XML 13 R4.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Feb. 11, 2020
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 Feb. 11, 2020
Document Effective Date dei_DocumentEffectiveDate Feb. 11, 2020
Prospectus Date rr_ProspectusDate Feb. 11, 2020
American Century Focused Dynamic Growth ETF  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading American Century Focused Dynamic Growth ETF
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks long-term capital growth.
Expense [Heading] rr_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
The following table describes the fees and expenses you may pay if you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s performance. Because the fund is new, the fund’s portfolio turnover rate is not available.
Expense Exchange Traded Fund Commissions [Text] rr_ExpenseExchangeTradedFundCommissions You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates Other expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The portfolio managers look for liquid stocks of early and rapid stage growth companies they believe will increase in value over time. The portfolio managers make their investment decisions based primarily on their fundamental analysis of individual companies, rather than on broad economic forecasts. Management of the fund is based on the belief that, over the long term, stock price movements follow growth in earnings, revenues and/or cash flow. The fund will invest primarily in securities of large cap companies, but may invest in companies of any market capitalization. The fund normally invests in a relatively limited number of companies, generally 30 to 45 securities, but may incorporate more securities to account for liquidity constraints.
The fund will invest principally in U.S. exchange-listed common stocks and American Depositary Receipts (ADRs). The fund uses ADRs to obtain exposure to foreign securities. ADRs are issued by a U.S. financial institution (depositary) and evidence ownership in a security or pool of securities issued by a foreign issuer that have been deposited with the depositary. The fund may only invest in exchange-traded ADRs that are registered with the Securities and Exchange Commission and trade on a U.S. exchange contemporaneously with the fund’s shares.
The portfolio managers use a variety of analytical research tools and techniques to identify the stocks of companies that meet their investment criteria. Under normal market conditions, the portfolio managers seek securities of companies whose earnings or revenues are not only growing, but growing at an accelerated pace. This includes companies whose growth rates are expected to accelerate relative to factors including recent trends, market expectations, peers and historical data. Among other variables, the portfolio managers will consider the fund’s growth and momentum profile relative to the benchmark, the Russell 1000 Growth Index. These techniques help the portfolio managers buy or hold the stocks of companies they believe have favorable growth prospects and sell the stocks of companies whose characteristics no longer meet their criteria. The fund is an actively managed exchange-traded fund (ETF) that does not seek to replicate the performance of a specified index.
The fund may engage in active and frequent trading of portfolio securities to achieve its principal investment strategies. This may cause higher transaction costs and may affect performance. It may also result in the realization and distribution of capital gains.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
Portfolio Transparency Risk -  Unlike traditional ETFs, the fund does not tell the public what assets it holds each day. Instead, the fund provides a verified intraday indicative value (VIIV), calculated and disseminated every second throughout the trading day. The VIIV is intended to provide investors with enough information to allow for an effective arbitrage mechanism that will keep the market price of the fund’s shares trading at or close to the underlying net asset value (NAV) per share of the fund. There is, however, a risk, which may increase during periods of market disruption or volatility, that market prices will vary significantly from the underlying NAV of the fund. Similarly, because the fund’s shares trade on the basis of a published VIIV, they may trade at a wider bid/ask spread than shares of ETFs that publish their portfolios on a daily basis, especially during periods of market disruption or volatility, and therefore, may cost investors more to trade. Although the fund seeks to benefit from keeping its portfolio information secret, some market participants may attempt to use the VIIV to identify the fund’s trading strategy, which if successful, could result in such market participants engaging in certain predatory trading practices that may have the potential to harm the fund and its shareholders. The fund’s website will contain a historical comparison of each Business Day’s final VIIV to that Business Day’s NAV and the specific methodology for calculating the VIIV.
•
Trading Issues Risk - Trading in fund shares on the Listing Exchange may be halted in certain circumstances. If at any time the securities representing 10% or more of the fund’s portfolio become subject to a trading halt or otherwise do not have a readily available market quotations, the fund’s advisor will request the Listing Exchange to halt trading of the fund. There may be other instances that require a trading halt specific to the VIIV. If there is a discrepancy of sufficient magnitude in the fund’s VIIV calculation, the fund’s advisor will request the Listing Exchange to halt trading. This “circuit breaker” is designed to prevent the VIIV from reflecting outlier prices. For more information see “The Verified Indicative Intraday Value” section below.
