Loans - Non-Accrual Loans, Segregated by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 59,631	$ 56,720
Commercial and industrial, Energy [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	525	590
Commercial and industrial, Other commercial [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	34,139	26,143
Commercial real estate, Buildings, land and other [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	21,833	27,035
Commercial real estate, Construction [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	301	0
Consumer Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	2,179	2,207
Consumer and Other [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 654	$ 745