Investments - Schedule of PCD Securities (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Investments, Debt and Equity Securities [Abstract]
Unpaid principal balance	$ 644
Allowance for expected credit losses at acquisition	(26)
Purchase (discount) premium	(149)
Purchase price	$ 469

Amount of allowance for credit loss at acquisition date of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 10
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922903-210455

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- Definition

Amount at par value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 10
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922903-210455

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- Definition

Amount at purchase price of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922903-210455

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- Definition

Amount of discount (premium) attributable to other factors on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 10
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922903-210455

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- References

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