Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative [Line Items]
Maturity date, derivative instrument	Jul. 15, 2015
Total interest rate swaps aggregate notional amount	$ 171,500,000
Number of interest rate swaps	41
Aggregate notional amount of mortgage banking derivatives	235,300,000
Aggregate fair value of net liability position	24,600,000
Collateral posted with counterparties	23,700,000
Interest rate caps [Member]
Derivative [Line Items]
Gain (loss) on cash flow hedge ineffectiveness		73,000
Interest rate swaps [Member]
Derivative [Line Items]
Notional amount of interest rate derivatives	300,000,000
Accumulated net after-tax losses related to effective cash flow hedges	11,700,000	12,700,000
Estimated amount of interest rate derivatives to be reclassified to interest expense	8,300,000
Recognized a net reduction to interest expense	142,000	136,000
Customer repurchase agreements and money market deposit accounts [Member] | Interest rate swaps starting July 12, 2012 [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	100,000,000
Customer repurchase agreements and money market deposit accounts [Member] | Interest rate swaps due July 15, 2015 [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	100,000,000
Derivatives designated as hedging instruments [Member] | Customer repurchase agreements and money market deposit accounts [Member] | Interest rate caps [Member]
Derivative [Line Items]
Maturity date, derivative instrument	May 01, 2013
Derivatives designated as hedging instruments [Member] | Customer repurchase agreements and money market deposit accounts [Member] | Interest rate caps [Member] | Minimum [Member]
Derivative [Line Items]
Strike rates	2.50%
Derivatives designated as hedging instruments [Member] | Customer repurchase agreements and money market deposit accounts [Member] | Interest rate caps [Member] | Maximum [Member]
Derivative [Line Items]
Strike rates	2.75%
Derivatives designated as hedging instruments [Member] | Customer repurchase agreements and money market deposit accounts [Member] | Interest rate swaps [Member] | Fixed-rate at approximately 4.73% [Member]
Derivative [Line Items]
Notional amount of interest rate derivatives	51,000,000
Maturity date, derivative instrument	Mar. 01, 2014
Derivatives designated as hedging instruments [Member] | Customer repurchase agreements and money market deposit accounts [Member] | Interest rate swaps due May 1, 2013 [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	100,000,000
Derivatives designated as hedging instruments [Member] | Consumer and commercial money market deposit accounts [Member] | Interest rate caps [Member] | Minimum [Member]
Derivative [Line Items]
Strike rates	6.00%
Derivatives designated as hedging instruments [Member] | Consumer and commercial money market deposit accounts [Member] | Interest rate caps [Member] | Maximum [Member]
Derivative [Line Items]
Strike rates	6.25%
Derivatives designated as hedging instruments [Member] | Consumer and commercial money market deposit accounts [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Notional amount of interest rate derivatives	8,700,000
Derivatives designated as hedging instruments [Member] | Consumer and commercial money market deposit accounts [Member] | Interest rate swaps [Member] | Fixed-rate at approximately 4.73% [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	$ 200,000,000
Maturity date, derivative instrument	Oct. 01, 2016
Fixed interest rate	4.73%
Interest rate swap, starting date	July 2012
Derivatives designated as hedging instruments [Member] | Consumer and commercial money market deposit accounts [Member] | Interest rate swaps [Member] | Fixed-rate at approximately 5.11% [Member]
Derivative [Line Items]
Maturity date, derivative instrument	Jul. 01, 2017
Fixed interest rate	5.11%