Derivative Financial Instruments (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) derivative_instruments	Dec. 31, 2017 USD ($) derivative_instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount to be reclassified from accumulated other comprehensive income to interest expense in next twelve months	$ 10,900,000
Interest rate swap terminated
Derivative Instruments, Gain (Loss) [Line Items]
Carrying amount of hedged assets (liabilities)	1,400,000
Cumulative amount of fair value hedging adjustment included in carrying amount of hedged assets (liabilities)	(1,600,000)
Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income on terminated derivative instruments	(7,313,000)	$ (19,000)
Fair value of interest rate derivatives in a net liability position	5,300,000
Forward commitments to sell mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	481,600,000	$ 551,900,000
Interest rate lock commitments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	235,800,000
Foreign currency derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 40,300,000
Covered call options
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	0	0
Cash flow hedging | Interest rate swap terminated
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	5
Notional amount	$ 650,000,000.0
Cash flow hedging | Interest expense | Interest rate swap terminated
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income on terminated derivative instruments	$ 427,000
Fair value hedging | Interest rate swap terminated
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	1
Designated as hedging instrument | Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 869,643,000
Designated as hedging instrument | Cash flow hedging | Interest rate swaps | Cash flow hedge of variable rate deposits
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	3
Designated as hedging instrument | Cash flow hedging | Interest rate collar | Cash flow hedge of variable rate deposits
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	1
Designated as hedging instrument | Fair value hedging | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	15
Notional amount	$ 173,000,000
Designated as hedging instrument | Fair value hedging | Interest rate swaps effective starting after December 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	3
Notional amount	$ 55,900,000
Not designed as hedging instrument | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 6,100,000,000