Loans - Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	$ 68,357	$ 61,007
Recorded Investment With No Allowance	49,983	32,588
Recorded Investment With Allowance	2,803	15,874
Total Recorded Investment	52,786	48,462
Related Allowance	1,389	6,926
Commercial and industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	545	545
Recorded Investment With No Allowance	525	531
Recorded Investment With Allowance	0	0
Total Recorded Investment	525	531
Related Allowance	0	0
Commercial and industrial, Other commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	40,764	31,429
Recorded Investment With No Allowance	29,322	15,337
Recorded Investment With Allowance	1,805	7,004
Total Recorded Investment	31,127	22,341
Related Allowance	613	4,140
Commercial real estate, Buildings, land and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	25,390	27,792
Recorded Investment With No Allowance	18,894	15,697
Recorded Investment With Allowance	998	8,870
Total Recorded Investment	19,892	24,567
Related Allowance	776	2,786
Commercial real estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	478	0
Recorded Investment With No Allowance	301	0
Recorded Investment With Allowance	0	0
Total Recorded Investment	301	0
Related Allowance	0	0
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	881	907
Recorded Investment With No Allowance	689	745
Recorded Investment With Allowance	0	0
Total Recorded Investment	689	745
Related Allowance	0	0
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	299	334
Recorded Investment With No Allowance	252	278
Recorded Investment With Allowance	0	0
Total Recorded Investment	252	278
Related Allowance	$ 0	$ 0