Accumulated Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Income by Component Net of Tax (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized holding gain on available-for-sale securities arising during the period	$ 1,644	$ 282	$ (2,428)	$ 1,093
Amount reclassified for net gains included in net income	(149)		(159)
Unrealized holding gain on available-for-sale debt securities arising during the period	(81)	96	(1,469)	372
Beginning balance			1,864
Ending balance	(987)		(987)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,258)		2,824
Unrealized holding gain on available-for-sale securities arising during the period	1,346		(2,746)
Amount reclassified for net gains included in net income	149		159
Unrealized loss on securities transferred from Available-for-Sale to Held-to-Maturity	(1,915)		(1,915)
Amortization of Held-to-maturity discount resulting from transfer	182		182
Total other comprehensive loss	(238)		(4,320)
Ending balance	(1,496)		(1,496)
Beginning balance	428		(960)
Unrealized holding gain on available-for-sale debt securities arising during the period	(457)		934
Amount reclassified for net gains included in net income	(51)		(54)
Unrealized loss on securities transferred from Available-for-Sale to Held-to-Maturity	651		651
Amortization of Held-to-maturity discount resulting from transfer	(62)		(62)
Total other comprehensive loss	81		1,469
Ending balance	509		509
Beginning balance	(830)		1,864
Unrealized holding gain on available-for-sale debt securities arising during the period	889		(1,812)
Amount reclassified for net gains included in net income	98		105
Unrealized loss on securities transferred from Available-for-Sale to Held-to-Maturity	(1,264)		(1,264)
Amortization of Held-to-maturity discount resulting from transfer	120		120
Total other comprehensive loss	(157)		(2,851)
Ending balance	$ (987)		$ (987)