ALLOWANCE FOR CREDIT LOSSES - Individual and Collective Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	$ 21,839,403	$ 20,998,766
Commercial Real Estate [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	8,845,740	8,741,864
Commercial and Industrial [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	4,363,457	4,170,667
Commercial Leases [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	346,579	266,720
Other [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	34,732	17,063
Total Commercial Loans and Leases [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	13,590,508	13,196,314
Direct Installment [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	1,778,123	1,905,535
Residential Mortgages [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	2,984,662	2,702,691
Indirect Installment [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	1,880,649	1,448,433
Consumer Lines of Credit [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	1,605,461	1,745,793
Consumer Loan [Member]
Valuation Allowance [Line Items]
Originated loans and leases outstanding, loans and leases	8,248,895	7,802,452
Originated Loans and Leases [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	4,756	3,654
Originated allowance, collectively evaluated for impairment	168,555	165,028
Originated loans and leases outstanding, loans and leases	17,377,969	15,345,490
Originated loans and leases outstanding, individually evaluated for impairment	32,888	20,986
Originated loans and leases outstanding, collectively evaluated for impairment	17,345,081	15,324,504
Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	44	439
Originated allowance, collectively evaluated for impairment	54,639	49,842
Originated loans and leases outstanding, loans and leases	5,978,629	5,174,783
Originated loans and leases outstanding, individually evaluated for impairment	11,198	11,114
Originated loans and leases outstanding, collectively evaluated for impairment	5,967,431	5,163,669
Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	4,712	3,215
Originated allowance, collectively evaluated for impairment	47,824	48,748
Originated loans and leases outstanding, loans and leases	3,892,822	3,495,247
Originated loans and leases outstanding, individually evaluated for impairment	21,690	9,872
Originated loans and leases outstanding, collectively evaluated for impairment	3,871,132	3,485,375
Originated Loans and Leases [Member] | Commercial Leases [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	7,500	5,646
Originated loans and leases outstanding, loans and leases	346,579	266,720
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	346,579	266,720
Originated Loans and Leases [Member] | Other [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	2,078	1,843
Originated loans and leases outstanding, loans and leases	34,732	17,063
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	34,732	17,063
Originated Loans and Leases [Member] | Total Commercial Loans and Leases [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	4,756	3,654
Originated allowance, collectively evaluated for impairment	112,041	106,079
Originated loans and leases outstanding, loans and leases	10,252,762	8,953,813
Originated loans and leases outstanding, individually evaluated for impairment	32,888	20,986
Originated loans and leases outstanding, collectively evaluated for impairment	10,219,874	8,932,827
Originated Loans and Leases [Member] | Direct Installment [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	13,833	20,936
Originated loans and leases outstanding, loans and leases	1,670,964	1,755,713
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	1,670,964	1,755,713
Originated Loans and Leases [Member] | Residential Mortgages [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	17,669	15,507
Originated loans and leases outstanding, loans and leases	2,457,380	2,036,226
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	2,457,380	2,036,226
Originated Loans and Leases [Member] | Indirect Installment [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	14,453	11,967
Originated loans and leases outstanding, loans and leases	1,880,487	1,448,268
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	1,880,487	1,448,268
Originated Loans and Leases [Member] | Consumer Lines of Credit [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	10,559	10,539
Originated loans and leases outstanding, loans and leases	1,116,376	1,151,470
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	1,116,376	1,151,470
Originated Loans and Leases [Member] | Consumer Loan [Member]
Valuation Allowance [Line Items]
Originated allowance, individually evaluated for impairment	0	0
Originated allowance, collectively evaluated for impairment	56,514	58,949
Originated loans and leases outstanding, loans and leases	7,125,207	6,391,677
Originated loans and leases outstanding, individually evaluated for impairment	0	0
Originated loans and leases outstanding, collectively evaluated for impairment	$ 7,125,207	$ 6,391,677