Stockholders' Equity - Reclassification From Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss on cash flow hedges	$ (39,336)	$ (25,531)	$ (19,534)
Income tax benefits	101,852	86,465	79,705
Loss on cash flow hedges, net	245,217	197,058	182,999
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest | Interest Rate Contract | Reclassification out of Accumulated Other Comprehensive Income
Loss on cash flow hedges	0	(219)	(449)
Income tax benefits	0	85	174
Loss on cash flow hedges, net	$ 0	$ (134)	$ (275)