Troubled debt restructuring according to their accruing status (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Non Covered Loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	$ 1,092,044	[1]	$ 950,337
Non Covered Loans [Member] | Commercial Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	311,657	[1]	189,602
Non Covered Loans [Member] | Construction [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	11,567	[1]	11,290
Non Covered Loans [Member] | Legacy [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	0	[1]	949
Non Covered Loans [Member] | Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	642,573	[1]	618,143
Non Covered Loans [Member] | Finance Leases Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	2,709	[1]	2,893
Non Covered Loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	123,538	[1]	127,460
Covered Under Loss Sharing Agreements With F D I C [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	10,972		21,448
Covered Under Loss Sharing Agreements With F D I C [Member] | Commercial Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	3,649		17,406
Covered Under Loss Sharing Agreements With F D I C [Member] | Construction [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	2,419		3,464
Covered Under Loss Sharing Agreements With F D I C [Member] | Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	4,842		335
Covered Under Loss Sharing Agreements With F D I C [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	62		243
Non Accrual [Member] | Non Covered Loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	257,350	[1]	188,104
Non Accrual [Member] | Non Covered Loans [Member] | Commercial Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	121,741	[1]	80,140
Non Accrual [Member] | Non Covered Loans [Member] | Construction [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	11,216	[1]	10,865
Non Accrual [Member] | Non Covered Loans [Member] | Legacy [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	0	[1]	949
Non Accrual [Member] | Non Covered Loans [Member] | Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	107,803	[1]	82,786
Non Accrual [Member] | Non Covered Loans [Member] | Finance Leases Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	1,966	[1]	2,623
Non Accrual [Member] | Non Covered Loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	14,624	[1]	10,741
Non Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	7,169		13,692
Non Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Commercial Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	2,050		10,017
Non Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Construction [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	2,419		3,464
Non Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	2,690		189
Non Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	10		22
Accrual [Member] | Non Covered Loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	834,694	[1]	762,233
Accrual [Member] | Non Covered Loans [Member] | Commercial Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	189,916	[1]	109,462
Accrual [Member] | Non Covered Loans [Member] | Construction [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	351	[1]	425
Accrual [Member] | Non Covered Loans [Member] | Legacy [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	0	[1]	0
Accrual [Member] | Non Covered Loans [Member] | Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	534,770	[1]	535,357
Accrual [Member] | Non Covered Loans [Member] | Finance Leases Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	743	[1]	270
Accrual [Member] | Non Covered Loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	108,914	[1]	116,719
Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	3,803		7,756
Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Commercial Portfolio Segment Member
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	1,599		7,389
Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Construction [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	0		0
Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	2,152		146
Accrual [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Financing Receivable Modifications Recorded Investment	$ 52		$ 221

[1] Excludes TDRs from discontinued operations.