By default the ps command displays a mixture of numeric and names for user IDs.
Its cutoff limit for textual user IDs is 8 characters.

To change this, use your own format string, e.g.:

ps -eHo user:14,pid,ppid,lstart,time,args

will display like this:

USER             PID  PPID                  STARTED     TIME COMMAND
root               2     0 Sun Aug  9 10:53:00 2015 00:00:00 [kthreadd]
root               3     2 Sun Aug  9 10:53:00 2015 00:00:01   [ksoftirqd/0]

                            [...]

felix           9597     1 Sun Aug  9 19:18:40 2015 00:00:00   /usr/lib/libreoffice/program/oosplash
felix           9614  9597 Sun Aug  9 19:18:40 2015 00:00:02     /usr/lib/libreoffice/program/soffice.bin --splash-pipe=6
felix          10033     1 Sun Aug  9 19:18:56 2015 00:00:00   /usr/bin/knotify4
longnameuser    6038     1 Sun Aug  9 19:59:27 2015 00:00:00   /bin/sh /usr/bin/startx -- -nolisten tcp :2
longnameuser    6069  6038 Sun Aug  9 19:59:28 2015 00:00:00     xinit /home/longnameuser/.xinitrc -- /usr/bin/X :2 -nolisten tcp :2 -auth /tmp/serverauth.asdf
root            6070  6069 Sun Aug  9 19:59:28 2015 00:00:00       /usr/bin/X :2 -nolisten tcp :2 -auth /tmp/serverauth.asdf