Nuveen Large Cap Select Fund (FLRYX) N-CSR 8 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	NUVEEN INVESTMENT FUNDS INC
Entity Central Index Key	0000820892
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	NUVEEN INVESTMENT FUNDS INC
Entity Central Index Key	0000820892
Entity Investment Company Type	N-1A
Document Period End Date	Aug. 31, 2024
C000015185 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Strategic Income Fund
Class Name	Class A Shares
Trading Symbol	FCDDX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class A Shares of the Nuveen Strategic Income 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 at https://www.nuveen.com/en‑us/mutual‑funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en‑us/mutual‑funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class A Shares $87  0.82% * Annualized for period less than one year.
Expenses Paid, Amount	$ 87
Expense Ratio, Percent	0.82%	[1]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Strategic Income Fund returned 11.04% for Class A Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund outperformed the Bloomberg US Aggregate Bond Index, which returned 7.3%. •  Top contributors to relative performance »   Out-of-benchmark allocation to mortgage credit, particularly agency credit risk transfers. »   Out-of-benchmark exposure to preferred securities. »   Out-of-benchmark exposure to below-investment-grade securities. •  Top detractors from relative performance »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1‑Year 5‑Year 10‑Year Class A Shares at NAV (excluding maximum sales charge) 11.04 % 2.63 % 2.85 % Class A Shares at maximum sales charge (Offering Price) 6.36 % 1.74 % 2.41 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.64 % Lipper Multi-Sector Income Funds Classification Average 9.66 % 1.94 % 2.80 %
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]	For most recent month-end performance, go to https://www.nuveen.com/en-us/mutual-funds/prospectuses or call (800) 257-8787.
Net Assets	$ 916,646,285
Holdings Count | Holding	607
Advisory Fees Paid, Amount	$ 3,993,167
Investment Company Portfolio Turnover	60%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 916,646,285 Total number of portfolio holdings 607 Portfolio turnover (%) 60% Total management fees paid for the year $ 3,993,167
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
C000015187 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Strategic Income Fund
Class Name	Class C Shares
Trading Symbol	FCBCX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class C Shares of the Nuveen Strategic Income 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 at https://www.nuveen.com/en‑us/mutual‑funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en‑us/mutual‑funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class C Shares $165 1.57% * Annualized for period less than one year.
Expenses Paid, Amount	$ 165
Expense Ratio, Percent	1.57%	[2]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Strategic Income Fund returned 10.11% for Class C Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund outperformed the Bloomberg US Aggregate Bond Index, which returned 7.3%. •  Top contributors to relative performance »   Out-of-benchmark allocation to mortgage credit, particularly agency credit risk transfers. »   Out-of-benchmark exposure to preferred securities. »   Out-of-benchmark exposure to below-investment-grade securities. •  Top detractors from relative performance »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1‑Year 5‑Year 10‑Year Class C Shares at NAV (excluding maximum sales charge) 10.11 % 1.87 % 2.25 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.64 % Lipper Multi-Sector Income Funds Classification Average 9.66 % 1.94 % 2.80 %
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]	For most recent month-end performance, go to https://www.nuveen.com/en-us/mutual-funds/prospectuses or call (800) 257-8787.
Net Assets	$ 916,646,285
Holdings Count | Holding	607
Advisory Fees Paid, Amount	$ 3,993,167
Investment Company Portfolio Turnover	60%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 916,646,285 Total number of portfolio holdings 607 Portfolio turnover (%) 60% Total management fees paid for the year $ 3,993,167
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
C000151934 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Strategic Income Fund
Class Name	Class R6 Shares
Trading Symbol	FSFRX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class R6 Shares of the Nuveen Strategic Income 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 at https://www.nuveen.com/en-us/mutual-funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class R6 Shares $51 0.48% * Annualized for period less than one year.
