Derivatives and Hedging Activities Effect of Derivative Instruments 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		Jan. 01, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ 175	[1]	$ (425)	[1]	$ 1,011	[2]	$ (358)	[2]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(263)		357		(284)		660
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net			2				(2)
Cumulative Effect of New Accounting Principle in Period of Adoption									$ 5
Interest Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(263)		357		(284)		660
Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ 175	[1]	$ (425)	[1]	$ 1,011	[2]	$ (358)	[2]

[1] There was an additional $2 thousand gain related to the ineffective portion for the three months ended as of June 30, 2017.

[2] There was an additional $(2) thousand loss related to the ineffective portion for the six months ended as of June 30, 2017. The guidance in ASU 2017-12 requires that amounts in accumulated other comprehensive income that are included in the assessment of effectiveness should be reclassified into earnings in the same period in which the hedged forecasted transactions impact earnings. Transition guidance for this ASU further states that upon adoption, previously recorded cumulative ineffectiveness for cash flow hedges existing at the adoption date be eliminated by means of a cumulative-effect adjustment to accumulated other comprehensive income with a corresponding adjustment to the opening balance of retained earnings as of the initial application date. There was a $5 thousand reclassification related to the adoption of ASU 2017-12 effective January 1, 2018.