Exchange format for business information
XBRL (eXtensible Business Reporting Language) is a freely available and global framework for exchanging business information. XBRL allows the expression of semantics commonly required in business reporting. The standard was originally based on XML, but now additionally supports reports in JSON and CSV formats, as well as the original XML-based syntax. XBRL is also increasingly used in its Inline XBRL variant, which embeds XBRL tags into an HTML document. One common use of XBRL is the exchange of financial information, such as in a company's annual financial report. The XBRL standard is developed and published by XBRL International, Inc. (XII).
XBRL is a standards-based way to communicate and exchange business information between business systems. These communications are defined by metadata set out in taxonomies, which capture the definition of individual reporting concepts as well as the relationships between concepts and other semantic meaning. Information being communicated or exchanged is provided within an XBRL instance.
Early users of XBRL included regulators such as the U.S. Federal Deposit Insurance Corporation and the Committee of European Banking Supervisors (CEBS). Common functions in many countries that make use of XBRL include regulators of stock exchanges and securities, banking regulators, business registrars, revenue reporting and tax-filing agencies, and national statistical agencies.
A list of known XBRL projects is published by XBRL International. Within the last ten years, the Securities and Exchange Commission (SEC), the United Kingdom's HM Revenue and Customs (HMRC), and Singapore's Accounting and Corporate Regulatory Authority (ACRA), had begun to require companies to use it, and other regulators were following suit. Development of the SEC's initial US GAAP Taxonomy was led by XBRL US and was accepted and deployed for use by public companies in 2008 in phases, with the largest filers going first: foreign companies which use International Financial Reporting Standards (IFRS) are expected to submit their financial returns to the SEC using XBRL once the IFRS taxonomy has been accepted by the SEC. In the UK in 2011, both HMRC and Companies House accepted XBRL in the iXBRL format. XBRL was adopted by the Ministry of Corporate Affairs (MCA) of India for filing financial and costing information with the Central Government.
Specification.
The current version of the base XBRL specification is 2.1, with errata corrections.
The current version of the Inline XBRL specification is 1.1 
Conformance suites are available to test processors of XBRL and Inline XBRL documents.
XBRL document structure.
In typical usage, XBRL consists of an "XBRL instance", containing primarily the business facts being reported, and a collection of taxonomies (called a Discoverable Taxonomy Set (DTS)), which define metadata about these facts, such as what the facts mean and how they relate to one another. XBRL uses XML Schema, XLink, and XPointer standards.
XBRL Instance.
The XBRL instance begins with the ;xbrl ; root element. There may be more than one XBRL instance embedded in a larger XML document. Xbrl Instance is also known as XBRL file. The XBRL instance itself holds the following information:
In the design of XBRL, all Item facts must be assigned a context.
This is an example of a fictitious Dutch company's International Financial Reporting Standards (IFRS) statement instance file :
 ;?xml version="1.0" encoding="UTF-8"? ;
 ;xbrli:xbrl
xmlns:ifrs-gp="[URL]
xmlns:iso4217="[URL]
xmlns:xbrli="[URL]
xmlns:xbrll="[URL]
xmlns:xlink="[URL] ;
 ;xbrll:schemaRef xlink:href="[URL] xlink:type="simple"/ ;
 ;ifrs-gp:OtherOperatingIncomeTotalFinancialInstitutions contextRef="J2004" 
 decimals="0" unitRef="EUR" ;38679000000 ;/ifrs-gp:OtherOperatingIncomeTotalFinancialInstitutions ;
 ;ifrs-gp:OtherAdministrativeExpenses contextRef="J2004" 
 decimals="0" unitRef="EUR" ;35996000000 ;/ifrs-gp:OtherAdministrativeExpenses ;
 ;ifrs-gp:OtherOperatingExpenses contextRef="J2004" 
 decimals="0" unitRef="EUR" ;870000000 ;/ifrs-gp:OtherOperatingExpenses ;
 ;ifrs-gp:OtherOperatingIncomeTotalByNature contextRef="J2004" 
 decimals="0" unitRef="EUR" ;10430000000 ;/ifrs-gp:OtherOperatingIncomeTotalByNature ;
 ;xbrli:context id="BJ2004" ;
 ;xbrli:entity ;
 ;xbrli:identifier scheme="www.iqinfo.com/xbrl" ;ACME ;/xbrli:identifier ;
 ;/xbrli:entity ;
 ;xbrli:period ;
 ;xbrli:instant ;2004-01-01 ;/xbrli:instant ;
 ;/xbrli:period ;
 ;/xbrli:context ;
 ;xbrli:context id="EJ2004" ;
 ;xbrli:entity ;
 ;xbrli:identifier scheme="www.iqinfo.com/xbrl" ;ACME ;/xbrli:identifier ;
 ;/xbrli:entity ;
 ;xbrli:period ;
 ;xbrli:instant ;2004-12-31 ;/xbrli:instant ;
 ;/xbrli:period ;
 ;/xbrli:context ;
 ;xbrli:context id="J2004" ;
 ;xbrli:entity ;
 ;xbrli:identifier scheme="www.iqinfo.com/xbrl" ;ACME ;/xbrli:identifier ;
 ;/xbrli:entity ;
 ;xbrli:period ;
 ;xbrli:startDate ;2004-01-01 ;/xbrli:startDate ;
 ;xbrli:endDate ;2004-12-31 ;/xbrli:endDate ;
 ;/xbrli:period ;
 ;/xbrli:context ;
 ;xbrli:unit id="EUR" ;
 ;xbrli:measure ;iso4217:EUR ;/xbrli:measure ;
 ;/xbrli:unit ;
 ;/xbrli:xbrl ;
XBRL Taxonomy.
