Segment Information (Premiums, Fees and Other Revenues by US and Foreign Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Premiums, Fees & Other Revenues	$ 51,961	$ 56,365	$ 49,015
UNITED STATES
Segment Reporting Information [Line Items]
Premiums, Fees & Other Revenues	36,869	42,250	34,191
Japan
Segment Reporting Information [Line Items]
Premiums, Fees & Other Revenues	5,020	5,460	6,183
Other Foreign
Segment Reporting Information [Line Items]
Premiums, Fees & Other Revenues	$ 10,072	$ 8,655	$ 8,641