all major parties with respect to its general rate case filing, authorizing annualized incremental revenues of $4 million in the first rate year, effective July 1, 2019, and $13 million in the second rate year, effective May 1, 2020. (c) The Company’s California subsidiary received approval for the third year (2020) step increase associated with its most recent general rate case authorization, effective January 1, 2020. In 2019, the step increase was effective May 11, 2019. On December 13, 2018, a settlement in this subsidiary’s general rate case filing was approved, authorizing rates effective January 1, 2018. (d) The Company’s Virginia subsidiary received an order approving increased water revenues by $1 million, inclusive of Water & Wastewater Infrastructure Service Charge (“WWISC”) revenues of $1 million, and decreased wastewater revenue by $1 million, for a net zero award including WWISC, or an overall decrease of $1 million excluding WWISC. Unprotected EADIT is being returned to customers over eight years, and base rates include a reduction of $1 million for EADIT. (e) The Company’s New York subsidiary implemented its third step increase associated with its most recent general rate case authorization, effective April 1, 2019.
Schedule of Annualized Incremental Revenues	Presented in the table below are annualized incremental revenues, assuming a constant water sales volume, resulting from infrastructure surcharge authorizations that became effective during 2018 through 2020: (In millions) 2020 2019 2018 Infrastructure surcharges by state: Missouri (a) $ 12 $ 14 $ 6 Pennsylvania (b) 27 11 — Kentucky (effective July 1, 2020) 1 — — New Jersey (c) 20 15 — Tennessee (effective January 1, 2020, September 1, 2019 and April 10, 2018) 2 1 1 Illinois (effective January 1, 2020, January 1, 2019 and January 1, 2018) 7 8 3 West Virginia (effective January 1, 2020, January 1, 2019 and January 1, 2018) 3 2 3 New York (effective August 1, 2019) — 2 — Indiana (effective March 14, 2018) — — 7 Virginia (effective March 1, 2018) — — 1 Total infrastructure surcharge authorizations $ 72 $ 53 $ 21 (a) In 2020, $2 million was effective December 14 and $10 million was effective June 27. In 2019, $5 million was effective December 21 and $9 million was effective June 24. In 2018, the effective date was December 15. (b) In 2020, $8 million was effective October 1, $4 million was effective July 1, $5 million was effective April 1 and $10 million was effective January 1. In 2019, $6 million was effective October 1, $3 million was effective July 1 and $2 million was effective April 1. (c) In 2020, $10 million was effective June 29 and $10 million was effective January 1. In 2019, the effective date was July 1. Presented in the table below are annualized incremental revenues, assuming a constant water sales volume, resulting from infrastructure surcharge authorizations that became effective after January 1, 2020: (In millions) Amount Infrastructure surcharge filings by state: Pennsylvania (effective January 1, 2021) $ 8 Illinois (effective January 1, 2021) 7 West Virginia (effective January 1, 2021) 5 Tennessee (effective January 1, 2021) 3 Total infrastructure surcharge filings $ 23
Summary of Composition of Regulatory Assets	Presented in the table below is the composition of regulatory assets as of December 31: 2020 2019 Deferred pension expense $ 374 $ 384 Removal costs recoverable through rates 314 305 Regulatory balancing accounts 57 96 Other 446 398 Less: Regulatory assets included in assets held for sale (a) (64) (55) Total regulatory assets $ 1,127 $ 1,128 (a) These regulatory assets are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information.
Summary of Composition of Regulatory Liabilities	Presented in the table below is the composition of regulatory liabilities as of December 31: 2020 2019 Income taxes recovered through rates $ 1,230 $ 1,258 Removal costs recovered through rates 301 297 Postretirement benefit liability 170 186 Other 111 102 Less: Regulatory liabilities included in liabilities related to assets held for sale (a) (42) (37) Total regulatory liabilities $ 1,770 $ 1,806 (a) These regulatory liabilities are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in liabilities related to assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Presented in the table below are operating revenues disaggregated for the year ended December 31, 2020: Revenues from Contracts with Customers Other Revenues Not from Contracts with Customers (a) Total Operating Revenues Regulated Businesses: Water services: Residential $ 1,895 $ — $ 1,895 Commercial 627 — 627 Fire service 147 — 147 Industrial 133 — 133 Public and other 201 — 201 Total water services 3,003 — 3,003 Wastewater services: Residential 134 — 134 Commercial 34 — 34 Industrial 3 — 3 Public and other 14 — 14 Total wastewater services 185 — 185 Miscellaneous utility charges 32 — 32 Alternative revenue programs — 25 25 Lease contract revenue — 10 10 Total Regulated Businesses 3,220 35 3,255 Market-Based Businesses 540 — 540 Other (17) (1) (18) Total operating revenues $ 3,743 $ 34 $ 3,777 (a) Includes revenues associated with provisional rates, alternative revenue programs, lease contracts and intercompany rent, which are outside the scope of ASC 606, and accounted for under other existing GAAP.

Acquisitions and Divestitures (

Acquisitions and Divestitures (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Components of Assets Held For Sale and Liabilities	Presented in the table below are the components of assets held for sale and liabilities related to assets held for sale of the New York subsidiary as of December 31, 2020: December 31, 2020 Property, plant and equipment $ 504 Current assets 12 Regulatory assets 64 Goodwill 39 Other assets 10 Assets held for sale $ 629 Current liabilities 14 Deferred income taxes 69 Regulatory liabilities 42 Other liabilities 12 Liabilities related to assets held for sale $ 137

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Summary of Major Classes of Property, Plant and Equipment by Category	Presented in the table below are the major classes of property, plant and equipment by category as of December 31: 2020 2019 Range of Remaining Useful Lives Weighted Average Useful Life Utility plant: Land and other non-depreciable assets $ 174 $ 166 Sources of supply 897 858 2 to 127 years 47 years Treatment and pumping facilities 3,984 3,750 3 to 111 years 41 years Transmission and distribution facilities 11,457 10,807 9 to 149 years 69 years Services, meters and fire hydrants 4,555 4,304 5 to 90 years 31 years General structures and equipment 2,003 1,748 1 to 109 years 16 years Waste collection 1,288 1,153 5 to 113 years 59 years Waste treatment, pumping and disposal 859 720 2 to 139 years 47 years Construction work in progress 837 801 Less: Utility plant included in assets held for sale (a) (646) (587) Total utility plant 25,408 23,720 Nonutility property 211 226 3 to 50 years 8 years Less: Nonutility plant included in assets held for sale (a) (5) (5) Total property, plant and equipment $ 25,614 $ 23,941 (a) This property, plant and equipment is related to the pending transactions contemplated by the Stock Purchase Agreement and is included in assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information.

Allowance for Uncollectible A_2

Allowance for Uncollectible Accounts (Tables)	12 Months Ended
	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Schedule of Allowances for Uncollectible Accounts	Presented in the table below are the changes in the allowances for uncollectible accounts for the years ended December 31: 2020 2019 2018 Balance as of January 1 $ (41) $ (45) $ (42) Amounts charged to expense (34) (28) (33) Amounts written off 12 32 34 Recoveries of amounts written off — — (4) Less: Allowance for uncollectible accounts included in assets held for sale (a) 3 — — Balance as of December 31 $ (60) $ (41) $ (45) (a) This portion of the allowance for uncollectible accounts is related to the pending transactions contemplated by the Stock Purchase Agreement among the Company, the Company’s New York subsidiary and an affiliate of Liberty Utilities Co., and is included in assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Changes in Goodwill Assets	Presented in the table below are the changes in the carrying value of goodwill for the years ended December 31, 2020 and 2019: Regulated Businesses Market-Based Businesses Consolidated Cost Accumulated Impairment Cost Accumulated Impairment Cost Accumulated Impairment Total Net Balance as of January 1, 2019 $ 3,494 $ (2,332) $ 574 $ (161) $ 4,068 $ (2,493) $ 1,575 Goodwill from acquisitions 3 — — — 3 — 3 Goodwill reduced through sale of Keystone operations — — (91) 53 (91) 53 (38) Less: Goodwill included in assets held for sale (a) (39) — — (39) — (39) Balance as of December 31, 2019 $ 3,458 $ (2,332) $ 483 $ (108) $ 3,941 $ (2,440) $ 1,501 Goodwill from acquisitions 5 — — — 5 — 5 Measurement period adjustments (2) — — — (2) — (2) Balance as of December 31, 2020 $ 3,461 $ (2,332) $ 483 $ (108) $ 3,944 $ (2,440) $ 1,504 (a) This goodwill is related to the pending transactions contemplated by the Stock Purchase Agreement and is included in assets held for sale on the Consolidated Balance Sheets as of December 31, 2020 and 2019. See Note 6—Acquisitions and Divestitures for additional information.
Intangible Assets Amortization Expense	Intangible asset amortization expense amounted to $12 million, $14 million and $12 million for the years ended December 31, 2020, 2019 and 2018, respectively. Estimated amortization expense for the next five years subsequent to December 31, 2020 is as follows: Amount 2021 $ 10 2022 8 2023 6 2024 5 2025 4

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Loss by Component, Net of Tax	Presented in the table below are the changes in accumulated other comprehensive loss by component, net of tax, for the years ended December 31, 2020 and 2019: Defined Benefit Plans Foreign Currency Translation Gain (Loss) on Cash Flow Hedge Accumulated Other Comprehensive Loss Employee Benefit Plan Funded Status Amortization of Prior Service Cost Amortization of Actuarial Loss Beginning balance as of January 1, 2019 $ (102) $ 1 $ 56 $ 1 $ 10 $ (34) Other comprehensive income (loss) before reclassification 8 — — — (13) (5) Amounts reclassified from accumulated other comprehensive loss — — 4 (1) — 3 Net other comprehensive income 8 — 4 (1) (13) (2) Ending balance as of December 31, 2019 $ (94) $ 1 $ 60 $ — $ (3) $ (36) Other comprehensive income (loss) before reclassification (12) — — — (4) (16) Amounts reclassified from accumulated other comprehensive loss — — 3 — — 3 Net other comprehensive income (loss) (12) — 3 — (4) (13) Ending balance as of December 31, 2020 $ (106) $ 1 $ 63 $ — $ (7) $ (49)
Schedule of Dividends Declared	During 2020, 2019 and 2018, the Company paid $389 million, $353 million and $319 million in cash dividends, respectively. Presented in the table below is the per share cash dividends paid for the years ended December 31: 2020 2019 2018 December $ 0.55 $ 0.50 $ 0.455 September $ 0.55 $ 0.50 $ 0.455 June $ 0.55 $ 0.50 $ 0.455 March $ 0.50 $ 0.455 $ 0.415

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Stock-Based Compensation Expense	Presented in the table below is the stock-based compensation expense recorded in O&M expense in the accompanying Consolidated Statements of Operations for the years ended December 31: 2020 2019 2018 RSUs and PSUs $ 19 $ 15 $ 15 Nonqualified employee stock purchase plan 2 2 1 Stock-based compensation 21 17 16 Income tax benefit (5) (4) (5) Stock-based compensation expense, net of tax $ 16 $ 13 $ 11
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Restricted Stock Unit Activity	Presented in the table below is RSU activity for the year ended December 31, 2020: Shares (in thousands) Weighted Average Grant Date Fair Value (per share) Non-vested total as of December 31, 2019 118 $ 85.41 Granted 55 129.39 Vested (71) 98.67 Forfeited (10) 97.24 Non-vested total as of December 31, 2020 92 $ 100.39
Performance Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Restricted Stock Unit Activity	Presented in the table below is PSU activity for the year ended December 31, 2020: Shares (in thousands) Weighted Average Grant Date Fair Value (per share) Non-vested total as of December 31, 2019 316 $ 83.89 Granted 149 116.27 Vested (160) 72.13 Forfeited (12) 108.36 Non-vested total as of December 31, 2020 293 $ 105.70
Summary of Weighted Average Assumptions	Presented in the table below are the weighted average assumptions used in the Monte Carlo simulation and the weighted average grant date fair values of PSUs granted for the years ended December 31: 2020 2019 2018 Expected volatility 16.65% 16.80% 17.23% Risk-free interest rate 1.28% 2.47% 2.36% Expected life (years) 3.0 3.0 3.0 Grant date fair value per share $159.64 $110.37 $73.62

