SECURITIES - Amortized Cost and Fair Value of Securities, by Contractual Maturities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Schedule Of Securities [Line Items]
Available for sale, due in one year or less, amortized cost	$ 54
Available for sale, due after one year but within five years, amortized cost	602
Available for sale, due after five years but within ten years, amortized cost	66
Available for sale, due after ten years, amortized cost	37
Available for sale, with contractual maturities, amortized cost	759
Amortized Cost	3,519	$ 3,622
Available for sale, due in one year or less, fair value	54
Available for sale, due after one year but within five years, fair value	559
Available for sale, due after five years but within ten years, fair value	63
Available for sale, due after ten years, fair value	37
Available for sale, with contractual maturities, fair value	713
Fair Value	3,177	3,275
Held to maturity, due in one year or less, amortized cost	3
Held to maturity, due after one year but within five years, amortized cost	130
Held to maturity, due after five years but within ten years, amortized cost	234
Held to maturity, due after ten years, amortized cost	772
Held to maturity, with contractual maturities, amortized cost	1,139
Amortized Cost	3,988	4,087
Held to maturity, due in one year or less, fair value	3
Held to maturity, due after one year but within five years, fair value	128
Held to maturity, due after five years but within ten years, fair value	218
Held to maturity, due after ten years, fair value	687
Held to maturity, with contractual maturities, fair value	1,036
Fair Value	3,587	3,687
Agency mortgage-backed securities
Schedule Of Securities [Line Items]
Available-for-sale, amortized cost	1,235
Amortized Cost	1,235	1,360
Available for sale, fair value	1,112
Fair Value	1,112	1,232
Held to maturity, amortized cost	1,096
Amortized Cost	1,096	1,178
Held to maturity, fair value	975
Fair Value	975	1,053
Agency collateralized mortgage obligations
Schedule Of Securities [Line Items]
Available-for-sale, amortized cost	1,028
Amortized Cost	1,028	1,110
Available for sale, fair value	892
Fair Value	892	972
Held to maturity, amortized cost	885
Amortized Cost	885	953
Held to maturity, fair value	764
Fair Value	764	833
Commercial mortgage-backed securities
Schedule Of Securities [Line Items]
Available-for-sale, amortized cost	497
Amortized Cost	497	430
Available for sale, fair value	460
Fair Value	460	395
Held to maturity, amortized cost	868
Amortized Cost	868	866
Held to maturity, fair value	812
Fair Value	$ 812	$ 818

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