本研究主要探討美國強制採用XBRL後對多角化公司價值減損的影響， Berger and Ofek (1995)指出多角化公司價值的減損主要因為內部各部門間資金配置不效率所產生，可藉由強化外部市場監督力道，增加資訊透明度，降低代理問題，進而幫助公司資源配置決策者做出正確的資源分配，使得多角化公司價值減損減少。強制採用XBRL後除了能降低資料處理成本外，可以提供報表使用者可以跨公司、跨期間及跨產業比較，減少資訊不對稱，故預期在強制採用XBRL後可以降低多角化公司價值減損的幅度。本研究以2006至2014年美國上市公司為研究對象，實證結果支持上述論點。

This study aims to discuss the impact of the United States’ mandatory adoption of XBRL toward the discount in value of diversified companies. Berger and Ofek (1995) pointed out that the main cause of the diminution in value in diversified companies is the inefficiency of fond allocations in between internal departments. By strengthening the power of supervision of external market, increasing information transparency and reducing agency problems in order to assist company resource allocation decision makers to make the right allocation, it will reduce diversification discount of the company. Mandatory adoption of XBRL could not only cut down the cost of data processing, but also allow statement user to make cross-company, cross-period and cross-industry comparison to reduce information asymmetry. Thus it is expected that with the mandatory adoption of XBRL, the range of value discount of diversified companies would be narrowed. Research objects in the study are listed companies in the United States from 2006 to 2014, with the evident-base result supporting thesis mentioned above.

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