Composition of loans held-in-portfolio-covered loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered Loans	$ 2,736,102	$ 2,984,427
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered Loans	1,638,634	1,710,229
Commercial And Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered Loans	107,333	102,575
Commercial Real Estate Construction Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered Loans	82,763	190,127
Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered Loans	867,075	934,373
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered Loans	$ 40,297	$ 47,123