Derivative Financial Instruments (Narrative) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2015 USD ($) contracts derivative_instruments	Dec. 31, 2014 USD ($) derivative_instruments	Dec. 31, 2013 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income to interest expense		$ 2,600,000
Basis Amortization of Hedged item no longer in a Hedging Relationship		172,000	$ 172,000
Mortgage loans held-for-sale		388,038,000	351,290,000
Derivative, Net Liability Position, Aggregate Fair Value		43,300,000
Forward commitments to sell mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		753,900,000	$ 753,900,000	$ 575,400,000
Interest Rate Lock Commitments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		326,700,000
Foreign Exchange Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		$ 22,000,000
Call Options Written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Number of Instruments Held | derivative_instruments		0	0
Not designed as hedging instrument | Interest rate cap
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | contracts		4
Derivative, notional amount		$ 446,500,000
Not designed as hedging instrument | Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		$ 3,400,000,000
Minimum | Not designed as hedging instrument | Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Lower Remaining Maturity Range		Jan. 31, 2016
Maximum | Not designed as hedging instrument | Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Lower Remaining Maturity Range		Feb. 28, 2045
Cash flow hedging | Designated as hedging instrument | Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net		$ 0	$ 0
Fair value hedging | Designated as hedging instrument | Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instruments		4
Derivative, notional amount		$ 16,400,000
Fair value hedging | Designated as hedging instrument | Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of derivatives, hedge ineffectiveness		$ 16,000	$ 5,000
Cash flow hedge of variable rate deposits [Member] | Cash flow hedging | Designated as hedging instrument | Interest rate cap
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instruments		2
Interest Rate Cap Two Hundred Sixteen Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Cash flow hedging | Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		$ 216,500,000
Derivative, Lower Remaining Maturity Range		Aug. 29, 2016
Interest Rate Cap Forty Three Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Cash flow hedging | Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		$ 43,500,000
Derivative, Lower Remaining Maturity Range		Aug. 22, 2016
Cash flow hedge of junior subordinated debentures | Cash flow hedging | Designated as hedging instrument | Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instruments		2
Derivative, Lower Remaining Maturity Range	Sep. 30, 2013
Cash flow hedge of junior subordinated debentures | Cash flow hedging | Designated as hedging instrument | Interest rate cap
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instruments		2
Derivative, notional amount		$ 90,000,000
Cash flow hedge of junior subordinated debentures | Cash flow hedging | Designated as hedging instrument | Interest rate swaps and caps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		225,000,000
FairValueHedgeInterestRateRiskAssociatedWithAnEmbeddedCapInFloatingRateLoans [Member] | Not designed as hedging instrument | Interest rate cap
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount		$ 96,500,000