Expenses Paid, Amount	$ 51
Expense Ratio, Percent	0.48%	[3]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Strategic Income Fund returned 11.28% for Class R6 Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund outperformed the Bloomberg US Aggregate Bond Index, which returned 7.3%. •  Top contributors to relative performance »   Out-of-benchmark allocation to mortgage credit, particularly agency credit risk transfers. »   Out-of-benchmark exposure to preferred securities. »   Out-of-benchmark exposure to below-investment-grade securities. •  Top detractors from relative performance »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1‑Year 5‑Year Since Inception Class R6 Shares at NAV 11.28 % 2.96 % 3.45 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.44 % Lipper Multi-Sector Income Funds Classification Average 9.66 % 1.94 % 3.03 %
Performance Inception Date	Jan. 20, 2015
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]	For most recent month-end performance, go to https://www.nuveen.com/en-us/mutual-funds/prospectuses or call (800) 257-8787.
Net Assets	$ 916,646,285
Holdings Count | Holding	607
Advisory Fees Paid, Amount	$ 3,993,167
Investment Company Portfolio Turnover	60%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 916,646,285 Total number of portfolio holdings 607 Portfolio turnover (%) 60% Total management fees paid for the year $ 3,993,167
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
C000015189 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Strategic Income Fund
Class Name	Class I Shares
Trading Symbol	FCBYX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class I Shares of the Nuveen Strategic Income 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 at https://www.nuveen.com/en‑us/mutual‑funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en‑us/mutual‑funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class I Shares $60  0.57% * Annualized for period less than one year.
Expenses Paid, Amount	$ 60
Expense Ratio, Percent	0.57%	[4]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Strategic Income Fund returned 11.32% for Class I Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund significantly outperformed the Bloomberg US Aggregate Bond Index, which returned 7.3%. •  Top contributors to relative performance »   Out-of-benchmark allocation to mortgage credit, particularly agency credit risk transfers. »   Out-of-benchmark exposure to preferred securities. »   Out-of-benchmark exposure to below-investment-grade securities. •  Top detractors from relative performance »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1‑Year 5‑Year 10‑Year Class I Shares at NAV 11.32 % 2.88 % 3.11 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.64 % Lipper Multi-Sector Income Funds Classification Average 9.66 % 1.94 % 2.80 %
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]	For most recent month-end performance, go to https://www.nuveen.com/en-us/mutual-funds/prospectuses or call (800) 257-8787.
Net Assets	$ 916,646,285
Holdings Count | Holding	607
Advisory Fees Paid, Amount	$ 3,993,167
Investment Company Portfolio Turnover	60%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 916,646,285 Total number of portfolio holdings 607 Portfolio turnover (%) 60% Total management fees paid for the year $ 3,993,167
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
C000015076 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Credit Income Fund
Class Name	Class A Shares
Trading Symbol	FJSIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class A Shares of the Nuveen Credit Income 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 at https://www.nuveen.com/en‑us/mutual‑funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en‑us/mutual‑funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class A Shares $111  1.04% * Annualized for period less than one year.
Expenses Paid, Amount	$ 111
Expense Ratio, Percent	1.04%	[5]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Credit Income Fund returned 14.38% for Class A Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund outperformed the Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index, which returned 12.53%. •  Top contributors to relative performance »   Security selection within the high-yield corporate bond allocation, notably in the communications, consumer non-cyclical, and technology industries. »   Out-of-benchmark allocation to mortgage credit, including agency credit risk transfers. »   Out-of-benchmark allocation to emerging markets debt (EMD), particularly below‑investment‑grade securities. •  Top detractors from relative performance »   Out-of-benchmark allocation to commercial mortgage-backed securities (CMBS), particularly exposure to office properties. »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1‑Year 5‑Year 10‑Year Class A Shares at NAV (excluding maximum sales charge) 14.38 % 3.86 % 3.30 % Class A Shares at maximum sales charge (Offering Price) 8.90 % 2.86 % 2.80 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.64 % Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index 12.53 % 4.44 % 4.65 % Lipper Global High Yield Funds Classification Average 12.05 % 3.56 % 3.61 %
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]	For most recent month‑end performance, go to https://www.nuveen.com/en‑us/mutual‑funds/prospectuses or call (800) 257‑8787.
