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	Sep. 30, 2014	Dec. 31, 2013
Derivatives Designated as Hedging Instruments [Member]
Derivative [Line Items]
Notional Amount, Fair Value	$ 1,140,454	$ 1,191,591
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedge Interest Rate Caps and Swaps [Member]
Derivative [Line Items]
Notional Amount, Fair Value	1,007,000	1,007,000
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedge Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount, Fair Value	133,454	184,591
Derivatives Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount, Fair Value	391,250	306,616
Derivatives Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount, Fair Value	382,021	259,832
Derivatives Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Notional Amount, Fair Value	9,229	46,784
Other Assets [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	5,766	9,982
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	3,141	9,883
Other Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedge Interest Rate Swaps [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	2,625	99
Other Assets [Member] | Derivatives Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	9,165	5,140
Other Assets [Member] | Derivatives Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	9,158	4,823
Other Assets [Member] | Derivatives Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Asset Derivatives, Fair Value	7	317
Other Liabilities [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	14,472	15,616
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	13,045	10,925
Other Liabilities [Member] | Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedge Interest Rate Swaps [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	1,427	4,691
Other Liabilities [Member] | Derivatives Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	9,167	4,970
Other Liabilities [Member] | Derivatives Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	9,150	4,823
Other Liabilities [Member] | Derivatives Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member]
Derivative [Line Items]
Liability Derivatives, Fair Value	$ 17	$ 147