Consolidated Balance Sheets (Parenthetical) $ in Millions	Dec. 31, 2019 USD ($) shares	Dec. 31, 2019 SFr / shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 SFr / shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares
Statement of Financial Position [Abstract]
Fixed maturities available for sale, at amortized cost | $	$ 82,580		$ 79,323
Debt Securities, Held-to-maturity, Fair Value | $	$ 13,005		$ 13,259
Common Shares, par value | SFr / shares		SFr 24.15		SFr 24.15
Common Shares, shares issued	479,783,864		479,783,864		479,783,864	479,783,864
Common Shares, shares outstanding	451,971,567		459,203,378		463,833,179
Common Shares in treasury, shares	27,812,297		20,580,486		15,950,685	13,815,148