You can carry as much cash as you wish out of the US, as long as you declare it. You don't have to PROVE its origin, but there may be questions - it's always a good idea to declare a few hours before departure. You do not have to declare non-cash instruments.
No one in any of the countries I have entered ever "expected" my arrival, and I have traveled with as much as $400k in mixed currencies. I always declared in the countries of entry, and there were sometimes delays as long as 45 minutes for explanations of the business I was conducting.
I never experienced any confiscation.