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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Investments - Mortgage loans other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Mortgage loans
Provision for Loan, Lease, and Other Losses	$ 0	$ 0	$ 1
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Total				$ 3,988	$ 3,995
Net carrying value of impaired mortgage loans
Impaired mortgage loans with a valuation allowance				8	4
Impaired mortgage loans without a valuation allowance				0	0
Total impaired mortgage loans				8	4
Valuation allowance on impaired mortgage loans	3	3	3	3	3
Rollforward of the valuation allowance on impaired mortgage loans
Beginning balance	3	3	3
Charge offs	0	0	(1)
Ending balance	3	3	3
Non-impaired mortgage loans
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans				3,927	3,934
Variable rate mortgage loans				53	57
Total				3,980	3,991
Non-impaired mortgage loans \| Below 1.0
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans				13	6
Variable rate mortgage loans				16	15
Total				29	21
Non-impaired mortgage loans \| 1.0 - 1.25
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans				161	221
Variable rate mortgage loans				0	0
Total				161	221
Non-impaired mortgage loans \| 1.26 - 1.50
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans				1,057	1,048
Variable rate mortgage loans				9	0
Total				1,066	1,048
Non-impaired mortgage loans \| Above 1.50
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans				2,696	2,659
Variable rate mortgage loans				28	42
Total				$ 2,724	$ 2,701
Mortgage loans
Average carrying value and interest income recognized on impaired mortgage loans
Average balance impaired mortgage loans	$ 5	$ 4	$ 7