Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Total derivative assets	$ 3,184	$ 867
Total derivative liabilities	904	831
Anticipated pre-tax gain (loss) reclassified from accumulated other comprehensive income (loss) to earnings	$ 354
Maximum Length of Time Hedged in Cash Flow Hedge	10 years
Net investment hedges income (loss) before taxes	$ 549	536
Credit Derivatives [Line Items]
Credit Risk Derivatives, at Fair Value, Asset Net (Liability)	(28)	21
Credit Derivative Protection Purchased Notional Amount	$ 237	6
Single Name Credit Default Swaps
Credit Derivatives [Line Items]
Credit Derivatives Written Max Length Of Maturities (less than)	1 year
Credit Risk Derivatives, at Fair Value, Asset Net (Liability)		1
Credit Default Swaps Referencing Indices
Credit Derivatives [Line Items]
Credit Derivatives Written Max Length Of Maturities (less than)	27 years
Credit Default Swap, Buying Protection
Credit Derivatives [Line Items]
Credit Risk Derivatives, at Fair Value, Asset Net (Liability)	$ 1	$ 0