Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Derivative [Line Items]
Maturity date, derivative instrument			Jul. 15, 2015
Total interest rate swaps aggregate notional amount	$ 188,100,000		$ 188,100,000
Number of interest rate swaps	45		45
Aggregate notional amount of mortgage banking derivatives	103,100,000		103,100,000
Aggregate fair value of net liability position	16,200,000		16,200,000
Collateral posted with counterparties	14,100,000		14,100,000
Interest rate swaps [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	300,000,000		300,000,000
Accumulated net after-tax losses related to effective cash flow hedges	8,600,000		8,600,000		12,700,000
Estimated amount of interest rate derivatives to be reclassified to interest expense			8,200,000
Recognized a net reduction to interest expense	145,000	139,000	287,000	275,000
Interest rate caps [Member]
Derivative [Line Items]
Gain (loss) on cash flow hedge ineffectiveness				73,000
Customer repurchase agreements and money market deposit accounts [Member] | Interest Rate Swaps Due July Twelve Two Thousand Twelve [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	100,000,000		100,000,000
Customer repurchase agreements and money market deposit accounts [Member] | Interest Rate Swaps Due July Fifteen Two Thousand Fifteen [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivatives	100,000,000		100,000,000
Derivatives designated as hedging instruments [Member] | Consumer and commercial money market deposit accounts [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivative	8,700,000		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 derivatives	200,000,000		200,000,000
Maturity date, derivative instrument			Oct. 01, 2016
Fixed interest rate	4.73%		4.73%
Interest rate swap, starting date	July 2012		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%		5.11%
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%		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%		6.25%
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]
Aggregate notional amount of interest rate derivative	51,000,000		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 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%		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%		2.75%
Derivatives designated as hedging instruments [Member] | Customer repurchase agreements and money market deposit accounts [Member] | Interest Rate Swaps Due May One Two Thousand Thirteen [Member]
Derivative [Line Items]
Aggregate notional amount of interest rate derivatives	$ 100,000,000		$ 100,000,000