State Street SPDR Portfolio Long Term Treasury Index ETF Investment Strategy - State Street SPDR Portfolio Long Term Treasury Index ETF	Jun. 30, 2026
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;text-transform:uppercase;">The Fund's Principal Investment Strategy</span>
Strategy Narrative [Text Block]	In seeking to track the performance of the Bloomberg Long U.S. Treasury Index (the “Index”), the Fund employs a sampling strategy, which means that the Fund is not required to purchase all of the securities represented in the Index. Instead, the Fund may purchase a subset of the securities in the Index in an effort to hold a portfolio of securities with generally the same risk and return characteristics of the Index. The quantity of holdings in the Fund will be based on a number of factors, including asset size of the Fund. Based on its analysis of these factors, SSGA Funds Management, Inc. (“SSGA FM” or the “Adviser”), the investment adviser to the Fund, either may invest the Fund's assets in a subset of securities in the Index or may invest the Fund's assets in substantially all of the securities represented in the Index in approximately the same proportions as the Index, as determined by the Adviser to be in the best interest of the Fund in pursuing its objective. The Fund is classified as “diversified” under the Investment Company Act of 1940, as amended; however, the Fund may become “non-diversified” solely as a result of tracking the Index (e.g., changes in weightings of one or more component securities). When the Fund is non-diversified, it may invest a relatively high percentage of its assets in a limited number of issuers.Under normal market conditions, the Fund will invest at least 80% of its net assets (plus the amount of borrowings for investment purposes) in the securities comprising the index it seeks to track. Prior to any change in this 80% investment policy, the Fund will provide shareholders with 60 days' notice. In addition, in seeking to track the Index, the Fund may invest in debt securities that are not included in the Index. The Fund may also invest in cash and cash equivalents or money market instruments (including money market funds advised by the Adviser) for cash management purposes. The Index is designed to measure the performance of public obligations of the U.S. Treasury that have a remaining maturity of 10 years or more.The Index includes all publicly issued, U.S. Treasury securities that have a remaining maturity of 10 years or more, are rated investment grade, and have $300 million or more of outstanding face value. In addition, the securities must be denominated in U.S. dollars and must be fixed rate and non-convertible. Excluded from the Index are certain special issues, such as flower bonds, targeted investor notes, state and local government series bonds, inflation protected public obligations of the U.S. Treasury, commonly known as “TIPS,” and coupon issues that have been stripped from bonds included in the Index. The Index is market capitalization weighted and the securities in the Index are updated on the last business day of each month. As of July 31, 2026, there were 99 securities in the Index.The Index is sponsored by Bloomberg Index Services Limited (the “Index Provider”), which is not affiliated with the Fund or the Adviser. The Index Provider determines the composition of the Index, relative weightings of the securities in the Index and publishes information regarding the market value of the Index.

State Street SPDR Portfolio Long Term Treasury Index ETF Investment Strategy - State Street SPDR Portfolio Long Term Treasury Index ETF

Jun. 30, 2026

<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;text-transform:uppercase;">The Fund's Principal Investment Strategy</span>

Strategy Narrative [Text Block]

In seeking to track the performance of the Bloomberg Long U.S. Treasury Index (the “Index”), the Fund employs a sampling strategy, which means that the Fund is not required to purchase all of the securities represented in the Index. Instead, the Fund may purchase a subset of the securities in the Index in an effort to hold a portfolio of securities with generally the same risk and return characteristics of the Index. The quantity of holdings in the Fund will be based on a number of factors, including asset size of the Fund. Based on its analysis of these factors, SSGA Funds Management, Inc. (“SSGA FM” or the “Adviser”), the investment adviser to the Fund, either may invest the Fund's assets in a subset of securities in the Index or may invest the Fund's assets in substantially all of the securities represented in the Index in approximately the same proportions as the Index, as determined by the Adviser to be in the best interest of the Fund in pursuing its objective. The Fund is classified as “diversified” under the Investment Company Act of 1940, as amended; however, the Fund may become “non-diversified” solely as a result of tracking the Index (e.g., changes in weightings of one or more component securities). When the Fund is non-diversified, it may invest a relatively high percentage of its assets in a limited number of issuers.Under normal market conditions, the Fund will invest at least 80% of its net assets (plus the amount of borrowings for investment purposes) in the securities comprising the index it seeks to track. Prior to any change in this 80% investment policy, the Fund will provide shareholders with 60 days' notice. In addition, in seeking to track the Index, the Fund may invest in debt securities that are not included in the Index. The Fund may also invest in cash and cash equivalents or money market instruments (including money market funds advised by the Adviser) for cash management purposes. The Index is designed to measure the performance of public obligations of the U.S. Treasury that have a remaining maturity of 10 years or more.The Index includes all publicly issued, U.S. Treasury securities that have a remaining maturity of 10 years or more, are rated investment grade, and have $300 million or more of outstanding face value. In addition, the securities must be denominated in U.S. dollars and must be fixed rate and non-convertible. Excluded from the Index are certain special issues, such as flower bonds, targeted investor notes, state and local government series bonds, inflation protected public obligations of the U.S. Treasury, commonly known as “TIPS,” and coupon issues that have been stripped from bonds included in the Index. The Index is market capitalization weighted and the securities in the Index are updated on the last business day of each month. As of July 31, 2026, there were 99 securities in the Index.The Index is sponsored by Bloomberg Index Services Limited (the “Index Provider”), which is not affiliated with the Fund or the Adviser. The Index Provider determines the composition of the Index, relative weightings of the securities in the Index and publishes information regarding the market value of the Index.