Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 54,956	$ 62,137
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	204	183
Total other comprehensive loss	204	183
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	55,160	62,320
Net income attributable to noncontrolling interests	(66)	(21)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 55,094	$ 62,299