Derivative Instruments - Assets and liabilities presented on a net basis due to the right of offset (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 1	$ 16
Derivative Asset gross amount offset	0	0
Net amount of assets presented	1	16
Derivative Liability, Fair Value, Gross Liability	106	13
Derivative liability gross amount offset	0	0
Net amount of liabilities presented	$ 106	$ 13