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Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Jun. 13, 2019
Entity Registrant Name dei_EntityRegistrantName American Century ETF Trust
Central Index Key dei_EntityCentralIndexKey 0001710607
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jun. 13, 2019
Document Effective Date dei_DocumentEffectiveDate Jan. 01, 2019
Prospectus Date rr_ProspectusDate Jan. 01, 2019
American Century ETF Trust | American Century Diversified Corporate Bond ETF  
Prospectus: rr_ProspectusTable  
Supplement [Text Block] ck0001710607_SupplementTextBlock
American Century ETF Trust
Prospectus Supplement
American Century Diversified Corporate Bond ETF
 
 
Supplement dated June 14, 2019 n Prospectus dated January 1, 2019
Expense [Heading] rr_ExpenseHeading The following replaces the Annual Fund Operating Expenses table on page 2 of the prospectus.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Expense Example [Heading] rr_ExpenseExampleHeading The following replaces the Example table on page 2 of the prospectus.
American Century ETF Trust | American Century Diversified Corporate Bond ETF | American Century Diversified Corporate Bond ETF Class  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.29% [1]
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.29%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 30
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 93
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 163
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 369
[1] The management fee has been restated to reflect the decrease in the management fee schedule effective June 14, 2019.