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Registrant Name dei_EntityRegistrantName THRIVENT SERIES FUND INC
Prospectus Date rr_ProspectusDate Apr. 30, 2018
Thrivent Limited Maturity Bond Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Thrivent Limited Maturity Bond Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock Thrivent Limited Maturity Bond Portfolio (the "Portfolio") seeks a high level of current income consistent with stability of principal.
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 64% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 64.00%
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 The principal strategies of the Portfolio are to invest in investment-grade corporate bonds, government bonds, municipal bonds, mortgage-backed securities (including commercially backed ones), asset-backed securities, and collateralized debt obligations (including collateralized loan obligations). Asset-backed securities are securities backed by notes or receivables originated by banks, credit card companies, or other providers of credit; collateralized debt obligations are types of asset-backed securities. Under normal market conditions, the Portfolio invests at least 80% of its net assets (plus the amount of any borrowing for investment purposes) in debt securities or preferred stock in at least the “Baa” major rating category by Moody’s or at least in the “BBB” major rating category by S&P or unrated securities considered to be of comparable quality by the Portfolio’s Adviser, with the dollar-weighted average effective maturity for the Portfolio expected to be between one and five years. Should the Adviser determine that the Portfolio would benefit from reducing the percentage of its assets invested in such investment grade securities from 80% to a lesser amount, we will notify you at least 60 days prior to the change.

The Portfolio may also invest in high yield, high risk bonds, notes, debentures and other debt obligations or preferred stock commonly known as “junk bonds.” At the time of purchase, these securities are rated within or below the “BB” major rating category by S&P or the “Ba” major rating category by Moody’s or are unrated but considered to be of comparable quality by the Adviser.

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 Adviser focuses on companies that it believes are financially sound and have strong cash flow, asset values and interest or dividend earnings. Some of these companies may be foreign ones. Additionally, the Portfolio may invest in leveraged loans, which are senior secured loans that are made by banks or other lending institutions to companies that are rated below investment grade. Please note that the Portfolio will likely use an interest rate management technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts for the purpose of managing the duration of the Portfolio. The Portfolio may utilize other derivatives (such as 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. The Portfolio may also pursue its investment strategy by investing in other mutual funds, including funds managed by the Adviser or an affiliate.
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.

Collateralized Debt Obligations Risk. The risks of an investment in a collateralized debt obligation (“CDO”) depend largely on the quality and type of the collateral and the tranche of the CDO in which the Portfolio invests. In addition to the typical risks associated with fixed income securities and asset-backed securities, CDOs carry additional risks including, but not limited to: (i) the possibility that distributions from collateral securities will not be adequate to make interest or other payments; (ii) the risk that the collateral may default, decline in value, and/or be downgraded; (iii) the Portfolio may invest in tranches of CDOs that are subordinate to other tranches; (iv) the structure and complexity of the transaction and the legal documents could lead to disputes among investors regarding the characterization of proceeds; (v) the investment return achieved by the Portfolio could be significantly different than those predicted by financial models; (vi) the lack of a readily available secondary market for CDOs; (vii) risk of forced “fire sale” liquidation due to technical defaults such as coverage test failures; and (viii) the CDO’s manager may perform poorly.

Credit Risk. Credit risk is the risk that an issuer of a debt security to which the Portfolio is exposed may no longer be able or willing to pay its debt. As a result of such an event, the debt security may decline in price and affect the value of the Portfolio.

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.

Foreign Securities Risk. Foreign securities are generally more volatile than their domestic counterparts, in part because of higher political and economic risks, lack of reliable information and fluctuations in currency exchange rates. Foreign securities may also be more difficult to resell than comparable U.S. securities because the markets for foreign securities are often less liquid. Even when a foreign security increases in price in its local currency, the appreciation may be diluted by adverse changes in exchange rates when the security’s value is converted to U.S. dollars. Foreign withholding taxes also may apply and errors and delays may occur in the settlement process for foreign securities.

