Risk/Return Detail Data - FidelityAssetManagerFunds-RetailComboPRO	Nov. 29, 2024 USD ($)
Risk/Return:
Registrant Name	Fidelity Charles Street Trust
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70%
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund /Class: Fidelity Asset Manager® 70% /Fidelity Asset Manager® 70%
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity Asset Manager® 70% seeks to maximize total return over the long term by allocating its assets among stocks, bonds, short-term instruments, and other investments.
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. 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.
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 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 operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 14 % of the average value of its portfolio.
Portfolio Turnover, Rate	14.00%
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]	Allocating the fund's assets among three main asset classes: the stock class (equity securities of all types, including funds that invest in such securities), the bond class (fixed-income securities of all types maturing in more than one year, including lower-quality debt securities which are sometimes referred to as high yield debt securities or junk bonds, and funds that invest in such securities), and the short-term/money market class (fixed-income securities of all types maturing in one year or less, including funds that invest in such securities). Maintaining a neutral mix over time of 70% of assets in stocks, 25% of assets in bonds, and 5% of assets in short-term and money market instruments. Adjusting allocation among asset classes gradually within the following ranges: stock class (50%-100%), bond class (0%-50%), and short-term/money market class (0%-50%). Investing in domestic and foreign issuers. Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity® funds to invest in particular security types or investment disciplines) and Fidelity's exchange-traded funds consistent with the asset classes discussed above.
Risk [Heading]	Principal Investment Risks
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 hypothetical composite of market indexes has characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance. Visit www.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]	www.fidelity.com
Performance Past Does Not Indicate Future [Text]	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	Year-by-Year Returns
Year to Date Return, Label	Year-to-Date Return
Bar Chart, Year to Date Return, Date	Sep. 30, 2024
Bar Chart, Year to Date Return	12.88%
Highest Quarterly Return, Label	Highest Quarter Return
Highest Quarterly Return, Date	Jun. 30, 2020
Highest Quarterly Return	17.66%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Mar. 31, 2020
Lowest Quarterly Return	(16.20%)
Performance Table Heading	Average Annual Returns
Performance Table Uses Highest Federal Rate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.
Performance Table Not Relevant to Tax Deferred	The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).
Performance Table Explanation after Tax Higher	Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.
Performance Table Narrative	After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70% | Fidelity Asset Manager 70%
Risk/Return:
Management fee	0.63%	[1],[2]
Distribution and/or Service (12b-1) fees	none
Other expenses	0.01%	[1]
Total annual operating expenses	0.64%
1 year	$ 65
3 years	205
5 years	357
10 years	$ 798
2014	5.61%
2015	(0.55%)
2016	7.08%
2017	18.70%
2018	(7.66%)
2019	22.83%
2020	17.18%
2021	13.98%
2022	(16.90%)
2023	16.45%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70% | Return Before Taxes | Fidelity Asset Manager 70%
Risk/Return:
Label	Return Before Taxes
Past 1 year	16.45%
Past 5 years	9.68%
Past 10 years	6.94%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70% | After Taxes on Distributions | Fidelity Asset Manager 70%
Risk/Return:
Label	Return After Taxes on Distributions
Past 1 year	15.89%
Past 5 years	8.64%
Past 10 years	5.69%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70% | After Taxes on Distributions and Sales | Fidelity Asset Manager 70%
Risk/Return:
Label	Return After Taxes on Distributions and Sale of Fund Shares
Past 1 year	9.98%
Past 5 years	7.46%
Past 10 years	5.20%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70% | SP001
Risk/Return:
Label	S&P 500® Index
Past 1 year	26.29%
Past 5 years	15.69%
Past 10 years	12.03%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 70% | F0022
Risk/Return:
Label	Fidelity Asset Manager 70% Composite Index℠
Past 1 year	16.88%
Past 5 years	9.39%
Past 10 years	7.14%

[1] B Adjusted to reflect current fees .

[2] A The management fee covers administrative services previously provided under separate services agreements with the fund, for which 0.14% was previously charged under the services agreements.