And that's a major slice -- 85%+? -- of the decrease in total credit card debt.
You hear on the news that credit card debt is going down; only rarely do you hear that it's principally because of writeoffs.
I've always sort of thought of unsecured debt (mostly what credit cards are, plus "personal loans" and the like) as kind of an inverse form of insurance. The model works if your "premiums" (i.e., interest and fees collected minus your actual cost of money) exceed the "claims" (i.e., write downs). Given that a bank can borrow at historical low rates, and fees are high, you can see how writing down $150B is a small price to pay to be "in" this market. In fact, it's probably cheaper for them in this case to write it down than it is to pay people in call centers to hound you about it.
/jordan