| Form N-CSR Cover | 6 Months Ended |
| Sep. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | NUVEEN INVESTMENT FUNDS INC |
| Entity Central Index Key | 0000820892 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Sep. 30, 2024 |
| Shareholder Report | 6 Months Ended | |
| Sep. 30, 2024 USD ($) Holding | ||
| Shareholder Report [Line Items] | ||
| Document Type | N-CSRS | |
| Amendment Flag | false | |
| Registrant Name | NUVEEN INVESTMENT FUNDS INC | |
| Entity Central Index Key | 0000820892 | |
| Entity Investment Company Type | N-1A | |
| Document Period End Date | Sep. 30, 2024 | |
| C000015152 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Nuveen Short Term Municipal Bond Fund | |
| Class Name | Class A Shares | |
| Trading Symbol | FSHAX | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the Class A Shares of the Nuveen Short Term Municipal Bond Fund for the period of April 1, 2024 to September 30, 2024. | |
| Shareholder Report Annual or Semi-Annual | semi-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. | |
| 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 six months? (based on a hypothetical $10,000 investment) Cost of a $10,000 investment Costs paid as a percentage of Class A Shares $33 0.65% * Annualized for period less than one year. | |
| Expenses Paid, Amount | $ 33 | |
| Expense Ratio, Percent | 0.65% | [1] |
| Net Assets | $ 424,417,570 | |
| Holdings Count | Holding | 296 | |
| Investment Company Portfolio Turnover | 13% | |
| Additional Fund Statistics [Text Block] | Fund Statistics (as of September 30, 2024) Fund net assets $ 424,417,570 Total number of portfolio holdings 296 Portfolio turnover (%) 13% | |
| 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. | |
| C000137682 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Nuveen Short Term Municipal Bond Fund | |
| Class Name | Class C Shares | |
| Trading Symbol | NAAEX | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the Class C Shares of the Nuveen Short Term Municipal Bond Fund for the period of April 1, 2024 to September 30, 2024. | |
| Shareholder Report Annual or Semi-Annual | semi-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. | |
| 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 six months? (based on a hypothetical $10,000 investment) Cost of a Costs paid as a percentage of Class C Shares $73 1.45% * Annualized for period less than one year. | |
| Expenses Paid, Amount | $ 73 | |
| Expense Ratio, Percent | 1.45% | [2] |
| Net Assets | $ 424,417,570 | |
| Holdings Count | Holding | 296 | |
| Investment Company Portfolio Turnover | 13% | |
| Additional Fund Statistics [Text Block] | Fund Statistics (as of September 30, 2024) Fund net assets $ 424,417,570 Total number of portfolio holdings 296 Portfolio turnover (%) 13% | |
| 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. | |
| C000015153 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Nuveen Short Term Municipal Bond Fund | |
| Class Name | Class I Shares | |
| Trading Symbol | FSHYX | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the Class I Shares of the Nuveen Short Term Municipal Bond Fund for the period of April 1, 2024 to September 30, 2024. | |
| Shareholder Report Annual or Semi-Annual | semi-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. | |
| 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 six months? (based on a hypothetical $10,000 investment) Cost of a $10,000 investment Costs paid as a percentage of Class I Shares $23 0.45% * Annualized for period less than one year. | |
| Expenses Paid, Amount | $ 23 | |
| Expense Ratio, Percent | 0.45% | [3] |
| Net Assets | $ 424,417,570 | |
| Holdings Count | Holding | 296 | |
| Investment Company Portfolio Turnover | 13% | |
| Additional Fund Statistics [Text Block] | Fund statistics (as of September 30, 2024) Fund net assets $ 424,417,570 Total number of portfolio holdings 296 Portfolio turnover (%) 13% | |
| 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. | |
| [1]Annualized for period less than one year.[2]Annualized for period less than one year.[3]Annualized for period less than one year. | ||
| Shareholder Report, Holdings (Details) | Sep. 30, 2024 | |
| C000015152 [Member] | BB or Lower [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [1] |
| C000015152 [Member] | N R not rated [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.50% | [1] |
| C000015152 [Member] | Standard & Poor's, AAA Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10.30% | [1] |
| C000015152 [Member] | Standard & Poor's, AA Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 48.20% | [1] |
| C000015152 [Member] | Standard & Poor's, A Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 31.30% | [1] |
| C000015152 [Member] | Standard & Poor's, BBB Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 3.80% | [1] |
| C000015152 [Member] | Municipal Bonds [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 100% | |
| C000137682 [Member] | BB or Lower [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [2] |
| C000137682 [Member] | N R not rated [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.50% | [2] |
| C000137682 [Member] | Standard & Poor's, AAA Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10.30% | [2] |
| C000137682 [Member] | Standard & Poor's, AA Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 48.20% | [2] |
| C000137682 [Member] | Standard & Poor's, A Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 31.30% | [2] |
| C000137682 [Member] | Standard & Poor's, BBB Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 3.80% | [2] |
| C000137682 [Member] | Municipal Bonds [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 100% | |
| C000015153 [Member] | BB or Lower [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [3] |
| C000015153 [Member] | N R not rated [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.50% | [3] |
| C000015153 [Member] | Standard & Poor's, AAA Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10.30% | [3] |
| C000015153 [Member] | Standard & Poor's, AA Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 48.20% | [3] |
| C000015153 [Member] | Standard & Poor's, A Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 31.30% | [3] |
| C000015153 [Member] | Standard & Poor's, BBB Rating [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 3.80% | [3] |
| C000015153 [Member] | Municipal Bonds [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 100% | |
| [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. | ||