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Components of Long-Term Debt	Presented in the table below are the components of long-term debt as of December 31: Rate Weighted Average Rate Maturity 2020 2019 Long-term debt of AWCC: (a) Senior notes—fixed rate 2.80%-8.27% 4.05% 2021-2050 $ 8,191 $ 7,191 Private activity bonds and government funded debt—fixed rate 0.60%-2.90% 1.64% 2021-2031 191 191 Long-term debt of other American Water subsidiaries: Private activity bonds and government funded debt—fixed rate 0.00%-5.50% 1.74% 2021-2048 735 724 Mortgage bonds—fixed rate 6.35%-9.69% 7.48% 2021-2039 565 578 Mandatorily redeemable preferred stock 8.47%-9.75% 8.57% 2024-2036 5 7 Finance lease obligations 12.25% 12.25% 2026 1 1 Long-term debt 9,688 8,692 Unamortized debt (discount) premium, net (b) (4) 1 Unamortized debt issuance costs (22) (21) Less current portion of long-term debt (329) (28) Total long-term debt $ 9,333 $ 8,644 (a) This indebtedness is considered “debt” for purposes of a support agreement between parent company and AWCC, which serves as a functional equivalent of a guarantee by parent company of AWCC’s payment obligations under such indebtedness. (b) Includes debt discount, net of fair value adjustments previously recognized in acquisition purchase accounting.
Schedule of Future Sinking Fund Payments and Debt Maturities	Presented in the table below are future sinking fund payments and debt maturities: Amount 2021 $ 329 2022 14 2023 356 2024 474 2025 597 Thereafter 7,918
Schedule of Long-Term Debt Issued	Presented in the table below are the issuances of long-term debt in 2020: Company Type Rate Weighted Average Rate Maturity Amount AWCC Senior notes—fixed rate 2.80%-3.45% 3.13% 2030-2050 $ 1,000 AWCC (a) Private activity bonds and government funded debt—fixed rate 0.60%-0.70% 0.42% 2023-2023 86 Other American Water subsidiaries Private Activity Mortgage Bonds 0.85%-1.20% 1.10% 2023-2027 225 Other American Water subsidiaries Private activity bonds and government funded debt—fixed rate 0.00%-5.00% 0.16% 2021-2048 23 Total issuances $ 1,334 (a) This indebtedness has a mandatory redemption provision callable in 2023.
Schedule of Long-term debt retired through optional redemptions or payments at maturities	Presented in the table below are the retirements and redemptions of long-term debt in 2020 through sinking fund provisions, optional redemption or payment at maturity: Company Type Rate Weighted Average Rate Maturity Amount AWCC Private activity bonds and government funded debt—fixed rate 1.79%-5.38% 5.29% 2020-2031 $ 87 Other American Water subsidiaries Private activity mortgage bonds 4.45%-5.60% 5.19% 2020 225 Other American Water subsidiaries Private activity bonds and government funded debt—fixed rate 0.00%-5.60% 2.08% 2020-2048 15 Other American Water subsidiaries Mortgage bonds 3.92%-9.71% 7.83% 2020-2021 13 Other American Water subsidiaries Mandatory redeemable preferred stock 8.49%-9.18% 8.64% 2031-2036 2 Total retirements and redemptions $ 342

Short-Term Debt (Tables)

Short-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Short-term Debt [Abstract]
Schedule of Company's Aggregate Credit Facility Commitments, Commercial Paper Limit, Letter of Credit Availability and Availability Capacity	Presented in the tables below are the aggregate credit facility commitments, commercial paper limit and letter of credit availability under the revolving credit facility, as well as the available capacity for each, as of December 31: 2020 Commercial Paper Limit Letters of Credit Total (a) (In millions) Total availability $ 2,100 $ 150 $ 2,250 Outstanding debt (786) (76) (862) Remaining availability as of December 31, 2020 $ 1,314 $ 74 $ 1,388 (a) Total remaining availability of $1.39 billion as of December 31, 2020 may be accessed through revolver draws. 2019 Commercial Paper Limit Letters of Credit Total (a) (In millions) Total availability $ 2,100 $ 150 $ 2,250 Outstanding debt (786) (76) (862) Remaining availability as of December 31, 2019 $ 1,314 $ 74 $ 1,388 (a) Total remaining availability of $1.39 billion as of December 31, 2019 may be accessed through revolver draws. Presented in the table below is the Company’s total available liquidity as of December 31, 2020 and 2019: Cash and Cash Equivalents Availability on Revolving Credit Facility Total Available Liquidity (In millions) Available liquidity as of December 31, 2020 $ 547 $ 1,388 $ 1,935 Available liquidity as of December 31, 2019 $ 60 $ 1,388 $ 1,448
Schedule Of Short-Term Borrowings Activity	Presented in the table below is the short-term borrowing activity for AWCC for the years ended December 31: 2020 2019 Average borrowings $ 1,047 $ 726 Maximum borrowings outstanding 2,172 1,271 Weighted average interest rates, computed on daily basis 1.16 % 2.54 % Weighted average interest rates, as of December 31 0.53 % 1.86 %

General Taxes (Tables)

General Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
General Taxes [Abstract]
Components of General Tax Expense from Continuing Operations	Presented in the table below is the components of general tax expense for the years ended December 31: 2020 2019 2018 Property and capital stock $ 140 $ 124 $ 120 Gross receipts and franchise 116 110 112 Payroll 36 35 33 Other general 11 11 12 Total general taxes $ 303 $ 280 $ 277

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Components of Income Tax Expense from Continuing Operations	Presented in the table below is the components of income tax expense for the years ended December 31: 2020 2019 2018 Current income taxes: State $ 8 $ 4 $ 26 Federal — — 1 Total current income taxes $ 8 $ 4 $ 27 Deferred income taxes: State $ 49 $ 54 $ 33 Federal 159 155 163 Amortization of deferred investment tax credits (1) (1) (1) Total deferred income taxes 207 208 195 Provision for income taxes $ 215 $ 212 $ 222
Reconciliation of Income Tax Expense from Continuing Operations	Presented in the table below is a reconciliation between the statutory federal income tax rate and the Company’s effective tax rate for the years ended December 31: 2020 2019 2018 Income tax at statutory rate 21.0 % 21.0 % 21.0 % Increases (decreases) resulting from: State taxes, net of federal taxes 4.8 % 5.4 % 5.5 % EADIT (2.1) % (0.9) % 1.5 % Other, net (0.4) % (0.1) % 0.2 % Effective tax rate 23.3 % 25.4 % 28.2 %
Components of Net Deferred Tax Liability from Continuing Operations	Presented in the table below are the components of the net deferred tax liability as of December 31: 2020 2019 Deferred tax assets: Advances and contributions $ 424 $ 410 Tax losses and credits 65 136 Regulatory income tax assets 329 335 Pension and other postretirement benefits 100 94 Other 165 151 Total deferred tax assets 1,083 1,126 Valuation allowance (19) (21) Total deferred tax assets, net of allowance $ 1,064 $ 1,105 Deferred tax liabilities: Property, plant and equipment $ 2,913 $ 2,760 Deferred pension and other postretirement benefits 97 77 Other 216 207 Total deferred tax liabilities 3,226 3,044 Less: Deferred tax liabilities included in liabilities related to assets held for sale (a) 69 67 Total deferred tax liabilities, net of deferred tax assets $ (2,093) $ (1,872) (a) These deferred tax liabilities are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in liabilities related to assets held for sale on the Consolidated Balance Sheets. See Note 6—Acquisitions and Divestitures for additional information.
Changes in Gross Liability Excluding Interest and Penalties for Unrecognized Tax Benefits	Presented in the table below are the changes in gross liability, excluding interest and penalties, for unrecognized tax benefits: Amount Balance as of January 1, 2019 $ 97 Increases in current period tax positions 17 Decreases in prior period measurement of tax positions (4) Balance as of December 31, 2019 $ 110 Increases in current period tax positions 18 Decreases in prior period measurement of tax positions (6) Balance as of December 31, 2020 $ 122
Changes in Valuation Allowance	Presented in the table below are the changes in the valuation allowance: Amount Balance as of January 1, 2018 $ 13 Increases in current period tax positions 1 Balance as of December 31, 2018 $ 14 Increases in current period tax positions 7 Balance as of December 31, 2019 $ 21 Decreases in current period tax positions (2) Balance as of December 31, 2020 $ 19

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Schedule of Significant Unobservable Inputs	Presented in the tables below are a reconciliation of the beginning and ending balances of the fair value measurements using significant unobservable inputs (Level 3) for 2020 and 2019, respectively: Level 3 Balance as of January 1, 2020 $ 349 Actual return on assets 3 Purchases, issuances and settlements, net 4 Balance as of December 31, 2020 $ 356 Level 3 Balance as of January 1, 2019 $ 230 Actual return on assets 25 Purchases, issuances and settlements, net 94 Balance as of December 31, 2019 $ 349
Schedule of Rollforward Changes in Benefit Obligation and Plan Assets	Presented in the table below is a rollforward of the changes in the benefit obligation and plan assets for the two most recent years, for all plans combined: Pension Benefits Other Benefits 2020 2019 2020 2019 Change in benefit obligation: Benefit obligation as of January 1, $ 2,161 $ 1,892 $ 374 $ 353 Service cost 31 28 4 4 Interest cost 73 82 12 15 Plan participants' contributions — — 2 2 Plan amendments — — 5 (1) Actuarial loss (gain) 233 264 13 25 Settlements (a) (3) — — — Gross benefits paid (109) (105) (29) (25) Federal subsidy — — 1 1 Benefit obligation as of December 31, $ 2,386 $ 2,161 $ 382 $ 374 Change in plan assets: Fair value of plan assets as of January 1, $ 1,747 $ 1,499 $ 532 $ 507 Actual return on plan assets 314 319 53 51 Employer contributions 41 33 (2) (2) Plan participants' contributions — — 2 2 Settlements (a) (3) — — — Benefits paid (109) (104) (29) (26) Fair value of plan assets as of December 31, $ 1,990 $ 1,747 $ 556 $ 532 Funded value as of December 31, $ (396) $ (414) $ 174 $ 158 Amounts recognized on the balance sheet: Noncurrent asset $ — $ — $ 173 $ 159 Current liability (2) (3) — — Noncurrent liability (388) (411) (1) (1) (Liabilities) assets related to assets held for sale (b) (6) — 2 — Net amount recognized $ (396) $ (414) $ 174 $ 158 (a) The Company paid $3 million of lump sum payment distributions from the Company’s New York Water Service Corporation Pension Plan for the year ended December 31, 2020. There were no lump sum payments made for the year ended December 31, 2019. (b) These balances are related to the pending transactions contemplated by the Stock Purchase Agreement and are included in assets held for sale and liabilities related to assets held for sale on the Consolidated Balance Sheets as of December 31, 2020. See Note 6—Acquisitions and Divestitures for additional information.
Summary of Accumulated Other Comprehensive Income and Regulatory Assets	Presented in the table below are the components of accumulated other comprehensive income and regulatory assets that have not been recognized as components of periodic benefit costs as of December 31: Pension Benefits Other Benefits 2020 2019 2020 2019 Net actuarial loss $ 436 $ 435 $ 49 $ 72 Prior service credit (16) (19) (217) (257) Net amount recognized $ 420 $ 416 $ (168) $ (185) Regulatory assets (liabilities) $ 366 $ 375 $ (168) $ (185) Accumulated other comprehensive income 54 41 — — Total $ 420 $ 416 $ (168) $ (185)
Schedule of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets	Presented in the tables below are the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for pension plans with a projected obligation in excess of plan assets as of December 31, 2020 and 2019: Projected Benefit Obligation Exceeds the Fair Value of Plans' Assets 2020 2019 Projected benefit obligation $ 2,386 $ 2,161 Fair value of plan assets 1,990 1,748 Accumulated Benefit Obligation Exceeds the Fair Value of Plans' Assets 2020 2019 Accumulated benefit obligation $ 2,188 $ 2,018 Fair value of plan assets 1,990 1,748
Schedule of Expected Cash Flows for Pension and Postretirement Benefit Plans	Presented in the table below is information about the expected cash flows for the pension and postretirement benefit plans: Pension Benefits Other Benefits 2021 expected employer contributions: To plan trusts $ 37 $ — To plan participants 2 —
Schedule of Expected Benefit Payments	Presented in the table below are the net benefits expected to be paid from the plan assets or the Company’s assets: Pension Benefits Other Benefits Expected Benefit Payments Expected Benefit Payments Expected Federal Subsidy Payments 2021 $ 127 $ 27 $ 1 2022 128 27 1 2023 133 27 1 2024 135 27 1 2025 137 26 1 2026-2030 692 123 4
Schedule of Significant Assumptions of Pension and Other Postretirement Benefit Plans	Presented in the table below are the significant assumptions related to the pension and other postretirement benefit plans: Pension Benefits Other Benefits 2020 2019 2018 2020 2019 2018 Weighted average assumptions used to determine December 31 benefit obligations: Discount rate 2.74% 3.44% 4.38% 2.56% 3.36% 4.32% Rate of compensation increase 3.51% 2.97% 3.00% N/A N/A N/A Medical trend N/A N/A N/A graded from graded from graded from 6.25% in 2021 6.50% in 2020 6.75% in 2019 to 5.00% in 2026+ to 5.00% in 2026+ to 5.00% in 2026+ Weighted average assumptions used to determine net periodic cost: Discount rate 3.44% 4.38% 3.75% 3.36% 4.32% 4.23% Expected return on plan assets 6.50% 6.20% 5.95% 3.68% 3.56% 4.77% Rate of compensation increase 2.97% 3.00% 3.02% N/A N/A N/A Medical trend N/A N/A N/A graded from graded from graded from 6.50% in 2020 6.75% in 2019 7.00% in 2018 to 5.00% in 2026+ to 5.00% in 2026+ to 4.50% in 2026+ NOTE “N/A” in the table above means assumption is not applicable.
Components of Net Periodic Benefit Costs	Presented in the table below are the components of net periodic benefit costs for the years ended December 31: 2020 2019 2018 Components of net periodic pension benefit cost: Service cost $ 31 $ 28 $ 34 Interest cost 73 82 76 Expected return on plan assets (111) (91) (97) Amortization of prior service (credit) cost (3) (3) 1 Amortization of actuarial loss 30 32 27 Settlements (a) 1 — — Net periodic pension benefit cost $ 21 $ 48 $ 41 Other changes in plan assets and benefit obligations recognized in other comprehensive income: Current year actuarial (gain) loss $ 12 $ (8) $ (60) Amortization of actuarial loss (3) (4) (7) Total recognized in other comprehensive income 9 (12) (67) Total recognized in net periodic benefit cost and other comprehensive income $ 30 $ 36 $ (26) Components of net periodic other postretirement benefit (credit) cost: Service cost $ 4 $ 4 $ 8 Interest cost 12 15 20 Expected return on plan assets (19) (18) (26) Amortization of prior service credit (34) (35) (23) Amortization of actuarial loss 2 3 3 Net periodic other postretirement benefit (credit) cost $ (35) $ (31) $ (18) (a) Due to the amount of lump sum payment distributions from the Company’s New York Water Service Corporation Pension Plan, settlement charges of less than $1 million were recorded for the year ended December 31, 2020. There were no settlement charges recorded for the year ended December 31, 2019. In accordance with existing regulatory accounting treatment, the Company has maintained the settlement charges in regulatory assets on the Consolidated Balance Sheets. The amount is being amortized in accordance with existing regulatory practice.
Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Schedule of Changes in Fair Value of Plan Assets	Presented in the tables below are the fair values and asset allocations of the pension plan assets as of December 31, 2020 and 2019, respectively, by asset category: Asset Category 2021 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of December 31, 2020 Cash $ 78 $ 78 $ — $ — 4 % Equity securities: 50 % U.S. large cap 420 420 — — 21 % U.S. small cap 124 124 — — 6 % International 367 8 169 190 18 % Real estate fund 120 — — 120 6 % REITs 7 — 7 — — % Fixed income securities: 50 % U.S. Treasury securities and government bonds 171 163 8 — 9 % Corporate bonds 594 — 594 — 30 % Mortgage-backed securities 9 — 9 — — % Municipal bonds 34 — 34 — 2 % Treasury futures 10 10 — — 1 % Long duration bond fund 10 7 3 — 1 % Guarantee annuity contracts 46 — — 46 2 % Total 100 % $ 1,990 $ 810 $ 824 $ 356 100 % Asset Category 2020 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of December 31, 2019 Cash $ 39 $ 39 $ — $ — 2 % Equity securities: 50 % U.S. large cap 358 358 — — 20 % U.S. small cap 84 78 6 — 5 % International 320 6 137 177 18 % Real estate fund 127 — — 127 7 % REITs 7 — 7 — — % Fixed income securities: 50 % U.S. Treasury securities and government bonds 169 158 11 — 10 % Corporate bonds 542 — 542 — 31 % Mortgage-backed securities 14 — 14 — 1 % Municipal bonds 26 — 26 — 1 % Treasury futures 8 8 — — 1 % Long duration bond fund 8 8 — — 1 % Guarantee annuity contracts 45 — — 45 3 % Total 100 % $ 1,747 $ 655 $ 743 $ 349 100 %
Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Schedule of Changes in Fair Value of Plan Assets	Presented in the tables below are the fair values and asset allocations of the postretirement benefit plan assets as of December 31, 2020 and 2019, respectively, by asset category: Asset Category 2021 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of December 31, 2020 Bargain VEBA: Cash $ 12 $ 12 $ — $ — 3 % Equity securities: 4 % U.S. large cap 14 14 — — 3 % Fixed income securities: 96 % U.S. Treasury securities and government bonds 389 308 81 — 93 % Long duration bond fund 5 5 — — 1 % Total bargain VEBA 100 % $ 420 $ 339 $ 81 $ — 100 % Non-bargain VEBA: Cash $ 1 $ 1 $ — $ — — Equity securities: 60 % U.S. large cap 51 51 — — 38 % International 33 33 — — 24 % Fixed income securities: 40 % Core fixed income bond fund (a) 50 — 50 — 38 % Total non-bargain VEBA 100 % $ 135 $ 85 $ 50 $ — 100 % Life VEBA: Equity securities: 70 % U.S. large cap $ — $ — $ — $ — — % Fixed income securities: 30 % Core fixed income bond fund (a) 1 1 — — 100 % Total life VEBA 100 % $ 1 $ 1 $ — $ — 100 % Total 100 % $ 556 $ 425 $ 131 $ — 100 % (a) Includes cash for margin requirements. Asset Category 2020 Target Allocation Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Percentage of Plan Assets as of 12/31/2019 Bargain VEBA: Cash $ 6 $ 6 $ — $ — 2 % Equity securities: 4 % U.S. large cap 13 13 — — 3 % Fixed income securities: 96 % U.S. Treasury securities and government bonds 373 298 75 — 94 % Long duration bond fund 4 4 — — 1 % Total bargain VEBA 100 % $ 396 $ 321 $ 75 $ — 100 % Non-bargain VEBA: Cash $ 4 $ 4 $ — $ — — Equity securities: 60 % U.S. large cap 48 48 — — 36 % International 30 30 — — 23 % Fixed income securities: 40 % Core fixed income bond fund (a) 50 — 50 — 41 % Total non-bargain VEBA 100 % $ 132 $ 82 $ 50 $ — 100 % Life VEBA: Equity securities: 70 % U.S. large cap $ 2 $ 2 $ — $ — 50 % Fixed income securities: 30 % Core fixed income bond fund (a) 2 2 — — 50 % Total life VEBA 100 % $ 4 $ 4 $ — $ — 100 % Total 100 % $ 532 $ 407 $ 125 $ — 100 % (a) Includes cash for margin requirements.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Annual Commitments Related to Minimum Quantities of Purchased Water Having Non-Cancelable Terms	Presented in the table below are the future annual commitments related to minimum quantities of purchased water having non-cancelable contracts: Amount 2021 $ 66 2022 67 2023 66 2024 52 2025 52 Thereafter 618

