Other Operating Expenses (Schedule Of Other Operating Expenses/(Income)) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total other operating expenses		$ 9,132	$ 1,300	$ 90,880
Litigation Settlement [Member]
Total other operating expenses	$ 6,000	6,000	796	84,476
Loss On Sale Of Transportation Equipment [Member]
Total other operating expenses		2,266		5,266
Loss On Disposal Of Property And Equipment [Member]
Total other operating expenses		$ 866	$ 504
Program Closure Expenses [Member]
Total other operating expenses				$ 1,138