Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	PRINCIPAL FUNDS, INC.
Prospectus Date	rr_ProspectusDate	Dec. 31, 2022
Bond Market Index Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<span style="color:#000000;font-family:Arial;font-size:12pt;font-weight:bold;text-transform:uppercase;">Bond Market Index Fund</span>
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Objective</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide current income.
Expense [Heading]	rr_ExpenseHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Fees and Expenses of the Fund</span>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.If you purchase Institutional Class shares through certain programs offered by certain financial intermediaries, you may be required to pay a commission and/or other forms of compensation to the broker, or to your Financial Professional or other financial intermediary.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Shareholder Fees (fees paid directly from your investment)</span>
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Annual Fund Operating Expenses</span> <br/><span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;margin-left:0%;">(expenses that you pay each year as a percentage of the value of your investment)</span>
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	<span style="font-family:Arial;font-size:8pt;">December 30, </span><span style="font-family:Arial;font-size:8pt;">2023</span>
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Portfolio Turnover</span>
Portfolio Turnover [Text Block]	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 rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. 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 113.4% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	113.40%
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Example</span>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example 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 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 Fund’s operating expenses remain the same. The calculation of costs takes into account any applicable contractual fee waivers and/or expense reimbursements for the period noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	<span style="color:#000000;font-family:Arial;font-size:10pt;margin-left:0.00%;">With respect to Class J shares, you would pay the following expenses if you did not redeem your shares </span><span style="color:#000000;font-family:Arial;font-size:10pt;">(all other classes would be the same as in the above example):</span>
Strategy [Heading]	rr_StrategyHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Principal Investment Strategies</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund uses a passive investment approach known as “sampling” to invest at least 80% of its net assets, plus any borrowings for investment purposes, in investments designed to track the Bloomberg U.S.Aggregate Bond Index (the “Index”) at the time of purchase. The Index is composed of investment grade, fixed-rate debt issues with maturities of one year or more, including government securities, corporate securities, and asset-backed and mortgage-backed securities (securitized products). As of November 30, 2022, the Index was composed of 12,671 issues. The Index is rebalanced monthly to reflect securities that have dropped out of or entered the Index in the preceding month. Generally, the Fund makes corresponding changes to its portfolio shortly after Index changes are made public. Because of the practical difficulties and expense of purchasing all of the securities in the Index, the Fund does not purchase all of the securities in the Index. Instead, the Fund uses a sampling methodology to purchase securities with generally the same risk and return characteristics of the Index. Under normal circumstances, the Fund maintains an average portfolio duration that is in line with the duration of the Index, which as of November 30, 2022 was 6.22 years. The Fund will not concentrate (i.e., invest more than 25% of its assets) its investments in a particular industry except to the extent the Index is so concentrated. As of November 30, 2022, the Index was not concentrated in any industry. The Fund’s strategies may result in the active and frequent trading of the Fund’s portfolio securities.
