Restructuring - Narrative (Details) - Organizational restructuring $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) entity	Sep. 30, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 27		$ 83
Minimum
Restructuring Cost and Reserve [Line Items]
Expected costs	250		250
Maximum
Restructuring Cost and Reserve [Line Items]
Expected costs	300		300
Continuing Operations
Restructuring Cost and Reserve [Line Items]
Restructuring expense	10	$ 26	46	$ 164
Discontinued Operations
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 17		$ 37
Number of regulated insurance entities that will be divested or dissolved | entity			4