Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale debt securities
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 0
Charged (Credited) to costs and expenses	82
Charged (Credited) to other accounts	0
Other deductions	(56)
Balance at end of year	26	$ 0
Accounts receivable, net
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	252	217	$ 207
Charged (Credited) to costs and expenses	(50)	51	18
Charged (Credited) to other accounts	(12)	0	(3)
Other deductions	(34)	(16)	(5)
Balance at end of year	156	252	217
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	196	199	72
Charged (Credited) to costs and expenses	10	(6)	(5)
Charged (Credited) to other accounts	1	3	132
Other deductions	0	0	0
Balance at end of year	207	196	199
Reinsurance recoverables
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	2	2	3
Charged (Credited) to costs and expenses	(1)	0	(1)
Charged (Credited) to other accounts	31	0	0
Other deductions	0	0	0
Balance at end of year	$ 32	$ 2	$ 2