Risk/Return Detail Data - FidelityAdvisorFreedomFunds-Z6ComboPRO	Sep. 08, 2023 USD ($)
Risk/Return:
Registrant Name	Fidelity Aberdeen Street Trust
FidelityAdvisorFreedomFunds-Z6ComboPRO | Fidelity Advisor Freedom 2025 Fund
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund/Class: Fidelity Advisor Freedom® 2025 Fund/Z6
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity Advisor Freedom® 2025 Fund seeks high total return with a
Objective, Secondary [Text Block]	secondary objective of principal preservation as the fund approaches its target date and beyond.
Expense [Heading]	Fee Table
Expense Narrative [Text Block]	The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.
Shareholder Fees Caption [Text]	Shareholder fees
(fees paid directly from your investment)	none
Operating Expenses Caption [Text]	Annual Operating Expenses
Portfolio Turnover [Heading]	Portfolio Turnover
Portfolio Turnover [Text Block]	The fund will not incur transaction costs, such as commissions, when it buys and sells shares of underlying Fidelity® funds (or "turns over" its portfolio), but it could incur transaction costs if it were to buy and sell other types of securities directly. If the fund were to buy and sell other types of securities directly, a higher portfolio turnover rate could indicate higher transaction costs and could result in higher taxes when fund shares are held in a taxable account. Such costs, if incurred, would not be reflected in annual operating expenses or in the example and would affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 21% of the average value of its portfolio.
Portfolio Turnover, Rate	21.00%
Expenses Restated to Reflect Current [Text]	Adjusted to reflect current fees.
Expense Example Narrative [Text Block]	This example helps compare the cost of investing in the fund with the cost of investing in other funds.Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Investing primarily in a combination of Fidelity® U.S. equity funds, international equity funds, bond funds, and short-term funds (underlying Fidelity® funds).Allocating assets according to a neutral asset allocation strategy shown in the glide path below that adjusts over time until it reaches an allocation similar to that of the Fidelity Advisor Freedom® Income Fund, approximately 10 to 19 years after the year 2025. Fidelity Management & Research Company LLC (FMR) (the Adviser) may modify the fund's neutral asset allocations from time to time when in the interests of shareholders. The neutral asset allocation shown in the glide path depicts the allocation to U.S. equity funds, international equity funds, bond funds (including U.S. investment grade bond, international bond, short-term inflation-protected bond, long-term inflation-protected bond, and long-term treasury bond), and short-term funds.Buying and selling futures contracts (both long and short positions) in an effort to manage cash flows efficiently, remain fully invested, or facilitate asset allocation.The Adviser, under normal market conditions, will make investments that are consistent with seeking high total return for several years beyond the fund's target retirement date in an effort to achieve the fund's overall investment objective.As of April 1, 2023, the fund's neutral asset allocation to underlying Fidelity® funds and futures was approximately: U.S. Equity Funds 33% International Equity Funds 22% International Bond Funds 5% U.S. Investment Grade Bond Funds 28% Long-Term Treasury Bond Funds 4% Long-Term Inflation-Protected Bond Funds 8% Short-Term Inflation-Protected Bond Funds 0% Short-Term Funds 0% * The Adviser may change these percentages over time. As a result of the active asset allocation strategy (discussed below), actual allocations may differ from the neutral allocations above. The allocation percentages may not add to 100% due to rounding. The Adviser, under normal market conditions, will use an active asset allocation strategy to increase or decrease asset class exposures relative to the neutral asset allocations reflected above by up to 10% for equity funds, bond funds and short-term funds to reflect the Adviser's market outlook, which is primarily focused on the intermediate term. The asset allocations in the glide path and pie chart above are referred to as neutral because they do not reflect any decisions made by the Adviser to overweight or underweight an asset class.The Adviser may also make active asset allocations within other asset classes (such as commodities, high yield debt (also referred to as junk bonds), floating rate debt, real estate debt, and emerging markets debt) from 0% to 10% of the fund's total assets individually, but no more than 25% in aggregate within those other asset classes. Such asset classes are not reflected in the neutral asset allocations reflected in the glide path and pie chart above. Emerging markets include countries that have an emerging stock market as defined by MSCI, countries or markets with low- to middle-income economies as classified by the World Bank, and other countries or markets that the Adviser identifies as having similar emerging markets characteristics.Designed for investors who anticipate retiring in or within a few years of 2025 (target retirement date) at or around age 65. When the neutral asset allocation of a fund matches Fidelity Advisor Freedom® Income Fund's neutral asset allocation (approximately 10 to 19 years after the year indicated in the fund's name), the Board of Trustees may combine the fund with Fidelity Advisor Freedom® Income Fund, without shareholder approval, and the fund's shareholders will become shareholders of Fidelity Advisor Freedom® Income Fund.
