Understanding XBRL Fact Values and Signs
Each numeric concept is either a debit or credit. So when entering numbers, you normally enter them as an absolute value — without a sign.
For example, the following table shows expense debits without a minus sign or parentheses.
You identify the number as a debit or credit through the XBRL concept’s Balance Type. For example, you tag the Staff costs expense with a concept that has a debit Balance Type.
When you want the number in the document to appear as a negative number, enter it with either a minus sign or parentheses. The following example shows all expenses typed as negatives in a Profit (Loss) table.
When you type the number as negative, you need to reverse the XBRL fact sign to keep its absolute value. If you don’t, you end up with negative debits. Negative debits cause document errors because they don’t calculate correctly.
For example, you have depreciation, which is a debit balance. However, you type the cost as (125,571). The XBRL Fact Value now shows that you have negative depreciation, or a credit balance, until you reverse the XBRL fact sign to get the debit balance again.
Here's another example where the profit (loss) section of your document might say, “We had a loss of £44,000,” making it a positive value in the narrative. However, you need to reverse the XBRL value sign for £44,000 so it matches the XBRL concept value of (loss).
Changing XBRL Fact Signs
Open the document and enable XBRL. Find the fact that needs a different fact sign. Click the Fact Properties icon (the X) below the document.
Fact Properties shows how the fact is set up and where to reverse its sign:
Source Link Value: How the number appears in the document
XBRL Fact Value: How the number’s value in the XBRL
Reverse Source Value Sign: Where you reverse the sign to make sure the XBRL Fact Value aligns with the XBRL concept’s Balance Type
In the Numeric Attributes section, select Yes for the Reverse Source Value Sign.
When you reverse the sign, the XBRL fact value changes, but the number in the document still appears with the sign you typed.
Click the green Apply Property Changes checkmark and Share your changes.