Voyageur Mutual Funds N-CSR 5 Nov 24 Certified annual shareholder report (management investment company) Financial data

Form N-CSR Cover

Form N-CSR Cover	12 Months Ended
	Aug. 31, 2024
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	Voyageur Mutual Funds
Entity Central Index Key	0000906236
Entity Investment Company Type	N-1A
Document Period End Date	Aug. 31, 2024

Shareholder Report

Shareholder Report	12 Months Ended
	Aug. 31, 2024 USD ($) Holding
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	Voyageur Mutual Funds
Entity Central Index Key	0000906236
Entity Investment Company Type	N-1A
Document Period End Date	Aug. 31, 2024
C000006409 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Minnesota High-Yield Municipal Bond Fund
Class Name	Class A
Trading Symbol	DVMHX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Minnesota High-Yield Municipal Bond Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 0.85 %
Expenses Paid, Amount	$ 89
Expense Ratio, Percent	0.85%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Minnesota High-Yield Municipal Bond Fund (Class A) returned 9.10% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Significant out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Minnesota High-Yield Municipal Bond Fund (Class A) – including sales charge 4.25 % 0.04 % 1.93 % Delaware Minnesota High-Yield Municipal Bond Fund (Class A) – excluding sales charge 9.10 % 0.97 % 2.40 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 223,706,331
Holdings Count | Holding	226
Advisory Fees Paid, Amount	$ 823,966
Investment Company Portfolio Turnover	19%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 226 Total advisory fees paid $ Portfolio turnover rate 19 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Healthcare Revenue Bonds 38.07 % Education Revenue Bonds 26.71 % Local General Obligation Bonds 10.63 % Transportation Revenue Bonds 6.43 % Special Tax Revenue Bonds 3.49 % State General Obligation Bonds 3.28 % Industrial Development Revenue/Pollution Control 3.26 % Housing Revenue Bonds 2.97 % Lease Revenue Bonds 1.40 % Electric Revenue Bonds 1.20 % Pre-Refunded Bonds 0.57 % State and territory allocation Minnesota 93.33 % Puerto Rico 4.68 %
Material Fund Change [Text Block]	Material Fund changes For the fiscal year ended August 31, 2024, the Fund introduced a new fee waiver for Class A shares of 0.84% (excluding certain items). This is a summary of certain changes to the Fund since the beginning of the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by December 31, 2024, at delawarefunds.com/literature
Material Fund Change Expenses [Text Block]	For the fiscal year ended August 31, 2024, the Fund introduced a new fee waiver for Class A shares of 0.84% (excluding certain items).
Summary of Change Legend [Text Block]	This is a summary of certain changes to the Fund since the beginning of the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by December 31, 2024, at delawarefunds.com/literature
Updated Prospectus Phone Number	800 523-1918
Updated Prospectus Web Address	delawarefunds.com/literature
C000006411 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Minnesota High-Yield Municipal Bond Fund
Class Name	Class C
Trading Symbol	DVMMX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Minnesota High-Yield Municipal Bond Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.60 %
Expenses Paid, Amount	$ 167
Expense Ratio, Percent	1.60%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Minnesota High-Yield Municipal Bond Fund (Class C) returned 8.28% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Significant out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Minnesota High-Yield Municipal Bond Fund (Class C) – including sales charge 7.28 % 0.21 % 1.63 % Delaware Minnesota High-Yield Municipal Bond Fund (Class C) – excluding sales charge 8.28 % 0.21 % 1.63 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 223,706,331
Holdings Count | Holding	226
Advisory Fees Paid, Amount	$ 823,966
Investment Company Portfolio Turnover	19%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 226 Total advisory fees paid $ Portfolio turnover rate 19 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Healthcare Revenue Bonds 38.07 % Education Revenue Bonds 26.71 % Local General Obligation Bonds 10.63 % Transportation Revenue Bonds 6.43 % Special Tax Revenue Bonds 3.49 % State General Obligation Bonds 3.28 % Industrial Development Revenue/Pollution Control 3.26 % Housing Revenue Bonds 2.97 % Lease Revenue Bonds 1.40 % Electric Revenue Bonds 1.20 % Pre-Refunded Bonds 0.57 % State and territory allocation Minnesota 93.33 % Puerto Rico 4.68 %
Material Fund Change [Text Block]	Material Fund changes For the fiscal year ended August 31, 2024, the Fund introduced a new fee waiver for Class C shares of 1.59% (excluding certain items). This is a summary of certain changes to the Fund since the beginning of the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by December 31, 2024, at delawarefunds.com/literature
Material Fund Change Expenses [Text Block]	For the fiscal year ended August 31, 2024, the Fund introduced a new fee waiver for Class C shares of 1.59% (excluding certain items).
