Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Total derivative assets	$ 867	$ 1,148
Total derivative liabilities	831	127
Anticipated pre-tax loss reclassified from accumulated other comprehensive income (loss) to earnings	$ 261
Maximum Length of Time Hedged in Cash Flow Hedge (future cash flows)	10 years
Net investment hedges income (loss) before taxes	$ 536	532	$ 526
Derivative [Line Items]
Credit protection derivatives outstanding notional amounts	6	145
Purchased credit protection, Liability	0	1
Single Name
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 100	110
Fair value asset (liability)		1
Credit Derivatives Written Max Length Of Maturities (less than)	1 year
Single Name | NAIC 1
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 36
Single Name | NAIC 2
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	60
Single Name | NAIC 3
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	4
Credit Default Index
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	692	4,953
Fair value asset (liability)	$ 20	$ 10
Credit Derivatives Written Max Length Of Maturities (less than)	28 years
Credit Default Index | NAIC 1
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 50
Credit Default Index | NAIC 3
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	570
Credit Default Index | NAIC 6
Derivative [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 72