Condensed Consolidated Balance Sheets (Parenthetical) In Thousands, except Share data	Jun. 30, 2011 USD ($)	Jun. 30, 2011 CHF	Dec. 31, 2010 USD ($)	Dec. 31, 2010 CHF
Condensed Consolidated Balance Sheets
Amortized costs of fixed maturity investments available for sale, at fair value	$ 318,711		$ 828,544
Common shares, par value		15.00		15
Common shares, issued	40,003,642	40,003,642	40,003,642	40,003,642
Common shares, outstanding	37,945,043	37,945,043	38,089,226	38,089,226
Treasury stock, shares	2,058,599	2,058,599	1,914,416	1,914,416