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Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName THRIVENT SERIES FUND INC
Prospectus Date rr_ProspectusDate Apr. 30, 2018
Thrivent Government Bond Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Thrivent Government Bond Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock Thrivent Government Bond Portfolio (the "Portfolio") seeks total return, consistent with preservation of capital. The Portfolio's investment objective may be changed without shareholder approval.
Expense [Heading] rr_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock This table describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. If you own a variable annuity contract or variable life insurance contract, you will have additional expenses including mortality and expense risk charges. Please refer to the prospectus for your variable contract for additional information about charges for those contracts.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption SHAREHOLDER FEES
(fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption ANNUAL PORTFOLIO 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 Portfolio 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 Portfolio shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Portfolio’s performance. During the most recent fiscal year, the Portfolio’s portfolio turnover rate was 422% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 422.00%
Expense Example [Heading] rr_ExpenseExampleHeading EXAMPLE
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock This example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. The Portfolio is an investment option for variable contracts, and the example does not include charges imposed by variable contracts. If variable contract charges were imposed, your expenses would be higher than those shown. The example assumes that you invest $10,000 in the Portfolio for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year, and that the Portfolio’s operating expenses remain the same. Although your actual cost may be higher or lower, based on the foregoing assumptions, your cost would be:
Strategy [Heading] rr_StrategyHeading Principal Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock Under normal circumstances, the Portfolio invests at least 80% of its net assets (plus the amount of borrowings for investment purposes) in U.S. government bonds. For purposes of this disclosure, “U.S. government bonds” are debt instruments issued or guaranteed by the U.S. government or its agencies and instrumentalities, including U.S. Treasuries, Treasury Inflation Protected Securities (TIPS), U.S. Government Agency debt, and mortgage-backed securities issued or guaranteed by the Government National Mortgage Association (GNMA or Ginnie Mae), the Federal National Mortgage Association (FNMA or Fannie Mae) or the Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac). Should the Adviser determine that the Portfolio would benefit from reducing the percentage of its net assets invested in U.S. government bonds from 80% to a lesser amount, it will notify you at least 60 days prior to the change.

The Portfolio’s portfolio securities may be of any maturity. The Adviser uses fundamental, quantitative and technical investment research techniques to determine what debt obligations to buy and sell. Fundamental techniques assess a security’s value based on an issuer’s financial profile, management, and business prospects while quantitative and technical techniques involve a more data-oriented analysis of financial information, market trends and price movements. The “total return” sought by the Portfolio consists of income earned on the Portfolio’s investments plus, if any, capital appreciation. The Portfolio may invest in U.S. dollar denominated sovereign debt of foreign governments. The Portfolio may also pursue its investment strategy by investing in other mutual funds, including funds managed by the Adviser or an affiliate.

The Portfolio may utilize derivatives (such as futures and swaps) for investment exposure or hedging purposes, including credit default swap agreements on security indexes. The Portfolio may enter into standardized derivatives contracts traded on domestic or foreign securities exchanges, boards of trade, or similar entities, and non-standardized derivatives contracts traded in the over-the-counter market.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock The Portfolio is subject to the following principal investment risks. Shares of the Portfolio will rise and fall in value and there is a risk that you could lose money by investing in the Portfolio. The Portfolio cannot be certain that it will achieve its investment objective.

Derivatives Risk. The use of derivatives (such as futures and credit default swaps) involves additional risks and transaction costs which could leave the Portfolio in a worse position than if it had not used these instruments. The use of derivatives can lead to losses because of adverse movements in the price or value of the underlying asset, index or rate, which may be magnified by certain features of the contract. Changes in the value of the derivative may not correlate as intended with the underlying asset, rate or index, and the Portfolio could lose much more than the original amount invested. Derivatives can be highly volatile, illiquid and difficult to value. Certain derivatives may also be subject to counterparty risk, which is that the other party in the transaction will not fulfill its contractual obligations due to its financial condition, market events, or other reasons.

Government Securities Risk. The Portfolio invests in securities issued or guaranteed by the U.S. government or its agencies and instrumentalities (such as Ginnie Mae, Fannie Mae or Freddie Mac securities). Securities issued or guaranteed by Ginnie Mae, Fannie Mae or Freddie Mac are not issued directly by the U.S. government. Ginnie Mae is a wholly owned U.S. corporation that is authorized to guarantee, with the full faith and credit of the U.S. government, the timely payment of principal and interest of its securities. By contrast, securities issued or guaranteed by U.S. government-related organizations such as Fannie Mae and Freddie Mac are not backed by the full faith and credit of the U.S. government. No assurance can be given that the U.S. government would provide financial support to its agencies and instrumentalities if not required to do so by law. In addition, the value of U.S. government securities may be affected by changes in the credit rating of the U.S. government.

