I have worked for bigger corps where my manager has no idea what I do, especially consulting service companies. If I’ve worked with 7 clients over 3 different account groups, I am the only one who knows what those 7 clients are, and what I did for them. In those cases I do document my accomplishments. I have even gone as far as create a brief presentation for when I get a new manager.
This also differs from a CV not only in being more detailed, but also flagging things like “successfully worked with XYZ account manager, who is widely known to be difficult to work with”.