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Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName THRIVENT SERIES FUND INC
Prospectus Date rr_ProspectusDate Apr. 30, 2018
Thrivent Real Estate Securities Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Thrivent Real Estate Securities Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The Thrivent Real Estate Securities Portfolio (the "Portfolio") seeks to provide long-term capital appreciation and high current income.
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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 In seeking to achieve its investment objective, the Portfolio focuses on income-producing common stocks and other equity securities of U.S. real estate companies. Under normal circumstances, the Portfolio invests at least 80% of its net assets (plus any borrowings for investment purposes) in companies that are primarily engaged in the real estate industry. This includes companies such as real estate investment trusts (REITs) and other real estate related investments. A real estate company generally derives at least 50% of its revenue from real estate ownership, leasing, management, development, financing or sale of residential, commercial or industrial real estate—or has at least 50% of its assets in real estate. Should the Adviser determine that the Portfolio would benefit from reducing the percentage of assets invested in companies that are primarily engaged in the real estate industry from 80% to a lesser amount, it will notify you at least 60 days prior to such a change.

This Portfolio may invest up to 20% of its assets in equity and fixed income securities of companies which are not principally engaged in the real estate industry or which are not income producing equity securities of companies principally engaged in the U.S. real estate industry.

The Portfolio may also pursue its investment strategy by investing in other mutual funds, including funds managed by the Adviser or an affiliate.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration Under normal circumstances, the Portfolio invests at least 80% of its net assets (plus any borrowings for investment purposes) in companies that are primarily engaged in the real estate industry.
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.

Interest Rate Risk. Interest rate risk is the risk that security prices (equity or fixed income) decline in value when interest rates rise. This effect of rising interest rates is generally more pronounced for high dividend paying stock than for stocks that pay little or no dividends. This may cause the value of real estate securities to decline during periods of rising interest rates, which would 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. 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.

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.

Real Estate Industry Risk. To the extent the Portfolio allocates assets to companies in the real estate business, the Portfolio is subject to real estate industry risk. Declines in real estate values, changes in interest rates or economic downturns can have a significant negative effect on companies in the real estate industry. Other adverse changes could include, but are not limited to, extended vacancies of properties, increased competition, overbuilding and changes in zoning law and government regulations.

Real Estate Investment Trust (“REIT”) Risk. REITs generally can be divided into three types: equity REITs, mortgage REITs, and hybrid REITs (which combine the characteristics of equity REITs and mortgage REITs). Equity REITs will be affected by changes in the values of, and income from, the properties they own, while mortgage REITs may be affected by the credit quality of the mortgage loans they hold. All REIT types may be affected by changes in interest rates. REITs are subject to additional risks, including the fact that they are dependent on specialized management skills that may affect the REITs’ abilities to generate cash flows for operating purposes and for making investor distributions. REITs may have limited diversification and are subject to the risks associated with obtaining financing for real property. As with any investment, there is a risk that REIT securities and other real estate industry investments may be overvalued at the time of purchase. In addition, a REIT can pass its income through to its investors without any tax at the entity level if it complies with various requirements under the Internal Revenue Code. There is the risk, however, that a REIT held by the Portfolio will fail to qualify for this tax-free pass-through treatment of its income. In addition, due to recent changes in the tax laws, certain tax benefits of REITs may not be passed through to mutual fund shareholders. By investing in REITs indirectly through the Portfolio, in addition to bearing a proportionate share of the expenses of the Portfolio, you will also indirectly bear similar expenses of the REITs in which the Portfolio invests.

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 Composite 1500® Equity REITs Index, which measures the performance of the stocks in the S&P Composite 1500® Index that are classified as members of the GICS® Equity Real Estate Investment Trusts industry. The Portfolio now compares its returns to the S&P Composite 1500® Equity REITs Index because the Portfolio’s complex no longer uses FTSE as an index provider. Call 800-847-4836 or visit Thrivent.com for performance results current to the most recent month-end.

The bar chart includes the effects of Portfolio expenses, but not charges or deductions against your variable contract, and assumes 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 includes the effects of Portfolio expenses, but not charges or deductions against your variable contract, and assumes 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         +32.72%
  
Worst Quarter:
      Q4 '08         (37.82)%   
Performance Table Heading rr_PerformanceTableHeading AVERAGE ANNUAL TOTAL RETURNS
(PERIODS ENDING DECEMBER 29, 2017)
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The Portfolio now compares its returns to the S&P Composite 1500® Equity REITs Index because the Portfolio’s complex no longer uses FTSE as an index provider.
Thrivent Real Estate Securities 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 0.75%
Other Expenses rr_OtherExpensesOverAssets 0.10%
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 0.85%
1 Year rr_ExpenseExampleYear01 $ 87
3 Years rr_ExpenseExampleYear03 271
5 Years rr_ExpenseExampleYear05 471
10 Years rr_ExpenseExampleYear10 $ 1,049
2008 rr_AnnualReturn2008 (37.24%)
2009 rr_AnnualReturn2009 29.08%
2010 rr_AnnualReturn2010 27.56%
2011 rr_AnnualReturn2011 8.83%
2012 rr_AnnualReturn2012 17.54%
2013 rr_AnnualReturn2013 2.18%
2014 rr_AnnualReturn2014 30.82%
2015 rr_AnnualReturn2015 2.75%
2016 rr_AnnualReturn2016 7.50%
2017 rr_AnnualReturn2017 5.96%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 32.72%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (37.82%)
1 Year rr_AverageAnnualReturnYear01 5.96%
5 Years rr_AverageAnnualReturnYear05 9.36%
10 Years rr_AverageAnnualReturnYear10 7.54%
Thrivent Real Estate Securities Portfolio | S&P Composite 1500 Equity REITs Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 4.58%
5 Years rr_AverageAnnualReturnYear05 5.97%
10 Years rr_AverageAnnualReturnYear10 3.67%
Thrivent Real Estate Securities Portfolio | FTSE NAREIT All Equity REIT Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 8.67%
5 Years rr_AverageAnnualReturnYear05 9.83%
10 Years rr_AverageAnnualReturnYear10 7.77%