The topic of vacations was not lined out in our divorce paperwork. Do I need my ex's permission to take the children out of state?

In Michigan you do... which state are you from?

Unless there is some sort of provision in your paperwork that says you cannot take the children out of the state (even for a vacation) you can leave the state for a vacation with them.

Normally unliess it spells it out in the custody agreement, you can. Most of the take out of state means to MOVE, not a vacation