Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Condensed Balance Sheet Statements, Captions [Line Items]
Total current assets	$ 73,226	$ 72,988
Total property and equipment, net	1,634,204	1,545,760
Investment in subsidiaries	0	0
Other assets	7,010	7,579
Total Assets	1,714,440	1,626,327
Current liabilities	228,028	211,959
Long-term liabilities	1,416,485	1,390,910
Total shareholders’ equity	69,927	23,458
Total Liabilities and Shareholders’ Equity	1,714,440	1,626,327
Eliminations [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Total current assets	(2,717,829)	(2,726,355)
Total property and equipment, net	(3,926)	(3,916)
Investment in subsidiaries	1,223,475	1,282,292
Other assets	0	0
Total Assets	(1,498,280)	(1,447,979)
Current liabilities	(2,720,849)	(2,729,375)
Long-term liabilities	15,878	15,878
Total shareholders’ equity	1,206,691	1,265,518
Total Liabilities and Shareholders’ Equity	(1,498,280)	(1,447,979)
Parent Company [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Total current assets	2,724,856	2,735,830
Total property and equipment, net	41,196	42,181
Investment in subsidiaries	(1,223,475)	(1,282,292)
Other assets	6,855	7,423
Total Assets	1,549,432	1,503,142
Current liabilities	90,083	114,805
Long-term liabilities	1,372,638	1,348,105
Total shareholders’ equity	86,711	40,232
Total Liabilities and Shareholders’ Equity	1,549,432	1,503,142
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Total current assets	66,199	63,513
Total property and equipment, net	1,593,134	1,503,695
Investment in subsidiaries	0	0
Other assets	155	156
Total Assets	1,659,488	1,567,364
Current liabilities	2,854,994	2,822,729
Long-term liabilities	27,969	26,927
Total shareholders’ equity	(1,223,475)	(1,282,292)
Total Liabilities and Shareholders’ Equity	1,659,488	1,567,364
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Total current assets	0	0
Total property and equipment, net	3,800	3,800
Investment in subsidiaries	0	0
Other assets	0	0
Total Assets	3,800	3,800
Current liabilities	3,800	3,800
Long-term liabilities	0	0
Total shareholders’ equity	0	0
Total Liabilities and Shareholders’ Equity	$ 3,800	$ 3,800