•
Early Close/Trading Halt Risk - An exchange or market may close early or issue trading halts on portfolio securities. In times of market volatility, if trading is halted in some of the securities that the fund holds, there may be a disconnect between the market price of those securities and the market price of the fund. If at any time the securities representing 10% or more of the fund’s portfolio become subject to a trading halt or otherwise do not have readily available market quotations, the fund’s advisor will request the Cboe BZX Exchange, Inc. (Listing Exchange) to halt trading on the fund, meaning that investors would not be able to trade their shares. During any such trading halt, the VIIV would continue to be calculated and disseminated. Trading halts may have a greater impact on the fund than traditional ETFs because of its lack of transparency. Additionally, the fund’s advisor monitors the bid and ask quotations for the securities the fund holds, and, if it determines that such a security does not have readily available market quotations (such as during an extended trading halt), it will post that fact and the name and weighting of that security in the fund’s VIIV calculation on the fund’s web site. This information should permit market participants to calculate the effect of that security on the VIIV calculation, determine their own fair value of the disclosed portfolio security, and better judge the accuracy of that day’s VIIV for the fund. An extended trading halt in a portfolio security could exacerbate discrepancies between the VIIV and the fund’s NAV.
•
Authorized Participant/ Authorized Participant Representative Concentration Risk - The creation and redemption process for the fund occurs through a confidential brokerage account (Confidential Account) with an agent, called an AP Representative, on behalf of an Authorized Participant. Each day, the AP Representative will be given the names and quantities of the securities to be deposited, in the case of a creation, or redeemed, in the case of a redemption (Creation Basket), allowing the AP Representative to buy and sell positions in the portfolio securities to permit creations or redemptions on the Authorized Participant’s behalf, without disclosing the information to the Authorized Participant. The fund may have a limited number of institutions that act as Authorized Participants and AP Representatives, none of which are obligated to engage in creation or redemption transactions. To the extent that these institutions exit the business or are unable to proceed with creation and/or redemption orders with respect to the fund and no other Authorized Participant is able to step forward to process creation and/or redemption orders, fund shares may trade at a discount to NAV and possibly face trading halts and/or delisting. This risk may be more pronounced in volatile markets, potentially where there are significant redemptions in ETFs generally. The fact that the fund is offering a novel and unique structure may affect the number of entities willing to act as Authorized Participants and AP Representatives. During times of market stress, Authorized Participants may be more likely to step away from this type of ETF than a traditional ETF.
•
Growth Stocks Risk - Investments in growth stocks may be more volatile than other stocks and the overall stock market. These stocks are typically priced higher than other stocks because of their growth potential, which may or may not be realized.
•
Focused Portfolio Risk - Investing in a limited number of companies carries more risk because changes in the value of a single company may have a more significant effect, either negative or positive on the fund’s value.
•
Style Risk - If at any time the market is not favoring the fund’s growth investment style, the fund’s gains may not be as big as, or its losses may be bigger than, those of other equity funds using different investment styles.
•
Market Risk - The value of the fund’s shares will go up and down based on the performance of the companies whose securities it owns and other factors generally affecting the securities market.
•
Depositary Receipts Risk - Investment in depositary receipts does not eliminate all the risks inherent in investing in securities of non-U.S. issuers. The market value of depositary receipts is dependent upon the market value of the underlying securities and fluctuations in the relative value of the currencies in which the depositary receipts and the underlying securities are quoted.
•
Market Trading Risk - The fund faces numerous market trading risks, including the potential lack of an active market for fund shares, losses from trading in secondary markets, periods of high volatility and disruption in the creation and/or redemption process of the fund. Any of these factors, among others, may lead to the fund’s shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than NAV when you buy shares of the fund in the secondary market, and you may receive less (or more) than NAV when you sell those shares in the secondary market. Premiums and discounts may be larger for this fund than other ETFs because of its unique structure and lack of transparency. The portfolio managers cannot predict whether shares will trade above (premium), below (discount) or at NAV.
For at least the first three years after launch of the fund, the Board of Trustees (board) will promptly meet if, for 30 or more days in any quarter or 15 days in a row, the absolute difference between either the market closing price or the bid/ask price, on one hand, and NAV, on the other, exceeds 1.00% or the bid/ask spread exceeds 1.00%. In such a circumstance, the board will consider the continuing viability of the fund, whether shareholders are being harmed, and what, if any, action would be appropriate to among other things, narrow the premium/discount or spread, as applicable. The board will then decide whether to take any such action. Potential actions may include, but are not limited to, changing lead market makers, listing the fund on a different exchange, changing the size of Creation Units, changing the fund’s investment objective or strategy, and liquidating the fund.
