The term "cash reserves" is not a standard accounting term or classification. "Cash reserves" is commonly used to refer to funds set aside by a company or organization for specific purposes, such as contingencies, future investments, or working capital needs. These reserves are typically considered as part of a company's cash and cash equivalents.

Under GAAP, cash (and cash equivalents) includes currency on hand, deposits in bank accounts, and any highly liquid investments that have an original maturity of three months or less. Cash equivalents are short-term investments that are readily convertible to known amounts of cash and have original maturities of three months or less from the date of purchase

That's a slightly different thing - a reserve account is what you've correctly linked, but what people here are talking about is just a basic balance sheet categories of cash and marketable securities;

https://d18rn0p25nwr6d.cloudfront.net/CIK-0000320193/386e8c0...

So they have $25 billion in cash/cash equivalents (T-bills), $31 billion in "Current Marketable Securities" which are just those that are liquid this year so short-term debt and the like, and then $110 billion in long-term marketable securities which can be medium term bonds and other investments on a >1 year timeline.

Add those up and you get to $166 billion which is a good proxy for the amount of money they can invest today.