Regulation S-X provides the home for these items within its non-operating captions. Rule 5-03.7(d) covers miscellaneous other income and Rule 5-03.9(b) covers miscellaneous income deductions, and both require material amounts to be stated separately on the face of the statement or in a note, with the nature of the underlying transactions made clear. In XBRL the net figure is usually tagged OtherNonoperatingIncomeExpense, with the income and expense sides tagged OtherNonoperatingIncome and OtherNonoperatingExpense when shown separately. The SEC element measures income net of expense, the opposite sign from this field.
The contents vary widely. Typical items include foreign currency transaction gains and losses, fair value changes on certain investments or derivatives not designated as hedges, gains and losses on debt extinguishment, the non-service components of pension and retirement cost, and some legal or insurance settlements. A company may put an item here in one period and give it its own line in another once it becomes material.
Because this line bundles unlike items, analysts treat it with caution. A small, stable amount is usually noise. A large swing deserves a look at the notes, since it can come from one-time events such as a large currency move or a debt refinancing that will not repeat. Many analysts exclude it when forecasting operating performance and focus instead on operating income, while keeping it in mind for pretax and net income.