The Committee was established in May 19th, 1976 by the 94th Congress. Senator Daniel K. Inouye (D-Hawaii) became the first chairman of the committee when it was established until 1979.
The Committee is "select" in that membership is temporary and rotated among members of the chamber. The committee comprises 15 members. Eight of those seats are reserved for one majority and one minority member of each of the following committees: Appropriations, Armed Services, Foreign Relations, and Judiciary.
Of the remaining seven, four are members of the majority, and three are members of the minority. In addition, the Majority Leader and Minority Leader are non voting ex officio members of the committee. Also, the Chairman and Ranking Member of the Committee on Armed Services (if not already a member of the select Committee) are ex officio members.
As part of its oversight responsibilities, the Committee performs an annual review of the intelligence budget submitted by the president and prepares legislation authorizing appropriations for the various civilian and military agencies and departments comprising the intelligence community.
These entities include the Office of the Director of National Intelligence, Central Intelligence Agency, Defense Intelligence Agency, National Security Agency, National Geospatial-Intelligence Agency, National Reconnaissance Office, as well as the intelligence-related components of Department of State, Federal Bureau of Investigation, Department of the Treasury, and Department of Energy.
The Committee makes recommendations to the Senate Armed Services Committee on authorizations for the intelligence-related components of the U.S. Army, U.S. Navy, U.S. Air Force, and U.S. Marine Corps. The Committee also conducts periodic investigations, audits, and inspections of intelligence activities and programs.
According to en.wikipedia