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S000012717 [Member] Investment Strategy - GLOBAL REAL ESTATE INDEX FUND
Mar. 31, 2026
Prospectus [Line Items]  
Strategy [Heading] PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]
Under normal circumstances, the Fund will invest substantially all (and at least 80%) of its net assets in equity securities included in the Index, in weightings that approximate the relative composition of the securities contained in the Index, and in American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”), and Global Depositary Receipts (“GDRs”) representing such securities. The Index is a free float-adjusted, market capitalization global index that consists of large, mid and small‑cap stocks across 23 Developed Markets (DM) and 24 Emerging Markets (EM) engaged in the ownership, development and management of specific core property type real estate, as determined by the index provider. The Index excludes companies, such as real estate services and real estate financing companies, that do not own properties. The Fund will concentrate its investments (i.e., invest at least 25% or more of its total assets) in issuers principally engaged in real estate activities.
As of May 29, 2026, the Index was comprised of 472 constituents with market capitalizations ranging from $18.13 million to $140.92 billion. The Index is rebalanced quarterly. The Fund generally rebalances its portfolio in accordance with the Index.
NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” the index it tracks and does not seek temporary defensive positions when markets decline or appear overvalued. NTI will buy and sell securities in response to changes in the Index as well as in response to subscriptions and redemptions. The Fund generally invests in substantially all of the securities in the Index in approximately the same proportions as the Index (i.e., replication). In certain circumstances, however, the Fund may not hold every security
in the Index or in the same proportion as the Index, such as to improve tax efficiency or when it may not be practicable to fully implement a replication strategy. Rather, it will use an optimization strategy to seek to construct a portfolio that minimizes tracking error versus the Index while managing transaction costs and realized capital gains and losses.
The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. A “non‑diversified” fund can invest a greater percentage of its assets in a small group of issuers or in any one issuer than a diversified fund can. Shareholder approval will not be sought if the Fund becomes non‑diversified due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.
In seeking to track the performance of the Index, from time to time the Fund may have a focused investment (i.e., investment exposure comprising more than 15% of its total assets) in one or more particular countries and/or geographic regions.
NTI expects that, under normal circumstances, the quarterly performance of the Fund, before fees and expenses, will track the performance of the Index within a 0.95 correlation coefficient.
The Index is created and sponsored by Morgan Stanley Capital International, Inc. (“MSCI”), as the index provider. MSCI determines the composition and relative weightings of the securities in the Index and publishes information regarding the market value of the Index. MSCI does not endorse any of the securities in the Index. It is not a sponsor of the Global Real Estate Index Fund and is not affiliated with the Fund in any way.
Strategy Portfolio Concentration [Text] The Fund will concentrate its investments (i.e., invest at least 25% or more of its total assets) in issuers principally engaged in real estate activities.