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Investment Securities (Narrative) (Details) $ in Millions		3 Months Ended
		Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Securities with no credit impairment in unrealized loss position		1,290
Loan interest receivable		$ 48		$ 36
Securities gains and losses		0	$ 0
Investment securities available-for-sale, Amortized Cost		22,559		17,116
Investment securities available-for-sale		19,452		16,986
Carrying value of securities pledged		2,800
Pledged to the FHLB as collateral for potential future borrowings		1,100
Collateral for potential future borrowings		1,700
Liabilities secured by pledged collateral		$ 1,200
U.S. Treasury and other U.S. government agency securities
Securities with no credit impairment in unrealized loss position		28
Investment securities available-for-sale, Amortized Cost		$ 2,918		3,010
Investment securities available-for-sale		$ 2,756		2,993
Residential Mortgage Backed Securities
Securities with no credit impairment in unrealized loss position		1,008
Investment securities available-for-sale, Amortized Cost	[1]	$ 14,390		13,397
Investment securities available-for-sale	[1]	$ 12,052		13,288
Commercial Mortgage Backed Securities
Securities with no credit impairment in unrealized loss position		254
Investment securities available-for-sale, Amortized Cost	[1]	$ 5,251		709
Investment securities available-for-sale	[1]	$ 4,644		$ 705
[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

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