iXBRL Skill

A vendor-neutral skill for working with Inline XBRL (iXBRL) and the underlying XBRL stack — covering the major regulators (SEC EDGAR, ESMA ESEF, UK FRC / Companies House / HMRC, Dutch SBR / KvK / AFM, EBA, EIOPA), the IFRS Accounting Taxonomy, FASB US-GAAP, and the Arelle validation toolchain.

Built for the people who actually file: accountants, auditors, controllers, investor-relations teams, banking and insurance supervisory-reporting analysts, and the engineers who write the code that produces their iXBRL.

What this skill gives you

• SKILL.md — first principles, regulator routing, and the validation pipeline. Loaded automatically when the skill triggers.
• references/ — load on demand:
  • spec.md — Inline XBRL 1.1, XBRL 2.1, XDT (Dimensions), Transformation Registry 4, calculation linkbase semantics.
  • taxonomies.md — IFRS, ESEF, US-GAAP / DEI / SRT, UK FRC Suite, Dutch NT / SBR, EBA & EIOPA DPM, plus EDINET / CNMV / SBR-AU / MCA.
  • esef.md — ESEF legal basis, Reporting Manual rules, anchoring, block tagging, report package, NCAs, and ESEF.* error codes.
  • sec-edgar.md — SEC iXBRL phase-in, EDGAR Filer Manual sections, DEI cover-page tagging, EFM.6.05.* codes, recent rules (Pay-Versus-Performance, cybersecurity disclosure, tailored shareholder reports).
  • validation.md — Arelle CLI, plugins, formula linkbase, Calc 1.1, a master list of ESEF.* / EFM.* / xbrl.* / xbrldie:* error codes with root cause and fix, and 25 anti-patterns that pass syntax but fail review.
• scripts/validate_with_arelle.sh — wraps arelleCmdLine with the right plugin chain per profile (esef, efm, ukfrc, hmrc, core).
• scripts/check_facts.py — pure-Python pre-flight that catches cheap-to-detect issues (missing decimals, dangling continuation chains, undefined contexts/units, non-ISO currency measures, decimals="INF" abuse, inconsistent duplicate facts) before you spend cycles in Arelle.

Source discipline

Every factual claim in this skill is tied to a primary source from the issuer or standard-setter (xbrl.org, ifrs.org, esma.europa.eu, sec.gov, fasb.org, frc.org.uk, sbr-nl.nl, eba.europa.eu, eiopa.europa.eu, the Arelle GitHub repository). Each references/*.md ends with a Sources list of the URLs consulted. Versions and rule numbers were verified at the time of writing — re-check the publisher's page before relying on a specific version for a regulated filing.

Install

This is an AI-agent skill — a self-contained directory of markdown and scripts that any agent harness supporting the skill convention can load.

Manual install

Drop the directory under your agent's skills root. Common locations include ~/.<agent>/skills/ixbrl/ or a project-local .agents/skills/ixbrl/. Most harnesses auto-discover the skill from the name and description in the SKILL.md frontmatter.

Install via the skills CLI

SKILL.md lives at the root of this public repo, so any runtime with the skills CLI can install it directly:

npx skills add MaxSchoon/ixbrl

skills.sh has no separate submission step — its directory is populated from CLI install telemetry. The skill becomes discoverable (via npx skills find ixbrl) and climbs the listing as people install it with the command above.

Compatibility

The skill is harness-agnostic. It works with any AI-agent runtime that:

1. Loads skills from a directory of markdown files with YAML frontmatter (name, description).
2. Routes user requests to relevant skills based on the description.
3. Lets the agent read additional reference files on demand.

That includes terminal-based coding agents, IDE-integrated agents, chat-based agents, and SDK-built custom agents. The skill makes no assumptions about which model or vendor you use — only about the skill-loading convention.

The bundled scripts require Python 3.10+, lxml, and (for full validation) pip install arelle-release. The skill is useful even without those dependencies — the references work on their own.

License

MIT — see LICENSE. Third-party attribution notices are in NOTICE.

Disclaimer

This skill is not legal, accounting, audit, or filing advice. iXBRL filings carry regulatory consequence; always verify against the live publisher source before relying on a specific rule for a regulated filing. The skill lowers the cost of getting to the right page of the right manual; it does not replace professional judgement.

Contributing

Issues and pull requests welcome. Two principles:

1. Source discipline. Every new factual claim must cite a primary authoritative URL the contributor has actually fetched.
2. Generality. This is a public, vendor-neutral skill. No product-specific naming, no internal jargon, no jurisdiction-narrow shortcuts presented as universal.