Summary of Change Legend [Text Block]	This is a summary of certain changes to the Fund since the beginning of the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by December 31, 2024, at delawarefunds.com/literature
Updated Prospectus Phone Number	800 523-1918
Updated Prospectus Web Address	delawarefunds.com/literature
C000135925 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Minnesota High-Yield Municipal Bond Fund
Class Name	Institutional Class
Trading Symbol	DMHIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Minnesota High-Yield Municipal Bond Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Class $ 0.60 %
Expenses Paid, Amount	$ 63
Expense Ratio, Percent	0.60%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Minnesota High-Yield Municipal Bond Fund (Institutional Class) returned 9.38% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Significant out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Minnesota High-Yield Municipal Bond Fund (Institutional Class) – including sales charge 9.38 % 1.24 % 2.65 % Delaware Minnesota High-Yield Municipal Bond Fund (Institutional Class) – excluding sales charge 9.38 % 1.24 % 2.65 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 223,706,331
Holdings Count | Holding	226
Advisory Fees Paid, Amount	$ 823,966
Investment Company Portfolio Turnover	19%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 226 Total advisory fees paid $ Portfolio turnover rate 19 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Healthcare Revenue Bonds 38.07 % Education Revenue Bonds 26.71 % Local General Obligation Bonds 10.63 % Transportation Revenue Bonds 6.43 % Special Tax Revenue Bonds 3.49 % State General Obligation Bonds 3.28 % Industrial Development Revenue/Pollution Control 3.26 % Housing Revenue Bonds 2.97 % Lease Revenue Bonds 1.40 % Electric Revenue Bonds 1.20 % Pre-Refunded Bonds 0.57 % State and territory allocation Minnesota 93.33 % Puerto Rico 4.68 %
Material Fund Change [Text Block]	Material Fund changes For the fiscal year ended August 31, 2024, the Fund introduced a new fee waiver for Institutional Class shares of 0.59% (excluding certain items). This is a summary of certain changes to the Fund since the beginning of the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by December 31, 2024, at delawarefunds.com/literature
Material Fund Change Expenses [Text Block]	For the fiscal year ended August 31, 2024, the Fund introduced a new fee waiver for Institutional Class shares of 0.59% (excluding certain items).
Summary of Change Legend [Text Block]	This is a summary of certain changes to the Fund since the beginning of the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by December 31, 2024, at delawarefunds.com/literature
Updated Prospectus Phone Number	800 523-1918
Updated Prospectus Web Address	delawarefunds.com/literature
C000006412 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware National High-Yield Municipal Bond Fund
Class Name	Class A
Trading Symbol	CXHYX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware National High-Yield Municipal Bond Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 0.85 %
Expenses Paid, Amount	$ 90
Expense Ratio, Percent	0.85%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware National High-Yield Municipal Bond Fund (Class A) returned 12.58% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware National High-Yield Municipal Bond Fund (Class A) – including sales charge 7.47 % 1.35 % 3.47 % Delaware National High-Yield Municipal Bond Fund (Class A) – excluding sales charge 12.58 % 2.29 % 3.94 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 3,340,888,050
Holdings Count | Holding	778
Advisory Fees Paid, Amount	$ 13,174,903
Investment Company Portfolio Turnover	19%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 778 Total advisory fees paid $ Portfolio turnover rate 19 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Industrial Development Revenue/Pollution Control 22.65 % Education Revenue Bonds 19.78 % Special Tax Revenue Bonds 14.05 % Healthcare Revenue Bonds 13.16 % Transportation Revenue Bonds 9.00 % State General Obligation Bonds 5.06 % Local General Obligation Bonds 3.90 % Housing Revenue Bonds 3.21 % Lease Revenue Bonds 2.71 % Electric Revenue Bonds 1.82 % State and territory allocation Puerto Rico 13.79 % California 12.17 % New York 10.29 % Texas 6.58 % Florida 6.30 % Illinois 5.74 % Wisconsin 3.64 % Virginia 3.48 % Arizona 3.44 % Pennsylvania 2.97 %
C000006414 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware National High-Yield Municipal Bond Fund
Class Name	Class C
Trading Symbol	DVHCX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware National High-Yield Municipal Bond Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.60 %
Expenses Paid, Amount	$ 169
Expense Ratio, Percent	1.60%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware National High-Yield Municipal Bond Fund (Class C) returned 11.71% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware National High-Yield Municipal Bond Fund (Class C) – including sales charge 10.71 % 1.54 % 3.16 % Delaware National High-Yield Municipal Bond Fund (Class C) – excluding sales charge 11.71 % 1.54 % 3.16 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 3,340,888,050
Holdings Count | Holding	778
Advisory Fees Paid, Amount	$ 13,174,903
Investment Company Portfolio Turnover	19%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 778 Total advisory fees paid $ Portfolio turnover rate 19 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Industrial Development Revenue/Pollution Control 22.65 % Education Revenue Bonds 19.78 % Special Tax Revenue Bonds 14.05 % Healthcare Revenue Bonds 13.16 % Transportation Revenue Bonds 9.00 % State General Obligation Bonds 5.06 % Local General Obligation Bonds 3.90 % Housing Revenue Bonds 3.21 % Lease Revenue Bonds 2.71 % Electric Revenue Bonds 1.82 % State and territory allocation Puerto Rico 13.79 % California 12.17 % New York 10.29 % Texas 6.58 % Florida 6.30 % Illinois 5.74 % Wisconsin 3.64 % Virginia 3.48 % Arizona 3.44 % Pennsylvania 2.97 %
C000074152 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware National High-Yield Municipal Bond Fund
Class Name	Institutional Class
Trading Symbol	DVHIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware National High-Yield Municipal Bond Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Class $ 0.60 %
Expenses Paid, Amount	$ 64
