They will never separate easily from the vine, until that vine actually rots away. Don't use that as a ripeness indicator. Leave the stem on each squash, use snippers to cut the stem, keeping most of the stem intact. I usually wait until all the leaves are dead and gone. Then bring the fruits into room temperatures for a few weeks before eating or storing.
Color isn't a good indication either. Try pushing your thumbnail into the squash. If the skin is soft enough that your nail pushes thru, then it's not ripe. The shell should be hard enough to repel your thumbnail. Within reason of course.

I've never seen a split Butternut until this year. It split lengthwise but appears to be healing nicely. I guess it will be OK but I'm gonna keep my eyes on it.

Thanks, guess I will leave them alone till the leaves are gone which won't be long with the cucumber beetles attacking everything. They have made an end to my zucchini and yellow squash and cuke plants. There are only a couple squash that really aren't full grown. As for the horizontal split one, forgot to mention that the cut part looks moldy and has looked that way for quite a while. I haven't tried the fingernail test to any of them yet but will later today. Thanks again.