LOAN PORTFOLIO - Corporation's Aging of Loans Held for Investment Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 881,954		$ 841,188
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	165,818	[1]	173,913	[2]	$ 102,604
Financing Receivable, Current	7,839,101		8,097,281
Loans held for investment	8,886,873		9,112,382
90 days past due and still accruing	106,809		139,987
Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	86,726		93,539
Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	128,325		164,889
Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	666,903	[3]	582,760
Fha Va And Other Government Guaranteed Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	82,231	[4],[5],[6]	96,216	[7],[8],[9]
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0	[4],[5],[6]	0
Financing Receivable, Current	44,627	[4],[5],[6]	46,925	[7],[8],[9]
Loans held for investment	126,858	[4],[5],[6]	143,141	[7],[8],[9]
90 days past due and still accruing	77,052	[4],[5],[6]	90,168	[7],[8],[9]
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	[4],[5],[6]	0	[7],[8],[9]
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	5,179	[4],[5],[6]	6,048	[7],[8],[9]
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	77,052	[3],[4],[5],[6]	90,168	[7],[8],[9],[10]
Residential Mortgage [Member]
Accounts Notes And Loans Receivable [Line Items]
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	162,676		170,766
Loans held for investment	3,296,031		3,344,719
Commercial And Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	169,886		162,882
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	2,010,569		2,083,631
Loans held for investment	2,180,455		2,246,513
90 days past due and still accruing	5,368		13,842
Commercial And Industrial [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	14,195		5,577
Commercial And Industrial [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	3,724		6,412
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	151,967	[3]	150,893
Commercial Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	186,511	[4]	88,534	[7]
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	3,142	[4]	3,147	[7]
Financing Receivable, Current	1,379,155	[4]	1,446,125	[7]
Loans held for investment	1,568,808	[4]	1,537,806	[7]
90 days past due and still accruing	3,281	[4]	12,472	[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	[4]	0	[7]
Commercial Mortgage Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	4,534	[4]	24,729	[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	181,977	[3],[4]	63,805	[7],[10]
Construction Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	124,951		156,195
Consumer Auto Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	85,011		105,058
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	762,947		829,922
Loans held for investment	847,958		934,980
90 days past due and still accruing	0		0
Consumer Auto Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	57,142		70,836
Consumer Auto Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	13,523		16,787
Consumer Auto Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	14,346	[3]	17,435
Finance Leases [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	10,720		13,223
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	222,615		215,942
Loans held for investment	233,335		229,165
90 days past due and still accruing	0		0
Finance Leases [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	7,714		7,664
Finance Leases [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	1,671		3,100
Finance Leases [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	1,335	[3]	2,459
Consumer Loan [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	25,257		30,110
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	610,078		632,894
Loans held for investment	635,335		663,004
90 days past due and still accruing	3,929		4,266
Consumer Loan [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	7,675		9,462
Consumer Loan [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	5,254		5,524
Consumer Loan [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	12,328	[3]	15,124
Commercial Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	36,893		51,188
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	40,582		32,142
Loans held for investment	77,475		83,330
90 days past due and still accruing	0		0
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 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 Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	36,893	[3]	39,466
Residential Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	1,933	[4]	6,042	[7]
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	13,777	[4]	14,949	[7]
Loans held for investment	15,710	[4]	20,991	[7]
90 days past due and still accruing	0	[4]	3,046	[7]
Residential Construction [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[4]	0	[7]
Residential Construction [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[4]	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	1,933	[3],[4]	6,042	[7],[10]
Land Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	11,940	[4]	12,511	[7]
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	0		0
Financing Receivable, Current	19,826	[4]	39,363	[7]
Loans held for investment	31,766	[4]	51,874	[7]
90 days past due and still accruing	478	[4]	176	[7]
Land Construction [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[4]	0	[7]
Land Construction [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	436	[4]	161	[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	11,504	[3],[4]	12,350	[7],[10]
Other Residential Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	271,572	[4]	275,424	[7]
Certain Loans Acquired In Transfer Accounted For As Debt Securities Carrying Amount	162,676	[4]	170,766
Financing Receivable, Current	2,734,925	[4]	2,755,388	[7]
Loans held for investment	3,169,173	[4]	3,201,578	[7]
90 days past due and still accruing	16,701	[4]	16,017	[7]
Other Residential Mortgage Loans [Member] | Financing Receivables 30 To 59 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	0	[4]	0	[7]
Other Residential Mortgage Loans [Member] | Financing Receivables 60 To 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	94,004	[4]	90,406	[7]
Other Residential Mortgage Loans [Member] | Financing Receivables Equal To Greater Than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Past Due	$ 177,568	[3],[4]	$ 185,018	[7],[10]

[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 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, 2016 amounted to $22.3 million and $0.1 million, respectively.

[2] 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.

[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] 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 and other 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, 2016 amounted to $9.9 million, $142.8 million, $4.6 million, $0.7 million, and $0.4 million, respectively.

[5] As of December 31, 2016, includes $43.7 million of defaulted loans collateralizing GNMA securities for which the Corporation has an unconditional option (but not an obligation) to repurchase the defaulted loans.

[6] 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 $29.3 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, 2016.

[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 and other 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.

[9] 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.

[10] 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.