General	12 Months Ended
Dec. 31, 2014
General [Abstract]
General	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 Australia, Bermuda, the United States, Canada, Europe, Hong Kong, Labuan and Singapore. References to $ are to the lawful currency of the United States and to CHF are to the lawful currency of Switzerland. The Company has reached definitive agreements to acquire the Hong Kong and Singapore operations of Royal & Sun Alliance Insurance plc ("RSA") for approximately $201,761, at current exchange rates, subject to adjustments at closing. In addition to the purchase price, the Company expects to contribute an additional $90,000 to capitalize the businesses on an ongoing basis. Subject to regulatory approvals in both Hong Kong and Singapore, as well as court approval in Singapore, the acquisition is expected to be completed in the early part of the second quarter of 2015. On May 1, 2014, the shareholders approved a 3-for-1 stock split of the Company's common shares. All historical share and per share amounts reflect the effect of the stock split. During the fourth quarter of 2014, the Company reorganized how it manages its business, and as a result it realigned its executive management team and changed its reportable segments to correspond to the reorganization. The Company's Bermuda direct insurance operations, except for the trade credit line of business, which had previously been included in the international insurance segment, was combined with the U.S. insurance segment, with the new segment renamed the "North American Insurance" segment. The remaining direct insurance operations of the international insurance segment was renamed the "Global Markets Insurance" segment. The Reinsurance segment remained unchanged. The newly created segments are included in note 17 and prior periods have been recast to conform to the new presentation.

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 Australia, Bermuda, the United States, Canada, Europe, Hong Kong, Labuan and Singapore. References to $ are to the lawful currency of the United States and to CHF are to the lawful currency of Switzerland.

The Company has reached definitive agreements to acquire the Hong Kong and Singapore operations of Royal & Sun Alliance Insurance plc ("RSA") for approximately $201,761, at current exchange rates, subject to adjustments at closing. In addition to the purchase price, the Company expects to contribute an additional $90,000 to capitalize the businesses on an ongoing basis. Subject to regulatory approvals in both Hong Kong and Singapore, as well as court approval in Singapore, the acquisition is expected to be completed in the early part of the second quarter of 2015.

On May 1, 2014, the shareholders approved a 3-for-1 stock split of the Company's common shares. All historical share and per share amounts reflect the effect of the stock split.

During the fourth quarter of 2014, the Company reorganized how it manages its business, and as a result it realigned its executive management team and changed its reportable segments to correspond to the reorganization. The Company's Bermuda direct insurance operations, except for the trade credit line of business, which had previously been included in the international insurance segment, was combined with the U.S. insurance segment, with the new segment renamed the "North American Insurance" segment. The remaining direct insurance operations of the international insurance segment was renamed the "Global Markets Insurance" segment. The Reinsurance segment remained unchanged. The newly created segments are included in note 17 and prior periods have been recast to conform to the new presentation.