Derivatives and Hedging Activities (Customer Related Derivative Positions - Not Designated as Hedges) (Details) $ in Thousands		Sep. 30, 2018 USD ($) position	Dec. 31, 2017 USD ($) position
Summary of customer related derivative positions, not designated as hedging
Fair Value		$ 1,375	$ 1,616
Not Designated as Hedging Instrument | Receive fixed, pay variable | Loan level swaps
Summary of customer related derivative positions, not designated as hedging
Number of Positions | position	[1]	246	246
Less than 1 year		$ 47,115	$ 36,023
Less than 2 years		65,256	61,500
Less than 3 years		168,249	152,287
Less than 4 years		57,508	111,147
Thereafter		619,232	591,385
Total		957,360	952,342
Fair Value		$ (22,233)	$ 3,875
Not Designated as Hedging Instrument | Pay fixed, receive variable | Loan level swaps
Summary of customer related derivative positions, not designated as hedging
Number of Positions | position	[1]	231	231
Less than 1 year		$ 47,115	$ 36,023
Less than 2 years		65,256	61,500
Less than 3 years		168,249	152,287
Less than 4 years		57,508	111,147
Thereafter		619,232	591,385
Total		957,360	952,342
Fair Value		$ 22,219	$ (3,880)
Not Designated as Hedging Instrument | Buys foreign currency, sells U.S. currency | Foreign exchange contracts
Summary of customer related derivative positions, not designated as hedging
Number of Positions | position	[1]	24	15
Less than 1 year		$ 43,013	$ 26,382
Less than 2 years		2,796	3,780
Total		45,809	30,162
Fair Value		$ (1,021)	$ 1,202
Not Designated as Hedging Instrument | Buys U.S. currency, sells foreign currency | Foreign exchange contracts
Summary of customer related derivative positions, not designated as hedging
Number of Positions | position	[1]	24	15
Less than 1 year		$ 43,013	$ 26,382
Less than 2 years		2,796	3,780
Total		45,809	30,162
Fair Value		$ 1,043	$ (1,188)

[1] The Company may enter into one dealer swap agreement which offsets multiple commercial borrower swap agreements.