Investments - OTTI losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Realized capital gains and losses by asset type
Gross	$ (16)	$ 0
Included in OCI	2	(1)
Net	(14)	(1)
Corporate
Realized capital gains and losses by asset type
Gross	(2)	0
Included in OCI	2	0
Net	0	0
Asset-backed securities (“ABS”)
Realized capital gains and losses by asset type
Gross	(2)	0
Included in OCI	1	0
Net	(1)	0
Residential mortgage-backed securities (“RMBS”)
Realized capital gains and losses by asset type
Gross	0	0
Included in OCI	(1)	0
Net	(1)	0
Commercial mortgage-backed securities (“CMBS”)
Realized capital gains and losses by asset type
Gross	0	0
Included in OCI	0	(1)
Net	0	(1)
Fixed income securities
Realized capital gains and losses by asset type
Gross	(4)	0
Included in OCI	2	(1)
Net	(2)	(1)
Limited partnership interests
Realized capital gains and losses by asset type
Gross	(1)	0
Included in OCI	0	0
Net	(1)	0
Other
Realized capital gains and losses by asset type
Gross	(11)	0
Included in OCI	0	0
Net	$ (11)	$ 0

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562

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- Definition

Amount before tax of other than temporary impairment loss (OTTI) on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss and attributable to parent entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569643-111683

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

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-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
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-Paragraph 1A
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-URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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