Investment Securities (Schedule of Unrealized Loss on Investments) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	$ 14,141	$ 2,630
Debt securities, available-for-sale, unrealized loss, less than 12 months	(216)	(21)
Debt securities, available-for-sale, fair value, 12 months or longer	5	5
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
U.S. Treasury and federal agencies
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	871	3
Debt securities, available-for-sale, unrealized loss, less than 12 months	(17)	0
Debt securities, available-for-sale, fair value, 12 months or longer	0	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
U.S. States and political subdivisions
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	121	83
Debt securities, available-for-sale, unrealized loss, less than 12 months	(2)	(1)
Debt securities, available-for-sale, fair value, 12 months or longer	0	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
Foreign government
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	57	7
Debt securities, available-for-sale, unrealized loss, less than 12 months	(1)	0
Debt securities, available-for-sale, fair value, 12 months or longer	0	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
Agency mortgage-backed residential
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	8,530	1,225
Debt securities, available-for-sale, unrealized loss, less than 12 months	(123)	(3)
Debt securities, available-for-sale, fair value, 12 months or longer	0	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
Mortgage-backed residential
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	1,109	316
Debt securities, available-for-sale, unrealized loss, less than 12 months	(5)	(4)
Debt securities, available-for-sale, fair value, 12 months or longer	4	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
Agency mortgage-backed commercial
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	2,764	926
Debt securities, available-for-sale, unrealized loss, less than 12 months	(59)	(13)
Debt securities, available-for-sale, fair value, 12 months or longer	0	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
Asset-backed
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	103	11
Debt securities, available-for-sale, unrealized loss, less than 12 months	0	0
Debt securities, available-for-sale, fair value, 12 months or longer	0	0
Debt securities, available-for-sale, unrealized loss, 12 months or longer	0	0
Corporate debt
Debt Securities [Line Items]
Debt securities, available-for-sale, fair value, less than 12 months	586	59
Debt securities, available-for-sale, unrealized loss, less than 12 months	(9)	0
Debt securities, available-for-sale, fair value, 12 months or longer	1	5
Debt securities, available-for-sale, unrealized loss, 12 months or longer	$ 0	$ 0

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 5
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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