what to do with idle cash

I have cash which I will not be using for a long time. What do I do to make it grow?

Terry Says:   What is a “long time” and how much are you willing to lose?  And what is your age — and the likelihood that you might need it sooner than “a long time”?

Those are all factors in this decision.  If you are working, you might want to open a Roth IRA — where you can invest the money in a variety of choices.  Start by going to Fidelity, Vanguard, or T. RowePrice and opening this kind of tax-free IRA — a Roth IRA.  Then divide the money between no more than three mutual funds, starting with a general stock market fund such as the S&P 500 stock index, and perhaps an equity income fund if you are over 50, and even leave some in a money market fund to give you confidence to stick with your other choices when the market declines.

BUT if your answer is that you can’t afford to lose ANY of this money, then leave it in  an FDIC-insured bank certificate of deposit, with a maturity no longer than one year — or in a bank money market deposit account.