LOAN PORTFOLIO - Corporation's Aging of Loans Held for Investment Portfolio (Detail) - USD ($) $ in Thousands	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 965,965		$ 841,188
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	172,332		173,913		$ 181,114	$ 102,604
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]
Fha Va And Other Government Guaranteed Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	89,555	[1],[5],[6]	96,216	[2],[7],[8]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0	[1],[5],[6]	0	[2],[7],[8]
Financing Receivable, Current	47,149	[1],[5],[6]	46,925	[2],[7],[8]
Loans held for investment	136,704	[1],[5],[6]	143,141	[2],[7],[8]
90 days past due and still accruing	84,217	[1],[5],[6]	90,168	[2],[7],[8]
Fha Va And Other Government Guaranteed Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	5,338	[1],[5],[6]	6,048	[2],[7],[8]
Fha Va And Other Government Guaranteed Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[1],[5],[6]	0	[2],[7],[8]
Fha Va And Other Government Guaranteed Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	84,217	[1],[3],[5],[6]	90,168	[2],[4],[7],[8]
Residential Mortgage [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	284,191	[5]	275,424	[7]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	169,190	[5]	170,766	[7]
Financing Receivable, Current	2,740,860	[5]	2,755,388	[7]
Loans held for investment	3,194,241	[5]	3,201,578	[7]
90 days past due and still accruing	16,725	[1],[5]	16,017	[2],[7]
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	[7]
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	[7]
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],[7]
Commercial And Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	163,333		162,882
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	2,180,083		2,245,114
Loans held for investment	2,343,416		2,407,996
90 days past due and still accruing	6,415	[1]	13,842	[2]
Commercial And Industrial [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	6,943		6,412
Commercial And Industrial [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	12,079		5,577
Commercial And Industrial [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	144,311	[3]	150,893	[4]
Commercial Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	221,984	[5]	88,534	[7]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	3,142	[5]	3,147	[7]
Financing Receivable, Current	1,299,365	[5]	1,446,125	[7]
Loans held for investment	1,524,491	[5]	1,537,806	[7]
90 days past due and still accruing	28,813	[1],[5]	12,472	[2],[7]
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	[7]
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	[7]
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],[7]
Auto loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	90,085		105,058
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	814,249		829,922
Loans held for investment	904,334		934,980
90 days past due and still accruing	0	[1]	0	[2]
Auto loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	13,489		16,787
Auto loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	61,558		70,836
Auto loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	15,038	[3]	17,435	[4]
Finance Leases [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	13,245		13,223
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	217,556		215,942
Loans held for investment	230,801		229,165
90 days past due and still accruing	0	[1]	0	[2]
Finance Leases [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	2,116		3,100
Finance Leases [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	8,993		7,664
Finance Leases [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	2,136	[3]	2,459	[4]
Consumer Loan [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	30,390		30,110
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	620,836		632,894
Loans held for investment	651,226		663,004
90 days past due and still accruing	3,882	[1]	4,266	[2]
Consumer Loan [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	6,044		5,524
Consumer Loan [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	10,287		9,462
Consumer Loan [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	14,059	[3]	15,124	[4]
Commercial Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	54,460		51,188
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	26,754		32,142
Loans held for investment	81,214		83,330
90 days past due and still accruing	15,423	[1]	0	[2]
Commercial Construction [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0		11,722
Commercial Construction [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0		0
Commercial Construction [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	54,460	[3]	39,466	[4]
Residential Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	5,948	[5]	6,042	[7]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0	[5]	0	[7]
Financing Receivable, Current	12,142	[5]	14,949	[7]
Loans held for investment	18,090	[5]	20,991	[7]
90 days past due and still accruing	3,031	[1],[5]	3,046	[2],[7]
Residential Construction [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[5]	0	[7]
Residential Construction [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[5]	0	[7]
Residential Construction [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	5,948	[3],[5]	6,042	[4],[7]
Land Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	12,774	[5]	12,511	[7]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	0	[5]	0	[7]
Financing Receivable, Current	34,051	[5]	39,363	[7]
Loans held for investment	46,825	[5]	51,874	[7]
90 days past due and still accruing	451	[1],[5]	176	[2],[7]
Land Construction [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	241	[5]	161	[7]
Land Construction [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[5]	0	[7]
Land Construction [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 12,533	[3],[5]	$ 12,350	[4],[7]

[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] As of March 31, 2016, includes $40.0 million of defaulted loans collateralizing Government National Mortgage Association ("GNMA") securities for which the Corporation has an unconditional option (but not an obligation) to repurchase the defaulted loans.

[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 December 31, 2015 amounted to $11.0 million, $162.9 million, $38.6 million, $5.7 million and $0.8 million, respectively.

[8] As of December 31, 2015, includes $38.5 million of defaulted loans collateralizing GNMA securities for which the Corporation has an unconditional option (but not an obligation) to repurchase the defaulted loans.