Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 4,458	$ 12,261	$ 88,317	$ 97,213
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	182	140	548	(949)
Total other comprehensive loss	182	140	548	(949)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	4,640	12,401	88,865	96,264
Net income attributable to noncontrolling interests	(7)	(27)	21	(76)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 4,633	$ 12,374	$ 88,886	$ 96,188