Investments (Net Unrealized Gains Losses on Investments) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Gain (Loss) on Securities [Line Items]
Net unrealized gains (losses) on investments	$ 43,820	$ 22,720
Fixed maturities | Available-for-sale | OTTI
Gain (Loss) on Securities [Line Items]
Net unrealized gains (losses) on investments	278	190
Fixed maturities | Available-for-sale | All other
Gain (Loss) on Securities [Line Items]
Net unrealized gains (losses) on investments	42,548	21,721
Derivatives designated as cash flow hedges
Gain (Loss) on Securities [Line Items]
Net unrealized gains (losses) on investments	1,017	811
Other investments
Gain (Loss) on Securities [Line Items]
Net unrealized gains (losses) on investments	(23)	$ (2)
Other investments | Held-to-maturity
Gain (Loss) on Securities [Line Items]
Net unrealized gains (losses) on investments	$ 0