Derivative Financial Instruments - Schedule of Effect of Derivative Instruments on the Consolidated Statements of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 104	$ (896)	$ 295	$ 28
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	260	436	1,139	1,332
Interest Rate Contract [Member] | Interest Income / (Expense) [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	215	410	913	1,354
Interest Rate Contract [Member] | Other Income / (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(4)	(1)	65	178
Interest Rate Contract [Member] | Other Income / (Expense) [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	45	26	226	(22)
Mortgage Contracts [Member] | Mortgage Banking Revenue [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 108	$ (895)	$ 230	$ (150)