Risk [Heading]	rr_RiskHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Principal Risks</span>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of your investment in the Fund changes with the value of the Fund’s investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund are listed below in alphabetical order and not in order of significance.Fixed-Income Securities Risk.  Fixed-income securities are subject to interest rate, credit quality, and liquidity risks. The market value of fixed-income securities generally declines when interest rates rise, and increased interest rates may adversely affect the liquidity of certain fixed-income securities. Moreover, an issuer of fixed-income securities could default on its payment obligations due to increased interest rates or for other reasons.High Portfolio Turnover Risk.  High portfolio turnover (more than 100%) caused by active and frequent trading of portfolio securities may result in accelerating the realization of taxable gains and losses, lower fund performance, and increased brokerage costs.Index Fund Risk.  Index funds use a passive investment approach and generally do not attempt to manage market volatility, use defensive strategies, or reduce the effect of any long-term periods of poor investment performance. Therefore, the Fund may hold securities that present risks that an investment advisor researching individual securities might seek to avoid. An index fund has operating and other expenses while an index does not. As a result, over time, index funds tend to underperform the index. The correlation between fund performance and index performance may also be affected by the type of passive investment approach used by a fund (sampling or replication), changes in securities markets, changes in the composition of the index, and the timing of purchases and sales of fund shares. Errors or delays in compiling or rebalancing the Index may impact the performance of the Fund and increase transaction costs.Industry Concentration Risk.  A fund that concentrates investments in a particular industry or group of industries has greater exposure than other funds to market, economic, and other factors affecting that industry or group of industries.Portfolio Duration Risk.  Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates, which means funds with longer average portfolio durations may be more volatile than those with shorter durations.Real Estate Securities Risk.  Investing in real estate securities subjects the fund to the risks associated with the real estate market (which are similar to the risks associated with direct ownership in real estate), including declines in real estate values, loss due to casualty or condemnation, property taxes, interest rate changes, increased expenses, cash flow of underlying real estate assets, regulatory changes (including zoning, land use, and rents), and environmental problems, as well as to the risks related to the management skill and creditworthiness of the issuer.Redemption and Large Transaction Risk.  Ownership of the Fund’s shares may be concentrated in one or a few large investors (such as funds of funds, institutional investors, and asset allocation programs) that may redeem or purchase shares in large quantities. These transactions may cause the Fund to sell securities to meet redemptions or to invest additional cash at times it would not otherwise do so, which may result in increased transaction costs, increased expenses, changes to expense ratios, and adverse effects to Fund performance. Such transactions may also accelerate the realization of taxable income if sales of portfolio securities result in gains. Moreover, reallocations by large shareholders among share classes of a fund may result in changes to the expense ratios of affected classes, which may increase the expenses paid by shareholders of the class that experienced the redemption.Securitized Products Risk.  Investments in securitized products are subject to risks similar to traditional fixed-income securities, such as credit, interest rate, liquidity, prepayment, extension, and default risk, as well as additional risks associated with the nature of the assets and the servicing of those assets. Unscheduled prepayments on securitized products may have to be reinvested at lower rates. A reduction in prepayments may increase the effective maturities of these securities, exposing them to the risk of decline in market value over time (extension risk).U.S. Government Securities Risk.  Yields available from U.S. government securities are generally lower than yields from many other fixed-income securities.U.S. Government-Sponsored Securities Risk.  Securities issued by U.S. government-sponsored enterprises such as the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association, and the Federal Home Loan Banks are not issued or guaranteed by the U.S. government.
Risk Lose Money [Text]	rr_RiskLoseMoney	<span style="color:#000000;font-family:Arial;font-size:10pt;">Many factors affect that value, and it is possible to lose money by investing in the Fund.</span>
