Investments (Fair Values by Contractual Maturity) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 11,536	$ 5,629
Maturing after one year through three years	53	2,304
Maturing after three years through five years	0	119
Residential-mortgage-backed securities	0	182
Total interest-bearing securities	$ 11,589	$ 8,234

Available-For Sale Securities, Debt Maturities, After One Through Three Years, Fair Value

No definition available.

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- Definition

Available-For-Sale Securities, Debt Maturities, After Three Through Five Years, Fair Value

+ References

No definition available.

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- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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