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A valuation allowance for financing receivables that are expected to be uncollectible.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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No definition available.

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Amount of direct write-downs of financing receivables charged against the allowance.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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No definition available.

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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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No definition available.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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Amount of loan with fixed rate of interest.

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Amount of loan with variable or adjustable rate of interest.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Investments (Details 14) - USD ($) $ in Millions	12 Months Ended
Investments (Details 14) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Total				$ 4,486	$ 4,338
Mortgage loans, non-impaired
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans				4,442	4,332
Variable rate mortgage loans				39	0
Total				4,481	4,332
Net carrying value of impaired mortgage loans
Impaired mortgage loans with a valuation allowance				5	6
Impaired mortgage loans without a valuation allowance				0	0
Total impaired mortgage loans				5	6
Valuation allowance on impaired mortgage loans	$ 3	$ 8	$ 21	3	3
Rollforward of the valuation allowance on impaired mortgage loans
Beginning balance	3	8	21
Net decrease in valuation allowance	0	(4)	(5)
Charge offs	0	(1)	(8)
Ending balance	3	3	8
Mortgage loans, non-impaired \| Below 1.0
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans				60	64
Variable rate mortgage loans				0	0
Total				60	64
Mortgage loans, non-impaired \| 1.0 - 1.25
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans				324	382
Variable rate mortgage loans				0	0
Total				324	382
Mortgage loans, non-impaired \| 1.26 - 1.50
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans				1,293	1,219
Variable rate mortgage loans				0	0
Total				1,293	1,219
Mortgage loans, non-impaired \| Above 1.50
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans				2,765	2,667
Variable rate mortgage loans				39	0
Total				$ 2,804	$ 2,667
Mortgage loans
Average carrying value and interest income recognized on impaired mortgage loans
Average impaired mortgage loans	$ 6	$ 11	$ 27