LOAN PORTFOLIO - Corporation's TDR Activity (Detail) - Entity Loan Modification Program [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Financing Receivable Modifications [Line Items]
Beginning Balance of TDRs	$ 582,647	$ 587,219
New TDRs	25,459	43,419
Increases to existing TDRs (disbursements)	1,175	6,771
Charge-offs post modification	(2,821)	(9,171)
Foreclosures	(3,643)	(7,043)
TDRs transferred to loans held for sale	0	(30,000)
Paid-off and partial payments	(13,022)	(18,819)
Ending balance of TDRs	$ 589,795	$ 572,376