OK, I should make it clear, the idle assets do not incl large amount of Idled CASH which I take it as given that anyone has $100K to $1 Million of IRA assets to park at Merrill for the BofA benefits, do not keep their IRA assets in large Cash amount. Most likely would be long term stock holdings, bonds, or whatever instruments but NOT CASH.

Hope this would satisfy the needs to be clear down to the minute details which in many cases are not really relevant to situations discussed. But hey, there is a need to clarify things and be accurate. We appreciate that.

PS
I would also like to point out - there are other options than the default accounts to hold your trading cash but you have to do some research to find them - and in some firms, the options require you to do manual sweep yourself, because the options are DELIBERATELY not being available as an auto sweep - Schwab is one of such firm. Fidelity on the other hand, has relatively decent yield money market funds that can be used as the Auto Sweep Account for the daily cash balance - the funds used for regular account and IRA accounts are different funds, with the one used for IRA account yield slightly higher. In the past the options can only be added via calling in. But IIRC Fido has put them in the drop down menu of default option to choose from in the brokerage account.
TD Ameritrade also has such option and it requires you to call in when we learn about it several years ago.

Just another case of Consumer beware as always.