Derivative Financial Instruments - Fair Value Derivatives (Details) - Derivatives designated as hedging instruments - Interest rate swap agreements - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Interest rate swap agreements	$ 12	$ 82
Derivative liability	9,159	3,630
Prepaid expenses and other current assets
Derivative [Line Items]
Interest rate swap agreements	0	42
Other long-term assets
Derivative [Line Items]
Interest rate swap agreements	12	40
Accrued other current liabilities
Derivative [Line Items]
Derivative liability	706	4
Derivative liabilities
Derivative [Line Items]
Derivative liability	$ 8,453	$ 3,626