An XBRL Taxonomy is a collection of taxonomy schemas and linkbases. A taxonomy schema is an XML schema document (file). Linkbases are XML documents (file) which follow the XLink specification. The schema must ultimately extend the XBRL instance schema document and typically extend other published XBRL schemas on the xbrl.org website.
Label Linkbase.
This linkbase provides human readable strings for concepts. Using the label linkbase, multiple languages can be supported, as well as multiple strings within each language.
XBRL aims to become a worldwide standard for electronic business reporting. This requires taxonomies to present business data in many different languages. Therefore, it is important to be able to create an element that is assigned with labels for different languages. There may also be different labels for different purposes. All labels are stored and linked to the elements in a label linkbase.
Elements defined in a schema are built to convey accounting meaning to computers. In order to make it easier for computers to process their names, they have to obey some rules. For example, the use of spaces is not allowed so 'Cash and Cash Equivalents' would be named 'CashAndCashEquivalents' . Additionally, big taxonomies such as IFRS obey specific rules of naming and labelling to ensure consistency within the schema. For example, there could be a list of words that are excluded from the names, e.g., :and:, "of" ..., or words that appear only in a particular order (i.e., 'Net' or 'Total' at the end of the label after a comma).
In the label linkbase, elements are connected to human readable labels using "concept-label" arcrole.
As mentioned above, elements can be assigned to labels in different languages. An example that describes definitions of labels of the IFRS element AssetsTotal in English, German and Polish is provided below.
 ;label xlink:type="resource" 
 xlink:role="[URL] 
 xlink:label="ifrs_AssetsTotal_lbl" 
 xml:lang="en" ;Assets, Total ;/label ;
 ;label xlink:type="resource" 
 xlink:role="[URL] 
 xlink:label="ifrs_AssetsTotal_lbl" 
 xml:lang="de" ;Vermögenswerte, Gesamt ;/label ;
 ;label xlink:type="resource" 
 xlink:role="[URL] 
 xlink:label="ifrs_AssetsTotal_lbl" 
 xml:lang="pl" ;Aktywa, Razem ;/label ;
To distinguish between languages, XBRL uses the XML attribute lang. Taxonomy creators may also define different labels for one element. One of the ideas of XBRL is that the information about the period and currency for which the element is reported is not contained within an element definition but is described by a context in instance documents. In financial reporting on the other hand, many terms express the date for which they are being reported, for instance Property, Plant and Equipment at the beginning of year and Property, Plant and Equipment at the end of year. XBRL allows the creation of different labels depending on the context in which an element will be used.
 ;label xlink:type="resource" 
 xlink:role="[URL] 
 xlink:label="ifrs_AssetsTotal_lbl" 
 xml:lang="en" ;Property, Plant and Equipment, Net ;/label ;
 ;label xlink:type="resource" 
 xlink:role="[URL] 
 xlink:label="ifrs_AssetsTotal_lbl" 
 xml:lang="en" ;Property, Plant and Equipment, Net, Beginning Balance ;/label ;
 ;label xlink:type="resource"
 xlink:role="[URL] 
 xlink:label="ifrs_AssetsTotal_lbl" 
 xml:lang="en" ;Property, Plant and Equipment, Net, Ending Balance ;/label ;
The example above shows how three different labels are assigned to one element by applying different role attributes on labels.
Reference Linkbase.
This linkbase associates concepts with citations of some body of authoritative literature.
Financial concepts appearing on business reports more often than not stem from regulatory documents issued by authorities. For example, the IFRS Taxonomy describes financial reports prepared based on IFRSs (Bound Volume).
