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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value Hedging [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 392	$ 774	$ 896	$ 1,566
Cash Flow Hedging [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative				241
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	816	(25)	924	132
Interest Rate Contract [Member] | Interest Income / (Expense) [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	467	552	944	1,173
Interest Rate Contract [Member] | Interest Income / (Expense) [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative
Interest Rate Contract [Member] | Other Income / (Expense) [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(75)	222	(48)	393
Interest Rate Contract [Member] | Other Income / (Expense) [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative				241
Interest Rate Contract [Member] | Other Income / (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	218	28	179	38
Other Contract [Member] | Mortgage Banking Revenue [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 598	$ (53)	$ 745	$ 94