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Reconciliation of Numerator and Denominator for Basic and Diluted Earnings Per Share	Presented in the table below is a reconciliation of the numerator and denominator for the basic and diluted earnings per share (“EPS”) calculations for the years ended December 31: 2020 2019 2018 Numerator: Net income attributable to common shareholders $ 709 $ 621 $ 567 Denominator: Weighted average common shares outstanding—Basic 181 181 180 Effect of dilutive common stock equivalents 1 — — Weighted average common shares outstanding—Diluted 182 181 180

Fair Values of Financial Inst_2

Fair Values of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Carrying Amounts and Fair Values of Financial Instruments	Presented in the tables below are the carrying amounts, including fair value adjustments previously recognized in acquisition purchase accounting, and the fair values of the Company’s financial instruments: Carrying Amount December 31, 2020 L e vel 1 Level 2 Level 3 Total Preferred stock with mandatory redemption requirements $ 5 $ — $ — $ 7 $ 7 Long-term debt (excluding finance lease obligations) 9,656 9,639 415 1,753 11,807 Carrying Amount December 31, 2019 L e vel 1 Level 2 Level 3 Total Preferred stock with mandatory redemption requirements $ 7 $ — $ — $ 9 $ 9 Long-term debt (excluding finance lease obligations) 8,664 7,689 417 1,664 9,770
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Presented in the tables below are assets and liabilities measured and recorded at fair value on a recurring basis and their level within the fair value hierarchy: At Fair Value as of December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Restricted funds $ 29 $ — $ — $ 29 Rabbi trust investments 19 — — 19 Deposits 4 — — 4 Other investments 11 — — 11 Total assets 63 — — 63 Liabilities: Deferred compensation obligations 24 — — 24 Total liabilities 24 — — 24 Total assets $ 39 $ — $ — $ 39 At Fair Value as of December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Restricted funds $ 31 $ — $ — $ 31 Rabbi trust investments 17 — — 17 Deposits 3 — — 3 Other investments 8 — — 8 Total assets 59 — — 59 Liabilities: Deferred compensation obligations 21 — — 21 Total liabilities 21 — — 21 Total assets (liabilities) $ 38 $ — $ — $ 38

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Summarized Segment Information	Presented in the tables below is summarized segment information as of and for the years ended December 31: 2020 Regulated Market-Based Other Consolidated Operating revenues $ 3,255 $ 540 $ (18) $ 3,777 Depreciation and amortization 562 26 16 604 Total operating expenses, net 2,102 421 6 2,529 Interest, net (291) 1 (105) (395) Income before income taxes 932 120 (128) 924 Provision for income taxes 217 29 (31) 215 Net income attributable to common shareholders 715 91 (97) 709 Total assets 22,357 891 1,518 24,766 Cash paid for capital expenditures 1,804 10 8 1,822 2019 Regulated Market-Based Other Consolidated Operating revenues $ 3,094 $ 539 $ (23) $ 3,610 Depreciation and amortization 529 37 16 582 Total operating expenses, net 1,964 480 (4) 2,440 Interest, net (295) 5 (92) (382) Income before income taxes 869 66 (102) 833 Provision for income taxes 215 20 (23) 212 Net income attributable to common shareholders 654 46 (79) 621 Total assets 20,318 1,008 1,356 22,682 Cash paid for capital expenditures 1,627 13 14 1,654 2018 Regulated Market-Based Other Consolidated Operating revenues $ 2,984 $ 476 $ (20) $ 3,440 Depreciation and amortization 500 29 16 545 Impairment charge — 57 — 57 Total operating expenses, net 1,912 441 (15) 2,338 Interest, net (280) 4 (74) (350) Income before income taxes 826 41 (80) 787 Provision for income taxes 224 11 (13) 222 Net income attributable to common shareholders 602 32 (67) 567 Total assets 18,680 999 1,544 21,223 Cash paid for capital expenditures 1,477 13 96 1,586

Unaudited Quarterly Data (Table

Unaudited Quarterly Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Data [Abstract]
Schedule Of Unaudited Quarterly Data	Presented in the tables below are supplemental, unaudited, consolidated, quarterly financial data for each of the four quarters in the years ended December 31, 2020 and 2019, respectively. The operating results for any quarter are not indicative of results that may be expected for a full year or any future periods. 2020 First Quarter Second Quarter Third Quarter Fourth Quarter Operating revenues $ 844 $ 931 $ 1,079 $ 923 Operating income 239 313 433 263 Net income attributable to common shareholders 124 176 264 145 Basic earnings per share: (a) Net income attributable to common shareholders $ 0.69 $ 0.97 $ 1.46 $ 0.80 Diluted earnings per share: Net income attributable to common shareholders 0.68 0.97 1.46 0.80 (a) Amounts may not sum due to rounding. 2019 First Quarter Second Quarter Third Quarter Fourth Quarter Operating revenues $ 813 $ 882 $ 1,013 $ 902 Operating income 238 302 406 224 Net income attributable to common shareholders 113 170 240 98 Basic earnings per share: (a) Net income attributable to common shareholders $ 0.62 $ 0.94 $ 1.33 $ 0.54 Diluted earnings per share: Net income attributable to common shareholders 0.62 0.94 1.33 0.54 (a) Amounts may not sum due to rounding.

Organization and Operation - Ad

Organization and Operation - Additional Details (Details)	Dec. 31, 2020state
Regulated Businesses
Segment Reporting Information [Line Items]
Number of states in which entity provides water and wastewater services	16

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets	$ 95	$ 103
Estimated refunds	23	25
Amortization of contributions in aid of construction	$ 32	29	$ 28
Payment terms from billing, period	30 days
Payments for environmental loss contingencies	$ 1
Remediation costs accrued	1	2
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets				$ 117
Operating lease liabilities				$ 115
Software
Significant Accounting Policies [Line Items]
Acquisition cost, carrying value	$ 360	$ 345
Market-Based Businesses
Significant Accounting Policies [Line Items]
Payment terms from billing, period	12 months
Maximum
Significant Accounting Policies [Line Items]
Payment terms from billing, period	1 year

Significant Accounting Polici_5

Significant Accounting Policies - Reconciliation Of Cash And Cash Equivalents, And Restricted Cash Reported (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 547	$ 60
Restricted funds	29	31
Cash and cash equivalents and restricted funds as presented on the Consolidated Statements of Cash Flows	$ 576	$ 91	$ 159	$ 83

Significant Accounting Polici_6

Significant Accounting Policies - Schedule of Allowance for Funds Used During Construction (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Funds
Significant Accounting Policies [Line Items]
Allowance for funds used during construction	$ 30	$ 28	$ 24
Borrowed Funds
Significant Accounting Policies [Line Items]
Allowance for funds used during construction	$ 13	$ 13	$ 13

Impact of Novel Coronavirus (_3

Impact of Novel Coronavirus (COVID-19) Pandemic - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Feb. 24, 2021regulatoryJurisdictionstate	Dec. 31, 2019USD ($)
Unusual Risk or Uncertainty [Line Items]
Regulatory assets | $	$ 1,127		$ 1,128
Regulatory liability | $	$ 1,770		$ 1,806
Subsequent Event
Unusual Risk or Uncertainty [Line Items]
Number of regulatory jurisdictions that began to seek to address the impacts of COVID-19 | regulatoryJurisdiction		11
Total number of regulatory jurisdictions | regulatoryJurisdiction		14
Number of regulatory jurisdictions that requested authorization for usage of deferred accounting to address the impacts of COVID-19, pending requests | regulatoryJurisdiction		2
Number of regulatory jurisdictions that obtained plan approval to address the impacts of COVID-19, cost recovery mechanisms | regulatoryJurisdiction		2
Number of states who have ordered active moratoria on the suspension of service disconnections due to non-payment | state		6
Number of states who have ordered active moratoria on the suspension of service disconnections due to non-payment, expired | state		8
Illinois
Unusual Risk or Uncertainty [Line Items]
Authorized cost recovery period	24 months
COVID-19
Unusual Risk or Uncertainty [Line Items]
Regulatory assets | $	$ 30
Regulatory liability | $	$ 4

