S000005563 [Member] Annual Total Returns

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Nuveen Real Estate Securities Fund | Class A

Prospectus [Line Items]

Annual Return [Percent]

^[1]

2.32%

5.78%

11.22%

(24.87%)

40.98%

(6.37%)

25.24%

(5.78%)

5.34%

6.58%

[1]	Class A year-to-date total return as of March 31, 2026 was 4.21%. The performance of the other share classes will differ due to their different expense structures.