LOANS AND LEASES - Consumer Loans by Payment Status (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Credit Quality [Line Items]
Carrying amount	$ 20,533,298	$ 14,896,943
Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,949,979	1,844,399
Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	2,429,843	1,844,574
Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,374,524	1,196,313
Originated Loans and Leases [Member]
Credit Quality [Line Items]
Carrying amount	13,843,870	12,547,987
Originated Loans and Leases [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,764,096	1,765,257
Originated Loans and Leases [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	1,683,383	1,446,776
Originated Loans and Leases [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,374,370	1,196,110
Acquired Loans [Member]
Credit Quality [Line Items]
Carrying amount	6,689,428	2,348,956
Acquired Loans [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	185,883	79,142
Acquired Loans [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	746,460	397,798
Acquired Loans [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	154	203
Consumer Loan [Member] | Originated Loans and Leases [Member]
Credit Quality [Line Items]
Carrying amount	5,941,899	5,507,770
Consumer Loan [Member] | Originated Loans and Leases [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	5,905,807	5,474,286
Consumer Loan [Member] | Originated Loans and Leases [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	36,092	33,484
Consumer Loan [Member] | Originated Loans and Leases [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,764,096	1,765,257
Consumer Loan [Member] | Originated Loans and Leases [Member] | Direct Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,747,660	1,750,305
Consumer Loan [Member] | Originated Loans and Leases [Member] | Direct Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	16,436	14,952
Consumer Loan [Member] | Originated Loans and Leases [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	1,683,383	1,446,776
Consumer Loan [Member] | Originated Loans and Leases [Member] | Residential Mortgages [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,669,019	1,433,409
Consumer Loan [Member] | Originated Loans and Leases [Member] | Residential Mortgages [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	14,364	13,367
Consumer Loan [Member] | Originated Loans and Leases [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Carrying amount	1,374,370	1,196,110
Consumer Loan [Member] | Originated Loans and Leases [Member] | Indirect Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,372,414	1,193,930
Consumer Loan [Member] | Originated Loans and Leases [Member] | Indirect Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,956	2,180
Consumer Loan [Member] | Originated Loans and Leases [Member] | Consumer Lines of Credit [Member]
Credit Quality [Line Items]
Carrying amount	1,120,050	1,099,627
Consumer Loan [Member] | Originated Loans and Leases [Member] | Consumer Lines of Credit [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,116,714	1,096,642
Consumer Loan [Member] | Originated Loans and Leases [Member] | Consumer Lines of Credit [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	3,336	2,985
Consumer Loan [Member] | Acquired Loans [Member]
Credit Quality [Line Items]
Carrying amount	1,600,981	678,716
Consumer Loan [Member] | Acquired Loans [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,599,787	678,204
Consumer Loan [Member] | Acquired Loans [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	1,194	512
Consumer Loan [Member] | Acquired Loans [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Carrying amount	185,883	79,142
Consumer Loan [Member] | Acquired Loans [Member] | Direct Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	185,883	79,142
Consumer Loan [Member] | Acquired Loans [Member] | Direct Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	0	0
Consumer Loan [Member] | Acquired Loans [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Carrying amount	746,460	397,798
Consumer Loan [Member] | Acquired Loans [Member] | Residential Mortgages [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	746,460	397,798
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	154	203
Consumer Loan [Member] | Acquired Loans [Member] | Indirect Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	154	203
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	668,484	201,573
Consumer Loan [Member] | Acquired Loans [Member] | Consumer Lines of Credit [Member] | Performing [Member]
Credit Quality [Line Items]
Carrying amount	667,290	201,061
Consumer Loan [Member] | Acquired Loans [Member] | Consumer Lines of Credit [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Carrying amount	$ 1,194	$ 512