Regulatory Matters - Summary of

Regulatory Matters - Summary of General Rate Cases Authorizations (Details) - USD ($) $ in Millions	Oct. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Public Utilities, General Disclosures
General rate case authorizations		$ 56	$ 45	$ 150
New Jersey
Public Utilities, General Disclosures
General rate case authorizations		39	0	40
Net of excess accumulated deferred income taxes, payable to customers		15
Net of excess accumulated deferred income taxes, unprotected, payable to customers		$ 133
Net of excess accumulated deferred income taxes, unprotected, payable to customers, period		15 years
Net of excess accumulated deferred income taxes, protected and unprotected, payable to customers		$ 32.5
New Jersey | November 1, 2020
Public Utilities, General Disclosures
Rate increase (decrease), amount		$ 39
Approved rate increase (decrease), reduction period		10 months
New Jersey | June 15, 2018
Public Utilities, General Disclosures
General rate case authorizations				40
Indiana
Public Utilities, General Disclosures
General rate case authorizations		$ 13	4	0
Indiana | July 1, 2019
Public Utilities, General Disclosures
General rate case authorizations			4
Indiana | May 1, 2020
Public Utilities, General Disclosures
General rate case authorizations		13
California
Public Utilities, General Disclosures
General rate case authorizations		5	4	10
Virginia
Public Utilities, General Disclosures
General rate case authorizations		(1)	0	0
Rate increase (decrease), amount		$ 1
Net of excess accumulated deferred income taxes, unprotected, payable to customers, period		8 years
Public utilities, rate increase (decrease), net amount		$ 0
Virginia | Water & Wastewater Infrastructure Service Charge
Public Utilities, General Disclosures
Rate increase (decrease), amount		(1)
Virginia | Wastewater
Public Utilities, General Disclosures
Rate increase (decrease), amount		(1)
Kentucky | June 28, 2019
Public Utilities, General Disclosures
General rate case authorizations		0	13	0
New York
Public Utilities, General Disclosures
General rate case authorizations		0	4	5
West Virginia | February 25, 2019
Public Utilities, General Disclosures
General rate case authorizations		0	19	0
Maryland | February 5, 2019
Public Utilities, General Disclosures
General rate case authorizations		0	1	0
Missouri | May 28, 2018
Public Utilities, General Disclosures
General rate case authorizations		0	0	33
Pennsylvania
Public Utilities, General Disclosures
Rate increase (decrease), amount	$ 71
Pennsylvania | January 1, 2018
Public Utilities, General Disclosures
General rate case authorizations		$ 0	$ 0	$ 62

Regulatory Matters - General Ra

Regulatory Matters - General Rate Cases Narrative (Details) - USD ($) $ in Millions	Jan. 05, 2021	Oct. 30, 2020	Aug. 28, 2020	Jun. 30, 2020	Apr. 29, 2020	Jan. 22, 2020	Oct. 11, 2019	Jul. 01, 2019
Iowa
Public Utilities, General Disclosures
Requested rate increase (decrease), amount			$ 3
Missouri
Public Utilities, General Disclosures
Requested rate increase (decrease), amount				$ 78
Pennsylvania
Public Utilities, General Disclosures
Rate increase (decrease), amount		$ 71
Rate increase (decrease), period		2 years
Pennsylvania | Rate Year 1
Public Utilities, General Disclosures
Requested rate increase (decrease), amount					$ 92
Pennsylvania | Rate Year 2
Public Utilities, General Disclosures
Requested rate increase (decrease), amount					$ 46
California
Public Utilities, General Disclosures
Requested rate increase (decrease), update period							100 days
Cost of capital filing delay period						1 year
California | Subsequent Event
Public Utilities, General Disclosures
Cost of capital filing delay period	1 year
California | January 1, 2021
Public Utilities, General Disclosures
Requested rate increase (decrease), amount								$ 26
Requested rate increase (decrease), amended, amount							$ 27
California | January 1, 2022
Public Utilities, General Disclosures
Requested rate increase (decrease), amount								10
Requested rate increase (decrease), amended, amount							10
California | January 1, 2023
Public Utilities, General Disclosures
Requested rate increase (decrease), amount								$ 11
Requested rate increase (decrease), amended, amount							$ 10

Regulatory Matters - Summary _2

Regulatory Matters - Summary of Infrastructure Surcharge Authorizations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	$ 72	$ 53	$ 21
January 1, 2021
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	23
Missouri
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	12	14	6
Missouri | December 14, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	2
Missouri | June 27, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	10
Missouri | December 21, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	5
Missouri | June 24, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	9
Pennsylvania
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	27	11	0
Pennsylvania | January 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	10
Pennsylvania | October 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	8
Pennsylvania | July 1, 2010
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	4
Pennsylvania | April 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	5
Pennsylvania | October 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations		6
Pennsylvania | July 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations		3
Pennsylvania | April 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations		2
Pennsylvania | January 1, 2021
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	8
Kentucky | July 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	1	0	0
New Jersey
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	20	15	0
New Jersey | January 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	10
New Jersey | June 29, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	10
Tennessee | January 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	2
Tennessee | September 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations		1
Tennessee | April 10, 2018
Public Utilities, General Disclosures
Infrastructure surcharge authorizations			1
Tennessee | January 1, 2021
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	3
Illinois | January 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	7
Illinois | January 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations		8
Illinois | January 1, 2018
Public Utilities, General Disclosures
Infrastructure surcharge authorizations			3
Illinois | January 1, 2021
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	7
West Virginia | January 1, 2020
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	3
West Virginia | January 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations		2
West Virginia | January 1, 2018
Public Utilities, General Disclosures
Infrastructure surcharge authorizations			3
West Virginia | January 1, 2021
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	5
New York | August 1, 2019
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	0	2	0
Indiana | March 14, 2018
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	0	0	7
Virginia | March 1, 2018
Public Utilities, General Disclosures
Infrastructure surcharge authorizations	$ 0	$ 0	$ 1

Regulatory Matters - Infrastruc

Regulatory Matters - Infrastructure Surcharge Authorizations Narrative (Details) - USD ($) $ in Millions	Jan. 15, 2021	May 29, 2020
Indiana | Subsequent Event
Public Utilities, General Disclosures
Requested infrastructure surcharge, amount	$ 8
New York
Public Utilities, General Disclosures
Requested infrastructure surcharge, amount		$ 1

Regulatory Matters - Summary _3

Regulatory Matters - Summary of Composition of Regulatory Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Regulatory assets	$ 1,127	$ 1,128
Deferred pension expense
Regulatory Assets [Line Items]
Regulatory assets	374	384
Removal costs recoverable through rates
Regulatory Assets [Line Items]
Regulatory assets	314	305
Regulatory balancing accounts
Regulatory Assets [Line Items]
Regulatory assets	57	96
Other
Regulatory Assets [Line Items]
Regulatory assets	446	398
Assets held for sale
Regulatory Assets [Line Items]
Regulatory assets	$ 64	$ 55

Regulatory Matters - Regulatory

Regulatory Matters - Regulatory Assets and Liabilities Narrative (Details) $ in Millions	Aug. 31, 2018USD ($)	Dec. 31, 2020USD ($)state	Dec. 31, 2019USD ($)
Regulatory Asset And Liabilities [Line Items]
Regulatory asset, earned revenue, percentage		50.00%
Number of proceedings, amortizing EADIT and crediting customers | state		9
Number of proceedings, pending amortization of EADIT | state		5
Postretirement Benefit Plan Assets
Regulatory Asset And Liabilities [Line Items]
Reduction to net accrued postretirement benefit obligation | $	$ 227
Deferred pension expense
Regulatory Asset And Liabilities [Line Items]
Regulatory assets underfunded status | $		$ 366	$ 375

Regulatory Matters - Summary _4

Regulatory Matters - Summary of Composition of Regulatory Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Liabilities [Line Items]
Regulatory liability	$ 1,770	$ 1,806
Income taxes recovered through rates
Regulatory Liabilities [Line Items]
Regulatory liability	1,230	1,258
Removal costs recovered through rates
Regulatory Liabilities [Line Items]
Regulatory liability	301	297
Postretirement benefit liability
Regulatory Liabilities [Line Items]
Regulatory liability	170	186
Other
Regulatory Liabilities [Line Items]
Regulatory liability	111	102
Assets held for sale
Regulatory Liabilities [Line Items]
Regulatory liability	$ 42	$ 37

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									$ 3,743
Other operating income									34
Operating revenues	$ 923	$ 1,079	$ 931	$ 844	$ 902	$ 1,013	$ 882	$ 813	3,777	$ 3,610	$ 3,440
Service, Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									(17)
Other operating income									(1)
Operating revenues									(18)
Regulated Businesses
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									3,220
Other operating income									35
Alternative revenue programs									25
Lease contract revenue									10
Operating revenues									3,255
Regulated Businesses | Water Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									3,003
Other operating income									0
Operating revenues									3,003
Regulated Businesses | Water Services | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									1,895
Other operating income									0
Operating revenues									1,895
Regulated Businesses | Water Services | Commercial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									627
Other operating income									0
Operating revenues									627
Regulated Businesses | Water Services | Fire Service
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									147
Operating revenues									147
Regulated Businesses | Water Services | Industrial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									133
Operating revenues									133
Regulated Businesses | Water Services | Public and Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									201
Other operating income									0
Operating revenues									201
Regulated Businesses | Wastewater Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									185
Operating revenues									185
Regulated Businesses | Wastewater Services | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									134
Operating revenues									134
Regulated Businesses | Wastewater Services | Commercial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									34
Operating revenues									34
Regulated Businesses | Wastewater Services | Industrial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									3
Operating revenues									3
Regulated Businesses | Wastewater Services | Public and Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									14
Operating revenues									14
Regulated Businesses | Miscellaneous Utility Charge
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									32
Operating revenues									32
Market-Based Businesses
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									540
Operating revenues									$ 540

Revenue Recognition - Contract

Revenue Recognition - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contract assets:
Contract assets	$ 39	$ 13	$ 14
Additions	60	27
Transfers to accounts receivable, net	34	28
Contract liabilities:
Contract liability	35	27	$ 20
Additions	120	62
Transfers to operating revenues	$ 112	$ 55

Revenue Recognition - Remaining

Revenue Recognition - Remaining Performance Obligations (Details) - Market-Based Businesses $ in Millions	Dec. 31, 2020USD ($)
U.S. Government
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 6,300
Municipalities and Commercial
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 478

Acquisitions and Divestitures -

Acquisitions and Divestitures - Additional Information (Details) customer in Thousands, $ in Millions	Dec. 12, 2019USD ($)	Nov. 20, 2019USD ($)customer	Jun. 04, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)Acquisition	Dec. 31, 2019USD ($)Acquisition	Dec. 31, 2018USD ($)Acquisition
Business Acquisition And Divestitures [Line Items]
Goodwill				$ 1,501	$ 1,504	$ 1,501	$ 1,575
Water Solutions Holding | Discontinued Operations, Disposed of by Sale
Business Acquisition And Divestitures [Line Items]
Total cash consideration for business divestiture	$ 31
Pre-tax loss on business divestiture				44
After-tax loss on business divestiture				35
New York American Water Company
Business Acquisition And Divestitures [Line Items]
Purchase price		$ 608
Number of customers | customer		125
Pivotal
Business Acquisition And Divestitures [Line Items]
Purchase price			$ 365
Regulated Water And Wastewater Systems | Business Acquisitions 2020
Business Acquisition And Divestitures [Line Items]
Number of companies acquired | Acquisition					23
Purchase price					$ 135
Purchase price allocation, assets acquired					159
Purchase price allocation, liabilities assumed					29
Purchase price allocation, contributions in aid of construction					21
Purchase price allocation, debt assumed					7
Regulated Water And Wastewater Systems | Business Acquisitions 2020 | Regulated Businesses
Business Acquisition And Divestitures [Line Items]
Additional goodwill					$ 5
Additional goodwill, number of acquisitions | Acquisition					2
Regulated Water And Wastewater Systems | Business Acquisitions 2019
Business Acquisition And Divestitures [Line Items]
Number of companies acquired | Acquisition						21
Purchase price						$ 235
Purchase price allocation, assets acquired				237		237
Purchase price allocation, contributions in aid of construction				5		$ 5
Regulated Water And Wastewater Systems | Business Acquisitions 2019 | Regulated Businesses
Business Acquisition And Divestitures [Line Items]
Number of companies acquired | Acquisition						3
Goodwill				$ 3		$ 3
Regulated Water And Wastewater Systems | Business Acquisitions 2018
Business Acquisition And Divestitures [Line Items]
Number of companies acquired | Acquisition							15
Purchase price							$ 33
Purchase price allocation, assets acquired							32
Purchase price allocation, contributions in aid of construction							$ 1
Regulated Water And Wastewater Systems | Business Acquisitions 2018 | Regulated Businesses
Business Acquisition And Divestitures [Line Items]
Number of companies acquired | Acquisition							1
Goodwill							$ 2

Acquisitions and Divestitures_2

Acquisitions and Divestitures - Components of Assets Held-for-sale (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Business Combinations [Abstract]
Property, plant and equipment	$ 504
Current assets	12
Regulatory assets	64
Goodwill	39	$ 39
Other assets	10
Assets held for sale	629	566
Current liabilities	14
Deferred income taxes	69
Regulatory liabilities	42
Other liabilities	12
Liabilities related to assets held for sale	$ 137	$ 128

