Just because everything is an idea doesn't mean that therefore logically nothing is materially real.
One does not follow from the other.
( TFD is sporting this season's finest necropants, Thu 6 Oct 2011, 2:37, archived)

unless somehow an idea can be materially real,
in which case what exactly do you mean by "materially real"? If the relationship between ideas is valid without any of them being "materially real" then what is the use of this concept, and how can we distinguish ideas that are materially real from those that aren't? I am putting it to you that "materially real" is only a label that we mentally apply to certain of our ideas; it is an artificial, abstract category of ideas that we have made up.
( Moon Girl Technologies horrendous beanbag, Thu 6 Oct 2011, 2:43, archived)

There is no understanding/conception/sensation of mind independent reality doesn't mean there is no mind independent reality.
What you are saying is indeed possible, but no more so than the possibility that empirical sense data has objectively real material causes independently from our ideas.
( TFD is sporting this season's finest necropants, Thu 6 Oct 2011, 2:52, archived)

but where do you get this idea of a mind independent reality from?

( Moon Girl Technologies horrendous beanbag, Thu 6 Oct 2011, 2:56, archived)

Where do you get any proof it is not there?

( TFD is sporting this season's finest necropants, Thu 6 Oct 2011, 2:58, archived)

It is absurd.
About as absurd as that celestial teapot. There is no reason to suggest it, and no evidence for it. Given what we know of teapots, there is no way one could be in distant space. And given what we know of ideas, there is no way that some of them could materialise somewhere independently of the mind that thought them up. Although if you really do want to admit the possibility of the latter, it opens up all kinds of religious possibilities that I won't go into.
( Moon Girl Technologies horrendous beanbag, Thu 6 Oct 2011, 3:06, archived)