Derivative Financial Instruments Derivative Financial Instruments (Narrative) (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) contracts derivative_instruments	Sep. 30, 2014 USD ($) derivative_instruments	Sep. 30, 2015 USD ($) contracts derivative_instruments	Sep. 30, 2014 USD ($) derivative_instruments	Dec. 31, 2014 derivative_instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income to interest expense in the next twelve months			$ 3,100,000
Basis Amortization of Hedged item no longer in a Hedging Relationship	$ 43,000	$ 43,000	129,000	$ 129,000
Derivative, Net Liability Position, Aggregate Fair Value	$ 58,500,000		$ 58,500,000
Interest Rate Cap | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | contracts	4		4
Notional amount	$ 446,500,000		$ 446,500,000
Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	3,300,000,000		3,300,000,000
Forward Commitments to Sell Mortgage Loans | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	731,100,000		731,100,000
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	455,700,000		455,700,000
Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 16,300,000		$ 16,300,000
Covered Call Options | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Number of Instruments Held | derivative_instruments	0	0	0	0	0
Minimum | Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, maturity date			Oct. 31, 2015
Maximum | Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, maturity date			Feb. 28, 2045
Cash Flow Hedging | Interest Rate Contract | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net			$ 0	$ 0
Fair Value Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	4		4
Notional amount	$ 16,700,000		$ 16,700,000
Fair Value Hedging | Interest Rate Contract | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Income Statement Gain/(Loss) due to Hedge Ineffectiveness	$ (21,000)	$ 0	$ (23,000)	$ (3,000)
Cash flow hedge of variable rate deposits | Cash Flow Hedging | Interest Rate Cap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	2		2
Interest Rate Cap Two Hundred Sixteen Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity | Cash Flow Hedging | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 216,500,000		$ 216,500,000
Derivative, maturity date			Aug. 29, 2016
Interest Rate Cap Forty Three Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity | Cash Flow Hedging | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 43,500,000		$ 43,500,000
Derivative, maturity date			Aug. 22, 2016
Cash Flow Hedge of Junior Subordinated Debentures | Cash Flow Hedging | Interest Rate Cap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	2		2
Cash Flow Hedge of Junior Subordinated Debentures | Cash Flow Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	2		2
De-designated Hedge | Interest Rate Cap | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 96,500,000		$ 96,500,000