LOANS AND LEASES - Consumer Loans by Payment Status (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Credit Quality [Line Items]
Carrying amount	$ 21,659,582	$ 20,998,766
Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,892,080	1,905,535
Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	2,850,970	2,702,691
Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,746,509	1,448,433
Originated Loans and Leases [Member]
Credit Quality [Line Items]
Carrying amount	16,885,181	15,345,490
Originated Loans and Leases [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,772,090	1,755,713
Originated Loans and Leases [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	2,297,558	2,036,226
Originated Loans and Leases [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,746,352	1,448,268
Acquired Loans [Member]
Credit Quality [Line Items]
Carrying amount	4,774,401	5,653,276
Acquired Loans [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	119,990	149,822
Acquired Loans [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	553,412	666,465
Acquired Loans [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	157	165
Consumer Loan [Member] | Originated Loans and Leases [Member]
Credit Quality [Line Items]
Carrying amount	6,952,293	6,391,677
Consumer Loan [Member] | Originated Loans and Leases [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	6,911,416	6,352,285
Consumer Loan [Member] | Originated Loans and Leases [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	40,877	39,392
Consumer Loan [Member] | Originated Loans and Leases [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,772,090	1,755,713
Consumer Loan [Member] | Originated Loans and Leases [Member] | Direct Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,756,297	1,739,060
Consumer Loan [Member] | Originated Loans and Leases [Member] | Direct Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	15,793	16,653
Consumer Loan [Member] | Originated Loans and Leases [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	2,297,558	2,036,226
Consumer Loan [Member] | Originated Loans and Leases [Member] | Residential Mortgages [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	2,279,790	2,019,816
Consumer Loan [Member] | Originated Loans and Leases [Member] | Residential Mortgages [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	17,768	16,410
Consumer Loan [Member] | Originated Loans and Leases [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,746,352	1,448,268
Consumer Loan [Member] | Originated Loans and Leases [Member] | Indirect Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,744,007	1,445,833
Consumer Loan [Member] | Originated Loans and Leases [Member] | Indirect Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	2,345	2,435
Consumer Loan [Member] | Originated Loans and Leases [Member] | Consumer Lines of Credit [Member]
Credit Quality [Line Items]
Carrying amount	1,136,293	1,151,470
Consumer Loan [Member] | Originated Loans and Leases [Member] | Consumer Lines of Credit [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,131,322	1,147,576
Consumer Loan [Member] | Originated Loans and Leases [Member] | Consumer Lines of Credit [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	4,971	3,894
Consumer Loan [Member] | Acquired Loans [Member]
Credit Quality [Line Items]
Carrying amount	1,190,832	1,410,775
Consumer Loan [Member] | Acquired Loans [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,189,149	1,408,765
Consumer Loan [Member] | Acquired Loans [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,683	2,010
Consumer Loan [Member] | Acquired Loans [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	119,990	149,822
Consumer Loan [Member] | Acquired Loans [Member] | Direct Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	119,921	149,751
Consumer Loan [Member] | Acquired Loans [Member] | Direct Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	69	71
Consumer Loan [Member] | Acquired Loans [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	553,412	666,465
Consumer Loan [Member] | Acquired Loans [Member] | Residential Mortgages [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	553,412	666,465
Consumer Loan [Member] | Acquired Loans [Member] | Residential Mortgages [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	0	0
Consumer Loan [Member] | Acquired Loans [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	157	165
Consumer Loan [Member] | Acquired Loans [Member] | Indirect Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	157	165
Consumer Loan [Member] | Acquired Loans [Member] | Indirect Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	0	0
Consumer Loan [Member] | Acquired Loans [Member] | Consumer Lines of Credit [Member]
Credit Quality [Line Items]
Carrying amount	517,273	594,323
Consumer Loan [Member] | Acquired Loans [Member] | Consumer Lines of Credit [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	515,659	592,384
Consumer Loan [Member] | Acquired Loans [Member] | Consumer Lines of Credit [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	$ 1,614	$ 1,939