Would they have to pay taxes all of the overseas earnings if they use just some of it? I figured they only paid tax on what they actually bring back here.
No, just what they repatriate. But they already have $22 BILLION in cash in the U.S., and they can borrow more for far less than their income tax rate, so why incur even a little tax?
The only reason for them to be concerned, is they've accumulated a vast amount of debt in a very short amount of time, all to put off dealing with the cash / tax problem.
That debt starts to add up, even when you're paying record low interest rates on it. Right now they're losing a billion a year just in interest on their debt, that's up from nothing three years ago. At the rate they're taking on debt, they'll be losing two billion dollars per year to interest within another two years. That starts to become a lot of money to be pissing away just on interest, all to avoid taxes. Over time it'll become a net larger sum than they would have paid in taxes on the cash.
It's not just about avoiding taxes. Bond rates are extremely low. If one believes rates will soon start to go up, taking on fixed rate debt can be a smart thing. As rates rise, the cash lying around can be used to generate returns above the rate on the debt. The tax angle makes it a double win.