LOAN PORTFOLIO- Corporation's Aging of Purchased Credit Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	$ 120,984		$ 118,154
60-89 Days, Past Due	128,454		139,659
90 days or more, Past Due	725,665	[1]	671,122	[2]
Total Past Due	975,103		928,935
Financing Receivable, Current	8,329,155		8,230,897
Loans held for investment	9,485,372		9,262,436		9,566,785
90 days past due and still accruing	162,121	[3]	147,226	[4]
Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	22		47
60-89 Days, Past Due	13,702		12,952
90 days or more, Past Due	16,450		15,661
Total Past Due	30,174		28,660
Financing Receivable, Current	150,940		73,944
Loans held for investment	181,114		102,604
Residential Mortgage [Member]
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	0	[5]	0	[6]
60-89 Days, Past Due	88,209	[5]	78,336	[6]
90 days or more, Past Due	191,014	[1],[5]	199,078	[2],[6]
Total Past Due	279,223	[5]	277,414	[6]
Financing Receivable, Current	2,719,134	[5]	2,481,709	[6]
Loans held for investment	3,175,958	[5]	2,857,617	[6]
90 days past due and still accruing	18,431	[3],[5]	18,371	[4],[6]
Residential Mortgage [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	0	[7]	0	[8]
60-89 Days, Past Due	13,572	[7]	12,571	[8]
90 days or more, Past Due	15,775	[7]	15,176	[8]
Total Past Due	29,347	[7]	27,747	[8]
Financing Receivable, Current	148,254	[7]	70,747	[8]
Loans held for investment	177,601	[7]	98,494	[8]
Commercial Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	0	[5]	0	[6]
60-89 Days, Past Due	1,564	[5]	15,482	[6]
90 days or more, Past Due	165,778	[1],[5]	171,281	[2],[6]
Total Past Due	167,342	[5]	186,763	[6]
Financing Receivable, Current	1,478,642	[5]	1,475,631	[6]
Loans held for investment	1,649,263	[5]	1,665,787	[6]
90 days past due and still accruing	23,393	[3],[5]	22,808	[4],[6]
Commercial Mortgage Loans [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	0	[7]	0	[8]
60-89 Days, Past Due	130	[7]	356	[8]
90 days or more, Past Due	653	[7]	443	[8]
Total Past Due	783	[7]	799	[8]
Financing Receivable, Current	2,496	[7]	2,594	[8]
Loans held for investment	3,279	[7]	3,393	[8]
Consumer Credit Card Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
30-59 Days Past Due	22		47
60-89 Days, Past Due	0		25
90 days or more, Past Due	22		42
Total Past Due	44		114
Financing Receivable, Current	190		603
Loans held for investment	$ 234		$ 717

[1] Includes non-performing loans and accruing loans which 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.

[2] Includes non-performing loans and accruing loans which 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.

[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. These balances include $30.1 million of residential mortgage loans insured by the FHA or guaranteed by the VA, which are over 18 months delinquent, and are no longer accruing interest as of March 31, 2015.

[4] 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 $40.4 million of residential mortgage loans insured by the FHA or guaranteed by the VA, which are over 18 months delinquent, and are no longer accruing interest as of December 31, 2014.

[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 and construction-residential loans past due 30-59 days as of March 31, 2015 amounted to $12.2 million, $177.4 million, $38.4 million, $6.1 million, and $1.6 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, 2014 amounted to $14.0 million, $189.1 million, $20.8 million, $0.8 million and $1.0 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 and commercial mortgage loans past due 30-59 days as of March 31, 2015 amounted to $32.0 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 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 December 31, 2014 amounted to $16.6 million and $0.8 million, respectively.