Other Revenues and Other Expenses Other Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 515	$ 345
Other revenues	631	439
Vision fee for service arrangements (1)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	140	0
Prepaid legal plans
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	109	101
Fee-based investment management
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	85	79
Recordkeeping and administrative services (2)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	53	49
Administrative services-only contracts
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	61	56
Other revenue from service contracts from customers
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	67	60
Other Income
Disaggregation of Revenue [Line Items]
Other revenues	$ 116	$ 94