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Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName THRIVENT SERIES FUND INC
Prospectus Date rr_ProspectusDate Apr. 30, 2018
Thrivent Mid Cap Stock Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Thrivent Mid Cap Stock Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock Thrivent Mid Cap Stock Portfolio (the "Portfolio") seeks long-term capital growth.
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 30% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 30.00%
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 any borrowing for investment purposes) in equity securities of mid-sized companies. The Adviser focuses mainly on the equity securities of mid-sized U.S. companies which have market capitalizations equivalent to those included in widely known indices such as the S&P MidCap 400 Index, MSCI USA Mid Cap Index, or the mid-sized company market capitalization classifications published by Lipper, Inc. These companies typically have a market capitalization of approximately $2 billion to $25 billion. Should the Adviser determine that the Portfolio would benefit from reducing the percentage of its assets invested in mid cap equity securities from 80% to a lesser amount, we will notify you at least 60 days prior to the change.

The Portfolio seeks to achieve its investment objective by investing in common stocks. The Adviser uses fundamental, quantitative, and technical investment research techniques to determine what securities 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 generally looks for mid-sized companies that, in its opinion:
  • have prospects for growth in their sales and earnings;
  • are in an industry with a good economic outlook;
  • have high-quality management; and/or
  • have a strong financial position.
The Portfolio may also pursue its investment strategy by investing in other mutual funds, including funds managed by the Adviser or an affiliate.

The Adviser may sell securities for a variety of reasons, such as to secure gains, limit losses, or reposition assets to more promising opportunities.
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.

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. Common stock of a company is subordinate to other securities issued by the company. If a company becomes insolvent, interests of investors owning common stock will be subordinated to the interests of other investors in, and general creditors of, the company.

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.

Mid Cap Risk. Medium-sized companies often have greater price volatility, lower trading volume, and less liquidity than larger, more-established companies. These companies tend to have smaller revenues, narrower product lines, less management depth and experience, smaller shares of their product or service markets, fewer financial resources, and less competitive strength than larger companies.

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.

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.
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 S&P MidCap 400 Index, which measures the performance of mid-sized companies. 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 YEAR-BY-YEAR TOTAL RETURN
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:
     Q3 '09         +19.42%
  
Worst Quarter:
      Q4 '08         (22.50)%   
Performance Table Heading rr_PerformanceTableHeading AVERAGE ANNUAL TOTAL RETURNS
(PERIODS ENDING DECEMBER 29, 2017)
Thrivent Mid Cap Stock 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 0.64%
Other Expenses rr_OtherExpensesOverAssets 0.03%
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 0.67%
1 Year rr_ExpenseExampleYear01 $ 68
3 Years rr_ExpenseExampleYear03 214
5 Years rr_ExpenseExampleYear05 373
10 Years rr_ExpenseExampleYear10 $ 835
2008 rr_AnnualReturn2008 (40.75%)
2009 rr_AnnualReturn2009 39.10%
2010 rr_AnnualReturn2010 25.59%
2011 rr_AnnualReturn2011 (6.28%)
2012 rr_AnnualReturn2012 14.29%
2013 rr_AnnualReturn2013 35.50%
2014 rr_AnnualReturn2014 11.93%
2015 rr_AnnualReturn2015 0.08%
2016 rr_AnnualReturn2016 28.71%
2017 rr_AnnualReturn2017 19.00%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.42%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.50%)
1 Year rr_AverageAnnualReturnYear01 19.00%
5 Years rr_AverageAnnualReturnYear05 18.38%
10 Years rr_AverageAnnualReturnYear10 9.93%
Thrivent Mid Cap Stock Portfolio | S&P MidCap 400 Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 16.24%
5 Years rr_AverageAnnualReturnYear05 15.01%
10 Years rr_AverageAnnualReturnYear10 9.97%