Allowance for Loan Losses - Investments in Loans Considered to be Impaired and Related Information on Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
With a related allowance recorded, Recorded Investment	$ 767	$ 8,801
With a related allowance recorded, Unpaid Principal Balance	1,469	10,550
With a related allowance recorded, Related Allowance	97	2,231
Without a related allowance recorded, Recorded Investment	52,089	73,840
Without a related allowance, Unpaid Principal Balance	67,122	97,716
Without a related allowance recorded, Related Allowance
Impaired Financing Receivable, Recorded Investment, Total	52,856	82,641
Impaired Financing Receivable, Unpaid Principal Balance, Total	68,591	108,266
Impaired Financing Receivable, Related Allowance	97	2,231
With a related allowance recorded, Average Recorded Investment	3,631	12,068
With a related allowance recorded, Interest Income Recognized	59	218
Without a related allowance recorded, Average Recorded Investment	63,693	95,648
Without a related allowance recorded, Interest Income Recognized	1,951	2,080
Impaired Financing Receivable, Average Recorded Investment, Total	67,324	107,716
Impaired Financing Receivable, Interest Income Recognized, Total	2,010	2,298
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
With a related allowance recorded, Recorded Investment		6,138
With a related allowance recorded, Unpaid Principal Balance		6,864
With a related allowance recorded, Related Allowance		1,226
Without a related allowance recorded, Recorded Investment	26,968	33,856
Without a related allowance, Unpaid Principal Balance	35,474	45,953
Without a related allowance recorded, Related Allowance
Impaired Financing Receivable, Recorded Investment, Total	26,968	39,994
Impaired Financing Receivable, Unpaid Principal Balance, Total	35,474	52,817
Impaired Financing Receivable, Related Allowance		1,226
With a related allowance recorded, Average Recorded Investment	1,895	5,796
With a related allowance recorded, Interest Income Recognized		218
Without a related allowance recorded, Average Recorded Investment	29,314	41,138
Without a related allowance recorded, Interest Income Recognized	929	1,112
Impaired Financing Receivable, Average Recorded Investment, Total	31,209	46,934
Impaired Financing Receivable, Interest Income Recognized, Total	929	1,330
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
With a related allowance recorded, Recorded Investment		1,864
With a related allowance recorded, Unpaid Principal Balance		2,790
With a related allowance recorded, Related Allowance		1,002
Without a related allowance recorded, Recorded Investment	9,580	11,419
Without a related allowance, Unpaid Principal Balance	9,703	12,227
Without a related allowance recorded, Related Allowance
Impaired Financing Receivable, Recorded Investment, Total	9,580	13,283
Impaired Financing Receivable, Unpaid Principal Balance, Total	9,703	15,017
Impaired Financing Receivable, Related Allowance		1,002
With a related allowance recorded, Average Recorded Investment		1,826
With a related allowance recorded, Interest Income Recognized
Without a related allowance recorded, Average Recorded Investment	11,439	11,672
Without a related allowance recorded, Interest Income Recognized	254	329
Impaired Financing Receivable, Average Recorded Investment, Total	11,439	13,498
Impaired Financing Receivable, Interest Income Recognized, Total	254	329
Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
With a related allowance recorded, Recorded Investment	681	799
With a related allowance recorded, Unpaid Principal Balance	1,383	896
With a related allowance recorded, Related Allowance	25	3
Without a related allowance recorded, Recorded Investment	7,391	17,713
Without a related allowance, Unpaid Principal Balance	12,353	27,486
Without a related allowance recorded, Related Allowance
Impaired Financing Receivable, Recorded Investment, Total	8,072	18,512
Impaired Financing Receivable, Unpaid Principal Balance, Total	13,736	28,382
Impaired Financing Receivable, Related Allowance	25	3
With a related allowance recorded, Average Recorded Investment	1,652	4,446
With a related allowance recorded, Interest Income Recognized	49
Without a related allowance recorded, Average Recorded Investment	14,112	22,299
Without a related allowance recorded, Interest Income Recognized	326	571
Impaired Financing Receivable, Average Recorded Investment, Total	15,764	26,745
Impaired Financing Receivable, Interest Income Recognized, Total	375	571
Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
With a related allowance recorded, Recorded Investment	53
With a related allowance recorded, Unpaid Principal Balance	53
With a related allowance recorded, Related Allowance	53
Without a related allowance recorded, Recorded Investment	8,026	10,827
Without a related allowance, Unpaid Principal Balance	9,464	12,025
Without a related allowance recorded, Related Allowance
Impaired Financing Receivable, Recorded Investment, Total	8,079	10,827
Impaired Financing Receivable, Unpaid Principal Balance, Total	9,517	12,025
Impaired Financing Receivable, Related Allowance	53
With a related allowance recorded, Average Recorded Investment	60
With a related allowance recorded, Interest Income Recognized	6
Without a related allowance recorded, Average Recorded Investment	8,714	20,533
Without a related allowance recorded, Interest Income Recognized	436	68
Impaired Financing Receivable, Average Recorded Investment, Total	8,774	20,533
Impaired Financing Receivable, Interest Income Recognized, Total	442	68
Other Consumer [Member]
Financing Receivable, Impaired [Line Items]
With a related allowance recorded, Recorded Investment	33
With a related allowance recorded, Unpaid Principal Balance	33
With a related allowance recorded, Related Allowance	19
Without a related allowance recorded, Recorded Investment	124	25
Without a related allowance, Unpaid Principal Balance	128	25
Without a related allowance recorded, Related Allowance
Impaired Financing Receivable, Recorded Investment, Total	157	25
Impaired Financing Receivable, Unpaid Principal Balance, Total	161	25
Impaired Financing Receivable, Related Allowance	19
With a related allowance recorded, Average Recorded Investment	24
With a related allowance recorded, Interest Income Recognized	4
Without a related allowance recorded, Average Recorded Investment	114	6
Without a related allowance recorded, Interest Income Recognized	6
Impaired Financing Receivable, Average Recorded Investment, Total	138	6
Impaired Financing Receivable, Interest Income Recognized, Total	$ 10