Expense Ratio, Percent	0.60%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware National High-Yield Municipal Bond Fund (Institutional Class) returned 12.78% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware National High-Yield Municipal Bond Fund (Institutional Class) – including sales charge 12.78 % 2.56 % 4.21 % Delaware National High-Yield Municipal Bond Fund (Institutional Class) – excluding sales charge 12.78 % 2.56 % 4.21 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 3,340,888,050
Holdings Count | Holding	778
Advisory Fees Paid, Amount	$ 13,174,903
Investment Company Portfolio Turnover	19%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 778 Total advisory fees paid $ Portfolio turnover rate 19 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Industrial Development Revenue/Pollution Control 22.65 % Education Revenue Bonds 19.78 % Special Tax Revenue Bonds 14.05 % Healthcare Revenue Bonds 13.16 % Transportation Revenue Bonds 9.00 % State General Obligation Bonds 5.06 % Local General Obligation Bonds 3.90 % Housing Revenue Bonds 3.21 % Lease Revenue Bonds 2.71 % Electric Revenue Bonds 1.82 % State and territory allocation Puerto Rico 13.79 % California 12.17 % New York 10.29 % Texas 6.58 % Florida 6.30 % Illinois 5.74 % Wisconsin 3.64 % Virginia 3.48 % Arizona 3.44 % Pennsylvania 2.97 %
C000006415 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free California Fund
Class Name	Class A
Trading Symbol	DVTAX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free California Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 0.80 %
Expenses Paid, Amount	$ 84
Expense Ratio, Percent	0.80%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free California Fund (Class A) returned 9.98% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free California Fund (Class A) – including sales charge 5.06 % 0.59 % 2.36 % Delaware Tax-Free California Fund (Class A) – excluding sales charge 9.98 % 1.52 % 2.83 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 287,208,829
Holdings Count | Holding	237
Advisory Fees Paid, Amount	$ 849,479
Investment Company Portfolio Turnover	25%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 237 Total advisory fees paid $ Portfolio turnover rate 25 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Education Revenue Bonds 18.26 % Healthcare Revenue Bonds 14.74 % Transportation Revenue Bonds 12.16 % Special Tax Revenue Bonds 11.60 % Industrial Development Revenue/Pollution Control 11.05 % State General Obligation Bonds 9.63 % Lease Revenue Bonds 5.45 % Electric Revenue Bonds 5.37 % Local General Obligation Bonds 3.02 % Housing Revenue Bonds 2.65 % State and territory allocation California 83.70 % Puerto Rico 12.70 % Guam 1.20 % US Virgin Islands 0.19 %
C000006417 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free California Fund
Class Name	Class C
Trading Symbol	DVFTX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free California Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.55 %
Expenses Paid, Amount	$ 162
Expense Ratio, Percent	1.55%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free California Fund (Class C) returned 9.05% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free California Fund (Class C) – including sales charge 8.05 % 0.74 % 2.06 % Delaware Tax-Free California Fund (Class C) – excluding sales charge 9.05 % 0.74 % 2.06 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 287,208,829
Holdings Count | Holding	237
Advisory Fees Paid, Amount	$ 849,479
Investment Company Portfolio Turnover	25%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 237 Total advisory fees paid $ Portfolio turnover rate 25 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Education Revenue Bonds 18.26 % Healthcare Revenue Bonds 14.74 % Transportation Revenue Bonds 12.16 % Special Tax Revenue Bonds 11.60 % Industrial Development Revenue/Pollution Control 11.05 % State General Obligation Bonds 9.63 % Lease Revenue Bonds 5.45 % Electric Revenue Bonds 5.37 % Local General Obligation Bonds 3.02 % Housing Revenue Bonds 2.65 % State and territory allocation California 83.70 % Puerto Rico 12.70 % Guam 1.20 % US Virgin Islands 0.19 %
C000135926 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free California Fund
Class Name	Institutional Class
Trading Symbol	DCTIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free California Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Class $ 0.55 %
Expenses Paid, Amount	$ 58
Expense Ratio, Percent	0.55%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free California Fund (Institutional Class) returned 10.15% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free California Fund (Institutional Class) – including sales charge 10.15 % 1.77 % 3.08 % Delaware Tax-Free California Fund (Institutional Class) – excluding sales charge 10.15 % 1.77 % 3.08 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 287,208,829
Holdings Count | Holding	237
Advisory Fees Paid, Amount	$ 849,479
Investment Company Portfolio Turnover	25%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 237 Total advisory fees paid $ Portfolio turnover rate 25 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Education Revenue Bonds 18.26 % Healthcare Revenue Bonds 14.74 % Transportation Revenue Bonds 12.16 % Special Tax Revenue Bonds 11.60 % Industrial Development Revenue/Pollution Control 11.05 % State General Obligation Bonds 9.63 % Lease Revenue Bonds 5.45 % Electric Revenue Bonds 5.37 % Local General Obligation Bonds 3.02 % Housing Revenue Bonds 2.65 % State and territory allocation California 83.70 % Puerto Rico 12.70 % Guam 1.20 % US Virgin Islands 0.19 %
C000006418 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free Idaho Fund
Class Name	Class A
Trading Symbol	VIDAX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free Idaho Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 0.86 %
Expenses Paid, Amount	$ 90
Expense Ratio, Percent	0.86%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free Idaho Fund (Class A) returned 9.19% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free Idaho Fund (Class A) – including sales charge 4.31 % 0.15 % 1.71 % Delaware Tax-Free Idaho Fund (Class A) – excluding sales charge 9.19 % 1.07 % 2.18 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 130,657,875
Holdings Count | Holding	110
Advisory Fees Paid, Amount	$ 476,040
