Schedule IV - Supplementary Reinsurance Information

12 Months Ended

Dec. 31, 2012

Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]

Schedule IV - Supplementary reinsurance information

Schedule IV

ALLIED WORLD ASSURANCE COMPANY HOLDINGS, AG

SUPPLEMENTARY REINSURANCE INFORMATION

(Expressed in thousands of United States dollars)

									Percentage
			(b)		(c)		(d)		of Amount
			Ceded		Assumed		Net		Assumed
	(a)		to Other		from Other		Amount		to Net
Property and Casualty:	Gross		Companies		Companies		(a) - (b) + (c)		(c) / (d)
Year ended December 31, 2012	$	1,569,021	$	491,448	$	760,250	$	1,837,823		41%
Year ended December 31, 2011	$	1,369,017	$	405,755	$	570,504	$	1,533,766		37%
Year ended December 31, 2010	$	1,234,204	$	365,942	$	524,193	$	1,392,455		38%