Is is ever legal for private citizens who are neither security nor law enforcement to detain another person against their wishes?

I know there is such a thing as citizens arrest but I don't know how that works. 
But aside from that one would risk charges of kidnapping and/or false imprisonment. 

Wikipedia has a quite lengthy article on Citizen's Arrest which covers many countries.

Where I live in NSW, Australia, anyone may arrest a person if:

• the person is in the act of committing an offence under any Act or statutory instrument, or
• the person has just committed any such offence, 
• the person has committed a serious indictable offence for which the person has not been tried.

The Law Enforcement (Powers and Responsibilities) Act 2002 of New South Wales allows the use of such force as is "reasonably necessary to make the arrest or to prevent the escape of the person after arrest".
"Reasonable" is ultimately determined by a magistrate, but generally means the use of no more force than is absolutely necessary.

The arresting person should:

• inform the person that they are under arrest and
• inform the person of the reasons for the arrest.
  

There have been some instances in which I would have arrested someone if I'd had the means.
I lack both martial arts and physical strength, so the only way I could manage it would be to trap the culprit in a locked space.
Under the circumstances (outdoors) that would not have been possible for me.

I have rung police when necessary; that's easier than trying to do the arresting. This post was edited by Benedict Arnold at February 16, 2018 10:27 AM MST

If they tie them spread out on their bed, probably not.

I someone enters my home illegally, I will detain them...if they survive their head being crushed by a baseball bat.

A private citizen may detain someone while police travel to their location when a crime has been witnessed. 

There are special relationships that allow one to detain another lawfully, such as the parent/minor child relationship.

In general we can't detain others against their will. It's called false imprisonment.