Goodwill and Other Intangibles - Narrative (Details) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Cumulative goodwill impairments				$ 6,100,000,000	$ 6,100,000,000
Goodwill impairments				0	0	$ 6,149,000,000
Goodwill	$ 78,678,000,000			79,552,000,000	79,749,000,000	78,678,000,000
Retail/ LTC
Goodwill [Line Items]
Goodwill impairments						6,149,000,000
Goodwill	10,806,000,000			10,807,000,000	10,807,000,000	10,806,000,000
Retail/ LTC | Long-Term Care Reporting Unit
Goodwill [Line Items]
Goodwill impairments	2,200,000,000	$ 0	$ 3,900,000,000
Goodwill				431,000,000
Health Care Benefits
Goodwill [Line Items]
Goodwill	$ 44,484,000,000			$ 45,130,000,000	$ 45,361,000,000	$ 44,484,000,000