LOANS AND LEASES - Outstanding Principal Balance and Carrying Amount of Loans Acquired in a Business Combination (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Document Period End Date	Jun. 30, 2019
Carrying amount	$ 22,543	$ 22,153
Loans Acquired In A Business Combination Accounted For Under ASC 310-30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	3,247	3,768
Carrying amount	2,998	3,570
Loans Acquired In A Business Combination Accounted For Under ASC 310-20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	504	602
Carrying amount	491	513
Loans Acquired In Business Combination Including Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	3,751	4,370
Carrying amount	$ 3,489	$ 4,083