Loans and Allowance for Credit Losses - Schedule of Impaired Loans that are Individually Evaluated (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Recorded Investment, Total Loans	$ 76,683	$ 64,849
Unpaid Principal Balance, Total Loans	85,867	75,893
Related Allowance	7,133	7,068
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment with no related allowance	20,881	17,066
Unpaid Principal Balance with no related allowance	21,384	17,417
Recorded Investment with related allowance	10,736	9,282
Unpaid Principal Balance with related allowance	13,742	12,304
Related Allowance	4,246	4,723
Commercial Real Estate - Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment with no related allowance	1,522	525
Unpaid Principal Balance with no related allowance	1,630	633
Recorded Investment with related allowance
Unpaid Principal Balance with related allowance
Related Allowance
Commercial Real Estate - Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment with no related allowance	23,054	15,746
Unpaid Principal Balance with no related allowance	27,779	22,550
Recorded Investment with related allowance	16,235	18,726
Unpaid Principal Balance with related allowance	16,940	19,358
Related Allowance	2,697	2,190
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment with no related allowance	362	324
Unpaid Principal Balance with no related allowance	381	342
Recorded Investment with related allowance	1,420	835
Unpaid Principal Balance with related allowance	1,467	888
Related Allowance	71	43
Residential [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment with no related allowance	98	106
Unpaid Principal Balance with no related allowance	99	106
Recorded Investment with related allowance	2,375	2,239
Unpaid Principal Balance with related allowance	2,445	2,295
Related Allowance	$ 119	$ 112