Inflation-Linked Security Risk. Inflation-linked debt securities, such as TIPS, are subject to the effects of changes in market interest rates caused by factors other than inflation (real interest rates). In general, the price of an inflation-linked security tends to decrease when real interest rates increase and can increase when real interest rates decrease. Interest payments on inflation-linked securities are unpredictable and will fluctuate as the principal and interest are adjusted for inflation. Any increase in the principal amount of an inflation-linked debt security will be considered taxable ordinary income, even though the Portfolio will not receive the principal until maturity.

There can also be no assurance that the inflation index used will accurately measure the real rate of inflation in the prices of goods and services. The Portfolio’s investments in inflation-linked securities may lose value in the event that the actual rate of inflation is different than the rate of the inflation index. In addition, inflation-linked securities are subject to the risk that the Consumer Price Index for All Urban Consumers (CPI-U) or other relevant pricing index may be discontinued, fundamentally altered in a manner materially adverse to the interests of an investor in the securities, altered by legislation or Executive Order in a materially adverse manner to the interests of an investor in the securities or substituted with an alternative index.

Interest Rate Risk. Interest rate risk is the risk that prices of debt securities decline in value when interest rates rise for debt securities that pay a fixed rate of interest. Debt securities with longer durations (a measure of price sensitivity of a bond or bond fund to changes in interest rates) or maturities (i.e., the amount of time until a bond’s issuer must pay its principal or face value) tend to be more sensitive to changes in interest rates than debt securities with shorter durations or maturities. Some municipal bonds may be repaid prior to maturity if interest rates decrease. Changes by the Federal Reserve to monetary policies could affect interest rates and the value of some securities.

Investment Adviser Risk. The Portfolio is actively managed and the success of its investment strategy depends significantly on the skills of the Adviser in assessing the potential of the investments in which the Portfolio invests. This assessment of investments may prove incorrect, resulting in losses or poor performance, even in rising markets.

Issuer Risk. Issuer risk is the possibility that factors specific to a company to which the Portfolio is exposed will affect the market prices of the company’s securities and therefore the value of the Portfolio. Some factors affecting the performance of a company include demand for the company’s products or services, the quality of management of the company and brand recognition and loyalty.

Liquidity Risk. Liquidity is the ability to sell a security relatively quickly for a price that most closely reflects the actual value of the security. Inventories of bonds are at or near historic lows in relation to market size, which has the potential to decrease liquidity and increase price volatility in the fixed income markets, particularly during periods of economic or market stress. As a result of this decreased liquidity, the Adviser may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on performance.

Market Risk. Over time, securities markets generally tend to move in cycles with periods when security prices rise and periods when security prices decline. The value of the Portfolio’s investments may move with these cycles and, in some instances, increase or decrease more than the applicable market(s) as measured by the Portfolio’s benchmark index(es). The securities markets may also decline because of factors that affect a particular industry.

Mortgage-Related and Other Asset-Backed Securities Risk. The value of mortgage-related and asset-backed securities will be influenced by the factors affecting the housing market and the assets underlying such securities. As a result, during periods of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid.

Other Funds Risk. The performance of the Portfolio is dependent, in part, upon the performance of other funds manged by the Adviser or an affiliate (“Other Funds”) in which the Portfolio may invest. As a result, the Portfolio is subject to the same risks as those faced by the Other Funds.

Portfolio Turnover Rate Risk. The Portfolio may engage in active and frequent trading of portfolio securities in implementing its principal investment strategies. A high rate of portfolio turnover (100% or more) involves correspondingly greater expenses which are borne by the Portfolio and its shareholders and may also result in short-term capital gains taxable to shareholders.

Sovereign Debt Risk. The Portfolio may invest in sovereign debt securities. These securities are issued or guaranteed by foreign governmental entities. These investments are subject to the risk that a governmental entity may delay or refuse to pay interest or repay principal on its sovereign debt, due, for example, to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity’s debt position in relation to the economy or the failure to put in place economic reforms required by the International Monetary Fund or other multilateral agencies. If a governmental entity defaults, it may ask for more time in which to pay or for further loans. There is no legal process for collecting sovereign debts that a government does not pay nor are there bankruptcy proceedings through which all or part of the sovereign debt that a governmental entity has not repaid may be collected.
Risk Lose Money [Text] rr_RiskLoseMoney Shares of the Portfolio will rise and fall in value and there is a risk that you could lose money by investing in the Portfolio.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The following bar chart and table provide an indication of the risks of investing in the Portfolio by showing changes in the Portfolio's performance from year to year and by showing how the Portfolio's average annual returns for one-, five- and ten-year periods compared to broad-based securities market indices. The indices are Bloomberg Barclays U.S. Agency Index and the Bloomberg Barclays U.S. Treasury Index. The Bloomberg Barclays U.S. Agency Index measures the performance of the agency sector of the U.S. government bond market. The Bloomberg Barclays U.S. Treasury Index measures the performance of the U.S. Treasury bond market. Call 800-847-4836 or visit Thrivent.com for performance results current to the most recent month-end.

