LOAN PORTFOLIO - Corporation's TDR Activity (Detail) - Entity Loan Modification Program [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Modifications [Line Items]
Beginning Balance of TDRs	$ 587,219	$ 647,048	$ 661,591
New TDRs	171,857	93,837	84,942
Increases to existing TDRs (disbursements)	7,027	6,575	3,921
Charge-offs post modification	(27,951)	(32,963)	(24,876)
Sales, net of charge-offs	0	(53,245)	(3,761)
Foreclosures	(21,591)	(25,059)	(16,834)
TDRs transferred from (to) held for sale	(34,541)	0	0
Paid-off and partial payments	(99,373)	(48,974)	(57,935)
Ending balance of TDRs	$ 582,647	$ 587,219	$ 647,048