Oh, I see.Keep in mind that the reason why it's called a balance sheet is because the assets must match liabilities.
In this case, we're looking at $90 trillion in total debts plus $180 trillion in unfunded liabilities.
Unfunded liabilities means approximately bugger all, in context. It's merely a statement that the government expects to pay for something in the future. It's not conventional debt, because it not has been borrowed / spent, and will be offset by future income. To give an idea of how misleading this can be, if we take the assumption that the USA needs to pay a defence budget every year, it has to pay something forever until the country ceases to exist, therefore has infinite liabilities. And yet the country is not bankrupt, obviously.
This is not a useful way to think about things.
It works more like this. There are $180 trillion liabilities owed over a certain period of time (presumably relating to the lifespans of its populace), in which case the USA will also earn over that period GDP multiplied by the same number of years. So if we imagine the number of years is 50 and the economy remains the same size for those 50 years ($25 trillion), that's ~$1,250 trillion in income. Paying out $180 trillion in unfunded liabilities, that leaves it a healthy $1,070 trillion spare for other things.
What is more interesting is the $90 trillion in debt compared to $180 trillion in assets. I don't think that's a problem - arguably it's quite a modest debt, overall. Contextually, when most people buy a house with a 10% deposit, they promptly saddle themselves with debts of around 90% of their assets.
The next interesting thing is to look at the US debt held abroad, which is over $7 trillion. The USA has $95 trillion debt, so in other words, over 90% of American debt is owed to other Americans. When that debt is repaid, and the interest on it is paid, it just goes back to America!
Again, this is not to undervalue that the distribution of assets and debt within sectors / entities of the wider economy matter. But there can be an awful lot of debt panic that turn out to be a lot less worrying than the very big numbers suggest.