Basis of Presentation and Significant Accounting Policies Revenue Recognition Parenthetical (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Revenues	$ 578,733	$ 498,008	$ 489,358	$ 443,635	$ 488,999	$ 450,533	$ 469,517	$ 439,910	$ 2,009,734	[1]	$ 1,848,959	[1]	$ 1,947,930	[1]
Barter
Revenues									$ 28,000		$ 28,000		$ 30,000

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