Basis Of Presentation And Significant Accounting Policies - Disaggregated Revenue Parenthetical (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating revenues	[1]	$ 489,358	$ 469,517	$ 932,993	$ 909,427
Barter
Operating revenues		$ 7,000	$ 7,000	$ 14,000	$ 14,000

[1] (1)See Note 2 for the disclosures of operating revenues and operating loss included in discontinued operations for the historical periods.