Risk [Heading]	Principal Investment Risks
Risk Narrative [Text Block]	Shareholders should consider that no target date fund is intended as a complete retirement program and there is no guarantee that any single fund will provide sufficient retirement income at or through your retirement. The fund's share price fluctuates, which means you could lose money by investing in the fund, including losses near, at or after the target retirement date. Asset Allocation Risk. The fund is subject to risks resulting from the Adviser's asset allocation decisions. The selection of underlying funds and the allocation of the fund's assets among various asset classes could cause the fund to lose value or its results to lag relevant benchmarks or other funds with similar objectives. In addition, the fund's active asset allocation strategy may cause the fund to have a risk profile different than that portrayed above from time to time and may increase losses. Investing in Other Funds. The fund bears all risks of investment strategies employed by the underlying funds, including the risk that the underlying funds will not meet their investment objectives. Stock Market Volatility. The Adviser will continue to invest the fund's assets in equity funds in the years following the fund's target retirement date in an effort to achieve the fund's overall investment objective. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. Interest Rate Changes. Interest rate increases can cause the price of a debt or money market security to decrease. Foreign Exposure. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile. Foreign exchange rates also can be extremely volatile. Industry Exposure. Market conditions, interest rates, and economic, regulatory, or financial developments could significantly affect a single industry or group of related industries. Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change. Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments. Correlation to Index. The performance of an underlying index fund and its index may vary somewhat due to factors such as fees and expenses of the underlying fund, transaction costs, sample selection, regulatory restrictions, and timing differences associated with additions to and deletions from the index. Errors in the construction or calculation of the index may occur from time to time and may not be identified and corrected for some period of time, which may have an adverse impact on an underlying fund and its shareholders. Passive Management Risk. Some of the underlying funds in which the fund invests are managed with a passive investment strategy, attempting to track the performance of an unmanaged index of securities, regardless of the current or projected performance of an underlying fund's index or of the actual securities included in the index. This differs from an actively managed fund, which typically seeks to outperform a benchmark index. As a result, the performance of these underlying funds could be lower than actively managed funds that may shift their portfolio assets to take advantage of market opportunities or lessen the impact of a market decline or a decline in the value of one or more issuers. An underlying index fund may be concentrated to approximately the same extent that its index concentrates in the securities of issuers in a particular industry or group of industries. Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks. "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time. Commodity-Linked Investing. The value of commodities and commodity-linked investments may be affected by the performance of the overall commodities markets as well as weather, political, tax, and other regulatory and market developments. Commodity-linked investments may be more volatile and less liquid than the underlying commodity, instruments, or measures. Commodity Futures. Investments in commodity futures contracts are also subject to the risk of the failure of any of the exchanges on which an underlying fund's positions trade or of its clearinghouses or counterparties. In addition, certain commodity exchanges limit fluctuations in certain futures contract prices during a single day by regulations referred to as "daily price fluctuation limits" or "daily limits." Under such daily limits, during a single trading day no trades may be executed at prices beyond the daily limit. If triggered, these limits could prevent the underlying fund from liquidating unfavorable positions and subject the underlying fund to losses or prevent it from entering into desired trades during the particular trading day. An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.
Risk Lose Money [Text]	You could lose money by investing in the fund.
Risk Not Insured Depository Institution [Text]	An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	Performance
Performance Narrative [Text Block]	The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance. Visit institutional.fidelity.com for more recent performance information.
Performance Information Illustrates Variability of Returns [Text]	The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time.
Performance Availability Website Address [Text]	institutional.fidelity.com
Performance Past Does Not Indicate Future [Text]	Past performance is not an indication of future performance.
Bar Chart [Heading]	Year-by-Year Returns
Annual Return, Inception Date	Jun. 06, 2017
Year to Date Return, Label	Year-to-Date Return
Bar Chart, Year to Date Return, Date	Mar. 31, 2023
Bar Chart, Year to Date Return	5.36%
Highest Quarterly Return, Label	Highest Quarter Return
Highest Quarterly Return, Date	Jun. 30, 2020
Highest Quarterly Return	13.50%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Mar. 31, 2020
Lowest Quarterly Return	(13.73%)
Performance Table Heading	Average Annual Returns
FidelityAdvisorFreedomFunds-Z6ComboPRO | Fidelity Advisor Freedom 2025 Fund | Fidelity Advisor Freedom 2025 Fund - Class Z6
Risk/Return:
Management fee	0.34%	[1]
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.34%	[1]
1 year	$ 35
3 years	109
5 years	191
10 years	$ 431
2018	(5.22%)
2019	20.49%
2020	14.38%
2021	10.02%
2022	(16.57%)
FidelityAdvisorFreedomFunds-Z6ComboPRO | Fidelity Advisor Freedom 2025 Fund | Return Before Taxes | Fidelity Advisor Freedom 2025 Fund - Class Z6
Risk/Return:
Label	Class Z6
Past 1 year	(16.57%)
Past 5 years	3.70%
Since Inception	4.58%
FidelityAdvisorFreedomFunds-Z6ComboPRO | Fidelity Advisor Freedom 2025 Fund | SP001
Risk/Return:
Label	S&P 500® Index
Past 1 year	(18.11%)
Past 5 years	9.42%
Since Inception	10.52%	[2]
FidelityAdvisorFreedomFunds-Z6ComboPRO | Fidelity Advisor Freedom 2025 Fund | F0551
Risk/Return:
Label	Fidelity Freedom 2025 Composite Index℠
Past 1 year	(16.51%)
Past 5 years	3.63%
Since Inception	4.57%	[2]

[1] AAdjusted to reflect current fees.

[2] AFrom June 6, 2017.