Investments (Net Unrealized Gains Losses on Investments by Asset Class) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Schedule Of Marketable Securities [Line Items]
Net unrealized gains (losses) on investments	$ 49,879	$ 28,474
Net unrealized losses on held to maturity securities transferred from available-for-sale	0
Derivatives designated as cash flow hedges
Schedule Of Marketable Securities [Line Items]
Net unrealized gains (losses) on investments	1,298	1,165
Fixed maturities | Available-for-sale
Schedule Of Marketable Securities [Line Items]
Net unrealized gains (losses) on investments	45,918	24,673
Fixed maturities | Fixed maturity securities on which an OTTI loss has been recognized
Schedule Of Marketable Securities [Line Items]
Net unrealized gains (losses) on investments	286	234
Equity securities, available-for-sale | Available-for-sale
Schedule Of Marketable Securities [Line Items]
Net unrealized gains (losses) on investments	2,408	2,427
Other investments
Schedule Of Marketable Securities [Line Items]
Net unrealized gains (losses) on investments	$ (31)	$ (25)