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	<span style="color:#000000;font-family:Arial;font-size:10pt;"> An investment in the Fund is not a deposit of a bank and is not </span><span style="color:#000000;font-family:Arial;font-size:10pt;">insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Performance</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You may get updated performance information at www.PrincipalAM.com.The bar chart shows the investment returns of the Fund’s Institutional Class shares for each full calendar year of operations for 10 years (or, if shorter, the life of the Fund). The table shows for the last one, five, and ten calendar year periods (or, if shorter, the life of the Fund), how the Fund’s average annual total returns compare with those of one or more broad measures of market performance.During 2014, the Institutional Class experienced a significant withdrawal of monies by an affiliate. As the remaining shareholders held relatively small positions, the total return amounts expressed herein are greater than those that would have been experienced without the withdrawal.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	<span style="color:#000000;font-family:Arial;font-size:10pt;margin-left:0%;">The bar chart shows the investment returns of the Fund’s Institutional Class shares for each full calendar year of operations </span><span style="color:#000000;font-family:Arial;font-size:10pt;">for 10 years (or, if shorter, the life of the Fund). The table shows for the last one, five, and ten calendar year periods (or, if shorter, the life of the Fund), how the Fund’s average annual total returns compare with those of one or more broad measures of market performance.</span>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<span style="font-family:Arial;font-size:10pt;">www.</span><span style="font-family:Arial;font-size:10pt;">PrincipalAM.com</span>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<span style="font-family:Arial;font-size:10pt;">Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.</span>
Bar Chart [Heading]	rr_BarChartHeading	<span style="font-family:Arial;font-size:10pt;font-weight:bold;">Total Returns as of December 31</span>
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest return for a quarter during the period of the bar chart above:Q1 20203.28%Lowest return for a quarter during the period of the bar chart above:Q1 2021(3.34)%Year-to-date return for Institutional Class shares:Q3 2022(14.56)%
Performance Table Heading	rr_PerformanceTableHeading	<span style="font-family:Arial;font-size:10pt;font-weight:bold;">Average Annual Total Returns</span> <br/><span style="font-family:Arial;font-size:10pt;font-weight:bold;margin-left:0%;">For the periods ended December 31, </span><span style="font-family:Arial;font-size:10pt;font-weight:bold;">2021</span>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="color:#000000;font-family:Arial;font-size:10pt;margin-left:0%;">After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect </span><span style="color:#000000;font-family:Arial;font-size:10pt;">the impact of state and local taxes.</span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#000000;font-family:Arial;font-size:10pt;"> Actual after-tax returns depend on an investor’s tax situation and may differ from those </span><span style="color:#000000;font-family:Arial;font-size:10pt;">shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.</span>
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	<span style="color:#000000;font-family:Arial;font-size:10pt;"> After-tax returns are shown for Institutional Class </span><span style="color:#000000;font-family:Arial;font-size:10pt;">shares only and would be different for the other share classes.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Institutional Class shares only and would be different for the other share classes.
Bond Market Index Fund | Class J
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of the offering price or NAV at the time Sales Load is paid, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.14%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.15%
Other Expenses	rr_OtherExpensesOverAssets	0.23%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.53%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.51%
1 year	rr_ExpenseExampleYear01	$ 152
3 years	rr_ExpenseExampleYear03	168
5 years	rr_ExpenseExampleYear05	294
10 years	rr_ExpenseExampleYear10	663
1 year	rr_ExpenseExampleNoRedemptionYear01	52
3 years	rr_ExpenseExampleNoRedemptionYear03	168
5 years	rr_ExpenseExampleNoRedemptionYear05	294
10 years	rr_ExpenseExampleNoRedemptionYear10	$ 663
1 Year	rr_AverageAnnualReturnYear01	(3.00%)
5 Years	rr_AverageAnnualReturnYear05	2.92%
10 Years	rr_AverageAnnualReturnYear10	2.11%
Bond Market Index Fund | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of the offering price or NAV at the time Sales Load is paid, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.14%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets
Other Expenses	rr_OtherExpensesOverAssets	0.03%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.18%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.16%
1 year	rr_ExpenseExampleYear01	$ 16
3 years	rr_ExpenseExampleYear03	56
5 years	rr_ExpenseExampleYear05	99
10 years	rr_ExpenseExampleYear10	$ 228
2012	rr_AnnualReturn2012	3.89%
2013	rr_AnnualReturn2013	(2.44%)
2014	rr_AnnualReturn2014	6.63%
2015	rr_AnnualReturn2015	0.23%
2016	rr_AnnualReturn2016	2.17%
2017	rr_AnnualReturn2017	3.31%
2018	rr_AnnualReturn2018	(0.20%)
2019	rr_AnnualReturn2019	8.47%
