S000005544 [Member] Annual Fund Operating Expenses - Nuveen Credit Income Fund	Aug. 31, 2025
Prospectus [Line Items]
Fee Waiver or Reimbursement over Assets, Date of Termination	July 31, 2027
Class A
Prospectus [Line Items]
Management Fees (as a percentage of Assets)	0.56%
Distribution and Service (12b-1) Fees	0.25%
Other Expenses (as a percentage of Assets):	0.26%
Expenses (as a percentage of Assets)	1.07%
Fee Waiver or Reimbursement	(0.11%)	[1]
Net Expenses (as a percentage of Assets)	0.96%
Class C
Prospectus [Line Items]
Management Fees (as a percentage of Assets)	0.56%
Distribution and Service (12b-1) Fees	1.00%
Other Expenses (as a percentage of Assets):	0.26%
Expenses (as a percentage of Assets)	1.82%
Fee Waiver or Reimbursement	(0.11%)	[1]
Net Expenses (as a percentage of Assets)	1.71%
Class I
Prospectus [Line Items]
Management Fees (as a percentage of Assets)	0.56%
Distribution and Service (12b-1) Fees	0.00%
Other Expenses (as a percentage of Assets):	0.26%
Expenses (as a percentage of Assets)	0.82%
Fee Waiver or Reimbursement	(0.11%)	[1]
Net Expenses (as a percentage of Assets)	0.71%

[1] The Fund’s investment adviser has agreed to waive fees and/or reimburse expenses through July 31, 2027 so that the total annual operating expenses of the Fund (excluding 12b-1 distribution and/or service fees, interest expenses, taxes, acquired fund fees and expenses, fees incurred in acquiring and disposing of portfolio securities and extraordinary expenses) do not exceed 0.75% of the average daily net assets of any class of Fund shares. This expense limitation may be terminated or modified prior to July 31, 2027 only with the approval of the Board of Directors of the Fund.