Investment Securities - Amortized Cost and Estimated Fair Value of Held-to-Maturity Securities and Available-for-Sale Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Held-to-Maturity, Fair Value	$ 66,853	$ 71,327
Total Amortized Cost	338,546	416,898
Total Gross Unrealized Gains	2,883	13,097
Total Gross Unrealized Losses	(5,148)	(261)
Total Fair Value	336,281	429,734
Equity Securities [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities Equity, No stated maturity Amortized Cost	1,679	2,279
Available-for-Sale Securities Equity, No stated maturity Gross Unrealized Gains	668	696
Available For Sale Securities Equity, No stated maturity Gross Unrealized Losses		(133)
Available-for-Sale Securities Equity, No stated maturity Fair Value	2,347	2,842
Available-for-Sale Securities Equity, Total Amortized Cost	1,679	2,279
Available-for-Sale Securities Equity, Total Gross Unrealized Gains	668	696
Available-for-Sale Securities Equity, Total Gross Unrealized Losses		(133)
Available-for-Sale Securities Equity, Total Fair Value	2,347	2,842
U.S. Treasuries [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities, Amortized Cost After 5 years to 10 years	4,966	4,960
Available-for-Sale Securities, Gross Unrealized Gains After 5 years to 10 years
Available-for-Sale Securities, Gross Unrealized Losses After 5 years to 10 years	(258)	(22)
Available-for-Sale Securities, Fair Value After 5 years to 10 years	4,708	4,938
Total Amortized Cost	4,966	4,960
Total Gross Unrealized Gains
Total Gross Unrealized Losses	(258)	(22)
Available-for-Sale Securities, Debt Total Fair Value	4,708	4,938
U.S. Government Corporations and Agencies [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities, Amortized Cost Within 1 year	5,999	1,517
Available-for-Sale Securities, Gross Unrealized Gains Within 1 year	16	9
Available-for-Sale Securities, Gross Unrealized Losses Within 1 year
Available-for-Sale Securities, Fair Value Within 1 year	6,015	1,526
Available-for-Sale Securities, Amortized Cost After 1 year to 5 years	112,989	148,120
Available-for-Sale Securities, Gross Unrealized Gains After 1 year to 5 years	114	1,509
Available-for-Sale Securities, Gross Unrealized Losses After 1 year to 5 years	(1,226)	(70)
Available-for-Sale Securities, Fair Value After 1 year to 5 years	111,877	149,559
Available-for-Sale Securities, Amortized Cost After 5 years to 10 years	10,816	20,953
Available-for-Sale Securities, Gross Unrealized Gains After 5 years to 10 years		109
Available-for-Sale Securities, Gross Unrealized Losses After 5 years to 10 years	(560)	(5)
Available-for-Sale Securities, Fair Value After 5 years to 10 years	10,256	21,057
Total Amortized Cost	129,804	170,590
Total Gross Unrealized Gains	130	1,627
Total Gross Unrealized Losses	(1,786)	(75)
Available-for-Sale Securities, Debt Total Fair Value	128,148	172,142
State and Political Subdivisions [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities, Amortized Cost Within 1 year	1,564	4,607
Available-for-Sale Securities, Gross Unrealized Gains Within 1 year	13	75
Available-for-Sale Securities, Gross Unrealized Losses Within 1 year
Available-for-Sale Securities, Fair Value Within 1 year	1,577	4,682
Available-for-Sale Securities, Amortized Cost After 1 year to 5 years	5,305	4,130
Available-for-Sale Securities, Gross Unrealized Gains After 1 year to 5 years	14	88
Available-for-Sale Securities, Gross Unrealized Losses After 1 year to 5 years	(29)	(19)
Available-for-Sale Securities, Fair Value After 1 year to 5 years	5,290	4,199
Available-for-Sale Securities, Amortized Cost After 5 years to 10 years	41,974	36,499
Available-for-Sale Securities, Gross Unrealized Gains After 5 years to 10 years	710	1,245
Available-for-Sale Securities, Gross Unrealized Losses After 5 years to 10 years	(698)	(7)
Available-for-Sale Securities, Fair Value After 5 years to 10 years	41,986	37,737
Available-for-Sale Securities, Amortized Cost Over 10 years	57,899	70,495
Available-for-Sale Securities, Gross Unrealized Gains Over 10 years	1,227	5,055
Available-for-Sale Securities, Gross Unrealized Losses Over 10 years	(322)
Available-for-Sale Securities, Fair Value Over 10 years	58,804	75,550
Total Amortized Cost	106,742	115,731
Total Gross Unrealized Gains	1,964	6,463
Total Gross Unrealized Losses	(1,049)	(26)
