LOAN PORTFOLIO - Credit Risk Payment Activity (Detail) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016		Sep. 30, 2016
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	$ 8,877,214		$ 8,886,873		$ 8,863,654
Other Residential Mortgage Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	3,152,772	[1]	3,169,173
Auto loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	834,212		847,958
Finance Leases [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	246,084		233,335
Other Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	1,481,456		1,483,293
Residential Real Estate [Member] | Fhava Guaranteed Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	121,568	[2]	126,858	[3]
Residential Real Estate [Member] | Other Residential Mortgage Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	3,152,772		3,169,173
Residential Real Estate [Member] | Performing Financing Receivable [Member] | Fhava Guaranteed Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	121,568	[2]	126,858	[3]
Residential Real Estate [Member] | Performing Financing Receivable [Member] | Other Residential Mortgage Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	2,820,633		2,845,630
Residential Real Estate [Member] | Purchased Credit Impaired [Member] | Fhava Guaranteed Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	0	[2],[4]	0	[3],[5]
Residential Real Estate [Member] | Purchased Credit Impaired [Member] | Other Residential Mortgage Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	153,609	[4]	162,676	[5]
Residential Real Estate [Member] | Nonperforming Financing Receivable [Member] | Fhava Guaranteed Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	0	[2]	0	[3]
Residential Real Estate [Member] | Nonperforming Financing Receivable [Member] | Other Residential Mortgage Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	178,530		160,867
Consumer [Member] | Auto loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	834,212		847,958
Consumer [Member] | Finance Leases [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	246,084		233,335
Consumer [Member] | Other Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	647,244		635,335
Consumer [Member] | Performing Financing Receivable [Member] | Auto loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	818,403		833,612
Consumer [Member] | Performing Financing Receivable [Member] | Finance Leases [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	244,196		232,000
Consumer [Member] | Performing Financing Receivable [Member] | Other Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	638,435		626,936
Consumer [Member] | Purchased Credit Impaired [Member] | Auto loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	0	[4]	0	[5]
Consumer [Member] | Purchased Credit Impaired [Member] | Finance Leases [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	0	[4]	0	[5]
Consumer [Member] | Purchased Credit Impaired [Member] | Other Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	0	[4]	0	[5]
Consumer [Member] | Nonperforming Financing Receivable [Member] | Auto loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	15,809		14,346
Consumer [Member] | Nonperforming Financing Receivable [Member] | Finance Leases [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	1,888		1,335
Consumer [Member] | Nonperforming Financing Receivable [Member] | Other Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans And Leases Receivable Gross Carrying Amount	$ 8,809		$ 8,399

[1] According to the Corporation's delinquency policy and consistent with the instructions for the preparation of the Consolidated Financial Statements for Bank Holding Companies (FR Y-9C) required by the Federal Reserve Board, residential mortgage, commercial mortgage, and construction loans are considered past due when the borrower is in arrears on two or more monthly payments. FHA/VA government-guaranteed loans, other residential mortgage loans, commercial mortgage loans, land loans, construction-residential loans and construction-commercial loans past due 30-59 days as of September 30, 2017 amounted to $9.4 million, $216.1 million, $33.8 million, $0.9 million, $6.4 million and $0.1 million, respectively.

[2] It is the Corporation's policy to report delinquent residential mortgage loans insured by the FHA or guaranteed by the VA as past due loans 90 days and still accruing as opposed to non-performing loans since the principal repayment is insured. This balance includes $28.9 million of residential mortgage loans insured by the FHA or guaranteed by the VA that are over 15 months delinquent, and are no longer accruing interest as of September 30, 2017.

[3] It is the Corporation's policy to report delinquent residential mortgage loans insured by the FHA or guaranteed by the VA as past due loans 90 days and still accruing as opposed to non-performing loans since the principal repayment is insured. This balance includes $29.3 million of residential mortgage loans insured by the FHA or guaranteed by the VA that are over 15 months delinquent, and are no longer accruing interest as of December 31, 2016.

[4] PCI loans are excluded from non-performing statistics due to the application of the accretion method, under which these loans will accrete interest income over the remaining life of the loans using estimated cash flow analyses.

[5] PCI loans are excluded from non-performing statistics due to the application of the accretion method, under which these loans will accrete interest income over the remaining life of the loans using estimated cash flow analyses.