Elements defined by this taxonomy refer to the specific terms and concepts explained in the standards. For this reason, a taxonomy is often provided with a reference linkbase that presents relationships between elements and external regulations or standards (the other solution is to enclose documentation in label linkbase). This helps instance creators and users understand the intended meaning of each element and provides support for its inclusion in the taxonomy.
The reference layer does not contain the full text of the regulations. Instead, it points to source documents by identifying their name and indicating the relevant paragraphs and clauses. This connection is created using "concept-reference" arcrole.
There are several types of references that could be provided for each element.
 ;reference xlink:type="resource" 
 xlink:role="[URL] 
 xlink:label="CashFlowsFromUsedInOperationsTotal_ref" ;
 ;ref:Name ;IAS ;/ref:Name ;
 ;ref:Number ;7 ;/ref:Number ;
 ;ref:Paragraph ;14 ;/ref:Paragraph ;
 ;/reference ;
 ;reference xlink:type="resource" 
 xlink:role="[URL]
 xlink:label="CashFlowsFromUsedInOperationsTotal_ref" ;
 ;ref:Name ;IAS ;/ref:Name ;
 ;ref:Number ;7 ;/ref:Number ;
 ;ref:Paragraph ;18 ;/ref:Paragraph ;
 ;ref:Subparagraph ;a ;/ref:Subparagraph ;
 ;/reference ;
The example above indicates references for Cash Flow from (Used in) Operations. First, it provides a reference to a document which explains how and where the element should be presented in terms of its placement and labeling. In IAS 7, paragraph 14 we read that the concept Cash Flows from Operating Activities exists and what it is derived from. Second, the measurement reference provides explanations about what determines the value of the element and how it should be calculated. This description can be found in IAS 7 paragraph 18.a.
XBRL also allows an element to be assigned other types of references containing examples, commentaries, etc.
Calculation Linkbase.
This linkbase associates concepts with other concepts so that values appearing in an instance document may be checked for consistency.
The idea of the calculation linkbase is to improve the quality of an XBRL report. It contains definitions of basic validation rules, which apply to all instance documents referring to a particular taxonomy. A hierarchical calculation linkbase sorts all monetary elements in this way so that lower level elements sum up to or are subtracted from one another so that the upper level concept is the result of these operations.
The sign of the relationship depends on the weight attribute that is assigned to the arc connecting two elements. An example is provided below.
 ;calculationArc xlink:type="arc" 
 xlink:arcrole="[URL] 
 xlink:from="GrossProfit" xlink:to="RevenueTotal" 
 order="1" weight="1" use="optional"/ ;
 ;calculationArc xlink:type="arc"
 xlink:arcrole="[URL]
 xlink:from="GrossProfit" xlink:to="CostOfSales" 
 order="2" weight="-1" use="optional"/ ;
The example shows that there are defined two calculation arcs providing details concerning relations between Gross profit, Revenue and Cost of Sales. In Income Statements, Gross profit is the difference between the other two.
Therefore, we assign weight attribute value to "1" on the arc connecting Gross profit and Revenue and "-1" between Gross profit and Cost of Sales.
The reason why there is a difference between calculation and presentation linkbases, is that the total element that stands for the summation of all others usually appears at the bottom in the financial statements whereas in the calculation linkbase it must be placed as the top concept.
There are two major rules concerning calculation relations in XBRL.
Firstly, we cannot carry out operations on elements that have different values of the periodType attribute. This is often called the cross-context rule and relates to defining some elements as "For period" (duration) and others as "As of date" (instant). For example, concepts that appear on the Balance Sheet are instant: which means that their value is presented for a specified day, while elements in the Income Statement or Statement of Cash Flows are duration: because they represent actions that took place over a period of time. The problem emerges for example in the Statement of Changes in Equity or Movements in Property, Plant and Equipment where instant elements mix with duration. The solution to this problem is a formula linkbase that will provide taxonomy creators with many more functions than just simple addition or subtraction.
Secondly, the double entry accounting rule requires XBRL taxonomy creators to define the credit/debit nature of monetary elements appearing in the Balance Sheets and Income Statements. This rule does not only disallow the addition of elements with opposite balance attributes—they must be subtracted—it also defines whether the numerical value contained within an element should be positive or negative.
Definition Linkbase.
This linkbase associates concepts with other concepts using a variety of arc roles to express relations such as is-a, whole-part, etc. Arc roles can be created by those who create XBRL taxonomies or commonly used arc roles can be added to the XBRL Link Role Registry (LRR).
The definition linkbase provides taxonomy creators with the opportunity to define different kinds of relations between elements. There are four standard types of relationships supported by the definition linkbase.
The first one is referred to as general-special. It distinguishes between concepts that have more generic or more specific meaning. For example, ZIP code is the US representation of Postal Code which is used worldwide. Therefore, to indicate that connection, taxonomy