Equity (Reclassifications out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Realized investment gains (losses), net	$ 1,667	$ (766)
Other income	(2,591)	1,254
Total foreign currency translation adjustment
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	3	5
Net Unrealized Investment Gains (Losses)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	(546)	(275)
Total amortization of defined benefit pension items
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	70	60
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	(473)	(210)
Amounts reclassified from AOCI
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Realized investment gains (losses), net	(3)	(5)
Other income	0	0
Amortization of defined benefit pension items:
Prior service cost	(1)	0
Actuarial gain (loss)	(69)	(60)
Amounts reclassified from AOCI | Total foreign currency translation adjustment
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	(3)	(5)
Amounts reclassified from AOCI | Net Unrealized Investment Gains (Losses)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	546	275
Amounts reclassified from AOCI | Total amortization of defined benefit pension items
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	(70)	(60)
Amounts reclassified from AOCI | Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	473	210
Amounts reclassified from AOCI | Net unrealized investment gains (losses) on available-for-sale securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net unrealized investment gains (losses)	158	260
Amounts reclassified from AOCI | Interest Rate | Cash flow hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net unrealized investment gains (losses)	(1)	(1)
Amounts reclassified from AOCI | Currency | Cash flow hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net unrealized investment gains (losses)	1	1
Amounts reclassified from AOCI | Currency/Interest rate | Cash flow hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net unrealized investment gains (losses)	$ 388	$ 15