"The idea of being transgender" it's not an idea anymore than you think about being cisgender. It's a false dichotomy created by cisgender people who fail to understand the issue or fall victim to the "gay agenda" rhetoric of right wing media.

A better way to phrase it is no trans person thinks of themselves as trans. A trans woman thinks of herself as a woman. A trans man thinks of himself as a man. So there's no "idea" of "being transgender" unless you're a cis person who thinks they know what they're talking about.

It's like the phrase "differently abled" only able bodied people think like that.