Small Company Disclosure Simplification Act of 2018 This bill exempts from requirements to use Extensible Business Reporting Language (XBRL) for Securities and Exchange Commission (SEC) filings: (1) emerging growth companies (in general, newly public companies with revenues below a specified threshold); and (2) on a temporary basis, certain other smaller companies. The SEC must conduct an analysis of the costs and benefits of XBRL requirements with respect to such companies. The SEC must report to Congress on the results of its analysis and other specified issues related to XBRL usage.