Ideas worth nothing without execution...I had at least two business ideas that here copied...they even started to execute, but one got banckrupt and the other case only part of the idea went forward;
1- You need to study the problem that you are trying to solve for large companies very well.
2 - See if the companies that would be your customers have competitions for startups or business ideas, and apply.
3 - If your idea is a solution that they need, they will give you money or/and resources for to execute the idea...