Investments - Allowance for Loan Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of January 1, 2020	$ 14	$ 0
Credit losses on securities for which credit losses were not previously recorded	36	14
Increase (decrease) on securities with allowance recorded in previous period	(2)	0
Write-offs	0	0
Recoveries of amounts previously written off	0	0
Balance at December 31, 2020	48	14
Commercial portfolio segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of January 1, 2020	67	12
Credit losses on securities for which credit losses were not previously recorded	1	5
Accounts Receivable, Sale	(7)	0
Increase (decrease) on securities with allowance recorded in previous period	(50)	52
Provision for expected credit loss	11	69
Write-offs	0	(2)
Recoveries of amounts previously written off	0	0
Balance at December 31, 2020	11	67
Commercial portfolio segment | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of January 1, 2020	$ 12
Balance at December 31, 2020		$ 12