Investment Company Portfolio Turnover	14%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 110 Total advisory fees paid $ Portfolio turnover rate 14 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Education Revenue Bonds 22.67 % Special Tax Revenue Bonds 22.61 % Healthcare Revenue Bonds 12.93 % Local General Obligation Bonds 8.49 % Housing Revenue Bonds 6.80 % Lease Revenue Bonds 6.70 % Transportation Revenue Bonds 6.29 % Electric Revenue Bonds 4.62 % Industrial Development Revenue/Pollution Control 4.07 % Water & Sewer Revenue Bonds 2.18 % State and territory allocation Idaho 82.58 % Puerto Rico 16.19 % Guam 0.54 %
C000006420 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free Idaho Fund
Class Name	Class C
Trading Symbol	DVICX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free Idaho Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.61 %
Expenses Paid, Amount	$ 168
Expense Ratio, Percent	1.61%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free Idaho Fund (Class C) returned 8.38% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free Idaho Fund (Class C) – including sales charge 7.38 % 0.34 % 1.42 % Delaware Tax-Free Idaho Fund (Class C) – excluding sales charge 8.38 % 0.34 % 1.42 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 130,657,875
Holdings Count | Holding	110
Advisory Fees Paid, Amount	$ 476,040
Investment Company Portfolio Turnover	14%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 110 Total advisory fees paid $ Portfolio turnover rate 14 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Education Revenue Bonds 22.67 % Special Tax Revenue Bonds 22.61 % Healthcare Revenue Bonds 12.93 % Local General Obligation Bonds 8.49 % Housing Revenue Bonds 6.80 % Lease Revenue Bonds 6.70 % Transportation Revenue Bonds 6.29 % Electric Revenue Bonds 4.62 % Industrial Development Revenue/Pollution Control 4.07 % Water & Sewer Revenue Bonds 2.18 % State and territory allocation Idaho 82.58 % Puerto Rico 16.19 % Guam 0.54 %
C000135927 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free Idaho Fund
Class Name	Institutional Class
Trading Symbol	DTIDX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free Idaho Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Class $ 0.61 %
Expenses Paid, Amount	$ 64
Expense Ratio, Percent	0.61%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free Idaho Fund (Institutional Class) returned 9.35% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free Idaho Fund (Institutional Class) – including sales charge 9.35 % 1.33 % 2.42 % Delaware Tax-Free Idaho Fund (Institutional Class) – excluding sales charge 9.35 % 1.33 % 2.42 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 130,657,875
Holdings Count | Holding	110
Advisory Fees Paid, Amount	$ 476,040
Investment Company Portfolio Turnover	14%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 110 Total advisory fees paid $ Portfolio turnover rate 14 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Education Revenue Bonds 22.67 % Special Tax Revenue Bonds 22.61 % Healthcare Revenue Bonds 12.93 % Local General Obligation Bonds 8.49 % Housing Revenue Bonds 6.80 % Lease Revenue Bonds 6.70 % Transportation Revenue Bonds 6.29 % Electric Revenue Bonds 4.62 % Industrial Development Revenue/Pollution Control 4.07 % Water & Sewer Revenue Bonds 2.18 % State and territory allocation Idaho 82.58 % Puerto Rico 16.19 % Guam 0.54 %
C000006421 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free New York Fund
Class Name	Class A
Trading Symbol	FTNYX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free New York Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 0.80 %
Expenses Paid, Amount	$ 84
Expense Ratio, Percent	0.80%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free New York Fund (Class A) returned 9.14% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free New York Fund (Class A) – including sales charge 4.25 % 0.37 % 2.11 % Delaware Tax-Free New York Fund (Class A) – excluding sales charge 9.14 % 1.30 % 2.58 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 264,476,608
Holdings Count | Holding	188
Advisory Fees Paid, Amount	$ 866,053
Investment Company Portfolio Turnover	21%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 188 Total advisory fees paid $ Portfolio turnover rate 21 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Special Tax Revenue Bonds 24.94 % Education Revenue Bonds 17.07 % Transportation Revenue Bonds 14.36 % Industrial Development Revenue/Pollution Control 9.00 % Healthcare Revenue Bonds 7.45 % Electric Revenue Bonds 6.20 % Lease Revenue Bonds 5.19 % Water & Sewer Revenue Bonds 4.85 % Local General Obligation Bonds 2.93 % Housing Revenue Bonds 2.66 % State and territory allocation New York 81.00 % Puerto Rico 14.73 % Guam 0.55 % US Virgin Islands 0.20 %
C000006423 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free New York Fund
Class Name	Class C
Trading Symbol	DVFNX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free New York Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund atdelawarefunds.com/literature.You can also request this information by contacting us at800 523-1918, weekdays from8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.55 %
Expenses Paid, Amount	$ 161
Expense Ratio, Percent	1.55%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free New York Fund (Class C) returned 8.34% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free New York Fund (Class C) – including sales charge 7.34 % 0.56 % 1.81 % Delaware Tax-Free New York Fund (Class C) – excluding sales charge 8.34 % 0.56 % 1.81 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 264,476,608
Holdings Count | Holding	188
Advisory Fees Paid, Amount	$ 866,053
Investment Company Portfolio Turnover	21%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 188 Total advisory fees paid $ Portfolio turnover rate 21 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Special Tax Revenue Bonds 24.94 % Education Revenue Bonds 17.07 % Transportation Revenue Bonds 14.36 % Industrial Development Revenue/Pollution Control 9.00 % Healthcare Revenue Bonds 7.45 % Electric Revenue Bonds 6.20 % Lease Revenue Bonds 5.19 % Water & Sewer Revenue Bonds 4.85 % Local General Obligation Bonds 2.93 % Housing Revenue Bonds 2.66 % State and territory allocation New York 81.00 % Puerto Rico 14.73 % Guam 0.55 % US Virgin Islands 0.20 %
C000135928 [Member]
Shareholder Report [Line Items]
Fund Name	Delaware Tax-Free New York Fund
Class Name	Institutional Class
Trading Symbol	DTNIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Delaware Tax-Free New York Fund (Fund) for the period of September 1, 2023, to August 31, 2024.
