Derivatives (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	$ 12,796		$ 11,512
Estimated Fair Value Assets	10,530		11,411
Estimated Fair Value Liabilities	5,545		6,975
Excess securities collateral received on derivatives	289		$ 252
Collateral Amount Not Provided Due to Downgrade Threshold	15
Derivative Instrument Detail [Abstract]
Net amounts reclassified into net derivatives gains (losses) on discontinued cash flow hedges	$ 1	$ (2)
Hedging exposure to variability in future cash flows for specific length of time	6 years		6 years
Accumulated Other Comprehensive Income Loss	$ 2,200		$ 2,000
Cumulative foreign currency translation gain (loss) recorded in accumulated other comprehensive income (loss) for net investment in foreign operations hedges	483		435
Excess securities collateral provided on derivatives	103		125
Securities collateral received which the company is permitted to sell or repledge, amount that has been sold or repledged	0
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	99
Over the Counter [Member]
Derivatives, Fair Value [Line Items]
Excess securities collateral received on derivatives	(341)		(398)
Excess securities collateral provided on derivatives	(1,300)		(1,200)
Cash collateral on derivative assets	(4,667)		(5,432)
Exchange-traded
Derivatives, Fair Value [Line Items]
Excess securities collateral received on derivatives	(1,100)		(1,000)
Excess securities collateral provided on derivatives	(131)		(184)
Cash collateral on derivative assets	0		0
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	172		166
Estimated Fair Value Liabilities	$ 45		$ 0