WASHINGTON — The Obama administration on Wednesday released formerly classified documents outlining a once-secret program of the National Security Agency that is collecting records of all domestic phone calls in the United States, as top officials testified before the Senate Judiciary Committee. As the hearing began, The Guardian newspaper published another document from the archives of Top Secret surveillance matters leaked to it by the former N.S.A. contractor Edward J. Snowden. It was a 32-page presentation describing the N.S.A.´s XKeyscore program, by which N.S.A. analysts can mine vast databases of phone and Internet information the agency has vacuumed up.