No definition available.

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
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-Paragraph 15
-Subparagraph (c)(1)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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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.

+ References

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

+ References

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- Definition

Amount of loan with fixed rate of interest.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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Amount of loan with variable or adjustable rate of interest.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(c))
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Amount of increase (decrease) in allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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Investments - Mortgage loans other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Total				$ 3,876	$ 3,938
Net carrying value of impaired mortgage loans
Impaired mortgage loans with a valuation allowance				4	5
Impaired mortgage loans without a valuation allowance				0	0
Total impaired mortgage loans				4	5
Valuation allowance on impaired mortgage loans	$ 3	$ 3	$ 8	3	3
Rollforward of the valuation allowance on impaired mortgage loans
Beginning balance	3	3	8
Net increase (decrease) in valuation allowance	1	0	(4)
Charge offs	(1)	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				3,844	3,933
Variable rate mortgage loans				28	0
Total				3,872	3,933
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				3	52
Variable rate mortgage loans				0	0
Total				3	52
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				326	321
Variable rate mortgage loans				0	0
Total				326	321
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				1,033	1,196
Variable rate mortgage loans				15	0
Total				1,048	1,196
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				2,482	2,364
Variable rate mortgage loans				13	0
Total				$ 2,495	$ 2,364
Mortgage loans
Average carrying value and interest income recognized on impaired mortgage loans
Average balance impaired mortgage loans	$ 7	$ 6	$ 11