•
Price Volatility Risk - The value of the fund’s shares may fluctuate significantly in the short term. The fund’s nontransparent structure may exacerbate this risk, particularly in volatile markets.
•
New Fund Risk - As a new fund, there can be no assurance that it will grow to or maintain an economically viable size.
•
Large-Cap Stock Risk - Larger companies are sometimes unable to attain the high growth rates of smaller companies, especially during extended periods of economic expansion.
•
High Portfolio Turnover Risk - The fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover may result in increased transaction costs to the fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities. 
•
Large Shareholder Risk - Certain shareholders, including other funds advised by the adviser, may from time to time own a substantial amount of the shares of the fund. In addition, a third party investor, the adviser or an affiliate of the adviser, an Authorized Participant, a market maker, or another entity may invest in the fund and hold its investment for a limited period of time solely to facilitate commencement of the fund or to facilitate the fund’s achieving a specified size or scale. There can be no assurance that any large shareholder would not redeem its investment or that the size of the fund would be maintained at such levels. Redemptions by large shareholders could have a significant negative impact on the fund. In addition, transactions by large shareholders may account for a large percentage of the trading volume on the Listing Exchange and may, therefore, have a material upward or downward effect on the market price of the shares.
•
Principal Loss Risk - At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss Risk - At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The fund’s performance history is not available as of the date of this prospectus. When the fund has investment results for a full calendar year, this section will feature charts that show annual total returns, highest and lowest quarterly returns and average annual total returns for the fund. This information indicates the volatility of the fund’s historical returns from year to year. For current performance information, please visit americancenturyetfs.com.
Performance information is designed to help you see how fund returns can vary. Keep in mind that past performance (before and after taxes) does not predict how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns Performance information is designed to help you see how fund returns can vary.
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess The fund’s performance history is not available as of the date of this prospectus. When the fund has investment results for a full calendar year, this section will feature charts that show annual total returns, highest and lowest quarterly returns and average annual total returns for the fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancenturyetfs.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Keep in mind that past performance (before and after taxes) does not predict how the fund will perform in the future.
American Century Focused Dynamic Growth ETF | American Century Focused Dynamic Growth ETF  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol FDG
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.45%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none [1]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.45%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 46
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 145
American Century Focused Large Cap Value ETF  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading American Century Focused Large Cap Value ETF
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks long-term capital growth.
Expense [Heading] rr_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
The following table describes the fees and expenses you may pay if you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s performance. Because the fund is new, the fund’s portfolio turnover rate is not available.
Expense Exchange Traded Fund Commissions [Text] rr_ExpenseExchangeTradedFundCommissions You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates Other expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the portfolio managers will invest at least 80% of the fund’s assets in securities of large capitalization companies. For purposes of this 80% test, the fund defines large capitalization companies as those with capitalizations within the range of the Russell 1000® Index. Though market capitalization may change from time to time, as of December 31, 2019, the total market capitalization range of the Russell 1000® Index was approximately $823.7 million to $1.3 trillion.
In selecting stocks for the fund, the portfolio managers look for companies whose stock price may not reflect the company’s value, by looking for companies that are temporarily out of favor in, or whose value is not yet recognized by, the market. To identify these companies, the portfolio managers consider earnings, cash flows and/or assets that may not be reflected accurately in the companies’ stock prices. The managers attempt to purchase the stocks of these undervalued companies and hold each stock until the price has increased to, or is higher than, a level the managers believe more accurately reflects the fair value of the company. The fund normally invests in a relatively limited number of companies, generally 30-50. The fund will invest principally in U.S. exchange-listed common stocks and American Depositary Receipts (ADRs). The fund uses ADRs to obtain exposure to foreign securities. ADRs are issued by a U.S. financial institution (depositary) and evidence ownership in a security or pool of securities issued by a foreign issuer that have been deposited with the depositary. The fund may only invest in exchange-traded ADRs that are registered with the Securities and Exchange Commission and trade on a U.S. exchange contemporaneously with the fund’s shares.
