Derivative Financial Instruments - Changes in Net Gain or Loss on Cash Flow Hedges Included in Accumulated Other Comprehensive Loss (Details) - Interest rate swap agreements - Cash flow hedges - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Changes in Net Gain or Loss on Cash Flow Hedges Included in Accumulated Other Comprehensive Loss
Balance at the beginning of the period	$ (10,560)	$ 24	$ (2,936)
Unrealized (loss) gain recognized in other comprehensive (loss) income, net of tax	(2,060)	1,171	(10,135)	$ 251
Reclassification to interest expense, net	419	567	870	1,511
Balance at the end of the period	$ (12,201)	$ 1,762	$ (12,201)	$ 1,762