A Calculated Risk

A detailed investigation into the complexities and limitations of XBRL Calculations
by: Shawn Rush, CompSci Resources, LLC

Consider the example below:

We have three facts all of which have the concept "CommonStockSharesOustanding". The dimensionless fact represents the total and the other two facts with dimensions represent the components or, in terms of a calculation, the operands. This is a quintessential application of dimensions - to break a data point into its components; however, there is no way to model it using XBRL calculations given the context restrictions.

Income and Cash Flows Statement

The relationship between the income statement and cash flows statement poses some interesting challenges regarding calculations. In the income statement, we show a number of items that ultimately add up to the total, "ProfitLoss". When creating the total for "NetCashProvidedByUsedInOperatingActivities" in the statement of cash flows, there are two options: the direct method and indirect method. To arrive at this total, the direct method adds and subtracts the cash items, whereas the indirect method starts with "ProfitLoss" and makes adjustments for non-cash items. As we will investigate below, the indirect method poses certain challenges when tagging XBRL.

Letís consider the following simplified income statement:

We can create the following simple calculation for "ProfitLoss" based on the balance types:

Revenues - DepreciationDepletionAndAmortization - AssetImpairmentCharges = ProfitLoss

Everything looks good so far. Now let us look at the corresponding cash flows statement:

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