Other Revenues and Other Expenses Other Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 734	$ 611
Other revenues	852	687
Equity Method Investee
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11	12
Reclassification, Segmentation Basis Change \| MIM
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		25
Vision fee for service arrangements
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	159	154
Prepaid legal plans
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	176	161
Institutional Client asset management fees (1)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	186	77
Administrative services-only contracts
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	81	74
Recordkeeping and administrative services (2)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	34	36
Other revenue related to service contracts from customers (1) (3)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	98	109
Other Income
Disaggregation of Revenue [Line Items]
Other revenues	$ 118	$ 76