How to split a 18000 word-file (word doc) into two or three smaller files?

Hello Everyone.

I read through the post but actually did not see anything related to doc. files. 

I have a word file to split and never did it before. The summary is in rich format and manually it does not keep formatting if I simply remove/cut/past sections of file. Is there a safe way to do it on SDL 2015? So translators would have only their specific smaller files and I would merge them back at the end.

Thank you.