Consolidated Balance Sheets (Parenthetical) In Millions, except Share data, unless otherwise specified	Mar. 31, 2014 USD ($)	Mar. 31, 2014 CHF	Dec. 31, 2013 USD ($)	Dec. 31, 2013 CHF
Statement of Financial Position [Abstract]
Fixed maturities available for sale, at amortized cost	$ 48,282		$ 48,406
Fixed maturities available for sale, hybrid financial instruments	319		302
Fixed maturities held to maturity, at amortized cost	6,080		6,263
Equity securities, at cost	845		841
Other investments, cost	2,823		2,671
Investments in partially-owned insurance companies, cost	$ 463		$ 467
Common Shares, par value		26.59		27.04
Common Shares, shares issued	342,832,412	342,832,412	342,832,412	342,832,412
Common Shares, shares outstanding	337,974,644	337,974,644	339,793,935	339,793,935
Common Shares in treasury, shares	4,857,768	4,857,768	3,038,477	3,038,477