2020	rr_AnnualReturn2020	7.29%
2021	rr_AnnualReturn2021	(1.67%)
Year to Date Return, Label	rr_YearToDateReturnLabel	<span style="font-family:Arial;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Year-to-date return for Institutional Class shares:</span>
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2022
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(14.56%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	<span style="font-family:Arial;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Highest return for a quarter during the period of the bar chart above:</span>
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.28%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	<span style="font-family:Arial;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Lowest return for a quarter during the period of the bar chart above:</span>
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2021
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.34%)
1 Year	rr_AverageAnnualReturnYear01	(1.67%)
5 Years	rr_AverageAnnualReturnYear05	3.36%
10 Years	rr_AverageAnnualReturnYear10	2.70%	[2]
Bond Market Index Fund | Class R-1
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of the offering price or NAV at the time Sales Load is paid, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.14%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.35%
Other Expenses	rr_OtherExpensesOverAssets	0.55%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.05%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	1.03%
1 year	rr_ExpenseExampleYear01	$ 105
3 years	rr_ExpenseExampleYear03	332
5 years	rr_ExpenseExampleYear05	577
10 years	rr_ExpenseExampleYear10	$ 1,281
1 Year	rr_AverageAnnualReturnYear01	(2.58%)
5 Years	rr_AverageAnnualReturnYear05	2.46%
10 Years	rr_AverageAnnualReturnYear10	1.70%
Bond Market Index Fund | Class R-3
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of the offering price or NAV at the time Sales Load is paid, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.14%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.34%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.74%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.72%
1 year	rr_ExpenseExampleYear01	$ 74
3 years	rr_ExpenseExampleYear03	235
5 years	rr_ExpenseExampleYear05	410
10 years	rr_ExpenseExampleYear10	$ 917
1 Year	rr_AverageAnnualReturnYear01	(2.29%)
5 Years	rr_AverageAnnualReturnYear05	2.76%
10 Years	rr_AverageAnnualReturnYear10	2.01%
Bond Market Index Fund | Class R-4
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of the offering price or NAV at the time Sales Load is paid, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.14%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.10%
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.55%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.53%
1 year	rr_ExpenseExampleYear01	$ 54
3 years	rr_ExpenseExampleYear03	174
5 years	rr_ExpenseExampleYear05	305
10 years	rr_ExpenseExampleYear10	$ 687
1 Year	rr_AverageAnnualReturnYear01	(2.05%)
5 Years	rr_AverageAnnualReturnYear05	3.01%
10 Years	rr_AverageAnnualReturnYear10	2.23%
Bond Market Index Fund | Class R-5
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Deferred Sales Charge (Load) (as a percentage of the offering price or NAV at the time Sales Load is paid, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.14%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets
Other Expenses	rr_OtherExpensesOverAssets	0.28%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.43%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.41%
1 year	rr_ExpenseExampleYear01	$ 42
3 years	rr_ExpenseExampleYear03	136
5 years	rr_ExpenseExampleYear05	239
10 years	rr_ExpenseExampleYear10	$ 540
1 Year	rr_AverageAnnualReturnYear01	(1.97%)
5 Years	rr_AverageAnnualReturnYear05	3.10%
10 Years	rr_AverageAnnualReturnYear10	2.33%
Bond Market Index Fund | Return After Taxes on Distributions | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.47%)
5 Years	rr_AverageAnnualReturnYear05	1.50%
10 Years	rr_AverageAnnualReturnYear10	1.34%	[2]
Bond Market Index Fund | Return After Taxes on Distributions and Sale of Fund Shares | Institutional Class
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.99%)
5 Years	rr_AverageAnnualReturnYear05	1.97%
10 Years	rr_AverageAnnualReturnYear10	1.58%	[2]
Bond Market Index Fund | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.54%)
5 Years	rr_AverageAnnualReturnYear05	3.57%
10 Years	rr_AverageAnnualReturnYear10	2.90%

[1] Principal Global Investors, LLC (“PGI”), the investment advisor, has contractually agreed to waive a portion of the Fund’s management fees through the period ending December 30, 2023. The fee waiver will reduce the Fund's management fees by 0.015% (expressed as a percent of average net assets on an annualized basis). It is expected that the fee waiver will continue through the period disclosed; however, Principal Funds, Inc. and PGI, the parties to the agreement, may mutually agree to terminate the fee waiver prior to the end of the period.

[2] During 2014, the Institutional Class experienced a significant withdrawal of monies by an affiliate. As the remaining shareholders held relatively small positions, the total return amounts expressed herein are greater than those that would have been experienced without the withdrawal.