Loans - Risk Category of Loans (Detail) (Non-PCI Loans [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	$ 6,906,857	$ 6,748,933
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	1,853,938	1,820,136
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	4,661,294	4,521,920
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	391,625	406,877
Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	6,589,852	6,411,735
Pass [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	1,732,647	1,689,613
Pass [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	4,490,448	4,348,642
Pass [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	366,757	373,480
Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	111,525	115,863
Special Mention [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	52,292	56,007
Special Mention [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	50,937	48,159
Special Mention [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	8,296	11,697
Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	199,271	215,340
Substandard [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	62,790	74,501
Substandard [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	119,909	125,119
Substandard [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	16,572	15,720
Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	6,209	5,995
Doubtful [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	6,209	15
Doubtful [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans
Doubtful [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Non-PCI Loans	$ 0	$ 5,980