The fund is an actively managed exchange-traded fund (ETF) that does not seek to replicate the performance of a specified index. The portfolio managers may sell stocks from the fund’s portfolio if they believe a stock no longer meets their valuation criteria, a stock’s risk parameters outweigh its return opportunity, more attractive alternatives are identified or specific events alter a stock’s prospects.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
Portfolio Transparency Risk -  Unlike traditional ETFs, the fund does not tell the public what assets it holds each day. Instead, the fund provides a verified intraday indicative value (VIIV), calculated and disseminated every second throughout the trading day. The VIIV is intended to provide investors with enough information to allow for an effective arbitrage mechanism that will keep the market price of the fund’s shares trading at or close to the underlying net asset value (NAV) per share of the fund. There is, however, a risk, which may increase during periods of market disruption or volatility, that market prices will vary significantly from the underlying NAV of the fund. Similarly, because the fund’s shares trade on the basis of a published VIIV, they may trade at a wider bid/ask spread than shares of ETFs that publish their portfolios on a daily basis, especially during periods of market disruption or volatility, and therefore, may cost investors more to trade. Although the fund seeks to benefit from keeping its portfolio information secret, some market participants may attempt to use the VIIV to identify the fund’s trading strategy, which if successful, could result in such market participants engaging in certain predatory trading practices that may have the potential to harm the fund and its shareholders. The fund’s website will contain a historical comparison of each business day’s final VIIV to that business day’s NAV and the specific methodology for calculating the VIIV.
•
Trading Issues Risk - Trading in fund shares on the Listing Exchange may be halted in certain circumstances. If at any time the securities representing 10% or more of the fund’s portfolio become subject to a trading halt or otherwise do not have a readily available market quotations, the fund’s advisor will request the Listing Exchange to halt trading of the fund. There may be other instances that require a trading halt specific to the VIIV. If there is a discrepancy of sufficient magnitude in the fund’s VIIV calculation, the fund’s advisor will request the Listing Exchange to halt trading. This “circuit breaker” is designed to prevent the VIIV from reflecting outlier prices. For more information see “The Verified Indicative Intraday Value” section below.
•
Early Close/Trading Halt Risk - An exchange or market may close early or issue trading halts on portfolio securities. In times of market volatility, if trading is halted in some of the securities that the fund holds, there may be a disconnect between the market price of those securities and the market price of the fund. If at any time the securities representing 10% or more of the fund’s portfolio become subject to a trading halt or otherwise do not have readily available market quotations, the fund’s advisor will request the Cboe BZX Exchange, Inc. (Listing Exchange) to halt trading on the fund, meaning that investors would not be able to trade their shares. During any such trading halt, the VIIV would continue to be calculated and disseminated. Trading halts may have a greater impact on the fund than traditional ETFs because of its lack of transparency. Additionally, the fund’s advisor monitors the bid and ask quotations for the securities the fund holds, and, if it determines that such a security does not have readily available market quotations (such as during an extended trading halt), it will post that fact and the name and weighting of that security in the fund’s VIIV calculation on the fund’s web site. This information should permit market participants to calculate the effect of that security on the VIIV calculation, determine their own fair value of the disclosed portfolio security, and better judge the accuracy of that day’s VIIV for the fund. An extended trading halt in a portfolio security could exacerbate discrepancies between the VIIV and the fund’s NAV.
•
Authorized Participant/ Authorized Participant Representative Concentration Risk - The creation and redemption process for the fund occurs through a confidential brokerage account (Confidential Account) with an agent, called an AP Representative, on behalf of an Authorized Participant. Each day, the AP Representative will be given the names and quantities of the securities to be deposited, in the case of a creation, or redeemed, in the case of a redemption (Creation Basket), allowing the AP Representative to buy and sell positions in the portfolio securities to permit creations or redemptions on the Authorized Participant’s behalf, without disclosing the information to the Authorized Participant. The fund may have a limited number of institutions that act as Authorized Participants and AP Representatives, none of which are obligated to engage in creation or redemption transactions. To the extent that these institutions exit the business or are unable to proceed with creation and/or redemption orders with respect to the fund and no other Authorized Participant is able to step forward to process creation and/or redemption orders, fund shares may trade at a discount to NAV and possibly face trading halts and/or delisting. This risk may be more pronounced in volatile markets, potentially where there are significant redemptions in ETFs generally. The fact that the fund is offering a novel and unique structure may affect the number of entities willing to act as Authorized Participants and AP Representatives. During times of market stress, Authorized Participants may be more likely to step away from this type of ETF than a traditional ETF.
