Derivative Financial Instruments (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) derivative_instruments	Dec. 31, 2018 USD ($) derivative_instruments
Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of interest rate derivatives in a net liability position	$ 123,700
Forward commitments to sell mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	837,200	$ 481,600
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount to be reclassified from accumulated other comprehensive income to interest expense in next twelve months	5,800
Designated as hedging instrument | Interest rate swap terminated
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of interest rate swap asset		1,400
Cumulative amount of fair value hedging adjustment included in carrying amount of hedged assets (liabilities)		1,600
Designated as hedging instrument | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income on terminated derivative instruments	(10,250)	$ (7,313)
Designated as hedging instrument | Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 1,328,214
Designated as hedging instrument | Cash flow hedging | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	15
Notional amount	$ 210,000
Designated as hedging instrument | Cash flow hedging | Interest rate collar
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	1
Designated as hedging instrument | 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
Designated as hedging instrument | 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	$ 4,700	$ 427
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	$ 162,900
Designated as hedging instrument | 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 | Fair value hedging | Interest rate swaps effective starting after current fiscal year end
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	1
Notional amount	$ 6,900
Not designed as hedging instrument | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	7,400,000
Not designed as hedging instrument | Forward commitments to sell mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	837,200
Not designed as hedging instrument | Interest rate lock commitments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	454,600
Not designed as hedging instrument | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 34,500
Not designed as hedging instrument | Covered call options
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	0	0
Not designed as hedging instrument | Mortgage banking derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instruments	0
Not designed as hedging instrument | Derivative contract held as economic hedge on MSRs
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 55,000
Number of interest rate swaps (derivative instrument) | derivative_instruments	4