Benefit Plans (Summary of non-service cost (benefit) in the condensed consolidated statements of operations (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total net periodic pension cost (benefit)	$ (11)	$ (7)	$ (33)	$ (21)
Insurance claims and policyholder's benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic defined benefits expense (reversal of expense), excluding service cost component	(3)	(2)	(9)	(6)
Other operating expenses
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic defined benefits expense (reversal of expense), excluding service cost component	$ (8)	$ (5)	$ (24)	$ (15)