•
Style Risk - If the market does not consider the individual stocks purchased by the fund to be undervalued, the value of the fund’s shares may decline, even if stock prices generally are rising.
•
Focused Portfolio Risk - Investing in a limited number of companies carries more risk because changes in the value of a single company may have a more significant effect, either negative or positive on the fund’s value.
•
Market Risk - The value of the fund’s shares will go up and down based on the performance of the companies whose securities it owns and other factors generally affecting the securities market.
•
Depositary Receipts Risk - Investment in depositary receipts does not eliminate all the risks inherent in investing in securities of non-U.S. issuers. The market value of depositary receipts is dependent upon the market value of the underlying securities and fluctuations in the relative value of the currencies in which the depositary receipts and the underlying securities are quoted.
•
Market Trading Risk - The fund faces numerous market trading risks, including the potential lack of an active market for fund shares, losses from trading in secondary markets, periods of high volatility and disruption in the creation and/or redemption process of the fund. Any of these factors, among others, may lead to the fund’s shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than NAV when you buy shares of the fund in the secondary market, and you may receive less (or more) than NAV when you sell those shares in the secondary market. Premiums and discounts may be larger for this fund than other ETFs because of its unique structure and lack of transparency. The portfolio managers cannot predict whether shares will trade above (premium), below (discount) or at NAV.
For at least the first three years after launch of the fund, the Board of Trustees (board) will promptly meet if, for 30 or more days in any quarter or 15 days in a row, the absolute difference between either the market closing price or the bid/ask price, on one hand, and NAV, on the other, exceeds 1.00% or the bid/ask spread exceeds 1.00%. In such a circumstance, the board will consider the continuing viability of the fund, whether shareholders are being harmed, and what, if any, action would be appropriate to among other things, narrow the premium/discount or spread, as applicable. The board will then decide whether to take any such action. Potential actions may include, but are not limited to, changing lead market makers, listing the fund on a different exchange, changing the size of Creation Units, changing the fund’s investment objective or strategy, and liquidating the fund.
•
Price Volatility Risk - The value of the fund’s shares may fluctuate significantly in the short term. The fund’s nontransparent structure may exacerbate this risk, particularly in volatile markets.
•
New Fund Risk - As a new fund, there can be no assurance that it will grow to or maintain an economically viable size.
•
Large-Cap Stock Risk - Larger companies are sometimes unable to attain the high growth rates of smaller companies, especially during extended periods of economic expansion. 
•
Large Shareholder Risk - Certain shareholders, including other funds advised by the adviser, may from time to time own a substantial amount of the shares of the fund. In addition, a third party investor, the adviser or an affiliate of the adviser, an Authorized Participant, a market maker, or another entity may invest in the fund and hold its investment for a limited period of time solely to facilitate commencement of the fund or to facilitate the fund’s achieving a specified size or scale. There can be no assurance that any large shareholder would not redeem its investment or that the size of the fund would be maintained at such levels. Redemptions by large shareholders could have a significant negative impact on the fund. In addition, transactions by large shareholders may account for a large percentage of the trading volume on the Listing Exchange and may, therefore, have a material upward or downward effect on the market price of the shares.
•
Principal Loss Risk - At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss Risk - At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The fund’s performance history is not available as of the date of this prospectus. When the fund has investment results for a full calendar year, this section will feature charts that show annual total returns, highest and lowest quarterly returns and average annual total returns for the fund. This information indicates the volatility of the fund’s historical returns from year to year. For current performance information, please visit americancenturyetfs.com.
Performance information is designed to help you see how fund returns can vary. Keep in mind that past performance (before and after taxes) does not predict how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns Performance information is designed to help you see how fund returns can vary.
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess The fund’s performance history is not available as of the date of this prospectus. When the fund has investment results for a full calendar year, this section will feature charts that show annual total returns, highest and lowest quarterly returns and average annual total returns for the fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancenturyetfs.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Keep in mind that past performance (before and after taxes) does not predict how the fund will perform in the future.
American Century Focused Large Cap Value ETF | American Century Focused Large Cap Value ETF  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol FLV
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none [2]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.42%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 43
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 135
[1] Other expenses are based on estimated amounts for the current fiscal year.
[2] Other expenses are based on estimated amounts for the current fiscal year.