Investments - OTTI losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	$ 0	$ (62)
Included in OCI	(1)	3
Net OTTI losses recognized in earnings	(1)	(59)
Corporate
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(9)
Included in OCI	0	3
Net OTTI losses recognized in earnings	0	(6)
Residential mortgage-backed securities (“RMBS”)
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(1)
Included in OCI	0	(3)
Net OTTI losses recognized in earnings	0	(4)
Fixed income securities
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(16)
Included in OCI	(1)	3
Net OTTI losses recognized in earnings	(1)	(13)
Equity securities
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(36)
Included in OCI	0	0
Net OTTI losses recognized in earnings	0	(36)
Limited partnership interests
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(7)
Included in OCI	0	0
Net OTTI losses recognized in earnings	0	(7)
Other
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(3)
Included in OCI	0	0
Net OTTI losses recognized in earnings	0	(3)
Commercial mortgage-backed securities (“CMBS”)
Realized capital gains and losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(6)
Included in OCI	(1)	3
Net OTTI losses recognized in earnings	$ (1)	$ (3)

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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e25351-111560

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=84161450&loc=SL4573702-111684

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4569643-111683

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 8B
-URI http://asc.fasb.org/extlink&oid=82897076&loc=SL6284393-111563

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No definition available.

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