Answer: it means that US governments, each in its own way and in different historical contexts, applied containment doctrine in its worldwide politics. This is true even in times of so-called "détente" (relaxation in international affairs promoted by Nixon, Kissinger, Brezhnev).
Explanation: it means that Cold War (1947-1989) forms one consistent era, historical period. Of course, it can be subdivided in various phases but containment doctrine can be understood as a basic paradigm or frame of reference of American (Western) international policy.