Consolidated Balance Sheets (Parenthetical) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015 USD ($)	Mar. 31, 2015 CHF	Dec. 31, 2014 USD ($)	Dec. 31, 2014 CHF
Statement of Financial Position [Abstract]
Fixed maturities available for sale, at amortized cost	$ 48,384		$ 47,826
Fixed maturities available for sale, hybrid financial instruments	284		274
Fixed maturities held to maturity, at amortized cost	7,307		7,589
Equity securities, at cost	447		440
Other investments, cost	$ 3,096		$ 2,999
Common Shares, par value		24.15		24.77
Common Shares, shares issued	342,832,412	342,832,412	342,832,412	342,832,412
Common Shares, shares outstanding	327,084,762	327,084,762	328,659,686	328,659,686
Common Shares in treasury, shares	15,747,650	15,747,650	14,172,726	14,172,726