Worldwide Employees: 67,884 (as of Apr 1st, 2016 from quarterly financial results)
US Employees: 8500 (as of Dec, 2015 from Cal Employment documents)
CA Employees: 5600 (as of Dec, 2015 from Cal Employment documents)
I know there was ~ 25000 employees in Thailand from a presentation I saw a couple of years ago, not sure what is it today. For the rest of the campuses, you can get this info from the intranet page.
It'll be interesting to see worldwide employees number on the next quarterly results.