LOANS AND LEASES - Net of Unearned Income (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	$ 20,817,436	$ 14,896,943
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	8,822,023	5,435,162
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,980,584	3,042,781
Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	238,724	196,636
Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	13,041,331	8,674,579
Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,925,995	1,844,399
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	2,609,663	1,844,574
Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,431,273	1,196,313
Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,769,376	1,301,200
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	39,798	35,878
Originated Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	14,569,696	12,547,987
Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	4,903,796	4,095,817
Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,159,197	2,711,886
Originated Loans and Leases [Member] | Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	238,724	196,636
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	8,301,717	7,004,339
Originated Loans and Leases [Member] | Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,757,830	1,765,257
Originated Loans and Leases [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,904,620	1,446,776
Originated Loans and Leases [Member] | Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,431,111	1,196,110
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	1,134,620	1,099,627
Originated Loans and Leases [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	39,798	35,878
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	6,247,740	2,348,956
Acquired Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,918,227	1,339,345
Acquired Loans [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	821,387	330,895
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] | Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	4,739,614	1,670,240
Acquired Loans [Member] | Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	168,165	79,142
Acquired Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	705,043	397,798
Acquired Loans [Member] | Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	162	203
Acquired Loans [Member] | Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	634,756	201,573
Acquired Loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	$ 0	$ 0