Derivative Financial Instruments (Narrative) (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) contracts derivative_instruments	Sep. 30, 2015 USD ($) derivative_instruments	Sep. 30, 2016 USD ($) contracts derivative_instruments	Sep. 30, 2015 USD ($) derivative_instruments	Dec. 31, 2015 derivative_instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income to interest expense in the next twelve months			$ 1,700,000
Derivative, Net Liability Position, Aggregate Fair Value	$ 80,600,000		$ 80,600,000
Interest Rate Cap | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | contracts	2		2
Notional amount	$ 175,000,000		$ 175,000,000
Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	4,100,000,000		4,100,000,000
Forward Commitments to Sell Mortgage Loans | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	1,300,000,000		1,300,000,000
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	683,600,000		683,600,000
Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 63,600,000		$ 63,600,000
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, 2016
Maximum | Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, maturity date			Feb. 28, 2045
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
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
Cash Flow Hedging | Cash flow hedge of variable rate deposits | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	2		2
Cash Flow Hedging | Interest Rate Swap, $250 million, July 2019 | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 250,000,000		$ 250,000,000
Cash Flow Hedging | Interest Rate Swap, $250 million, July 2019 | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	250,000,000		250,000,000
Cash Flow Hedging | Interest Rate Swap, $275 million, August 2019 | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	275,000,000		275,000,000
Cash Flow Hedging | Interest Rate Swap, $275 million, August 2019 | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 275,000,000		$ 275,000,000
Cash Flow Hedging | Cash Flow Hedge of Junior Subordinated Debentures | 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 Hedging | Cash Flow Hedge of Junior Subordinated Debentures | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	1		1
Fair Value Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of Interest Rate Derivatives Held | derivative_instruments	7		7
Notional amount	$ 71,300,000		$ 71,300,000
Fair Value Hedging | Interest Rate Contract | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Income Statement Gain/(Loss) due to Hedge Ineffectiveness	$ 35,000	$ (21,000)	$ 13,000	$ (23,000)