Shareholder Report Annual or Semi-Annual	annual shareholder report
Additional Information [Text Block]	You can find additional information about the Fund at delawarefunds.com/literature. You can also request this information by contacting us at 800 523-1918, weekdays from 8:30am to 6:00pm ET.
Additional Information Phone Number	800 523-1918
Additional Information Website	delawarefunds.com/literature
Expenses [Text Block]	What were the Fund's costs for the last 12 months? (Based on a hypothetical $10,000 investment) Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Class $ 0.55 %
Expenses Paid, Amount	$ 58
Expense Ratio, Percent	0.55%
Factors Affecting Performance [Text Block]	Management’s discussion of Fund performance Performance highlights Delaware Tax-Free New York Fund (Institutional Class) returned 9.52% (excluding sales charge) for the 12 months ended August 31, 2024. Top contributors to performance: Municipal yields fell over the fiscal year against a backdrop of slowing inflation and anticipation that the US Federal Reserve (Fed) would eventually cut rates. As a result, the longer end of the curve outperformed. Lower-investment-grade and below-investment-grade segments drove performance. The catalyst was a strong technical backdrop of diminutive high yield issuance coupled with inflows to municipal mutual funds, particularly high yield funds. Key contributors to performance included: Overweight to the long bond (22+ years) segment of the curve Overweight to BBB-rated credit Meaningful out-of-benchmark allocation to below-investment-grade securities Top detractors from performance: The front end of the curve – which is, by its nature, shorter in duration – detracted from performance over the fiscal year, as this maturity segment lagged relative to the intermediate and long ends of the curve. Key detractors from performance included: Modest out-of-benchmark allocation to the front end (0-1 year) of the curve Allocation to pre-refunded bonds, predominantly on the front end of the curve
Performance Past Does Not Indicate Future [Text]	Keep in mind that the Fund's past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]	Fund performance The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 fiscal years of the Class. It also assumes a $10,000 initial investment at the beginning of the first full fiscal year in a broad-based Growth of $10,000 investment For the period August 31, 2014, through August 31, 2024
Average Annual Return [Table Text Block]	Average annual total returns (as of August 31, 2024) 1 year 5 year 10 year Delaware Tax-Free New York Fund (Institutional Class) – including sales charge 9.52 % 1.58 % 2.84 % Delaware Tax-Free New York Fund (Institutional Class) – excluding sales charge 9.52 % 1.58 % 2.84 % Bloomberg Municipal Bond Index 6.09 % 1.02 % 2.43 %
No Deduction of Taxes [Text Block]	The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block]	Visit delawarefunds.com/performance for the most recent performance information.
Net Assets	$ 264,476,608
Holdings Count | Holding	188
Advisory Fees Paid, Amount	$ 866,053
Investment Company Portfolio Turnover	21%
Additional Fund Statistics [Text Block]	Fund statistics Fund net assets $ Total number of portfolio holdings 188 Total advisory fees paid $ Portfolio turnover rate 21 %
Holdings [Text Block]	Fund holdings The tables below show the investment makeup of the Fund, with each category representing a percentage of the total net assets of the Fund. Sector allocation Special Tax Revenue Bonds 24.94 % Education Revenue Bonds 17.07 % Transportation Revenue Bonds 14.36 % Industrial Development Revenue/Pollution Control 9.00 % Healthcare Revenue Bonds 7.45 % Electric Revenue Bonds 6.20 % Lease Revenue Bonds 5.19 % Water & Sewer Revenue Bonds 4.85 % Local General Obligation Bonds 2.93 % Housing Revenue Bonds 2.66 % State and territory allocation New York 81.00 % Puerto Rico 14.73 % Guam 0.55 % US Virgin Islands 0.20 %

Shareholder Report, Line Graph

Shareholder Report, Line Graph (Details) - USD ($)	12 Months Ended	60 Months Ended	120 Months Ended
	Aug. 31, 2024	Aug. 31, 2024	Aug. 31, 2024	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2014
C000006409 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Minnesota High-Yield Municipal Bond Fund (Class A) – including sales charge
Account Value	$ 12,103	$ 12,103	$ 12,103	$ 11,093	$ 11,212	$ 12,293	$ 11,621	$ 11,527	$ 10,640	$ 10,541	$ 10,453	$ 9,850	$ 9,550
Average Annual Return, Percent	4.25%	0.04%	1.93%
C000006409 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Minnesota High-Yield Municipal Bond Fund (Class A) – excluding sales charge
Average Annual Return, Percent	9.10%	0.97%	2.40%
C000006411 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Minnesota High-Yield Municipal Bond Fund (Class C) – including sales charge
Account Value	$ 11,756	$ 11,756	$ 11,756	10,858	11,056	12,210	11,633	11,626	10,813	10,792	10,782	10,246	10,000
Average Annual Return, Percent	7.28%	0.21%	1.63%
C000006411 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Minnesota High-Yield Municipal Bond Fund (Class C) – excluding sales charge
Average Annual Return, Percent	8.28%	0.21%	1.63%
C000135925 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Minnesota High-Yield Municipal Bond Fund (Institutional Class) – including sales charge
Account Value	$ 12,990	$ 12,990	$ 12,990	11,877	11,962	13,084	12,349	12,207	11,250	11,107	10,987	10,337	10,000
Average Annual Return, Percent	9.38%	1.24%	2.65%
C000135925 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Minnesota High-Yield Municipal Bond Fund (Institutional Class) – excluding sales charge
Average Annual Return, Percent	9.38%	1.24%	2.65%
C000006412 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware National High-Yield Municipal Bond Fund (Class A) – including sales charge
Account Value	$ 14,064.84	$ 14,064.84	$ 14,064.84	12,493.45	12,738.56	14,230.71	12,682.59	12,546.71	11,530.55	11,108.72	11,030.21	10,002.58	9,550
Average Annual Return, Percent	7.47%	1.35%	3.47%
C000006412 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware National High-Yield Municipal Bond Fund (Class A) – excluding sales charge
Average Annual Return, Percent	12.58%	2.29%	3.94%
C000006414 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware National High-Yield Municipal Bond Fund (Class C) – including sales charge
Account Value	$ 13,650.92	$ 13,650.92	$ 13,650.92	12,220.17	12,550.83	14,130.6	12,693.86	12,640.6	11,705.62	11,361.89	11,374.99	10,395.44	10,000
Average Annual Return, Percent	10.71%	1.54%	3.16%
C000006414 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware National High-Yield Municipal Bond Fund (Class C) – excluding sales charge
Average Annual Return, Percent	11.71%	1.54%	3.16%
C000074152 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware National High-Yield Municipal Bond Fund (Institutional Class) – including sales charge
Account Value	$ 15,099.3	$ 15,099.3	$ 15,099.3	13,388.73	13,608.72	15,157.06	13,483.59	13,290.28	12,188.18	11,712.6	11,607.65	10,496.64	10,000
Average Annual Return, Percent	12.78%	2.56%	4.21%
