General	6 Months Ended
Jun. 30, 2011
General
General	1. GENERAL Allied World Assurance Company Holdings, AG, a Swiss holding company ("Allied World Switzerland"), through its wholly-owned subsidiaries (collectively, the "Company"), provides property and casualty insurance and reinsurance on a worldwide basis through operations in Bermuda, the United States, Europe, Hong Kong and Singapore. On November 26, 2010, the Company received approval from the Supreme Court of Bermuda to change the place of incorporation of the ultimate parent company from Bermuda to Switzerland (the "Redomestication"), which was completed on December 1, 2010. The ultimate parent company is now Allied World Switzerland, which wholly owns the former public company, Allied World Assurance Company Holdings, Ltd ("Allied World Bermuda"). After the Redomestication, the Company continues to report under accounting principles generally accepted in the United States of America ("U.S. GAAP") and the Company's common shares continue to trade on the New York Stock Exchange under the symbol "AWH," the same symbol under which the common shares were listed prior to the Redomestication. In addition, the Company remains subject to U.S. Securities and Exchange Commission ("SEC") reporting requirements and continues to report consolidated financial results in U.S. dollars. The Company believes the Redomestication provides the ability to maintain a competitive worldwide effective corporate tax rate.

General

6 Months Ended

Jun. 30, 2011

1. GENERAL

Allied World Assurance Company Holdings, AG, a Swiss holding company ("Allied World Switzerland"), through its wholly-owned subsidiaries (collectively, the "Company"), provides property and casualty insurance and reinsurance on a worldwide basis through operations in Bermuda, the United States, Europe, Hong Kong and Singapore.

On November 26, 2010, the Company received approval from the Supreme Court of Bermuda to change the place of incorporation of the ultimate parent company from Bermuda to Switzerland (the "Redomestication"), which was completed on December 1, 2010. The ultimate parent company is now Allied World Switzerland, which wholly owns the former public company, Allied World Assurance Company Holdings, Ltd ("Allied World Bermuda"). After the Redomestication, the Company continues to report under accounting principles generally accepted in the United States of America ("U.S. GAAP") and the Company's common shares continue to trade on the New York Stock Exchange under the symbol "AWH," the same symbol under which the common shares were listed prior to the Redomestication. In addition, the Company remains subject to U.S. Securities and Exchange Commission ("SEC") reporting requirements and continues to report consolidated financial results in U.S. dollars. The Company believes the Redomestication provides the ability to maintain a competitive worldwide effective corporate tax rate.