High Yield Risk. High yield securities – commonly known as “junk bonds” – to which the Portfolio is exposed are considered predominantly speculative with respect to the issuer’s continuing ability to make principal and interest payments. If the issuer of the security is in default with respect to interest or principal payments, the value of the Portfolio may be negatively affected.

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. In addition, both mortgage-backed and asset-backed securities are sensitive to changes in the repayment patterns of the underlying security. If the principal payment on the underlying asset is repaid faster or slower than the holder of the asset-backed or mortgage-backed security anticipates, the price of the security may fall, particularly if the holder must reinvest the repaid principal at lower rates or must continue to hold the security when interest rates rise. This effect may cause the value of the Portfolio to decline and reduce the overall return of the Portfolio. 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.

Leveraged Loan Risk. Leveraged loans (also known as bank loans) are subject to the risks typically associated with debt securities. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Portfolio to value them or dispose of them at an acceptable price. Below investment-grade leveraged loans are typically more credit sensitive. In the event of fraud or misrepresentation, the Portfolio may not be protected under federal securities laws with respect to leveraged loans that may not be in the form of “securities.” The settlement period for some leveraged loans may be more than seven days.

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.

Preferred Securities Risk. There are certain additional risks associated with investing in preferred securities, including, but not limited to, preferred securities may include provisions that permit the issuer, at its discretion, to defer or omit distributions for a stated period without any adverse consequences to the issuer; preferred securities are generally subordinated to bonds and other debt instruments in a company’s capital structure in terms of having priority to corporate income and liquidation payments, and therefore will be subject to greater credit risk than more senior debt instruments; preferred securities may be substantially less liquid than many other securities, such as common stocks or U.S. Government securities; generally, traditional preferred securities offer no voting rights with respect to the issuing company unless preferred dividends have been in arrears for a specified number of periods, at which time the preferred security holders may elect a number of directors to the issuer’s board; and in certain varying circumstances, an issuer of preferred securities may redeem the securities prior to a specified date.

Volatility Risk. Volatility risk is the risk that certain types of securities shift in and out of favor depending on market and economic conditions as well as investor sentiment. Bonds may exhibit price fluctuations due to changes in interest rates or bond yield levels.
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 a broad-based securities market index. The index is the Bloomberg Barclays Government/Credit 1-3 Year Bond Index, which measures the performance of government and corporate fixed-rate debt securities with maturities of 1-3 years. Call 800-847-4836 or visit Thrivent.com for performance results current to the most recent month-end.

The bar chart and table include the effects of Portfolio expenses, but not charges or deductions against your variable contract, and assume that you sold your investment 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 a Portfolio has performed in the past 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 a broad-based securities market index.
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 a Portfolio has performed in the past 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 table include the effects of Portfolio expenses, but not charges or deductions against your variable contract, and assume that you sold your investment 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:
     Q2 '09         +5.67%
  
Worst Quarter:
      Q3 '08         (3.16)%   
Performance Table Heading rr_PerformanceTableHeading AVERAGE ANNUAL TOTAL RETURNS
(PERIODS ENDING DECEMBER 29, 2017)
Thrivent Limited Maturity 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 0.40%
Other Expenses rr_OtherExpensesOverAssets 0.05%
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 (6.46%)
2009 rr_AnnualReturn2009 14.04%
2010 rr_AnnualReturn2010 5.25%
2011 rr_AnnualReturn2011 0.90%
2012 rr_AnnualReturn2012 4.32%
2013 rr_AnnualReturn2013 0.45%
2014 rr_AnnualReturn2014 1.68%
2015 rr_AnnualReturn2015 0.73%
2016 rr_AnnualReturn2016 2.84%
2017 rr_AnnualReturn2017 2.62%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.67%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.16%)
1 Year rr_AverageAnnualReturnYear01 2.61%
5 Years rr_AverageAnnualReturnYear05 1.66%
10 Years rr_AverageAnnualReturnYear10 2.52%
Thrivent Limited Maturity Bond Portfolio | Bloomberg Barclays Government/Credit 1-3 Year Bond Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 0.84%
5 Years rr_AverageAnnualReturnYear05 0.84%
10 Years rr_AverageAnnualReturnYear10 1.85%