INVESTMENT SECURITIES - Contractual Maturities, Available for Sale (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Amortized Cost
Due within one year	$ 856
Due after one year through five years	2,846
Due after five years through ten years	2,317
Due after ten years	2,728
Mortgage and asset-backed securities	3,466
Amortized Cost	12,213	$ 12,104
Fair Value
Due within one year	854
Due after one year through five years	2,803
Due after five years through ten years	2,247
Due after ten years	2,801
Mortgage and asset-backed securities	3,398
Fair Value	$ 12,103	$ 12,302