LOAN PORTFOLIO- Corporation's Aging of Purchased Credit Impaired Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2016		Dec. 31, 2015		Sep. 30, 2015
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 920,393		$ 841,188
Financing Receivable, Current	7,775,120		8,097,281
Loans held for investment	8,863,654		9,112,382		$ 9,140,462
90 days past due and still accruing	110,538	[1]	139,987	[2]
Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	118,315		164,889
Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	124,828		93,539
Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	677,250	[3]	582,760	[4]
Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	39,952		39,304
Financing Receivable, Current	128,189		134,609
Loans held for investment	168,141		173,913
Purchased Credit Impaired Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	12,048		16,094
Purchased Credit Impaired Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0		0
Purchased Credit Impaired Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	27,904		23,210
Residential Mortgage [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	3,299,942		3,344,719
Residential Mortgage [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	38,669	[5]	38,312	[6]
Financing Receivable, Current	126,345	[5]	132,454	[6]
Loans held for investment	165,014	[5]	170,766	[6]
30-59 Days past due Mortgages	22,300		23,600
Residential Mortgage [Member] | Purchased Credit Impaired Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	12,048	[5]	16,094	[6]
Residential Mortgage [Member] | Purchased Credit Impaired Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[5]	0	[6]
Residential Mortgage [Member] | Purchased Credit Impaired Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	26,621	[5]	22,218	[6]
Commercial Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	199,676	[7]	88,534	[8]
Financing Receivable, Current	1,342,211	[7]	1,446,125	[8]
Loans held for investment	1,545,014	[7]	1,537,806	[8]
90 days past due and still accruing	4,791	[1],[7]	12,472	[2],[8]
30-59 Days past due Mortgages	7,600		38,600
Commercial Mortgage Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	3,436	[7]	24,729	[8]
Commercial Mortgage Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[7]	0	[8]
Commercial Mortgage Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	196,240	[3],[7]	63,805	[4],[8]
Commercial Mortgage Loans [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	1,283	[5]	992	[6]
Financing Receivable, Current	1,844	[5]	2,155	[6]
Loans held for investment	3,127	[5]	3,147	[6]
30-59 Days past due Mortgages	400
Commercial Mortgage Loans [Member] | Purchased Credit Impaired Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[5]	0	[6]
Commercial Mortgage Loans [Member] | Purchased Credit Impaired Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[5]	0	[6]
Commercial Mortgage Loans [Member] | Purchased Credit Impaired Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 1,283	[5]	$ 992	[6]

[1] 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. These balances include $29.6 million of residential mortgage loans insured by the FHA or guaranteed by the VA, which are over 15 months delinquent and are no longer accruing interest as of September 30, 2016.

[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. These balances include $37.3 million of residential mortgage loans insured by the FHA or guaranteed by the VA, which are over 15 months delinquent and are no longer accruing interest as of December 31, 2015.

[3] Includes non-performing loans and accruing loans that are contractually delinquent 90 days or more (i.e., FHA/VA guaranteed loans and credit cards). Credit card loans continue to accrue finance charges and fees until charged-off at 180 days.

[4] Includes non-performing loans and accruing loans that are contractually delinquent 90 days or more (i.e. FHA/VA guaranteed loans and credit cards). Credit card loans continue to accrue finance charges and fees until charged-off at 180 days.

[5] 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 and commercial mortgage loans are considered past due when the borrower is in arrears two or more monthly payments. PCI residential mortgage loans and commercial mortgage loans past due 30-59 days as of September 30, 2016 amounted to $22.3 million and $0.4 million, respectively.

[6] 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 and commercial mortgage loans are considered past due when the borrower is in arrears two or more monthly payments. PCI residential mortgage loans past due 30-59 days as of December 31, 2015 amounted to $23.6 million.

[7] 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 two or more monthly payments. FHA/VA government-guaranteed loans, other residential mortgage loans, commercial mortgage loans, land loans and construction-residential loans past due 30-59 days as of September 30, 2016 amounted to $8.7 million, $144.3 million, $7.6 million, $0.7 million and $0.3 million, respectively.

[8] 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 two or more monthly payments. FHA/VA government-guaranteed loans, other residential mortgage loans, commercial mortgage loans, land loans and construction-residential loans past due 30-59 days as of December 31, 2015 amounted to $11.0 million, $162.9 million, $38.6 million, $5.7 million and $0.8 million, respectively.