INVESTMENT SECURITIES - Contractual Maturities of Debt Securities Available for Sale (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Amortized Cost
Due within one year	$ 632
Due after one year through five years	2,267
Due after five years through ten years	2,543
Due after ten years	1,450
Mortgage and asset-backed securities	6,609
Amortized Cost	13,501	$ 12,437
Fair Value
Due within one year	635
Due after one year through five years	2,340
Due after five years through ten years	2,570
Due after ten years	1,429
Mortgage and asset-backed securities	6,667
Fair Value	$ 13,641	$ 12,951

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

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