Net Assets	$ 87,654,718
Holdings Count | Holding	251
Advisory Fees Paid, Amount	$ 480,574
Investment Company Portfolio Turnover	133%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 87,654,718 Total number of portfolio holdings 251 Portfolio turnover (%) 133% Total management fees paid for the year $ 480,574
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
C000015078 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Credit Income Fund
Class Name	Class C Shares
Trading Symbol	FCSIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class C Shares of the Nuveen Credit Income 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 at https://www.nuveen.com/en‑us/mutual‑funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en‑us/mutual‑funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class C Shares $191  1.79% * Annualized for period less than one year.
Expenses Paid, Amount	$ 191
Expense Ratio, Percent	1.79%	[6]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Credit Income Fund returned 13.57% for Class C Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund outperformed the Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index, which returned 12.53%. •  Top contributors to relative performance »   Security selection within the high-yield corporate bond allocation, notably in the communications, consumer non-cyclical, and technology industries. »   Out-of-benchmark allocation to mortgage credit, including agency credit risk transfers. »   Out-of-benchmark allocation to emerging markets debt (EMD), particularly below‑investment‑grade securities. •  Top detractors from relative performance »   Out-of-benchmark allocation to commercial mortgage-backed securities (CMBS), particularly exposure to office properties. »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1-Year 5-Year 10-Year Class C Shares at NAV (excluding maximum sales charge) 13.57 % 3.09 % 2.68 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.64 % Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index 12.53 % 4.44 % 4.65 % Lipper Global High Yield Funds Classification Average 12.05 % 3.56 % 3.61 %
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]	For most recent month-end performance, go to https://www.nuveen.com/en-us/mutual-funds/prospectuses or call (800) 257-8787.
Net Assets	$ 87,654,718
Holdings Count | Holding	251
Advisory Fees Paid, Amount	$ 480,574
Investment Company Portfolio Turnover	133%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 87,654,718 Total number of portfolio holdings 251 Portfolio turnover (%) 133% Total management fees paid for the year $ 480,574
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
C000015080 [Member]
Shareholder Report [Line Items]
Fund Name	Nuveen Credit Income Fund
Class Name	Class I Shares
Trading Symbol	FJSYX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about the Class I Shares of the Nuveen Credit Income 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 at https://www.nuveen.com/en‑us/mutual‑funds/prospectuses. You can also request this information by contacting us at (800) 257-8787.
Material Fund Change Notice [Text Block]	This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number	(800) 257-8787
Additional Information Website	https://www.nuveen.com/en‑us/mutual‑funds/prospectuses
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Cost of a  $10,000 investment  Costs paid as a percentage of Class I Shares $85  0.79% * Annualized for period less than one year.
Expenses Paid, Amount	$ 85
Expense Ratio, Percent	0.79%	[7]
Factors Affecting Performance [Text Block]	How did the Fund perform last year? What affected the Fund’s performance? Performance Highlights •  The Nuveen Credit Income Fund returned 14.67% for Class I Shares at net asset value (NAV) for the 12 months ended August 31, 2024. The Fund outperformed the Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index, which returned 12.53%. •  Top contributors to relative performance »   Security selection within the high-yield corporate bond allocation, notably in the communications, consumer non-cyclical, and technology industries. »   Out-of-benchmark allocation to mortgage credit, including agency credit risk transfers. »   Out-of-benchmark allocation to emerging markets debt (EMD), particularly below‑investment‑grade securities. •  Top detractors from relative performance »   Out-of-benchmark allocation to commercial mortgage-backed securities (CMBS), particularly exposure to office properties. »   Shorter-duration positioning. Performance Attribution
Performance Past Does Not Indicate Future [Text]	Performance data shown represents past performance and does not predict or guarantee future results.
Line Graph [Table Text Block]
Average Annual Return [Table Text Block]	Average Annual Total Returns 1‑Year 5‑Year 10‑Year Class I Shares at NAV 14.67 % 4.07 % 3.54 % Bloomberg U.S. Aggregate Bond Index 7.30 % (0.04 )% 1.64 % Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index 12.53 % 4.44 % 4.65 % Lipper Global High Yield Funds Classification Average 12.05 % 3.56 % 3.61 %
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]	For most recent month‑end performance, go to https://www.nuveen.com/en‑us/mutual‑funds/prospectuses or call (800) 257‑8787.