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Major Classes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Public Utility, Property, Plant and Equipment [Line Items]
Construction work in progress	$ 837	$ 801
Total utility plant	25,408	23,720
Nonutility property	211	226
Less: Nonutility plant included in assets held for sale	(5)	(5)
Total property, plant and equipment	$ 25,614	23,941
Weighted Average Useful Life	8 years
Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	3 years
Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	50 years
Utility Plant
Public Utility, Property, Plant and Equipment [Line Items]
Less: Utility plant included in assets held for sale	$ (646)	(587)
Utility Plant | Land and other non-depreciable assets
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	174	166
Utility Plant | Sources of supply
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 897	858
Weighted Average Useful Life	47 years
Utility Plant | Sources of supply | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	2 years
Utility Plant | Sources of supply | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	127 years
Utility Plant | Treatment and pumping facilities
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 3,984	3,750
Weighted Average Useful Life	41 years
Utility Plant | Treatment and pumping facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	3 years
Utility Plant | Treatment and pumping facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	111 years
Utility Plant | Transmission and distribution facilities
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 11,457	10,807
Weighted Average Useful Life	69 years
Utility Plant | Transmission and distribution facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	9 years
Utility Plant | Transmission and distribution facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	149 years
Utility Plant | Services, meters and fire hydrants
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 4,555	4,304
Weighted Average Useful Life	31 years
Utility Plant | Services, meters and fire hydrants | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	5 years
Utility Plant | Services, meters and fire hydrants | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	90 years
Utility Plant | General structures and equipment
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 2,003	1,748
Weighted Average Useful Life	16 years
Utility Plant | General structures and equipment | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	1 year
Utility Plant | General structures and equipment | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	109 years
Utility Plant | Waste collection
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 1,288	1,153
Weighted Average Useful Life	47 years
Utility Plant | Waste collection | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	5 years
Utility Plant | Waste collection | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	113 years
Utility Plant | Waste treatment, pumping and disposal
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant excluding Construction work in progress	$ 859	$ 720
Weighted Average Useful Life	59 years
Utility Plant | Waste treatment, pumping and disposal | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	2 years
Utility Plant | Waste treatment, pumping and disposal | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Range of Remaining Useful Lives	139 years

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 520	$ 508	$ 497
Provision for depreciation, percentage of aggregate average depreciable asset	2.82%	2.96%	3.09%
Capital expenditures acquired on account but unpaid as of year end	$ 221	$ 235	$ 181
Investment tax credit		$ 164
Other Current Assets
Property, Plant and Equipment [Line Items]
Investment tax credit, receivable	33
Other Long-term Assets
Property, Plant and Equipment [Line Items]
Investment tax credit, receivable	$ 131

Allowance for Uncollectible A_3

Allowance for Uncollectible Accounts - Schedule of Allowances for Uncollectible Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of January 1	$ (41)	$ (45)	$ (42)
Amounts charged to expense	(34)	(28)	(33)
Amounts written off	12	32	34
Recoveries of amounts written off	0	0	(4)
Less: Allowance for uncollectible accounts included in assets held for sale	3	0	0
Balance as of December 31	$ (60)	$ (41)	$ (45)

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Summary of Changes in Goodwill Assets (Details) - USD ($) $ in Millions	Dec. 12, 2019	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Cost, beginning balance		$ 3,941	$ 4,068
Accumulated Impairment, beginning balance		(2,440)	(2,493)
Total Net, beginning balance		1,501	1,575
Goodwill from acquisitions		5	3
Less: Goodwill included in assets held for sale		(39)	(39)
Measurement period adjustments, cost		(2)
Cost, ending balance		3,944	3,941
Accumulated Impairment, ending balance		(2,440)	(2,440)
Total Net, ending balance		1,504	1,501
Operating Segments | Regulated Businesses
Goodwill [Roll Forward]
Cost, beginning balance		3,458	3,494
Accumulated Impairment, beginning balance		(2,332)	(2,332)
Goodwill from acquisitions		5	3
Less: Goodwill included in assets held for sale			(39)
Measurement period adjustments, cost		(2)
Cost, ending balance		3,461	3,458
Accumulated Impairment, ending balance		(2,332)	(2,332)
Operating Segments | Market-Based Businesses
Goodwill [Roll Forward]
Cost, beginning balance		483	574
Accumulated Impairment, beginning balance		(108)	(161)
Cost, ending balance		483	483
Accumulated Impairment, ending balance		$ (108)	(108)
Keystone
Goodwill [Roll Forward]
Goodwill reduced through sale, costs			(91)
Goodwill reduced through sale, accumulated impairments			53
Goodwill reduced through sale, net	$ 38		(38)
Keystone | Operating Segments | Market-Based Businesses
Goodwill [Roll Forward]
Goodwill reduced through sale, costs			(91)
Goodwill reduced through sale, accumulated impairments			$ 53

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Additional Information (Details) $ in Millions	Dec. 12, 2019USD ($)	Dec. 31, 2020USD ($)Acquisition	Dec. 31, 2019USD ($)Acquisition	Dec. 31, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
Goodwill from acquisitions		$ 5	$ 3
Finite-lived intangible assets, amortization		12	14	$ 12
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets		78	78
Finite-lived intangible assets, accumulated amortization			20
Finite-lived intangible assets, amortization		9
Finite-lived intangible assets, net		49
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets		13	13
Finite-lived intangible assets, accumulated amortization			4
Finite-lived intangible assets, amortization		3
Finite-lived intangible assets, net		6
Keystone
Finite-Lived Intangible Assets [Line Items]
Goodwill reduced through sale, net	$ 38		(38)
Operating Segments | Regulated Businesses
Finite-Lived Intangible Assets [Line Items]
Goodwill from acquisitions		$ 5	$ 3
Business Acquisitions 2020 | Regulated Water And Wastewater Systems
Finite-Lived Intangible Assets [Line Items]
Number of companies acquired | Acquisition		23
Business Acquisitions 2020 | Regulated Businesses | Regulated Water And Wastewater Systems
Finite-Lived Intangible Assets [Line Items]
Additional goodwill, number of acquisitions | Acquisition		2
Business Acquisitions 2019 | Regulated Water And Wastewater Systems
Finite-Lived Intangible Assets [Line Items]
Number of companies acquired | Acquisition			21
Business Acquisitions 2019 | Regulated Businesses | Regulated Water And Wastewater Systems
Finite-Lived Intangible Assets [Line Items]
Number of companies acquired | Acquisition			3

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Amortization of Intangibles (Details) $ in Millions	Dec. 31, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 10
2022	8
2023	6
2024	5
2025	$ 4

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 10, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2015
Stockholders Equity Note [Line Items]
Shares of common stock repurchased (in shares)		0	400,000
Aggregate cost of shares repurchased			$ 36	$ 45
Share of common stock available for repurchase (in shares)		5,100,000
Dividends paid		$ 389	$ 353	$ 319
Dividends declared per common share (USD per share)	$ 0.55	$ 2.20	$ 2	$ 1.82
Maximum
Stockholders Equity Note [Line Items]
Shares available under the program to purchase outstanding common stock (in shares)					10,000,000
DRIP
Stockholders Equity Note [Line Items]
Shares available for grant (in shares)		4,200,000

Shareholders' Equity - Changes

Shareholders' Equity - Changes in Accumulated Other Comprehensive Loss by Component, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	$ 6,121	$ 5,864
Other comprehensive income (loss) before reclassification	(16)	(5)
Amounts reclassified from accumulated other comprehensive loss	3	3
Net other comprehensive income	(13)	(2)
Ending Balance	6,454	6,121
Employee Benefit Plan Funded Status
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	(94)	(102)
Other comprehensive income (loss) before reclassification	(12)	8
Net other comprehensive income	(12)	8
Ending Balance	(106)	(94)
Amortization of Prior Service Cost
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	1	1
Ending Balance	1	1
Amortization of Actuarial Loss
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	60	56
Amounts reclassified from accumulated other comprehensive loss	3	4
Net other comprehensive income	3	4
Ending Balance	63	60
Foreign Currency Translation
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	0	1
Amounts reclassified from accumulated other comprehensive loss		(1)
Net other comprehensive income	0	(1)
Ending Balance	0	0
Gain (Loss) on Cash Flow Hedge
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	(3)	10
Other comprehensive income (loss) before reclassification	(4)	(13)
Net other comprehensive income	(4)	(13)
Ending Balance	(7)	(3)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	(36)	(34)
Ending Balance	$ (49)	$ (36)

Shareholders' Equity - Dividend

Shareholders' Equity - Dividends (Details) - $ / shares	3 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Equity [Abstract]
Dividends declared per common share (USD per share)	$ 0.55	$ 0.55	$ 0.55	$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 0.455	$ 0.455	$ 0.455	$ 0.455	$ 0.415

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, capitalized amount	$ 0	$ 0	$ 0
Vesting period	3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock distribution period	30 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock distribution period	15 months
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost (less than)	$ 4,000,000
Total fair value of shares vested	$ 5,000,000	4,000,000	4,000,000
Weighted-average period	1 year 4 months 2 days
Performance Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Unrecognized compensation cost (less than)	$ 4,000,000
Total fair value of shares vested	$ 18,000,000	$ 14,000,000	$ 12,000,000
Weighted-average period	11 months 1 day
Historical volatility, stock price, period	3 years
Expected term	3 years
2017 Omnibus Equity Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares authorized for grant (in shares)				7,200,000
Shares available for grant (in shares)	6,700,000
2007 Omnibus Equity Compensation Plan | Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year	1 year	1 year
2007 Omnibus Equity Compensation Plan | Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years	3 years	3 years
Nonqualified employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	1,700,000
Lesser of fair market value	85.00%
Stock issuable (in shares)	2,000,000
Shares issued (in shares)	86,000	88,000	95,000

Stock-Based Compensation - Expe

Stock-Based Compensation - Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 21	$ 17	$ 16
Income tax benefit	(5)	(4)	(5)
Stock-based compensation expense, net of tax	16	13	11
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	19	15	15
Nonqualified employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2	$ 2	$ 1

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Restricted Stock Unit Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Restricted Stock Units Without Performance Restrictions
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested, beginning (in shares) | shares	118
Granted (in shares) | shares	55
Vested (in shares) | shares	(71)
Forfeited (in shares) | shares	(10)
Non-vested, ending (in shares) | shares	92
Weighted-average grant date fair value (USD per share), non-vested total beginning balance | $ / shares	$ 85.41
Weighted-average grant date fair value (USD per share), granted | $ / shares	129.39
Weighted-average grant date fair value (USD per share), vested | $ / shares	98.67
Weighted-average grant date fair value (USD per share), forfeited | $ / shares	97.24
Weighted-average grant date fair value (USD per share), non-vested total ending balance | $ / shares	$ 100.39
Performance Condition
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested, beginning (in shares) | shares	316
Granted (in shares) | shares	149
Vested (in shares) | shares	(160)
Forfeited (in shares) | shares	(12)
Non-vested, ending (in shares) | shares	293
Weighted-average grant date fair value (USD per share), non-vested total beginning balance | $ / shares	$ 83.89
Weighted-average grant date fair value (USD per share), granted | $ / shares	116.27
Weighted-average grant date fair value (USD per share), vested | $ / shares	72.13
Weighted-average grant date fair value (USD per share), forfeited | $ / shares	108.36
Weighted-average grant date fair value (USD per share), non-vested total ending balance | $ / shares	$ 105.70

Stock Based Compensation - Su_2

Stock Based Compensation - Summary of Weighted-Average Assumptions (Details) - Performance Condition - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	16.65%	16.80%	17.23%
Risk-free interest rate	1.28%	2.47%	2.36%
Expected life (years)	3 years	3 years	3 years
Grant date fair value per share (USD per share)	$ 159.64	$ 110.37	$ 73.62