Available-for-Sale Securities, Debt Total Fair Value	107,657	122,168
Residential Mortgage-Backed Securities [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities, Amortized Cost After 5 years to 10 years	10,008	20,140
Available-for-Sale Securities, Gross Unrealized Gains After 5 years to 10 years	5	777
Available-for-Sale Securities, Gross Unrealized Losses After 5 years to 10 years	(53)
Available-for-Sale Securities, Fair Value After 5 years to 10 years	9,960	20,917
Available-for-Sale Securities, Amortized Cost Over 10 years	25,721	66,962
Available-for-Sale Securities, Gross Unrealized Gains Over 10 years	20	2,861
Available-for-Sale Securities, Gross Unrealized Losses Over 10 years	(221)
Available-for-Sale Securities, Fair Value Over 10 years	25,520	69,823
Total Amortized Cost	35,729	87,102
Total Gross Unrealized Gains	25	3,638
Total Gross Unrealized Losses	(274)
Available-for-Sale Securities, Debt Total Fair Value	35,480	90,740
Collateralized Mortgage Obligations [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities, Amortized Cost After 1 year to 5 years	73	41
Available-for-Sale Securities, Gross Unrealized Gains After 1 year to 5 years
Available-for-Sale Securities, Gross Unrealized Losses After 1 year to 5 years
Available-for-Sale Securities, Fair Value After 1 year to 5 years	73	41
Available-for-Sale Securities, Amortized Cost After 5 years to 10 years		626
Available-for-Sale Securities, Gross Unrealized Gains After 5 years to 10 years		7
Available-for-Sale Securities, Gross Unrealized Losses After 5 years to 10 years
Available-for-Sale Securities, Fair Value After 5 years to 10 years		633
Available-for-Sale Securities, Amortized Cost Over 10 years	7,341	25,698
Available-for-Sale Securities, Gross Unrealized Gains Over 10 years	40	645
Available-for-Sale Securities, Gross Unrealized Losses Over 10 years	(253)	(5)
Available-for-Sale Securities, Fair Value Over 10 years	7,128	26,338
Total Amortized Cost	7,414	26,365
Total Gross Unrealized Gains	40	652
Total Gross Unrealized Losses	(253)	(5)
Available-for-Sale Securities, Debt Total Fair Value	7,201	27,012
Corporate Bonds [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost Within 1 year	11,148	3,026
Held-to-Maturity, Gross Unrealized Gains Within 1 year	122	7
Held-to-Maturity, Gross Unrealized Losses Within 1 year
Held-to-Maturity, Fair Value Within 1 year	11,270	3,033
Held-to-Maturity After 1 year to 5 years, Amortized Cost	54,855	66,819
Held-to-Maturity After 1 year to 5 years, Gross Unrealized Gains	992	1,526
Held-to-Maturity After 1 year to 5 years, Gross Unrealized Losses	(264)	(51)
Held-to-Maturity After 1 year to 5 years, Fair Value	55,583	68,294
Held-to-Maturity, Amortized Cost	66,003	69,845
Held-to-Maturity, Gross Unrealized Gains	1,114	1,533
Held-to-Maturity, Gross Unrealized Losses	(264)	(51)
Held-to-Maturity, Fair Value	66,853	71,327
Available-for-Sale Securities, Amortized Cost After 1 year to 5 years	18,838	4,993
Available-for-Sale Securities, Gross Unrealized Gains After 1 year to 5 years	52	21
Available-for-Sale Securities, Gross Unrealized Losses After 1 year to 5 years	(411)
Available-for-Sale Securities, Fair Value After 1 year to 5 years	18,479	5,014
Available-for-Sale Securities, Amortized Cost After 5 years to 10 years	16,474
Available-for-Sale Securities, Gross Unrealized Gains After 5 years to 10 years	4
Available-for-Sale Securities, Gross Unrealized Losses After 5 years to 10 years	(1,117)
Available-for-Sale Securities, Fair Value After 5 years to 10 years	15,361
Total Amortized Cost	35,312	4,993
Total Gross Unrealized Gains	56	21
Total Gross Unrealized Losses	(1,528)
Available-for-Sale Securities, Debt Total Fair Value	33,840	5,014
Money Market Mutual Funds [Member]
Schedule of Available for Sale and Held To Maturity Securities [Line Items]
Available-for-Sale Securities Equity, No stated maturity Amortized Cost	16,900	4,878
Available-for-Sale Securities Equity, No stated maturity Gross Unrealized Gains
Available For Sale Securities Equity, No stated maturity Gross Unrealized Losses
Available-for-Sale Securities Equity, No stated maturity Fair Value	16,900	4,878
Total Amortized Cost	16,900	4,878
Total Gross Unrealized Gains
Total Gross Unrealized Losses
Available-for-Sale Securities, Debt Total Fair Value	$ 16,900	$ 4,878