Rendering

Component: (Network and Table)
Network
100890 - Disclosure - Changes in Gross Liability Excluding Interest and Penalties for Unrecognized Tax Benefits (Details)
(http://www.amwater.com/20161231/taxonomy/role/DisclosureChangesInGrossLiabilityExcludingInterestAndPenaltiesForUnrecognizedTaxBenefitsDetails)
Table(Implied)
Slicers (applies to each fact value in each table cell)
Reporting Entity [Axis]0001410636 (http://www.sec.gov/CIK)
Income Tax Disclosure [Abstract]Period [Axis]
2016-01-01 - 2016-12-31
2015-01-01 - 2015-12-31
Income Tax Disclosure [Abstract]
 
 
Beginning Balance
233,000,000  
195,000,000  
Increases in current period tax positions
10,000,000  
39,000,000  
Decreases in prior period measurement of tax positions
(74,000,000) 
(1,000,000) 
Ending Balance
169,000,000  
 
233,000,000