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, 2017	Jun. 30, 2016	Mar. 31, 2016	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	$ (4)	$ (1,547)	$ (2,146)	$ (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	(324)	(1,554)	(2,159)	(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	$ 320	$ 7	$ 13	$ 320