Newbie post, I know

Here's the story: I already have a publisher on for my IP (next-gen consoles, not just Steam, etc.). All I have to do is give them the demo & sign the contract. This will be the first time I have ever done something like this, and I was wondering if it was appropriate to submit my game idea on here, have you guys review it, tell me what I'm doing wrong, etc (I'm under an NDA, but it is just to protect each other's property). Would somebody steal the idea, and if they did, would we have the legal power to sue them if I did post it on here?

I don't understand. You already have a publisher. So you want to post your concept? your pitch? Why? Tell you you're doing what wrong?
It's probably a bad idea given the NDA, BTW.

I hate to be the one to break it to you but it sounds like all you have is a publisher willing to listen to your pitch. That is a lot different from a publisher agreeing to fund your game, otherwise they would have already sent you the contract and you would be discussing this with your lawyer.

FYI - "ideas" are not protected by copyright. They can be protected as confidential information under an NDA or if they constitute a trade secret, however in order to sue someone for breach of those rights requires that you keep the idea secret and not disclose it in a public forum. Once it is in the public domain, anyone can use the idea, including the publisher you are pitching.

Good luck!

Newbie post, I know

Here's the story: I already have a publisher on for my IP (next-gen consoles, not just Steam, etc.). All I have to do is give them the demo & sign the contract. This will be the first time I have ever done something like this, and I was wondering if it was appropriate to submit my game idea on here, have you guys review it, tell me what I'm doing wrong, etc (I'm under an NDA, but it is just to protect each other's property). Would somebody steal the idea, and if they did, would we have the legal power to sue them if I did post it on here?

1) What Tom Sloper said! Very confusing indeed!
2) I'd run your idea by your publisher, not some random people on the Internet...
3) If your idea needs random on the Internet to correct it, nobody is going to "steal" it.
4) If you posted your idea here and somebody would "steal" it, you would have copyright on your side (and/or the publisher, if you transfered your "idea" to them).
5) NDAs protect trade secrets, which are only protected as long as they are secret. If you reveal a trade secret of your publisher here, they could sue _you_, but not anyone else using the secret, unless they have other rights to it (like trademark, copyright or patent).

I already have a publisher on for my IP (next-gen consoles, not just Steam, etc.). All I have to do is give them the demo & sign the contract.

As Kdog said what you currently have is an expression of willingness to look at your pitch - nothing more. Read The acquisition process for more info on the very long road you have ahead of you.

Publishers are always willing to look at a pitch and always say enthusiastic things about your idea. Out of all the games ideas they see (and say enthusiastic things about) they will actually sign about 10% at most. I have spent over 20 years working with developers to pitch their ideas and in that time I have seen countless, countless pitches where the publisher said "love your idea" or even "yes we want this game" and then.....
1. Sent a rejection letter later.
2. Sent nothing, failed to reply to emails, didn't take calls and wasn't heard from again.
3. Took months to get around to sending a contract, negotiated the contract, the developer signed it and then the publisher spent 6 weeks making excuses as to why their Director hadn't signed it (during which time the developer spent money on making the game) - then announced that they wouldn't be going ahead with the game.

This will be the first time I have ever done something like this, and I was wondering if it was appropriate to submit my game idea on here, have you guys review it, tell me what I'm doing wrong, etc (I'm under an NDA, but it is just to protect each other's property). Would somebody steal the idea, and if they did, would we have the legal power to sue them if I did post it on here?
If you make an actual game that is protected by copyright but ideas are not protected by copyright law so someone could steal your idea. It is unlikely that they will but they might.