C000074152 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware National High-Yield Municipal Bond Fund (Institutional Class) – excluding sales charge
Average Annual Return, Percent	12.78%	2.56%	4.21%
C000006415 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free California Fund (Class A) – including sales charge
Account Value	$ 12,621.29	$ 12,621.29	$ 12,621.29	11,475.97	11,376.92	12,708.76	11,883.71	11,696.29	10,830.95	10,723.56	10,655.85	9,895.48	9,550
Average Annual Return, Percent	5.06%	0.59%	2.36%
C000006415 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free California Fund (Class A) – excluding sales charge
Average Annual Return, Percent	9.98%	1.52%	2.83%
C000006417 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free California Fund (Class C) – including sales charge
Account Value	$ 12,263.52	$ 12,263.52	$ 12,263.52	11,246.02	11,232.22	12,627.46	11,908.55	11,809.1	11,009.34	10,981.82	10,994.03	10,286.82	10,000
Average Annual Return, Percent	8.05%	0.74%	2.06%
C000006417 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free California Fund (Class C) – excluding sales charge
Average Annual Return, Percent	9.05%	0.74%	2.06%
C000135926 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free California Fund (Institutional Class) – including sales charge
Account Value	$ 13,550.11	$ 13,550.11	$ 13,550.11	12,301.37	12,153.45	13,542.48	12,631.01	12,400.65	11,454.74	11,312.99	11,213.47	10,387.44	10,000.01
Average Annual Return, Percent	10.15%	1.77%	3.08%
C000135926 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free California Fund (Institutional Class) – excluding sales charge
Average Annual Return, Percent	10.15%	1.77%	3.08%
C000006418 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free Idaho Fund (Class A) – including sales charge
Account Value	$ 11,850	$ 11,850	$ 11,850	10,853	10,909	12,120	11,424	11,225	10,471	10,413	10,365	9,809	9,550
Average Annual Return, Percent	4.31%	0.15%	1.71%
C000006418 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free Idaho Fund (Class A) – excluding sales charge
Average Annual Return, Percent	9.19%	1.07%	2.18%
C000006420 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free Idaho Fund (Class C) – including sales charge
Account Value	$ 11,518	$ 11,518	$ 11,518	10,627	10,763	12,038	11,434	11,319	10,638	10,659	10,690	10,192	10,000
Average Annual Return, Percent	7.38%	0.34%	1.42%
C000006420 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free Idaho Fund (Class C) – excluding sales charge
Average Annual Return, Percent	8.38%	0.34%	1.42%
C000135927 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free Idaho Fund (Institutional Class) – including sales charge
Account Value	$ 12,705	$ 12,705	$ 12,705	11,619	11,638	12,898	12,127	11,885	11,060	10,971	10,893	10,283	10,000
Average Annual Return, Percent	9.35%	1.33%	2.42%
C000135927 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free Idaho Fund (Institutional Class) – excluding sales charge
Average Annual Return, Percent	9.35%	1.33%	2.42%
C000006421 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free New York Fund (Class A) – including sales charge
Account Value	$ 12,320	$ 12,320	$ 12,320	11,288	11,255	12,500	11,734	11,538	10,683	10,621	10,616	9,868	9,550
Average Annual Return, Percent	4.25%	0.37%	2.11%
C000006421 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free New York Fund (Class A) – excluding sales charge
Average Annual Return, Percent	9.14%	1.30%	2.58%
C000006423 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free New York Fund (Class C) – including sales charge
Account Value	$ 11,967	$ 11,967	$ 11,967	11,046	11,088	12,411	11,739	11,631	10,849	10,867	10,945	10,249	10,000
Average Annual Return, Percent	7.34%	0.56%	1.81%
C000006423 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free New York Fund (Class C) – excluding sales charge
Average Annual Return, Percent	8.34%	0.56%	1.81%
C000135928 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free New York Fund (Institutional Class) – including sales charge
Account Value	$ 13,226	$ 13,226	$ 13,226	12,076	12,012	13,319	12,471	12,222	11,298	11,194	11,162	10,349	10,000
Average Annual Return, Percent	9.52%	1.58%	2.84%
C000135928 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Delaware Tax-Free New York Fund (Institutional Class) – excluding sales charge
Average Annual Return, Percent	9.52%	1.58%	2.84%
Bloomberg Municipal Bond Index [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Bloomberg Municipal Bond Index
Account Value	$ 12,708	$ 12,708	$ 12,708	$ 11,979	$ 11,778	$ 12,891	$ 12,468	$ 12,077	$ 11,108	$ 11,054	$ 10,958	$ 10,252	$ 10,000
Average Annual Return, Percent	6.09%	1.02%	2.43%

Shareholder Report, Holdings (D

Shareholder Report, Holdings (Details)	Aug. 31, 2024
C000006409 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	4.68%
C000006409 [Member] | MINNESOTA
Holdings [Line Items]
Percent of Net Asset Value	93.33%
C000006409 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	38.07%
C000006409 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.71%
C000006409 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.63%
C000006409 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.43%
C000006409 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.49%
C000006409 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.28%
C000006409 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.97%
C000006409 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
C000006409 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
C000006409 [Member] | Pre Refunded Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.57%
C000006409 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.26%
C000006411 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	4.68%
C000006411 [Member] | MINNESOTA
Holdings [Line Items]
Percent of Net Asset Value	93.33%
C000006411 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	38.07%
C000006411 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.71%
C000006411 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.63%
C000006411 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.43%
C000006411 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.49%
C000006411 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.28%
C000006411 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.97%
C000006411 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
C000006411 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
C000006411 [Member] | Pre Refunded Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.57%
C000006411 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.26%
C000135925 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	4.68%
C000135925 [Member] | MINNESOTA
Holdings [Line Items]
Percent of Net Asset Value	93.33%
C000135925 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	38.07%
C000135925 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.71%
C000135925 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.63%
C000135925 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.43%
C000135925 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.49%