Long-Term Debt - Components of

Long-Term Debt - Components of Long-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 9,688	$ 8,692
Unamortized debt (discount) premium, net	(4)	1
Unamortized debt issuance costs	(22)	(21)
Less current portion of long-term debt	(329)	(28)
Total long-term debt	9,333	8,644
Other American Water subsidiaries | Mandatorily redeemable preferred stock | Long Term Debt
Debt Instrument [Line Items]
Long-term debt	$ 5	7
Weighted Average Rate	8.57%
Other American Water subsidiaries | Mandatorily redeemable preferred stock | Minimum | Long Term Debt
Debt Instrument [Line Items]
Rate	8.47%
Maturity	2024
Other American Water subsidiaries | Mandatorily redeemable preferred stock | Maximum | Long Term Debt
Debt Instrument [Line Items]
Rate	9.75%
Maturity	2036
Other American Water subsidiaries | Private activity bonds and government funded debt | Minimum
Debt Instrument [Line Items]
Rate	0.00%
Maturity	2021
Other American Water subsidiaries | Private activity bonds and government funded debt | Maximum
Debt Instrument [Line Items]
Rate	5.00%
Maturity	2048
Other American Water subsidiaries | Private activity bonds and government funded debt | Fixed rate | Long Term Debt
Debt Instrument [Line Items]
Long-term debt	$ 735	724
Weighted Average Rate	1.74%
Other American Water subsidiaries | Private activity bonds and government funded debt | Fixed rate | Minimum | Long Term Debt
Debt Instrument [Line Items]
Rate	0.00%
Maturity	2021
Other American Water subsidiaries | Private activity bonds and government funded debt | Fixed rate | Maximum | Long Term Debt
Debt Instrument [Line Items]
Rate	5.50%
Maturity	2048
Other American Water subsidiaries | Mortgage bonds | Fixed rate | Long Term Debt
Debt Instrument [Line Items]
Long-term debt	$ 565	578
Weighted Average Rate	7.48%
Other American Water subsidiaries | Mortgage bonds | Fixed rate | Minimum | Long Term Debt
Debt Instrument [Line Items]
Rate	6.35%
Maturity	2021
Other American Water subsidiaries | Mortgage bonds | Fixed rate | Maximum | Long Term Debt
Debt Instrument [Line Items]
Rate	9.69%
Maturity	2039
Other American Water subsidiaries | Finance lease obligation | Long Term Debt
Debt Instrument [Line Items]
Long-term debt	$ 1	1
Rate	12.25%
Weighted Average Rate	12.25%
Maturity	2026
American Water Capital Corp. | Senior notes | Minimum
Debt Instrument [Line Items]
Rate	2.80%
Maturity	2030
American Water Capital Corp. | Senior notes | Maximum
Debt Instrument [Line Items]
Rate	3.45%
Maturity	2050
American Water Capital Corp. | Senior notes | Fixed rate | Long Term Debt
Debt Instrument [Line Items]
Long-term debt	$ 8,191	7,191
Weighted Average Rate	4.05%
American Water Capital Corp. | Senior notes | Fixed rate | Minimum | Long Term Debt
Debt Instrument [Line Items]
Rate	2.80%
Maturity	2021
American Water Capital Corp. | Senior notes | Fixed rate | Maximum | Long Term Debt
Debt Instrument [Line Items]
Rate	8.27%
Maturity	2050
American Water Capital Corp. | Private activity bonds and government funded debt | Minimum
Debt Instrument [Line Items]
Rate	0.60%
Maturity	2023
American Water Capital Corp. | Private activity bonds and government funded debt | Maximum
Debt Instrument [Line Items]
Rate	0.70%
Maturity	2023
American Water Capital Corp. | Private activity bonds and government funded debt | Fixed rate | Long Term Debt
Debt Instrument [Line Items]
Long-term debt	$ 191	$ 191
Weighted Average Rate	1.64%
American Water Capital Corp. | Private activity bonds and government funded debt | Fixed rate | Minimum | Long Term Debt
Debt Instrument [Line Items]
Rate	0.60%
Maturity	2021
American Water Capital Corp. | Private activity bonds and government funded debt | Fixed rate | Maximum | Long Term Debt
Debt Instrument [Line Items]
Rate	2.90%
Maturity	2031

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details)	Apr. 14, 2020USD ($)	Apr. 08, 2020USD ($)treasury_lock_agreement	Mar. 31, 2020USD ($)treasury_lock_agreement	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Long-term debt				$ 9,688,000,000	$ 8,692,000,000
Redeemable debt, amount outstanding				$ 868,000,000
Weighted average interest rate				1.85%
Debt issuance cost				$ 15,000,000
Proceeds from long-term debt				1,334,000,000	1,530,000,000	$ 1,358,000,000
Total availability				2,250,000,000	2,250,000,000
Ineffectiveness recognized on hedge instruments				$ 0	$ 0
Minimum
Debt Instrument [Line Items]
Line of credit facility consolidated debt to consolidated capitalization ratio				0.63
Designated as Hedging Instrument | Treasury lock agreements
Debt Instrument [Line Items]
Derivative, number of instruments held | treasury_lock_agreement			4
Debt instrument, term			10 years
Derivative notional amount, per contract			$ 100,000,000
Derivative, average fixed interest rate			0.94%
Derivative, number of instruments terminated | treasury_lock_agreement		4
Aggregate notional amount		$ 400,000,000
Net loss from terminated forward swaps		$ 6,000,000
Designated as Hedging Instrument | Minimum | Treasury lock agreements
Debt Instrument [Line Items]
Amortization period for forward swap with interest		10 years
Private activity bonds and government funded debt | American Water Capital Corp.
Debt Instrument [Line Items]
Proceeds from long-term debt				$ 86,000,000
Private activity bonds and government funded debt | American Water Capital Corp. | Minimum
Debt Instrument [Line Items]
Interest rate				0.60%
Private activity bonds and government funded debt | Other American Water subsidiaries
Debt Instrument [Line Items]
Proceeds from long-term debt				$ 23,000,000
Private activity bonds and government funded debt | Other American Water subsidiaries | Minimum
Debt Instrument [Line Items]
Interest rate				0.00%
Private activity bonds and government funded debt | Collateralized Debt Obligations | Other American Water subsidiaries
Debt Instrument [Line Items]
Long-term debt				$ 734,000,000
Line of credit
Debt Instrument [Line Items]
Line of credit facility consolidated debt to consolidated capitalization ratio				0.70
Senior notes | American Water Capital Corp.
Debt Instrument [Line Items]
Debt instrument, face amount	$ 1,000,000,000
Proceeds from long-term debt	989,000,000			$ 1,000,000,000
Senior notes | American Water Capital Corp. | Minimum
Debt Instrument [Line Items]
Interest rate				2.80%
Senior notes | Senior Note 3.45% Due 2029 | American Water Capital Corp.
Debt Instrument [Line Items]
Debt instrument, face amount	$ 500,000,000
Interest rate	2.80%
Senior notes | Senior Note 4.15% Due 2049 | American Water Capital Corp.
Debt Instrument [Line Items]
Debt instrument, face amount	$ 500,000,000
Interest rate	3.45%
Senior notes | Senior Note 7.21% Due 2019 | American Water Capital Corp.
Debt Instrument [Line Items]
Repayments of debt	$ 28,000,000

Long-Term Debt - Future Sinking

Long-Term Debt - Future Sinking Fund Payments and Debt Maturities (Details) $ in Millions	Dec. 31, 2020USD ($)
Debt Disclosure [Abstract]
2021	$ 329
2022	14
2023	356
2024	474
2025	597
Thereafter	$ 7,918

Long-Term Debt - Issued (Detail

Long-Term Debt - Issued (Details) - USD ($) $ in Millions	Apr. 14, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total issuances		$ 1,334	$ 1,530	$ 1,358
Other American Water subsidiaries | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Total issuances		$ 23
Other American Water subsidiaries | Private activity bonds and government funded debt | Minimum
Debt Instrument [Line Items]
Rate		0.00%
Maturity		2021
Other American Water subsidiaries | Private activity bonds and government funded debt | Maximum
Debt Instrument [Line Items]
Rate		5.00%
Maturity		2048
Other American Water subsidiaries | Private activity bonds and government funded debt | Weighted Average
Debt Instrument [Line Items]
Rate		0.16%
Other American Water subsidiaries | Private activity mortgage bonds
Debt Instrument [Line Items]
Total issuances		$ 225
Other American Water subsidiaries | Private activity mortgage bonds | Minimum
Debt Instrument [Line Items]
Rate		0.85%
Maturity		2023
Other American Water subsidiaries | Private activity mortgage bonds | Maximum
Debt Instrument [Line Items]
Rate		1.20%
Maturity		2027
Other American Water subsidiaries | Private activity mortgage bonds | Weighted Average
Debt Instrument [Line Items]
Rate		1.10%
American Water Capital Corp. | Senior notes
Debt Instrument [Line Items]
Total issuances	$ 989	$ 1,000
American Water Capital Corp. | Senior notes | Minimum
Debt Instrument [Line Items]
Rate		2.80%
Maturity		2030
American Water Capital Corp. | Senior notes | Maximum
Debt Instrument [Line Items]
Rate		3.45%
Maturity		2050
American Water Capital Corp. | Senior notes | Weighted Average
Debt Instrument [Line Items]
Rate		3.13%
American Water Capital Corp. | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Total issuances		$ 86
American Water Capital Corp. | Private activity bonds and government funded debt | Minimum
Debt Instrument [Line Items]
Rate		0.60%
Maturity		2023
American Water Capital Corp. | Private activity bonds and government funded debt | Maximum
Debt Instrument [Line Items]
Rate		0.70%
Maturity		2023
American Water Capital Corp. | Private activity bonds and government funded debt | Weighted Average
Debt Instrument [Line Items]
Rate		0.42%

Long-Term Debt - Retired Throug

Long-Term Debt - Retired Through Optional Redemptions or Payments at Maturities (Details) - Debt retired during the year $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Total retirements and redemptions	$ 342
Other American Water subsidiaries | Mandatorily redeemable preferred stock
Debt Instrument [Line Items]
Total retirements and redemptions	$ 2
Other American Water subsidiaries | Private activity mortgage bonds
Debt Instrument [Line Items]
Maturity	2020
Total retirements and redemptions	$ 225
Other American Water subsidiaries | Mortgage bonds
Debt Instrument [Line Items]
Total retirements and redemptions	$ 13
Minimum | Other American Water subsidiaries | Mandatorily redeemable preferred stock
Debt Instrument [Line Items]
Rate	8.49%
Maturity	2031
Minimum | Other American Water subsidiaries | Private activity mortgage bonds
Debt Instrument [Line Items]
Rate	4.45%
Minimum | Other American Water subsidiaries | Mortgage bonds
Debt Instrument [Line Items]
Rate	3.92%
Maturity	2020
Maximum | Other American Water subsidiaries | Mandatorily redeemable preferred stock
Debt Instrument [Line Items]
Rate	9.18%
Maturity	2036
Maximum | Other American Water subsidiaries | Private activity mortgage bonds
Debt Instrument [Line Items]
Rate	5.60%
Maximum | Other American Water subsidiaries | Mortgage bonds
Debt Instrument [Line Items]
Rate	9.71%
Maturity	2021
Weighted Average | Other American Water subsidiaries | Mandatorily redeemable preferred stock
Debt Instrument [Line Items]
Rate	8.64%
Weighted Average | Other American Water subsidiaries | Private activity mortgage bonds
Debt Instrument [Line Items]
Rate	5.19%
Weighted Average | Other American Water subsidiaries | Mortgage bonds
Debt Instrument [Line Items]
Rate	7.83%
Fixed rate | Other American Water subsidiaries | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Total retirements and redemptions	$ 15
Fixed rate | American Water Capital Corp. | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Total retirements and redemptions	$ 87
Fixed rate | Minimum | Other American Water subsidiaries | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Rate	0.00%
Maturity	2020
Fixed rate | Minimum | American Water Capital Corp. | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Rate	1.79%
Maturity	2020
Fixed rate | Maximum | Other American Water subsidiaries | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Rate	5.60%
Maturity	2048
Fixed rate | Maximum | American Water Capital Corp. | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Rate	5.38%
Maturity	2031
Fixed rate | Weighted Average | Other American Water subsidiaries | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Rate	2.08%
Fixed rate | Weighted Average | American Water Capital Corp. | Private activity bonds and government funded debt
Debt Instrument [Line Items]
Rate	5.29%

Short-Term Debt - Additional In

Short-Term Debt - Additional Information (Details)	Mar. 20, 2020USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Apr. 01, 2020USD ($)
Short-term Debt [Line Items]
Total availability			$ 2,250,000,000	$ 2,250,000,000
Outstanding debt			(786,000,000)	(786,000,000)
Short-term debt			$ 1,388,000,000	1,388,000,000
Line of credit facility consolidated debt to consolidated capitalization ratio, required			0.70
Maturity in More Than Three Months
Short-term Debt [Line Items]
Proceeds from short-term borrowings with maturities greater than three months			$ 0
Revolving Credit Facility
Short-term Debt [Line Items]
Short-term debt			1,388,000,000	1,388,000,000
Revolving Credit Facility | Letter of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity			150,000,000	150,000,000
Letters of credit outstanding, amount			$ 76,000,000	$ 76,000,000
American Water Capital Corp.
Short-term Debt [Line Items]
Maximum borrowing capacity					$ 500,000,000
Interest rate during period			1.16%	2.54%
American Water Capital Corp. | Term loan
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 750,000,000
Proceeds from lines of credit	500,000,000		$ 500,000,000
Additional maximum borrowing capacity	$ 250,000,000
Fair value of amount outstanding			500,000,000
American Water Capital Corp. | Term loan | London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Debt, basis spread on variable rate	0.80%
American Water Capital Corp. | Revolving Credit Facility
Short-term Debt [Line Items]
Proceeds from lines of credit			$ 0
Proceeds from short-term debt		$ 650,000,000
Repayments of short-term debt		$ 650,000,000

Short-Term Debt - Schedule of C

Short-Term Debt - Schedule of Company's Aggregate Credit Facility Commitments, Commercial Paper Limit, Letter of Credit Availability and Availability Capacity (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Total availability	$ 2,100	$ 2,100
Total availability	2,250	2,250
Outstanding debt	(786)	(786)
Outstanding debt	(862)	(862)
Remaining availability	1,314	1,314
Availability on Revolving Credit Facility	1,388	1,388
Revolving Credit Facility
Short-term Debt [Line Items]
Availability on Revolving Credit Facility	1,388	1,388
Revolving Credit Facility | Letter of Credit
Short-term Debt [Line Items]
Total availability	150	150
Outstanding debt	(76)	(76)
Remaining availability	$ 74	$ 74

Short-Term Debt - Schedule of A

Short-Term Debt - Schedule of Availability Liquidity (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Cash and cash equivalents	$ 547	$ 60
Availability on Revolving Credit Facility	1,388	1,388
Total Available Liquidity	1,935	1,448
Revolving Credit Facility
Short-term Debt [Line Items]
Availability on Revolving Credit Facility	$ 1,388	$ 1,388

