v3.26.1
Revenue Recognition - Disaggregated Revenues (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers $ 1,350 $ 1,272 $ 2,553 $ 2,406
Other Revenues Not from Contracts with Customers 5 4 9 12
Operating revenues 1,355 1,276 2,562 2,418
Operating Segments | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,263 1,173 2,370 2,214
Other Revenues Not from Contracts with Customers 5 5 9 13
Operating revenues 1,268 1,178 2,379 2,227
Alternative revenue programs 4 4 6 10
Lease contract revenue 1 1 3 3
Operating Segments | Water Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,138 1,052 2,126 1,981
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 1,138 1,052 2,126 1,981
Operating Segments | Wastewater Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 113 107 220 208
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 113 107 220 208
Operating Segments | Miscellaneous utility charges | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 12 14 24 25
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 12 14 24 25
Operating Segments | Residential | Water Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 689 637 1,282 1,197
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 689 637 1,282 1,197
Operating Segments | Residential | Wastewater Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 74 71 148 139
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 74 71 148 139
Operating Segments | Commercial | Water Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 259 243 488 455
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 259 243 488 455
Operating Segments | Commercial | Wastewater Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 25 21 47 39
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 25 21 47 39
Operating Segments | Fire service | Water Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 49 48 97 93
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 49 48 97 93
Operating Segments | Industrial | Water Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 56 46 104 91
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 56 46 104 91
Operating Segments | Industrial | Wastewater Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 3 5 5 10
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 3 5 5 10
Operating Segments | Public and other | Water Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 85 78 155 145
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 85 78 155 145
Operating Segments | Public and other | Wastewater Services | Regulated Businesses        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 11 10 20 20
Other Revenues Not from Contracts with Customers 0 0 0 0
Operating revenues 11 10 20 20
Other        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 87 99 183 192
Other Revenues Not from Contracts with Customers 0 (1) 0 (1)
Operating revenues $ 87 $ 98 $ 183 $ 191