Derivative Instruments and Hedging Activities Derivative Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of interest rate derivatives	$ 693		$ 693		$ (194)
Interest Rate Swap No. 2 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, term of contract			5 years		5 years
Fair value of interest rate derivatives	24		$ 24		$ 135
Unrealized gain (loss) on interest rate cash flow hedges	2	$ 37	$ 2	$ 93
Interest Rate Swap No. 1 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, term of contract			10 years		10 years
Fair value of interest rate derivatives	(1,082)		$ (1,082)		$ (70)
Unrealized gain (loss) on interest rate cash flow hedges	(47)	(12)	(96)	(4)
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of interest rate derivatives	(1,058)		(1,058)		$ 65
Unrealized gain (loss) on interest rate cash flow hedges	$ (45)	$ 25	$ (94)	$ 89