Consolidated Balance Sheets (Parenthetical) $ in Millions	Jun. 30, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares
Statement of Financial Position [Abstract]
Available for sale, at amortized cost	$ 80,363	$ 79,536
Fixed maturities available for sale, hybrid financial instruments	2	2
Held to maturity, at Fair Value	10,560	10,670
Equity securities, at cost	697	706
Other investments, cost	$ 4,410	$ 4,270
Common Shares, shares issued | shares	479,783,864	479,783,864
Common Shares, shares outstanding | shares	465,375,141	465,968,716
Common Shares in treasury, shares | shares	14,408,723	13,815,148