Sounds like Joshua has a real jerk for a boss. Here's how I see it - it is your intellectual property, not your bosses. You are justifying your paycheck, and this kind of work is used to judge how much of a raise you should get and if/when you can get a promotion. I have employees that regularly come up with good ideas, and I always give them credit, and let them hear me say that to the higher ups. That way, I get lots more good ideas from them, and it works out to the highest good for everyone, especially the company!

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There are ways to deal with a theiving boss:
1. If the product of your work is an Excel or Word document, go into File, Properties, and write your name in the Author's block. Most dimwit bosses don't know about that feature. It has provided me with great joy to be able to prove that a document was of my creation to my thieving bosses boss, and was actually able to prove that a document I created at Company A had been passed around and was now in use at Company B. The Company B boss claimed that he created it, but I knew my own work and could prove it. That was good fun.
2. I had a (literal) genius friend who was working with underwater robots in the oil patch in Norway, and his boss constantly hacked into his computer and stole his work, and presented it as his own. There was no possibility of quitting that job without repatriating to the US, which is a pain, and not desirable especially if you like the company. What the guy finally did was to create work that looked like a great deal/steal, but he put incorrect data in it. Of course, smart guy that he was, he was the only one who could tell. When his boss presented the stolen work in a meeting as his own creation, the guy proceeded to shoot him down big time, embarrassing him in front of his own big wigs and making him look like an idiot. Needless to say, he didn't steal any more documents.
3. Do not complain to upper management that your boss is stealing your work. That just makes you look bad, even if you can prove it. The way I've handled it is to go to my bosses boss when my boss was out of the building, and say, since [name] isn't here right now, I have this great idea that I'm wondering if I should pursue. I present the idea, and it's clear to him who it came from even if my boss steals the idea. They know, even if they don't come out and say.