C000135925 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.28%
C000135925 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.97%
C000135925 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
C000135925 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
C000135925 [Member] | Pre Refunded Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.57%
C000135925 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.26%
C000006412 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	13.79%
C000006412 [Member] | ARIZONA
Holdings [Line Items]
Percent of Net Asset Value	3.44%
C000006412 [Member] | CALIFORNIA
Holdings [Line Items]
Percent of Net Asset Value	12.17%
C000006412 [Member] | FLORIDA
Holdings [Line Items]
Percent of Net Asset Value	6.30%
C000006412 [Member] | ILLINOIS
Holdings [Line Items]
Percent of Net Asset Value	5.74%
C000006412 [Member] | NEW YORK
Holdings [Line Items]
Percent of Net Asset Value	10.29%
C000006412 [Member] | PENNSYLVANIA
Holdings [Line Items]
Percent of Net Asset Value	2.97%
C000006412 [Member] | TEXAS
Holdings [Line Items]
Percent of Net Asset Value	6.58%
C000006412 [Member] | VIRGINIA
Holdings [Line Items]
Percent of Net Asset Value	3.48%
C000006412 [Member] | WISCONSIN
Holdings [Line Items]
Percent of Net Asset Value	3.64%
C000006412 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.16%
C000006412 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	19.78%
C000006412 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000006412 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9%
C000006412 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.05%
C000006412 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.06%
C000006412 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.21%
C000006412 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.71%
C000006412 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.82%
C000006412 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.65%
C000006414 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	13.79%
C000006414 [Member] | ARIZONA
Holdings [Line Items]
Percent of Net Asset Value	3.44%
C000006414 [Member] | CALIFORNIA
Holdings [Line Items]
Percent of Net Asset Value	12.17%
C000006414 [Member] | FLORIDA
Holdings [Line Items]
Percent of Net Asset Value	6.30%
C000006414 [Member] | ILLINOIS
Holdings [Line Items]
Percent of Net Asset Value	5.74%
C000006414 [Member] | NEW YORK
Holdings [Line Items]
Percent of Net Asset Value	10.29%
C000006414 [Member] | PENNSYLVANIA
Holdings [Line Items]
Percent of Net Asset Value	2.97%
C000006414 [Member] | TEXAS
Holdings [Line Items]
Percent of Net Asset Value	6.58%
C000006414 [Member] | VIRGINIA
Holdings [Line Items]
Percent of Net Asset Value	3.48%
C000006414 [Member] | WISCONSIN
Holdings [Line Items]
Percent of Net Asset Value	3.64%
C000006414 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.16%
C000006414 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	19.78%
C000006414 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000006414 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9%
C000006414 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.05%
C000006414 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.06%
C000006414 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.21%
C000006414 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.71%
C000006414 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.82%
C000006414 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.65%
C000074152 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	13.79%
C000074152 [Member] | ARIZONA
Holdings [Line Items]
Percent of Net Asset Value	3.44%
C000074152 [Member] | CALIFORNIA
Holdings [Line Items]
Percent of Net Asset Value	12.17%
C000074152 [Member] | FLORIDA
Holdings [Line Items]
Percent of Net Asset Value	6.30%
C000074152 [Member] | ILLINOIS
Holdings [Line Items]
Percent of Net Asset Value	5.74%
C000074152 [Member] | NEW YORK
Holdings [Line Items]
Percent of Net Asset Value	10.29%
C000074152 [Member] | PENNSYLVANIA
Holdings [Line Items]
Percent of Net Asset Value	2.97%
C000074152 [Member] | TEXAS
Holdings [Line Items]
Percent of Net Asset Value	6.58%
C000074152 [Member] | VIRGINIA
Holdings [Line Items]
Percent of Net Asset Value	3.48%
C000074152 [Member] | WISCONSIN
Holdings [Line Items]
Percent of Net Asset Value	3.64%
C000074152 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.16%
C000074152 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	19.78%
C000074152 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000074152 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9%
C000074152 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.05%
C000074152 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.06%
C000074152 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.21%
C000074152 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.71%
C000074152 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.82%
C000074152 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.65%
C000006415 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	1.20%
C000006415 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	12.70%
C000006415 [Member] | VIRGIN ISLANDS, US
Holdings [Line Items]
Percent of Net Asset Value	0.19%
C000006415 [Member] | CALIFORNIA
Holdings [Line Items]
Percent of Net Asset Value	83.70%
C000006415 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.74%
C000006415 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	18.26%
C000006415 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.02%
C000006415 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.16%
C000006415 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.60%
C000006415 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9.63%
C000006415 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.65%
C000006415 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.45%
C000006415 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.37%
C000006415 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.05%
C000006417 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	1.20%
C000006417 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	12.70%
C000006417 [Member] | VIRGIN ISLANDS, US
Holdings [Line Items]
Percent of Net Asset Value	0.19%
C000006417 [Member] | CALIFORNIA
Holdings [Line Items]
Percent of Net Asset Value	83.70%
C000006417 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.74%
C000006417 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	18.26%
C000006417 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.02%
C000006417 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.16%
C000006417 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.60%
C000006417 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9.63%
C000006417 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.65%
C000006417 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.45%
C000006417 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.37%
C000006417 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.05%
C000135926 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	1.20%
