LOAN PORTFOLIO - Loans Held for Investment on Which Accrual of Interest Income had been Discontinued (Detail) - Nonperforming Financing Receivable [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Non-performing loans:
Nonaccrual loans held for investment	$ 272,778	$ 315,973
Commercial loans[Member] | Mortgage Receivable [Member]
Non-performing loans:
Nonaccrual loans held for investment	93,192	109,536
Commercial loans[Member] | Commercial And Industrial Sector [Member]
Non-performing loans:
Nonaccrual loans held for investment	22,507	30,382
Commercial loans[Member] | Construction Loans [Member] | Land [Member]
Non-performing loans:
Nonaccrual loans held for investment	5,831	6,260
Commercial loans[Member] | Construction Loans [Member] | Residential [Member]
Non-performing loans:
Nonaccrual loans held for investment	1,869	2,102
Consumer Portfolio [Member] | Auto loans [Member]
Non-performing loans:
Nonaccrual loans held for investment	10,528	11,212
Consumer Portfolio [Member] | Other Loans [Member]
Non-performing loans:
Nonaccrual loans held for investment	5,793	7,865
Consumer Portfolio [Member] | Finance leases loans [Member]
Non-performing loans:
Nonaccrual loans held for investment	1,009	1,329
Residential mortgage loans [Member]
Non-performing loans:
Nonaccrual loans held for investment	$ 132,049	$ 147,287