One initial study looked at the characteristics of companies that have become early members of XBRL International. Bhattacharya and Premuroso (2006) investigated performance, market, and structure-related variables and found that early members of XBRL International demonstrate superior corporate governance and future operating performance (as measured by several performance ratios) relative to their non-adopting peers. They also found that firm leverage (the percentage of capital raised with debt) and the type of audit firm employed were correlated to early XBRL membership.