Net Assets	$ 87,654,718
Holdings Count | Holding	251
Advisory Fees Paid, Amount	$ 480,574
Investment Company Portfolio Turnover	133%
Additional Fund Statistics [Text Block]	Fund Statistics (as of August 31, 2024) Fund net assets $ 87,654,718 Total number of portfolio holdings 251 Portfolio turnover (%) 133% Total management fees paid for the year $ 480,574
Holdings [Text Block]	(1)
Credit Ratings Selection [Text Block]	The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
Material Fund Change [Text Block]	How has the Fund changed? • Management fees: For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Material Fund Change Expenses [Text Block]	• Management fees:
Summary of Change Legend [Text Block]	For more complete information, you may review the Fund’s next prospectus, which is expected to be available by December 30, 2024 at https://www.nuveen.com/en-us/mutual-funds/prospectuses
Updated Prospectus Phone Number	(800) 257- 8787
Updated Prospectus Web Address	https://www.nuveen.com/en-us/mutual-funds/prospectuses
Accountant Change Disagreements [Text Block]	Changes in independent registered public accounting firm On October 24, 2024, the Fund’s Board of Directors engaged PricewaterhouseCoopers LLP (“PwC”) as the independent registered public accounting firm for the Fund and dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Fund subject to the completion of the August 31, 2024 fiscal year end audit. During the Fund’s fiscal years ended August 31, 2024 and August 31, 2023, and the subsequent interim period through October 29, 2024, there have been no disagreements with KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedures.
[1]Annualized for period less than one year.[2]Annualized for period less than one year.[3]Annualized for period less than one year.[4]Annualized for period less than one year.[5]Annualized for period less than one year.[6]Annualized for period less than one year.[7]Annualized for period less than one year.

Shareholder Report, Line Graph

Shareholder Report, Line Graph (Details) - USD ($)	12 Months Ended	60 Months Ended	115 Months Ended	120 Months Ended
	Aug. 31, 2024	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	Jan. 20, 2015	Aug. 31, 2014
C000015185 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class A Shares at maximum sales charge (Offering Price)
Account Value	$ 12,690	$ 12,690	$ 12,690	$ 12,690	$ 11,428	$ 11,126	$ 12,397	$ 11,747	$ 11,148	$ 10,201	$ 10,262	$ 9,857	$ 9,269		$ 9,579
Average Annual Return, Percent	6.36%	1.74%		2.41%
C000015185 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class A Shares at NAV (excluding maximum sales charge)
Account Value	$ 13,248	$ 13,248	13,248	$ 13,248	11,931	11,616	12,942	12,264	11,638	10,650	10,713	10,290	9,677		10,000
Average Annual Return, Percent	11.04%	2.63%		2.85%
C000015187 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class C Shares at NAV (excluding maximum sales charge)
Account Value	$ 12,487	$ 12,487	12,487	$ 12,487	11,245	10,948	12,289	11,740	11,215	10,346	10,490	10,145	9,606		10,000
Average Annual Return, Percent	10.11%	1.87%		2.25%
C000151934 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class R6 Shares at NAV
Account Value	$ 13,859	$ 13,859	$ 13,859	$ 13,859	12,455	12,081	13,416	12,671	11,976	10,923	10,952	10,477	9,820	$ 10,000
Average Annual Return, Percent	11.28%	2.96%	3.45%
C000015189 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class I Shares at NAV
Account Value	$ 13,589	$ 13,589	$ 13,589	$ 13,589	12,207	11,855	13,184	12,462	11,789	10,763	10,802	10,343	9,702		10,000
Average Annual Return, Percent	11.32%	2.88%		3.11%
C000015076 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class A Shares at maximum sales charge (Offering Price)
Account Value	$ 13,181	$ 13,181	13,181	$ 13,181	11,524	10,784	12,014	10,872	10,907	10,388	10,026	9,003	8,607		9,524
Average Annual Return, Percent	8.90%	2.86%		2.80%
C000015076 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class A Shares at NAV (excluding maximum sales charge)
Account Value	$ 13,841	$ 13,841	13,841	$ 13,841	12,101	11,323	12,615	11,416	11,452	10,908	10,527	9,453	9,037		10,000
Average Annual Return, Percent	14.38%	3.86%		3.30%
C000015078 [Member] | Without Sales Load [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class C Shares at NAV (excluding maximum sales charge)
Account Value	$ 13,032	$ 13,032	13,032	$ 13,032	11,394	10,661	11,972	10,928	11,031	10,587	10,297	9,313	8,975		10,000
Average Annual Return, Percent	13.57%	3.09%		2.68%
C000015080 [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Class I Shares at NAV
Account Value	$ 14,166	$ 14,166	14,166	$ 14,166	12,354	11,529	12,827	11,583	11,606	11,014	10,607	9,506	9,064		10,000
Average Annual Return, Percent	14.67%	4.07%		3.54%
Bloomberg U S Aggregate Bond Index [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index
Account Value	$ 11,765	$ 11,765	11,765	$ 11,765	10,965	11,098	12,542	12,553	11,789	10,701	10,814	10,761	10,156	$ 10,000	10,000
Average Annual Return, Percent	7.30%	(0.04%)		1.64%
Bloomberg U S Aggregate Bond C000151934 Index [Member]
Account Value [Line Items]
Account Value	$ 11,473	$ 11,473	$ 11,473	$ 11,473	10,693	10,822	12,231	12,241	11,497	10,435	10,546	10,494	9,903
Average Annual Return, Percent			1.44%
Lipper Multi Sector Income Funds Classification Average [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Lipper Multi-Sector Income Funds Classification Average
Average Annual Return, Percent	9.66%	1.94%	3.03%	2.80%
