Loans - Schedule of Loan Portfolio Non-Covered and Covered PCI Loans and Non-PCI Loans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	$ 11,471,447	$ 10,842,125
Covered loans	96,165	180,674
Total loans	11,567,612	11,022,799
Commercial real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	5,410,906	4,843,153
Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	1,565,492	1,451,717
Covered loans	799	2,306
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	1,995,084	2,084,826
Covered loans	26,249	46,517
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	4,981,675	4,417,709
Covered loans	61,494	120,268
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	429,231	425,444
Covered loans		1,924
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	2,499,965	2,462,429
Covered loans	7,623	9,659
Home equity [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	449,009	485,458
Automobile [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	901,399	786,528
Other Consumer [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	215,084	179,731
Non-PCI Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	10,761,344	9,855,135
Covered loans
Total loans	10,761,344	9,855,135
Non-PCI Loans [Member] | Commercial real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	4,928,797	4,171,939
Non-PCI Loans [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	1,527,172	1,404,826
Covered loans
Non-PCI Loans [Member] | Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	1,820,136	1,832,743
Covered loans
Non-PCI Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	4,521,920	3,772,084
Covered loans
Non-PCI Loans [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	406,877	399,855
Covered loans
Non-PCI Loans [Member] | Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	2,485,239	2,445,627
Covered loans
Non-PCI Loans [Member] | Home equity [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	410,875	438,881
Non-PCI Loans [Member] | Automobile [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	901,399	786,528
Non-PCI Loans [Member] | Other Consumer [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	214,898	179,417
PCI Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	710,103	986,990
Covered loans	96,165	180,674
Total loans	806,268	1,167,664
PCI Loans [Member] | Commercial real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	482,109	671,214
PCI Loans [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	38,320	46,891
Covered loans	799	2,306
PCI Loans [Member] | Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	174,948	252,083
Covered loans	26,249	46,517
PCI Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	459,755	645,625
Covered loans	61,494	120,268
PCI Loans [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	22,354	25,589
Covered loans		1,924
PCI Loans [Member] | Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	14,726	16,802
Covered loans	7,623	9,659
PCI Loans [Member] | Home equity [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	38,134	46,577
PCI Loans [Member] | Automobile [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans
PCI Loans [Member] | Other Consumer [Member] | Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	$ 186	$ 314