The 'conversion, can be achieved by number formatting. A custom format
$#,##0,, \M
will give your Millions format, where each comma (shown in red) reduces the display by a factor of a thousand.
The number you would read from the cell is unaltered, that is it is still 376 Billion.
It is also possible to divide by 1E6, in which case the unit of measure becomes millions rather than $s.