Derivatives and Hedging Activities Derivatives not designated as hedges, effect on statement of operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments in Financial Statements			Other income/ (expense)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (92)	$ (4)	$ 166	$ (326)
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(139)	(324)	(47)	(646)
Not Designated as Hedging Instrument [Member] | Loan Participations and Assignments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 47	$ 320	$ 213	$ 320