Who "owns" a project idea after a grant application is rejected or declined? This past year I put in an application to a federal agency (US) for a post-doctoral fellowship and collaborated on it with a three profs/research scientists on the proposal.  If funded, one of them will act as my post-doc supervisor and the other two as collaborators, all bring necessary skills and methodological capacity to the project.  The project idea was my own that I had before meeting or discussing it with these collaborators, I chose to work with these people because they are researchers whose work I was familiar with and they are located in a city I'm interested in living in. 

I have accepted a different post-doc since that application was submitted and I expect that application to be rejected because it was still a bit rough when submitted and it's a pretty competitive grant.  Since I took the other position, I won't be doing this project with these collaborators in under this recent application.  This is my first time as part of a multiple collaborator application, so I am wondering:

Who has ownership of an idea after grant rejection/do all members of a proposal collaboration have to be informed of any member independently moving forward with an idea from the proposal?
If you can prove you are the originator of the idea with timestamped emails, notebook with dates, journals, etc. then that may be sufficient to prove priority for the idea when registering intellectual property (IP).

If the collaborators furthered the idea with you, then they own part of the idea, and may make a claim to any IP that is generated.

If you worked on this idea / project while you were being paid by University X, then University X may also own partial rights to the idea/IP.

Keeping the previous in mind, anyone that contributed to the idea could use the idea in another proposal.

If you are the originator of the idea, you can submit the idea to another group. If intellectual property is produced from the project, others that helped you develop the idea (including University X) could try to claim partial rights. You are not required to inform prior collaborators that you are using the idea, although it is a courtesy to ask them to collaborate on the new project if it is accepted.

Normally, grant application ideas are somewhat vague since you rarely know what you are going to find during the project. No one "owns" this idea until it becomes intellectual property through patents, trademarks, etc. That is when you really need to consider who contributed.

Note: Intellectual Property rights differ in every country, and Universities have very different policies. Check your local legislation and University contract.