The Portfolio no longer uses the Bloomberg Barclays U.S. Aggregate Bond Index because, effective August 28, 2017, based on approval of the Portfolio's Board of Directors and shareholders, the portfolio's investment objective and principal strategies were changed, which had the effect of converting the Portfolio from one whose securities were selected based on which securities were in an index to one that is actively managed and invests primarily in U.S. government securities. At the same time, the Portfolio's name changed from Thrivent Bond Index Portfolio to Thrivent Government Bond Portfolio. As a result, performance information presented below with respect to periods prior to August 28, 2017, reflects the performance of an investment portfolio that was materially different from the investment portfolio of Thrivent Government Bond Portfolio.

The bar chart and the table include the effects of Portfolio expenses, but not charges or deductions against your variable contract, and assume that you sold your shares at the end of the period. Because shares of the Portfolio are offered through variable life insurance and variable annuity contracts, you should carefully review the variable contract prospectus for information on applicable charges and expenses. If the charges and deductions against your variable contract were included, returns would be lower than those shown.

How the Portfolio has performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future. Performance information provides some indication of the risks of investing in the Portfolio by showing changes in the Portfolio's performance over time.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide an indication of the risks of investing in the Portfolio by showing changes in the Portfolio’s performance from year to year and by showing how the Portfolio’s average annual returns for one-, five- and ten-year periods compared to broad-based securities market indices.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The indices are Bloomberg Barclays U.S. Agency Index and the Bloomberg Barclays U.S. Treasury Index. The Bloomberg Barclays U.S. Agency Index measures the performance of the agency sector of the U.S. government bond market. The Bloomberg Barclays U.S. Treasury Index measures the performance of the U.S. Treasury bond market.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-847-4836
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress Thrivent.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture How the Portfolio has performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Annual Return (%)
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart and the table include the effects of Portfolio expenses, but not charges or deductions against your variable contract, and assume that you sold your shares at the end of the period. Because shares of the Portfolio are offered through variable life insurance and variable annuity contracts, you should carefully review the variable contract prospectus for information on applicable charges and expenses. If the charges and deductions against your variable contract were included, returns would be lower than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best Quarter:
     Q3 '09         +5.17%
  
Worst Quarter:
      Q4 '16         (3.49)%   
Performance Table Heading rr_PerformanceTableHeading AVERAGE ANNUAL TOTAL RETURNS
(PERIODS ENDING DECEMBER 29, 2017)
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Portfolio no longer uses the Bloomberg Barclays U.S. Aggregate Bond Index because, effective August 28, 2017, based on approval of the Portfolio's Board of Directors and shareholders, the portfolio's investment objective and principal strategies were changed, which had the effect of converting the Portfolio from one whose securities were selected based on which securities were in an index to one that is actively managed and invests primarily in U.S. government securities.
Thrivent Government Bond Portfolio | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (load) Imposed On Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice
Maximum Deferred Sales Charge (load) (as a percentage of the net asset value at time of purchase or redemption, whichever is lower) rr_MaximumDeferredSalesChargeOverOther
Management Fees rr_ManagementFeesOverAssets 0.35%
Other Expenses rr_OtherExpensesOverAssets 0.10%
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 0.45%
1 Year rr_ExpenseExampleYear01 $ 46
3 Years rr_ExpenseExampleYear03 144
5 Years rr_ExpenseExampleYear05 252
10 Years rr_ExpenseExampleYear10 $ 567
2008 rr_AnnualReturn2008 (0.82%)
2009 rr_AnnualReturn2009 8.47%
2010 rr_AnnualReturn2010 9.24%
2011 rr_AnnualReturn2011 8.21%
2012 rr_AnnualReturn2012 4.94%
2013 rr_AnnualReturn2013 (2.47%)
2014 rr_AnnualReturn2014 6.52%
2015 rr_AnnualReturn2015 0.80%
2016 rr_AnnualReturn2016 1.49%
2017 rr_AnnualReturn2017 2.96%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.17%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2016
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.49%)
1 Year rr_AverageAnnualReturnYear01 2.96%
5 Years rr_AverageAnnualReturnYear05 1.82%
10 Years rr_AverageAnnualReturnYear10 3.86%
Thrivent Government Bond Portfolio | Bloomberg Barclays U.S. Agency Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.06%
5 Years rr_AverageAnnualReturnYear05 1.32%
10 Years rr_AverageAnnualReturnYear10 2.85%
Thrivent Government Bond Portfolio | Bloomberg Barclays U.S. Treasury Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.31%
5 Years rr_AverageAnnualReturnYear05 1.27%
10 Years rr_AverageAnnualReturnYear10 3.31%
Thrivent Government Bond Portfolio | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 2.10%
10 Years rr_AverageAnnualReturnYear10 4.01%