LOANS AND LEASES - Net of Unearned Income (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	$ 21,839,403	$ 20,998,766
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	8,845,740	8,741,864
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	4,363,457	4,170,667
Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	346,579	266,720
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	34,732	17,063
Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	13,590,508	13,196,314
Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,778,123	1,905,535
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	2,984,662	2,702,691
Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,880,649	1,448,433
Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,605,461	1,745,793
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	8,248,895	7,802,452
Originated Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	17,377,969	15,345,490
Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	5,978,629	5,174,783
Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,892,822	3,495,247
Originated Loans and Leases [Member] | Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	346,579	266,720
Originated Loans and Leases [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	34,732	17,063
Originated Loans and Leases [Member] | Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	10,252,762	8,953,813
Originated Loans and Leases [Member] | Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,670,964	1,755,713
Originated Loans and Leases [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	2,457,380	2,036,226
Originated Loans and Leases [Member] | Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,880,487	1,448,268
Originated Loans and Leases [Member] | Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,116,376	1,151,470
Originated Loans and Leases [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	7,125,207	6,391,677
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	4,461,434	5,653,276
Acquired Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	2,867,111	3,567,081
Acquired Loans [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	470,635	675,420
Acquired Loans [Member] | Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	0	0
Acquired Loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	0	0
Acquired Loans [Member] | Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,337,746	4,242,501
Acquired Loans [Member] | Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	107,159	149,822
Acquired Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	527,282	666,465
Acquired Loans [Member] | Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	162	165
Acquired Loans [Member] | Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	489,085	594,323
Acquired Loans [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	$ 1,123,688	$ 1,410,775