Short-Term Debt - Schedule of S

Short-Term Debt - Schedule of Short-Term Borrowings Activity (Details) - American Water Capital Corp. - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Average borrowings	$ 1,047	$ 726
Maximum borrowings outstanding	$ 2,172	$ 1,271
Weighted average interest rates, computed on daily basis	1.16%	2.54%
Weighted average interest rates, as of December 31	0.53%	1.86%

General Taxes - Components of G

General Taxes - Components of General Tax Expense from Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
General Taxes [Abstract]
Property and capital stock	$ 140	$ 124	$ 120
Gross receipts and franchise	116	110	112
Payroll	36	35	33
Other general	11	11	12
Total general taxes	$ 303	$ 280	$ 277

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense from Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current income taxes:
State	$ 8	$ 4	$ 26
Federal	0	0	1
Total current income taxes	8	4	27
Deferred income taxes:
State	49	54	33
Federal	159	155	163
Amortization of deferred investment tax credits	(1)	(1)	(1)
Total deferred income taxes	207	208	195
Provision for income taxes	$ 215	$ 212	$ 222

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense from Continuing Operations (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax at statutory rate	21.00%	21.00%	21.00%
State taxes, net of federal taxes	4.80%	5.40%	5.50%
EADIT	(2.10%)	(0.90%)	1.50%
Other, net	(0.40%)	(0.10%)	0.20%
Effective tax rate	23.30%	25.40%	28.20%

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Liability from Continuing Operations (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Advances and contributions	$ 424	$ 410
Tax losses and credits	65	136
Regulatory income tax assets	329	335
Pension and other postretirement benefits	100	94
Other	165	151
Total deferred tax assets	1,083	1,126
Valuation allowance	(19)	(21)	$ (14)	$ (13)
Total deferred tax assets, net of allowance	1,064	1,105
Deferred tax liabilities:
Property, plant and equipment	2,913	2,760
Deferred pension and other postretirement benefits	97	77
Other	216	207
Total deferred tax liabilities	3,226	3,044
Less: Deferred tax liabilities included in liabilities related to assets held for sale	69	67
Total deferred tax liabilities, net of deferred tax assets	$ (2,093)	$ (1,872)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Examination [Line Items]
Unrecognized tax benefit excluding interest and penalties, that would affect the effective tax rate	$ 12
Federal
Income Tax Examination [Line Items]
Net operating loss carryforwards	366	$ 673
State
Income Tax Examination [Line Items]
Net operating loss carryforwards	$ 357	$ 453
Net operating loss carryforwards expiration date	The state NOL carryforwards began to expire in 2020 and will continue through 2040

Income Taxes - Changes in Gross

Income Taxes - Changes in Gross Liability Excluding Interest and Penalties for Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 110	$ 97
Increases in current period tax positions	18	17
Decreases in prior period measurement of tax positions	(6)	(4)
Ending Balance	$ 122	$ 110

Income Taxes - Changes in Valua

Income Taxes - Changes in Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement in Valuation Allowances [Roll Forward]
Beginning Balance	$ 21	$ 14	$ 13
Increases (decreases) in current period tax positions	(2)	7	1
Ending Balance	$ 19	$ 21	$ 14

Employee Benefits - Additional

Employee Benefits - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent	5.25%
Minimum reduction of expected future service of plan participants	10.00%
Cumulative gains losses as percentage of benefit obligations or plan assets	10.00%
Cost of contribution plan	$ 12	$ 12	$ 12
Additional cost of contribution plan	$ 15	$ 13	$ 11
Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Expected blended return on weighted assets percentage	3.68%
Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets percentage	6.50%

Employee Benefits - Schedule of

Employee Benefits - Schedule of Changes in Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
U.S. small cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 84
Percentage of Plan Assets		5.00%
U.S. small cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 78
Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%	100.00%
Fair value of plan assets	$ 1,990	$ 1,747	$ 1,499
Percentage of Plan Assets	100.00%	100.00%
Pension Plan Asset | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 810	$ 655
Pension Plan Asset | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	824	743
Pension Plan Asset | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	356	349
Pension Plan Asset | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 78	$ 39
Percentage of Plan Assets	4.00%	2.00%
Pension Plan Asset | Cash | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 78	$ 39
Pension Plan Asset | Equity securities:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	50.00%	50.00%
Pension Plan Asset | U.S. large cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 420	$ 358
Percentage of Plan Assets	21.00%	20.00%
Pension Plan Asset | U.S. large cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 420	$ 358
Pension Plan Asset | U.S. small cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 124
Percentage of Plan Assets	6.00%
Pension Plan Asset | U.S. small cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 124
Pension Plan Asset | U.S. small cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		6
Pension Plan Asset | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 367	$ 320
Percentage of Plan Assets	18.00%	18.00%
Pension Plan Asset | International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 8	$ 6
Pension Plan Asset | International | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	169	137
Pension Plan Asset | International | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	190	177
Pension Plan Asset | Real estate fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 120	$ 127
Percentage of Plan Assets	6.00%	7.00%
Pension Plan Asset | Real estate fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 120	$ 127
Pension Plan Asset | REITs
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7	$ 7
Percentage of Plan Assets	0.00%	0.00%
Pension Plan Asset | REITs | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7	$ 7
Pension Plan Asset | Fixed income securities:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	50.00%	50.00%
Pension Plan Asset | U.S. Treasury securities and government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 171	$ 169
Percentage of Plan Assets	9.00%	10.00%
Pension Plan Asset | U.S. Treasury securities and government bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 163	$ 158
Pension Plan Asset | U.S. Treasury securities and government bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	11
Pension Plan Asset | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 594	$ 542
Percentage of Plan Assets	30.00%	31.00%
Pension Plan Asset | Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 594	$ 542
Pension Plan Asset | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 9	$ 14
Percentage of Plan Assets	0.00%	1.00%
Pension Plan Asset | Mortgage-backed securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 9	$ 14
Pension Plan Asset | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 34	$ 26
Percentage of Plan Assets	2.00%	1.00%
Pension Plan Asset | Municipal bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 34	$ 26
Pension Plan Asset | Treasury futures
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 10	$ 8
Percentage of Plan Assets	1.00%	1.00%
Pension Plan Asset | Treasury futures | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 10	$ 8
Pension Plan Asset | Long duration bond fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 10	$ 8
Percentage of Plan Assets	1.00%	1.00%
Pension Plan Asset | Long duration bond fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7	$ 8
Pension Plan Asset | Long duration bond fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3
Pension Plan Asset | Guarantee annuity contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 46	$ 45
Percentage of Plan Assets	2.00%	3.00%
Pension Plan Asset | Guarantee annuity contracts | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 46	$ 45
Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%	100.00%
Fair value of plan assets	$ 556	$ 532	$ 507
Percentage of Plan Assets	100.00%	100.00%
Postretirement Benefit Plan Assets | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%	100.00%
Fair value of plan assets	$ 420	$ 396
Percentage of Plan Assets	100.00%	100.00%
Postretirement Benefit Plan Assets | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%	100.00%
Fair value of plan assets	$ 135	$ 132
Percentage of Plan Assets	100.00%	100.00%
Postretirement Benefit Plan Assets | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%	100.00%
Fair value of plan assets	$ 1	$ 4
Percentage of Plan Assets	100.00%	100.00%
Postretirement Benefit Plan Assets | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 425	$ 407
Postretirement Benefit Plan Assets | Level 1 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	339	321
Postretirement Benefit Plan Assets | Level 1 | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	85	82
Postretirement Benefit Plan Assets | Level 1 | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	4
Postretirement Benefit Plan Assets | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	131	125
Postretirement Benefit Plan Assets | Level 2 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	81	75
Postretirement Benefit Plan Assets | Level 2 | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	50
Postretirement Benefit Plan Assets | Cash | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 12	$ 6
Percentage of Plan Assets	3.00%	2.00%
Postretirement Benefit Plan Assets | Cash | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1	$ 4
Postretirement Benefit Plan Assets | Cash | Level 1 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	6
Postretirement Benefit Plan Assets | Cash | Level 1 | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1	$ 4
Postretirement Benefit Plan Assets | Equity securities: | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	4.00%	4.00%
Postretirement Benefit Plan Assets | Equity securities: | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	60.00%	60.00%
Postretirement Benefit Plan Assets | Equity securities: | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	70.00%	70.00%
Postretirement Benefit Plan Assets | U.S. large cap | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 14	$ 13
Percentage of Plan Assets	3.00%	3.00%
Postretirement Benefit Plan Assets | U.S. large cap | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 51	$ 48
Percentage of Plan Assets	38.00%	36.00%
Postretirement Benefit Plan Assets | U.S. large cap | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 2
Percentage of Plan Assets	0.00%	50.00%
Postretirement Benefit Plan Assets | U.S. large cap | Level 1 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 14	$ 13
Postretirement Benefit Plan Assets | U.S. large cap | Level 1 | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51	48
Postretirement Benefit Plan Assets | U.S. large cap | Level 1 | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	2
Postretirement Benefit Plan Assets | International | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 33	$ 30
Percentage of Plan Assets	24.00%	23.00%
Postretirement Benefit Plan Assets | International | Level 1 | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 33	$ 30
Postretirement Benefit Plan Assets | Fixed income securities: | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	96.00%	96.00%
Postretirement Benefit Plan Assets | Fixed income securities: | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	40.00%	40.00%
Postretirement Benefit Plan Assets | Fixed income securities: | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Target allocation	30.00%	30.00%
Postretirement Benefit Plan Assets | U.S. Treasury securities and government bonds | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 389	$ 373
Percentage of Plan Assets	93.00%	94.00%
Postretirement Benefit Plan Assets | U.S. Treasury securities and government bonds | Level 1 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 308	$ 298
Postretirement Benefit Plan Assets | U.S. Treasury securities and government bonds | Level 2 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	81	75
Postretirement Benefit Plan Assets | Long duration bond fund | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 5	$ 4
Percentage of Plan Assets	1.00%	1.00%
Postretirement Benefit Plan Assets | Long duration bond fund | Level 1 | Bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 5	$ 4
Postretirement Benefit Plan Assets | Core fixed income bond fund | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 50	$ 50
Percentage of Plan Assets	38.00%	41.00%
Postretirement Benefit Plan Assets | Core fixed income bond fund | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1	$ 2
Percentage of Plan Assets	100.00%	50.00%
Postretirement Benefit Plan Assets | Core fixed income bond fund | Level 1 | Life VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1	$ 2
Postretirement Benefit Plan Assets | Core fixed income bond fund | Level 2 | Non-bargain VEBA:
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 50	$ 50

Employee Benefits - Schedule _2

Employee Benefits - Schedule of Significant Unobservable Inputs (Details) - Pension Plan Asset - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets beginning balance	$ 1,747	$ 1,499
Actual return on assets	314	319
Fair value of plan assets ending balance	1,990	1,747
Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets beginning balance	349
Fair value of plan assets ending balance	356	349
Level 3 | Guaranteed Annuity Contracts And Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets beginning balance	349	230
Actual return on assets	3	25
Purchases, issuances and settlements, net	4	94
Fair value of plan assets ending balance	$ 356	$ 349

Employee Benefits - Schedule _3

Employee Benefits - Schedule of Rollforward Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts recognized on the balance sheet:
Noncurrent liability	$ (388)	$ (411)
Pension Plan Asset
Change in benefit obligation:
Benefit obligation beginning balance	2,161	1,892
Service cost	31	28	$ 34
Interest cost	73	82	76
Plan participants' contributions	0	0
Plan amendments	0	0
Actuarial loss (gain)	233	264
Settlements	(3)	0
Gross benefits paid	(109)	(105)
Federal subsidy	0	0
Benefit obligation ending balance	2,386	2,161	1,892
Change in plan assets:
Fair value of plan assets beginning balance	1,747	1,499
Actual return on assets	314	319
Employer contributions	41	33
Plan participants' contributions	0	0
Settlements	(3)	0
Benefits paid	(109)	(104)
Fair value of plan assets ending balance	1,990	1,747	1,499
Funded status ending balance	(396)	(414)
Amounts recognized on the balance sheet:
Noncurrent asset	0	0
Current liability	(2)	(3)
Noncurrent liability	(388)	(411)
(Liabilities) assets related to assets held for sale	(6)	0
Net amount recognized	(396)	(414)
Pension Plan Asset | New York Water Service Corporation Pension Plan
Amounts recognized on the balance sheet:
Payment for settlement	3
Postretirement Benefit Plan Assets
Change in benefit obligation:
Benefit obligation beginning balance	374	353
Service cost	4	4	8
Interest cost	12	15	20
Plan participants' contributions	2	2
Plan amendments	5	(1)
Actuarial loss (gain)	13	25
Settlements	0	0
Gross benefits paid	(29)	(25)
Federal subsidy	1	1
Benefit obligation ending balance	382	374	353
Change in plan assets:
Fair value of plan assets beginning balance	532	507
Actual return on assets	53	51
Employer contributions	(2)	(2)
Plan participants' contributions	2	2
Settlements	0	0
Benefits paid	(29)	(26)
Fair value of plan assets ending balance	556	532	$ 507
Funded status ending balance	174	158
Amounts recognized on the balance sheet:
Noncurrent asset	173	159
Current liability	0	0
Noncurrent liability	(1)	(1)
(Liabilities) assets related to assets held for sale	2	0
Net amount recognized	$ 174	$ 158

