Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY ADVISOR SERIES VIII

Prospectus Date

rr_ProspectusDate

Dec. 30, 2014

A T C | Fidelity Advisor Global Equity Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity Advisor^® Global Equity Income Fund/A, T, C

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks reasonable income. In pursuing this objective, the fund will also consider the potential for capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds. More information about these and other discounts is available from your investment professional and in the Fund Distribution section beginning on page (Click Here) of the prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual operating expenses
(expenses that you pay each year as a % of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

December 31, 2015

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 operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 112% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

112.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

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 your shareholder 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 and if you hold your shares:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Sell All Shares

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

Hold Shares

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Investing in securities issued throughout the world.
• Normally investing at least 80% of assets in equity securities.
• Normally investing primarily in income-producing equity securities.
• Seeking to exceed the yield on the MSCI ACWI (All Country World Index) Index (the Index).
• Potentially investing in other types of equity securities and debt securities, including lower-quality debt securities.
• Allocating investments across different countries and regions.
• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. 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 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. 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.
• 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. 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.
• "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.

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]

rr_RiskLoseMoney

You could lose money by investing in the fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

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]

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Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Index Information section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.advisor.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

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Year-by-Year Returns

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Calendar Year

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	7.87%	December 31, 2013
Lowest Quarter Return	1.38%	June 30, 2013
Year-to-Date Return	3.53%	September 30, 2014

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

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

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. 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. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. 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.

For the periods ended
December 31, 2013

A T C | Fidelity Advisor Global Equity Income Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

5.75%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

1.68%

Total annual operating expenses

rr_ExpensesOverAssets

2.63%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.18%

^[2]

Total annual operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.45%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

714

3 years

rr_ExpenseExampleYear03

1,221

5 years

rr_ExpenseExampleYear05

1,773

10 years

rr_ExpenseExampleYear10

3,271

1 year

rr_ExpenseExampleNoRedemptionYear01

714

3 years

rr_ExpenseExampleNoRedemptionYear03

1,221

5 years

rr_ExpenseExampleNoRedemptionYear05

1,773

10 years

rr_ExpenseExampleNoRedemptionYear10

3,271

2013

rr_AnnualReturn2013

24.99%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2014

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

3.53%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2013

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.87%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2013

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

1.38%

A T C | Fidelity Advisor Global Equity Income Fund | Class T

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

3.50%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other expenses

rr_OtherExpensesOverAssets

1.76%

Total annual operating expenses

rr_ExpensesOverAssets

2.96%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.26%

^[2]

Total annual operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.70%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

517

3 years

rr_ExpenseExampleYear03

1,099

5 years

rr_ExpenseExampleYear05

1,727

10 years

rr_ExpenseExampleYear10

3,414

1 year

rr_ExpenseExampleNoRedemptionYear01

517

3 years

rr_ExpenseExampleNoRedemptionYear03

1,099

5 years

rr_ExpenseExampleNoRedemptionYear05

1,727

10 years

rr_ExpenseExampleNoRedemptionYear10

3,414

A T C | Fidelity Advisor Global Equity Income Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[3]

Management fee

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

1.73%

Total annual operating expenses

rr_ExpensesOverAssets

3.43%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.23%

^[2]

Total annual operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

2.20%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

On Class C shares redeemed less than one year after purchase.

1 year

rr_ExpenseExampleYear01

323

3 years

rr_ExpenseExampleYear03

919

5 years

rr_ExpenseExampleYear05

1,660

10 years

rr_ExpenseExampleYear10

3,615

1 year

rr_ExpenseExampleNoRedemptionYear01

223

3 years

rr_ExpenseExampleNoRedemptionYear03

919

5 years

rr_ExpenseExampleNoRedemptionYear05

1,660

10 years

rr_ExpenseExampleNoRedemptionYear10

3,615

A T C | Fidelity Advisor Global Equity Income Fund | Return Before Taxes | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

17.80%

Life of class

rr_AverageAnnualReturnSinceInception

13.27%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2012

A T C | Fidelity Advisor Global Equity Income Fund | Return Before Taxes | Class T

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class T - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

20.22%

Life of class

rr_AverageAnnualReturnSinceInception

14.56%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2012

A T C | Fidelity Advisor Global Equity Income Fund | Return Before Taxes | Class C

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class C - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

23.01%

Life of class

rr_AverageAnnualReturnSinceInception

16.46%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2012

A T C | Fidelity Advisor Global Equity Income Fund | Return After Taxes on Distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

17.12%

Life of class

rr_AverageAnnualReturnSinceInception

12.79%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2012

A T C | Fidelity Advisor Global Equity Income Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

10.76%

Life of class

rr_AverageAnnualReturnSinceInception

10.33%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2012

A T C | Fidelity Advisor Global Equity Income Fund | MSCI ACWI (All Country World Index) Index (reflects no deduction for fees or expenses)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

MSCI ACWI (All Country World Index) Index

Past 1 year

rr_AverageAnnualReturnYear01

23.24%

Life of class

rr_AverageAnnualReturnSinceInception

16.99%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2012

[1] Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

[2] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse Class A, Class T, and Class C of the fund to the extent that total operating expenses (excluding interest, certain taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of their respective average net assets, exceed the following rates: Class A: 1.45%, Class T: 1.70%, Class C: 2.20%. These arrangements will remain in effect through December 31, 2015. FMR may not terminate these arrangements before the expiration date without the approval of the Board of Trustees.

[3] On Class C shares redeemed less than one year after purchase.

[4] From May 2, 2012.