C000135926 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	12.70%
C000135926 [Member] | VIRGIN ISLANDS, US
Holdings [Line Items]
Percent of Net Asset Value	0.19%
C000135926 [Member] | CALIFORNIA
Holdings [Line Items]
Percent of Net Asset Value	83.70%
C000135926 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.74%
C000135926 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	18.26%
C000135926 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.02%
C000135926 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.16%
C000135926 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.60%
C000135926 [Member] | State General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9.63%
C000135926 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.65%
C000135926 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.45%
C000135926 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.37%
C000135926 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.05%
C000006418 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	0.54%
C000006418 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	16.19%
C000006418 [Member] | IDAHO
Holdings [Line Items]
Percent of Net Asset Value	82.58%
C000006418 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.93%
C000006418 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.67%
C000006418 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.49%
C000006418 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.29%
C000006418 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.61%
C000006418 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.80%
C000006418 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.70%
C000006418 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.62%
C000006418 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.07%
C000006418 [Member] | Water And Sewer Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.18%
C000006420 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	0.54%
C000006420 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	16.19%
C000006420 [Member] | IDAHO
Holdings [Line Items]
Percent of Net Asset Value	82.58%
C000006420 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.93%
C000006420 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.67%
C000006420 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.49%
C000006420 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.29%
C000006420 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.61%
C000006420 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.80%
C000006420 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.70%
C000006420 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.62%
C000006420 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.07%
C000006420 [Member] | Water And Sewer Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.18%
C000135927 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	0.54%
C000135927 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	16.19%
C000135927 [Member] | IDAHO
Holdings [Line Items]
Percent of Net Asset Value	82.58%
C000135927 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.93%
C000135927 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.67%
C000135927 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.49%
C000135927 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.29%
C000135927 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.61%
C000135927 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.80%
C000135927 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.70%
C000135927 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.62%
C000135927 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.07%
C000135927 [Member] | Water And Sewer Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.18%
C000006421 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	0.55%
C000006421 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	14.73%
C000006421 [Member] | VIRGIN ISLANDS, US
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000006421 [Member] | NEW YORK
Holdings [Line Items]
Percent of Net Asset Value	81%
C000006421 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.45%
C000006421 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.07%
C000006421 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.93%
C000006421 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.36%
C000006421 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.94%
C000006421 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.66%
C000006421 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.19%
C000006421 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000006421 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9%
C000006421 [Member] | Water And Sewer Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.85%
C000006423 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	0.55%
C000006423 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	14.73%
C000006423 [Member] | VIRGIN ISLANDS, US
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000006423 [Member] | NEW YORK
Holdings [Line Items]
Percent of Net Asset Value	81%
C000006423 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.45%
C000006423 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.07%
C000006423 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.93%
C000006423 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.36%
C000006423 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.94%
C000006423 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.66%
C000006423 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.19%
C000006423 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000006423 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9%
C000006423 [Member] | Water And Sewer Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.85%
C000135928 [Member] | GUAM
Holdings [Line Items]
Percent of Net Asset Value	0.55%
C000135928 [Member] | PUERTO RICO
Holdings [Line Items]
Percent of Net Asset Value	14.73%
C000135928 [Member] | VIRGIN ISLANDS, US
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000135928 [Member] | NEW YORK
Holdings [Line Items]
Percent of Net Asset Value	81%
C000135928 [Member] | Healthcare Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.45%
C000135928 [Member] | Education Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.07%
C000135928 [Member] | Local General Obligation Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.93%
C000135928 [Member] | Transportation Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.36%
C000135928 [Member] | Special Tax Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.94%
C000135928 [Member] | Housing Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.66%
C000135928 [Member] | Lease Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.19%
C000135928 [Member] | Electric Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000135928 [Member] | Industrial Development Revenue Pollution Control Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	9%
C000135928 [Member] | Water And Sewer Revenue Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.85%