Investments - PCI Securities Acquired During the Period (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fixed maturity securities
Contractually required payments receivable	$ 2,161	$ 2,407
Cash flows expected to be collected	1,790	2,053
Fair value	1,428	1,497
Mortgage loans
Contractually required payments receivable	894	304
Cash flows expected to be collected	857	290
Fair value	$ 633	$ 220

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- Definition

Fair value at acquisition of acquired loans accounted for as available-for-sale debt securities with evidence of deterioration of credit quality.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

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Amount of cash flows expected to be collected at acquisition of acquired loans accounted for as available-for-sale debt securities with evidence of deterioration of credit quality.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

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Amount of contractually required payments receivable at acquisition of acquired loans accounted for as available-for-sale debt securities with evidence of deterioration of credit quality.

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