Derivative Financial Instruments - Fair Value Derivatives (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Interest rate swap agreements	$ 82	$ 52
Derivatives designated as hedging instruments | Interest rate swap agreements
Derivative [Line Items]
Interest rate swap agreements	82	52
Derivative liability	3,630	5,905
Derivatives designated as hedging instruments | Prepaid expenses and other current assets | Interest rate swap agreements
Derivative [Line Items]
Interest rate swap agreements	42	0
Derivatives designated as hedging instruments | Other long-term assets | Interest rate swap agreements
Derivative [Line Items]
Interest rate swap agreements	40	52
Derivatives designated as hedging instruments | Accrued other current liabilities | Interest rate swap agreements
Derivative [Line Items]
Derivative liability	4	844
Derivatives designated as hedging instruments | Derivative liabilities | Interest rate swap agreements
Derivative [Line Items]
Derivative liability	$ 3,626	$ 5,061