Fair Value Measurement (Details 2) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Asset (Liability) Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt and lines of credit	$ (220,188)	$ (294,085)
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt and lines of credit	$ (412,214)	$ (273,983)