Derivative Financial Instruments - Changes in Fair Value of Derivative Contracts (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net loss (gain) recognized in other comprehensive income (loss)	$ (2,174)	$ 2,858
Interest rate swap agreements
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain recognized in earnings	(47)	(92)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	3,548	5,853
Loss (gain) recognized in other comprehensive income (loss)	2,130	(2,640)
Amounts reclassified from other comprehensive income (loss) to earnings	61	(212)
Net loss (gain) recognized in other comprehensive income (loss)	2,191	(2,852)
Ending balance	$ 5,692	$ 2,909

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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