LOAN PORTFOLIO- Corporation's Aging of Purchased Credit Impaired Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 965,965		$ 841,188
Financing Receivable, Current	7,993,045		8,258,764
Loans held for investment	9,131,342		9,273,865		$ 9,485,372
90 days past due and still accruing	158,957	[1]	139,987	[2]
Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	139,155		164,889
Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	92,917		93,539
Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	733,893	[3]	582,760	[4]
Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	38,932		39,304
Financing Receivable, Current	133,400		134,609
Loans held for investment	172,332		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	12,999		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	25,933		23,210
Residential Mortgage [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	284,191	[5]	275,424	[6]
Financing Receivable, Current	2,740,860	[5]	2,755,388	[6]
Loans held for investment	3,194,241	[5]	3,201,578	[6]
90 days past due and still accruing	16,725	[1],[5]	16,017	[2],[6]
30-59 Days past due Mortgages	155,900		162,900
Residential Mortgage [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	94,576	[5]	90,406	[6]
Residential Mortgage [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] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	189,615	[3],[5]	185,018	[4],[6]
Residential Mortgage [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	37,940	[7]	38,312	[8]
Financing Receivable, Current	131,250	[7]	132,454	[8]
Loans held for investment	169,190	[7]	170,766	[8]
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	12,999	[7]	16,094	[8]
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	[7]	0	[8]
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	24,941	[7]	22,218	[8]
Commercial Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	221,984	[5]	88,534	[6]
Financing Receivable, Current	1,299,365	[5]	1,446,125	[6]
Loans held for investment	1,524,491	[5]	1,537,806	[6]
90 days past due and still accruing	28,813	[1],[5]	12,472	[2],[6]
30-59 Days past due Mortgages	74,800		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	10,408	[5]	24,729	[6]
Commercial Mortgage 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] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	211,576	[3],[5]	63,805	[4],[6]
Commercial Mortgage Loans [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	992	[7]	992	[8]
Financing Receivable, Current	2,150	[7]	2,155	[8]
Loans held for investment	3,142	[7]	3,147	[8]
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	[7]	0	[8]
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	[7]	0	[8]
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	$ 992	[7]	$ 992	[8]

[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 $34.9 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 March 31, 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 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, 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, construction-commercial and construction-residential loans past due 30-59 days as of March 31, 2016 amounted to $10.0 million, $155.9 million, $74.8 million, $0.5 million, $5.2 million and $0.7 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, 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.

[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 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 March 31, 2016 amounted to $23.5 million.

[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 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.