Changes in Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Interest rate contracts	$ (84,172)	$ (84,748)	$ (83,686)
Provision for taxes	(34,743)	(1,112)	(71,418)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Provision for taxes	(1,094)	(1,484)	(1,361)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Provision for taxes	(1,094)	(1,484)	(1,361)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] | Interest Rate Swap [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Interest rate contracts	9,460	9,459	8,671
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Losses on cash flow hedges	$ 8,366	$ 7,975	$ 7,310