Bloomberg U S Corporate High Yield 2 Issuer Capped Bond Index [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Corporate High Yield 2% Issuer Capped Bond Index
Account Value	$ 15,754	$ 15,754	$ 15,754	$ 15,754	$ 14,000	$ 13,062	$ 14,611	$ 13,267	$ 12,677	$ 11,897	$ 11,506	$ 10,592	$ 9,707		$ 10,000
Average Annual Return, Percent	12.53%	4.44%		4.65%
Lipper Global High Yield Funds Classification Average [Member]
Account Value [Line Items]
Line Graph and Table Measure Name	Lipper Global High Yield Funds Classification Average
Average Annual Return, Percent	12.05%	3.56%		3.61%

Shareholder Report, Holdings (D

Shareholder Report, Holdings (Details)	Aug. 31, 2024
C000015185 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	25.80%	[1]
C000015185 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	13.80%	[1]
C000015185 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	14.30%	[1]
C000015185 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.90%	[1]
C000015185 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%	[1]
C000015185 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	25.50%	[1]
C000015185 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[1]
C000015185 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	13.10%
C000015185 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	19.30%
C000015185 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	34%
C000015185 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	1.10%
C000015185 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.10%
C000015185 [Member] | US Government Corporations and Agencies Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.50%
C000015185 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	6.70%
C000015185 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	5.70%
C000015185 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%
C000015185 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.40%
C000015185 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	0.60%
C000015185 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.10%
C000015187 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	25.80%	[2]
C000015187 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	13.80%	[2]
C000015187 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	14.30%	[2]
C000015187 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.90%	[2]
C000015187 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%	[2]
C000015187 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	25.50%	[2]
C000015187 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[2]
C000015187 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	13.10%
C000015187 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	19.30%
C000015187 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	34%
C000015187 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	1.10%
C000015187 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.10%
C000015187 [Member] | US Government Corporations and Agencies Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.50%
C000015187 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	6.70%
C000015187 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	5.70%
C000015187 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%
C000015187 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.40%
C000015187 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	0.60%
C000015187 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.10%
C000151934 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	25.80%	[3]
C000151934 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	13.80%	[3]
C000151934 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	14.30%	[3]
C000151934 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.90%	[3]
C000151934 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%	[3]
C000151934 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	25.50%	[3]
C000151934 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[3]
C000151934 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	13.10%
C000151934 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	19.30%
C000151934 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	34%
C000151934 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	1.10%
C000151934 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.10%
C000151934 [Member] | US Government Corporations and Agencies Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.50%
C000151934 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	6.70%
C000151934 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	5.70%
C000151934 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%
C000151934 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.40%
C000151934 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	0.60%
C000151934 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.10%
C000015189 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	25.80%	[4]
C000015189 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	13.80%	[4]
C000015189 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	14.30%	[4]
C000015189 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.90%	[4]
C000015189 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%	[4]
C000015189 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	25.50%	[4]
C000015189 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[4]
C000015189 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	13.10%
