Investments - Other-than-temporary impairment losses (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	$ (7)	$ 0
Included in OCI	0	(1)
Net OTTI losses recognized in earnings	(7)	(1)
CMBS
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	0	0
Included in OCI	0	(1)
Net OTTI losses recognized in earnings	0	(1)
Fixed income securities
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	0	0
Included in OCI	0	(1)
Net OTTI losses recognized in earnings	0	(1)
Limited partnership interests
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(1)	0
Included in OCI	0	0
Net OTTI losses recognized in earnings	(1)	0
Other
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(6)	0
Included in OCI	0	0
Net OTTI losses recognized in earnings	$ (6)	$ 0

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: 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=SL7669686-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration