Derivatives - Summary of Types of Derivatives by Their Locations within Statements of Operations (Detail) (Forward Starting Interest Rate Swaps [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Forward Starting Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on FHLB borrowings	$ 150	$ 150	$ 450	$ 350