Securities Available-for-Sale - Fair Value and Age of Gross Unrealized Losses by Investment Category (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	41	5
Available-for-sale Securities, Less Than 12 Months, Fair Value	$ 274,942	$ 22,883
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(6,913)	(116)
Available-for-sale Securities, 12 Months or More, Number of Securities	2
Available-for-sale Securities, 12 Months or More, Fair Value	10,088
Available-for-sale Securities, 12 Months or More, Unrealized Losses	(863)
Available-for-sale Securities, Fair Value, Total	285,030	22,883
Available-for-sale Securities, Unrealized Losses, Total	(7,776)	(116)
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	16	2
Available-for-sale Securities, Less Than 12 Months, Fair Value	126,017	11,370
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(2,581)	(53)
Available-for-sale Securities, Fair Value, Total	126,017	11,370
Available-for-sale Securities, Unrealized Losses, Total	(2,581)	(53)
Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	3
Available-for-sale Securities, Less Than 12 Months, Fair Value	39,522
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(603)
Available-for-sale Securities, Fair Value, Total	39,522
Available-for-sale Securities, Unrealized Losses, Total	(603)
Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	2
Available-for-sale Securities, Less Than 12 Months, Fair Value	22,822
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(685)
Available-for-sale Securities, Fair Value, Total	22,822
Available-for-sale Securities, Unrealized Losses, Total	(685)
Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	4
Available-for-sale Securities, Less Than 12 Months, Fair Value	39,052
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(1,305)
Available-for-sale Securities, Fair Value, Total	39,052
Available-for-sale Securities, Unrealized Losses, Total	(1,305)
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	16	3
Available-for-sale Securities, Less Than 12 Months, Fair Value	47,529	11,285
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(1,739)	(52)
Available-for-sale Securities, 12 Months or More, Number of Securities	2
Available-for-sale Securities, 12 Months or More, Fair Value	10,088
Available-for-sale Securities, 12 Months or More, Unrealized Losses	(863)
Available-for-sale Securities, Fair Value, Total	57,617	11,285
Available-for-sale Securities, Unrealized Losses, Total	(2,602)	(52)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Less Than 12 Months, Number of Securities	41	5
Available-for-sale Securities, Less Than 12 Months, Fair Value	274,942	22,655
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	(6,913)	(105)
Available-for-sale Securities, 12 Months or More, Number of Securities	2
Available-for-sale Securities, 12 Months or More, Fair Value	10,088
Available-for-sale Securities, 12 Months or More, Unrealized Losses	(863)
Available-for-sale Securities, Fair Value, Total	285,030	22,655
Available-for-sale Securities, Unrealized Losses, Total	$ (7,776)	$ (105)