Consolidated Balance Sheets (Parenthetical) $ in Millions	Mar. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares
Statement of Financial Position [Abstract]
Fixed maturities available for sale, at amortized cost	$ 75,991	$ 43,149
Fixed maturities available for sale, hybrid financial instruments	3	31
Fixed maturities held to maturity, at amortized cost	11,580	8,552
Equity securities, at cost	841	441
Other investments, cost	$ 4,233	$ 2,993
Common Shares, shares issued | shares	479,783,864	342,832,412
Common Shares, shares outstanding | shares	464,283,520	324,563,441
Common Shares in treasury, shares | shares	15,500,344	18,268,971