OTHER COMPREHENSIVE INCOME (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,959
Other comprehensive (loss) income before reclassifications	(16)
Amounts reclassified from AOCI	4
Net current period other comprehensive (loss) income	(12)
Balance at end of period	4,974
Unrealized Net Gains (Losses) on Debt Securities Available for Sale [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	65
Other comprehensive (loss) income before reclassifications	(21)
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	(21)
Balance at end of period	44
Unrealized Net Gains (Losses) on Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(40)
Other comprehensive (loss) income before reclassifications	4
Amounts reclassified from AOCI	4
Net current period other comprehensive (loss) income	8
Balance at end of period	(32)
Unrecognized Pension and Postretirement Obligations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(64)
Other comprehensive (loss) income before reclassifications	1
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	1
Balance at end of period	(63)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(39)
Balance at end of period	$ (51)