Employee Benefits - Summary of

Employee Benefits - Summary of Accumulated Other Comprehensive Income and Regulatory Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 436	$ 435
Prior service credit	(16)	(19)
Net amount recognized	420	416
Regulatory assets (liabilities)	366	375
Accumulated other comprehensive income	54	41
Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	49	72
Prior service credit	(217)	(257)
Net amount recognized	(168)	(185)
Regulatory assets (liabilities)	(168)	(185)
Accumulated other comprehensive income	$ 0	$ 0

Employee Benefits - Schedule _4

Employee Benefits - Schedule of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Projected benefit obligation	$ 2,386	$ 2,161
Fair value of plan assets	1,990	1,748
Accumulated benefit obligation	2,188	2,018
Fair value of plan assets	$ 1,990	$ 1,748

Employee Benefits - Schedule _5

Employee Benefits - Schedule of Expected Cash Flow for Pension and Post Retirement Benefit Plans (Details) $ in Millions	Dec. 31, 2020USD ($)
To plan trusts | Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions	$ 37
To plan trusts | Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions	0
To plan participants | Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions	2
To plan participants | Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions	$ 0

Employee Benefits - Schedule _6

Employee Benefits - Schedule of Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2020USD ($)
Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
2021	$ 127
2022	128
2023	133
2024	135
2025	137
2026-2030	692
Postretirement Benefit Plan Assets
Defined Benefit Plan Disclosure [Line Items]
2021	27
2022	27
2023	27
2024	27
2025	26
2026-2030	123
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt [Abstract]
2021	1
2022	1
2023	1
2024	1
2025	1
2026-2030	$ 4

Employee Benefits - Schedule _7

Employee Benefits - Schedule of Significant Assumptions of Pension and Other Postretirement Benefit Plans (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan Asset
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.74%	3.44%	4.38%
Rate of compensation increase	3.51%	2.97%	3.00%
Discount rate	3.44%	4.38%	3.75%
Expected return on plan assets	6.50%	6.20%	5.95%
Rate of compensation increase	2.97%	3.00%	3.02%
Other Postretirement Benefit Cost
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.56%	3.36%	4.32%
Discount rate	3.36%	4.32%	4.23%
Expected return on plan assets	3.68%	3.56%	4.77%
Other Postretirement Benefit Cost | Maximum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate, benefit obligations, percentage	6.25%	6.50%	6.75%
Health care cost trend rate, net periodic costs, percentage	6.50%	6.75%	7.00%
Other Postretirement Benefit Cost | Minimum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate, benefit obligations, percentage	5.00%	5.00%	5.00%
Health care cost trend rate, benefit obligation, year	2026	2026	2026
Health care cost trend rate, net periodic costs, percentage	5.00%	5.00%	4.50%
Health care cost trend rate, net periodic costs, year	2026	2026	2026

Employee Benefits - Schedule _8

Employee Benefits - Schedule of Net Periodic Benefit Cost Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Amortization of actuarial loss	$ (3)	$ (4)	$ (7)
Pension Plan Asset
Components of net periodic pension benefit cost and other postretirement benefit cost
Service cost	31	28	34
Interest cost	73	82	76
Expected return on plan assets	(111)	(91)	(97)
Amortization of prior service (credit) cost	(3)	(3)	1
Amortization of actuarial loss	30	32	27
Settlements	1	0	0
Net periodic pension benefit cost	21	48	41
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Current year actuarial (gain) loss	12	(8)	(60)
Amortization of actuarial loss	(3)	(4)	(7)
Total recognized in other comprehensive income	9	(12)	(67)
Total recognized in net periodic benefit cost and other comprehensive income	30	36	(26)
Pension Plan Asset | New York Water Service Corporation Pension Plan
Components of net periodic pension benefit cost and other postretirement benefit cost
Settlements	1
Other Postretirement Benefit Cost
Components of net periodic pension benefit cost and other postretirement benefit cost
Service cost	4	4	8
Interest cost	12	15	20
Expected return on plan assets	(19)	(18)	(26)
Amortization of prior service (credit) cost	(34)	(35)	(23)
Amortization of actuarial loss	2	3	3
Net periodic pension benefit cost	$ (35)	$ (31)	$ (18)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) Customer in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2015Customer	Jun. 27, 2015	Jun. 26, 2015	Jun. 23, 2015Customer
Commitments And Contingencies [Line Items]
Estimated capital expenditures under legal and binding contractual obligations	$ 484
Loss contingency, probable loss	10
Dunbar | WVAWC
Commitments And Contingencies [Line Items]
Number of customers impacted due to failure of main that caused that water outages and low pressure | Customer							25
Percentage of impacted customers to which service was restored					20.00%	80.00%
Number of customers for whom system was reconfigured to maintain service while final repair was completed | Customer				3
Monterey | Cal Am | SWRCB
Commitments And Contingencies [Line Items]
Approved cost estimates		$ 279
Aggregate costs	154
Allowance for funds used during construction	36
Binding Agreement
Commitments And Contingencies [Line Items]
Litigation settlement amount awarded to other party, pre tax, net	126
Litigation settlement amount awarded to other party	0.5
Insurance settlements receivable	0.5
Binding Agreement | WVAWC
Commitments And Contingencies [Line Items]
Litigation settlement amount awarded to other party	19
Maximum
Commitments And Contingencies [Line Items]
Loss contingency, possible loss	$ 4
Maximum | Monterey | Cal Am | SWRCB
Commitments And Contingencies [Line Items]
Approved recovery amount			$ 50

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Annual Commitments Related to Minimum Quantities of Purchased Water Having Non-Cancelable Terms (Details) $ in Millions	Dec. 31, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
2021	$ 66
2022	67
2023	66
2024	52
2025	52
Thereafter	$ 618

Earnings Per Common Share - Rec

Earnings Per Common Share - Reconciliation of Numerator and Denominator for Basic and Diluted Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 145	$ 264	$ 176	$ 124	$ 98	$ 240	$ 170	$ 113	$ 709	$ 621	$ 567
Weighted average common shares outstanding—Basic (in shares)									181	181	180
Effect of dilutive common stock equivalents (in shares)									1	0	0
Weighted average common shares outstanding—Diluted (in shares)									182	181	180

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Maximum
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	1,000,000	1,000,000	1,000,000

Fair Values of Financial Inst_3

Fair Values of Financial Instruments - Carrying Amounts and Fair Values of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock with mandatory redemption requirements, carrying amount	$ 5	$ 7
Long-term debt (excluding finance lease obligations), carrying amount	9,656	8,664
Preferred stock with mandatory redemption requirements, fair value	7	9
Long-term debt (excluding finance lease obligations), fair value	11,807	9,770
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock with mandatory redemption requirements, fair value	0	0
Long-term debt (excluding finance lease obligations), fair value	9,639	7,689
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock with mandatory redemption requirements, fair value	0	0
Long-term debt (excluding finance lease obligations), fair value	415	417
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock with mandatory redemption requirements, fair value	7	9
Long-term debt (excluding finance lease obligations), fair value	$ 1,753	$ 1,664

Fair Values of Financial Inst_4

Fair Values of Financial Instruments - Fair Value Measurements of Assets and Liabilities on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets:
Restricted funds	$ 29	$ 31
Rabbi trust investments	19	17
Deposits	4	3
Other investments	11	8
Total assets	63	59
Liabilities:
Deferred compensation obligations	24	21
Total liabilities	24	21
Total assets (liabilities)	39	38
Level 1
Assets:
Restricted funds	29	31
Rabbi trust investments	19	17
Deposits	4	3
Other investments	11	8
Total assets	63	59
Liabilities:
Deferred compensation obligations	24	21
Total liabilities	24	21
Total assets (liabilities)	39	38
Level 2
Assets:
Restricted funds	0	0
Rabbi trust investments	0	0
Deposits	0	0
Other investments	0	0
Total assets	0	0
Liabilities:
Deferred compensation obligations	0	0
Total liabilities	0	0
Total assets (liabilities)	0	0
Level 3
Assets:
Restricted funds	0	0
Rabbi trust investments	0	0
Deposits	0	0
Other investments	0	0
Total assets	0	0
Liabilities:
Deferred compensation obligations	0	0
Total liabilities	0	0
Total assets (liabilities)	$ 0	$ 0

Leases (Details)

Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Carrying value of finance lease assets	$ 147	$ 147
Operating and financing leases, rent expense, net	$ 14	$ 16
Lease and rental expense			$ 35
Real Property
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, term of contract	39 years
Future minimum sublease rentals, thereafter	$ 52
Vehicles
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, term of contract	6 years
Equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, term of contract	5 years
Operating and Maintenance Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Future minimum sublease rentals, 2021	$ 4
Future minimum sublease rentals, 2022	4
Future minimum sublease rentals, 2023	4
Future minimum sublease rentals, 2024	4
Future minimum sublease rentals, 2025	$ 4
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, renewal term	1 year
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, renewal term	60 years
Utility Plant | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lessee, finance lease, term of contract	30 years
Utility Plant | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lessee, finance lease, term of contract	40 years

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Leases [Abstract]
Cash paid for amounts in lease liabilities	$ 14
Right-of-use asset obtained in exchange for operating lease liability	$ 2

Leases - Remaining Lease Term a

Leases - Remaining Lease Term and Discount Rate (Details)	Dec. 31, 2020
Weighted-average Remaining Lease Term [Abstract]
Finance lease, weighted average remaining lease term	5 years
Operating lease, weighted average remaining lease term	19 years
Weighted-average Discount Rate [Abstract]
Finance lease, weighted average discount rate, percent	12.00%
Operating lease, weighted average discount rate, percent	4.00%

Leases - Future Maturities of L

Leases - Future Maturities of Lease Liabilities (Details) $ in Millions	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 13
2022	12
2023	8
2024	7
2025	7
Thereafter	94
Imputed interest	$ (49)

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020stateSegment
Regulated Businesses
Segment Reporting Information [Line Items]
Number of reportable segment | Segment	1
Number of states in which entity provides water and wastewater services	16
Market-Based Businesses
Segment Reporting Information [Line Items]
Number of states in which entity provides water and wastewater services	16

Segment Information - Summarize

Segment Information - Summarized Segment Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating revenues	$ 923	$ 1,079	$ 931	$ 844	$ 902	$ 1,013	$ 882	$ 813	$ 3,777	$ 3,610	$ 3,440
Depreciation and amortization									604	582	545
Impairment charge									0	0	57
Total operating expenses, net									2,529	2,440	2,338
Interest, net									(395)	(382)	(350)
Income before income taxes									924	833	787
Provision for income taxes									215	212	222
Net income attributable to common shareholders	145	$ 264	$ 176	$ 124	98	$ 240	$ 170	$ 113	709	621	567
Total assets	24,766				22,682				24,766	22,682	21,223
Cash paid for capital expenditures									1,822	1,654	1,586
Regulated Businesses
Segment Reporting Information [Line Items]
Operating revenues									3,255
Market-Based Businesses
Segment Reporting Information [Line Items]
Operating revenues									540
Operating Segments | Regulated Businesses
Segment Reporting Information [Line Items]
Operating revenues									3,255	3,094	2,984
Depreciation and amortization									562	529	500
Impairment charge											0
Total operating expenses, net									2,102	1,964	1,912
Interest, net									(291)	(295)	(280)
Income before income taxes									932	869	826
Provision for income taxes									217	215	224
Net income attributable to common shareholders									715	654	602
Total assets	22,357				20,318				22,357	20,318	18,680
Cash paid for capital expenditures									1,804	1,627	1,477
Operating Segments | Market-Based Businesses
Segment Reporting Information [Line Items]
Operating revenues									540	539	476
Depreciation and amortization									26	37	29
Impairment charge											57
Total operating expenses, net									421	480	441
Interest, net									1	5	4
Income before income taxes									120	66	41
Provision for income taxes									29	20	11
Net income attributable to common shareholders									91	46	32
Total assets	891				1,008				891	1,008	999
Cash paid for capital expenditures									10	13	13
Other
Segment Reporting Information [Line Items]
Operating revenues									(18)	(23)	(20)
Depreciation and amortization									16	16	16
Impairment charge											0
Total operating expenses, net									6	(4)	(15)
Interest, net									(105)	(92)	(74)
Income before income taxes									(128)	(102)	(80)
Provision for income taxes									(31)	(23)	(13)
Net income attributable to common shareholders									(97)	(79)	(67)
Total assets	$ 1,518				$ 1,356				1,518	1,356	1,544
Cash paid for capital expenditures									$ 8	$ 14	$ 96

Unaudited Quarterly Data - Sche

Unaudited Quarterly Data - Schedule Of Unaudited Quarterly Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Quarterly Financial Data [Abstract]
Operating revenues	$ 923	$ 1,079	$ 931	$ 844	$ 902	$ 1,013	$ 882	$ 813	$ 3,777		$ 3,610		$ 3,440
Operating income	263	433	313	239	224	406	302	238	1,248		1,170		1,102
Net income attributable to common shareholders	$ 145	$ 264	$ 176	$ 124	$ 98	$ 240	$ 170	$ 113	$ 709		$ 621		$ 567
Basic earnings per share:
Net income attributable to common shareholders (USD per share)	$ 0.80	$ 1.46	$ 0.97	$ 0.69	$ 0.54	$ 1.33	$ 0.94	$ 0.62	$ 3.91	[1]	$ 3.44	[1]	$ 3.16	[1]
Diluted earnings per share:
Net income attributable to common shareholders (USD per share)	$ 0.80	$ 1.46	$ 0.97	$ 0.68	$ 0.54	$ 1.33	$ 0.94	$ 0.62	$ 3.91	[1]	$ 3.43	[1]	$ 3.15	[1]
[1]	Amounts may not calculate due to rounding.