Derivatives and Hedging Activities (Customer Related Derivative Positions - Not Designated as Hedges) (Details) $ in Thousands		Jun. 30, 2018 USD ($) position	Dec. 31, 2017 USD ($) position
Summary of customer related derivative positions, not designated as hedging
Fair Value		$ 1,878	$ 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]	244	246
Less than 1 year		$ 59,965	$ 36,023
Less than 2 years		61,506	61,500
Less than 3 years		176,919	152,287
Less than 4 years		57,508	111,147
Thereafter		614,476	591,385
Total		970,374	952,342
Fair Value		$ (17,467)	$ 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]	229	231
Less than 1 year		$ 59,965	$ 36,023
Less than 2 years		61,506	61,500
Less than 3 years		176,919	152,287
Less than 4 years		57,508	111,147
Thereafter		614,476	591,385
Total		970,374	952,342
Fair Value		$ 17,456	$ (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]	28	15
Less than 1 year		$ 48,077	$ 26,382
Less than 2 years			3,780
Total		48,077	30,162
Fair Value		$ (1,041)	$ 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]	28	15
Less than 1 year		$ 48,077	$ 26,382
Less than 2 years			3,780
Total		48,077	30,162
Fair Value		$ 1,067	$ (1,188)

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