C000015189 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	19.30%
C000015189 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	34%
C000015189 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	1.10%
C000015189 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.10%
C000015189 [Member] | US Government Corporations and Agencies Securities [Member]
Holdings [Line Items]
Percent of Total Investments	6.50%
C000015189 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	6.70%
C000015189 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	5.70%
C000015189 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%
C000015189 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.40%
C000015189 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	0.60%
C000015189 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.10%
C000015076 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	76.20%	[5]
C000015076 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	10.60%	[5]
C000015076 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%	[5]
C000015076 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%	[5]
C000015076 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	6.40%	[5]
C000015076 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.40%	[5]
C000015076 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	8%
C000015076 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	57.10%
C000015076 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%
C000015076 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	3.60%
C000015076 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	3%
C000015076 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	1.80%
C000015076 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	8.70%
C000015076 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.60%
C000015076 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	4.60%
C000015076 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%
C000015076 [Member] | Common Stock [Member]
Holdings [Line Items]
Percent of Total Investments	0%
C000015078 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	76.20%	[6]
C000015078 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	10.60%	[6]
C000015078 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%	[6]
C000015078 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%	[6]
C000015078 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	6.40%	[6]
C000015078 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.40%	[6]
C000015078 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	8%
C000015078 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	57.10%
C000015078 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%
C000015078 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	3.60%
C000015078 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	3%
C000015078 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	1.80%
C000015078 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	8.70%
C000015078 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.60%
C000015078 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	4.60%
C000015078 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%
C000015078 [Member] | Common Stock [Member]
Holdings [Line Items]
Percent of Total Investments	0%
C000015080 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	76.20%	[7]
C000015080 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	10.60%	[7]
C000015080 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%	[7]
C000015080 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%	[7]
C000015080 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	6.40%	[7]
C000015080 [Member] | N A not applicable [Member]
Holdings [Line Items]
Percent of Total Investments	6.40%	[7]
C000015080 [Member] | Asset-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	8%
C000015080 [Member] | Corporate Bond Securities [Member]
Holdings [Line Items]
Percent of Total Investments	57.10%
C000015080 [Member] | Collateralized Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Total Investments	10.40%
C000015080 [Member] | Sovereign Debt Securities [Member]
Holdings [Line Items]
Percent of Total Investments	3.60%
C000015080 [Member] | One Thousand Par or similar Institutional Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	3%
C000015080 [Member] | Short Term Repurchase Agreements [Member]
Holdings [Line Items]
Percent of Total Investments	1.80%
C000015080 [Member] | Variable Rate Senior Loan Interests [Member]
Holdings [Line Items]
Percent of Total Investments	8.70%
C000015080 [Member] | Contingent Capital Securities [Member]
Holdings [Line Items]
Percent of Total Investments	2.60%
C000015080 [Member] | Investments Purchased with Collateral from Securities Lending [Member]
Holdings [Line Items]
Percent of Total Investments	4.60%
C000015080 [Member] | Twenty Five Par or similar Retail Preferred [Member]
Holdings [Line Items]
Percent of Total Investments	0.20%
C000015080 [Member] | Common Stock [Member]
Holdings [Line Items]
Percent of Total Investments	0%
[1]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.[2]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.[3]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.[4]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.[5]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.[6]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.[7]The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.