Other Revenues and Other Expenses Other Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 324	$ 324	$ 669	$ 661
Other revenues	456	478	895	972
Prepaid legal plans
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	99	86	200	172
Fee-based investment management
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	71	69	150	146
Recordkeeping and administrative services
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	46	52	95	102
Administrative services-only contracts
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	54	53	110	106
Other revenue from service contracts from customers
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	54	64	114	135
Other Income
Disaggregation of Revenue [Line Items]
Other revenues	$ 132	$ 154	$ 226	$ 311