Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 01, 2012
Dreyfus Stock Index Fund, Inc. (Prospectus Summary) | Dreyfus Stock Index Fund, Inc.
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Fund Summary
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The fund seeks to match the total return of the Standard & Poor's® 500 Composite Stock Price Index (S&P 500® Index).
Expense, Heading	rr_ExpenseHeading	Fees and Expenses
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. These figures do not reflect any fees or charges imposed by participating insurance companies under their Variable Annuity contracts (VA contracts) or Variable Life Insurance policies (VLI policies).
Operating Expenses, Caption	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	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 may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 3.27% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	3.27%
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example below is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. The Example does not reflect fees and expenses incurred under VA contracts and VLI policies; if they were reflected, the figures in the Example would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategy
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	To pursue its goal, the fund generally is fully invested in stocks included in the S&P 500® Index and in futures whose performance is tied to the index. The fund generally invests in all 500 stocks in the S&P 500 Index in proportion to their weighting in the index. The S&P 500 Index is an unmanaged index of 500 common stocks chosen to reflect the industries of the U.S. economy and is often considered a proxy for the stock market in general. S&P weights each company's stock in the index by its market capitalization, adjusted by the number of available float shares divided by the company's total shares outstanding, which means larger companies with more available float shares have greater representation in the index than smaller ones. The fund attempts to have a correlation between its performance and that of the S&P 500 Index of at least .95 before fees and expenses. A correlation of 1.00 would mean that the fund and the index were perfectly correlated. "Standard & Poor's®," "S&P®," "Standard & Poor's® 500," and "S&P 500®" are trademarks of Standard & Poor's Financial Services LLC and have been licensed for use by the fund. The fund is not sponsored, endorsed, sold or promoted by Standard & Poor's and Standard and Poor's makes no representation regarding the advisability of investing in the fund.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	An investment in the fund is not a bank deposit. It is not insured or guaranteed by the FDIC or any other government agency. It is not a complete investment program. The fund's share price fluctuates, sometimes dramatically, which means you could lose money. o Risks of stock investing. Stocks generally fluctuate more in value than bonds and may decline significantly over short time periods. There is the chance that stock prices overall will decline because stock markets tend to move in cycles, with periods of rising prices and falling prices. The market value of a stock may decline due to general weakness in the stock market or because of factors that affect the company or its particular industry. o Indexing strategy risk. The fund uses an indexing strategy. It does not attempt to manage market volatility, use defensive strategies or reduce the effects of any long-term periods of poor index performance. The correlation between fund and index performance may be affected by the fund's expenses, changes in securities markets, changes in the composition of the index and the timing of purchases and redemptions of fund shares. o Non-diversification risk. The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.
Risk, Lose Money	rr_RiskLoseMoney	The fund's share price fluctuates, sometimes dramatically, which means you could lose money.
Risk, Nondiversified Status	rr_RiskNondiversifiedStatus	The fund is non-diversified, which means that the fund may invest a relatively high percentage of its assets in a limited number of issuers. Therefore, the fund's performance may be more vulnerable to changes in the market value of a single issuer or group of issuers and more susceptible to risks associated with a single economic, political or regulatory occurrence than a diversified fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the fund is not a bank deposit. It is not insured or guaranteed by the FDIC or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The following bar chart and table provide some indication of the risks of investing in the fund. The table compares the average annual total returns of the fund's shares to those of a broad measure of market performance. The fund's past performance is no guarantee of future results. More recent performance information may be available at www.dreyfus.com. Performance information reflects the fund's expenses only and does not reflect the fees and charges imposed by participating insurance companies under their VA contracts or VLI policies. Because these fees and charges will reduce total return, policyowners should consider them when evaluating and comparing the fund's performance. Policyowners should consult the prospectus for their contract or policy for more information.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table provide some indication of the risks of investing in the fund.
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.dreyfus.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The fund's past performance is no guarantee of future results.
Bar Chart, Heading	rr_BarChartHeading	Year-by-Year Total Returns as of 12/31 each year (%) -- Initial Shares
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	The bar chart shows changes in the performance of the fund's Initial shares from year to year.
Bar Chart, Closing	rr_BarChartClosingTextBlock	Best Quarter               Q2, 2009: 15.87%           Worst Quarter              Q4, 2008: -22.00%
Index No Deduction for Fees, Expenses, Taxes	rr_IndexNoDeductionForFeesExpensesTaxes	reflects no deduction for fees, expenses or taxes
Performance Table, Narrative	rr_PerformanceTableNarrativeTextBlock	The table compares the average annual total returns of the fund's shares to those of a broad measure of market performance.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns (as of 12/31/11)
Dreyfus Stock Index Fund, Inc. (Prospectus Summary) | Dreyfus Stock Index Fund, Inc. | S&P 500 Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	S&P 500 Index reflects no deduction for fees, expenses or taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.09%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.25%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.92%
Dreyfus Stock Index Fund, Inc. (Prospectus Summary) | Dreyfus Stock Index Fund, Inc. | Initial Shares
Risk Return [Abstract]	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (Rule 12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses (including shareholder services fees)	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.27%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	28
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	87
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	152
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	343
Annual Return 2002	rr_AnnualReturn2002	(22.36%)
Annual Return 2003	rr_AnnualReturn2003	28.36%
Annual Return 2004	rr_AnnualReturn2004	10.64%
Annual Return 2005	rr_AnnualReturn2005	4.69%
Annual Return 2006	rr_AnnualReturn2006	15.50%
Annual Return 2007	rr_AnnualReturn2007	5.26%
Annual Return 2008	rr_AnnualReturn2008	(37.14%)
Annual Return 2009	rr_AnnualReturn2009	26.33%
Annual Return 2010	rr_AnnualReturn2010	14.84%
Annual Return 2011	rr_AnnualReturn2011	1.88%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	15.87%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.00%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Initial Shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.88%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.45%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.69%
Dreyfus Stock Index Fund, Inc. (Prospectus Summary) | Dreyfus Stock Index Fund, Inc. | Service Shares
Risk Return [Abstract]	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (Rule 12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses (including shareholder services fees)	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.52%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	53
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	167
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	291
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	653
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Service Shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.62%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.70%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.43%