Derivative Financial Instruments - Fair Value Derivatives (Details) - Derivatives designated as hedging instruments - Interest rate swap agreements - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Interest rate swap agreements	$ 27	$ 82
Derivative liability	5,719	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	27	40
Accrued other current liabilities
Derivative [Line Items]
Derivative liability	108	4
Derivative liabilities
Derivative [Line Items]
Derivative liability	$ 5,611	$ 3,626