I googled about usage and grammar of that. There are several usages First, as an objective. For example, I think that it is not a good idea. Second, as a subjective, such as That he choose to take a bus to work is not a good idea. Third, as an extension after an adjective, such as I am glad that he survived the situation. Forth, as an extension of it, such as it is a good idea that voting is compulsory in australia. Firth, the usage of so...that and such....that. I am so happy that he survived the storm. Voting is a good idea that everyone has a say.
However, my question is that can one use that after a noun to explain more?
For example, I am a fool that I lost my key and got myself locked outside my door. Voting is a good idea that everyone has a say.