Derivative Instruments and Hedging Activities - Consolidated Statements of Financial Condition Related to Fair Value of Derivative Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Other Assets [Member] | Derivatives designated as hedging instruments [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	$ 528	$ 675
Other Assets [Member] | Derivatives designated as hedging instruments [Member] | Cash flow hedge interest rate caps and swaps [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	16	23
Other Assets [Member] | Derivatives designated as hedging instruments [Member] | Fair value hedge interest rate swaps [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	512	652
Other Assets [Member] | Derivatives not designated as hedging instrument [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	6,941	7,241
Other Assets [Member] | Derivatives not designated as hedging instrument [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	6,508	7,002
Other Assets [Member] | Derivatives not designated as hedging instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	433	239
Other Liabilities [Member] | Derivatives designated as hedging instruments [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	18,222	19,395
Other Liabilities [Member] | Derivatives designated as hedging instruments [Member] | Cash flow hedge interest rate caps and swaps [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	16,122	17,198
Other Liabilities [Member] | Derivatives designated as hedging instruments [Member] | Fair value hedge interest rate swaps [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	2,100	2,197
Other Liabilities [Member] | Derivatives not designated as hedging instrument [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	7,270	7,199
Other Liabilities [Member] | Derivatives not designated as hedging instrument [Member] | Interest rate swaps [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	6,508	6,999
Other Liabilities [Member] | Derivatives not designated as hedging instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	$ 762	$ 200