Basis of Presentation and Significant Accounting Policies Dreamcatcher (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Dec. 27, 2013	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
Variable Interest Entity [Line Items]
Federal Communications Commission Regulation, Proceeds Received From Auction												$ 191,000
Total operating 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]
Total operating profit		$ 165,965	$ 37,124	$ 98,066	$ 187,285	$ 123,419	$ (29,452)	$ 12,653	$ (20,967)	488,440	[1]	85,653	[1]	408,772	[1]
Dreamcatcher Stations
Variable Interest Entity [Line Items]
Federal Communications Commission Regulation, Proceeds Received From Auction												26,000
Dreamcatcher Stations | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total operating revenues										78,000		72,000		73,000
Total operating profit										$ 18,000		$ 12,000		$ 16,000
Dreamcatcher | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Financial or Other Support, Amount	$ 200
Dreamcatcher | Dreamcatcher Stations
Variable Interest Entity [Line Items]
Business Combination, Consideration Transferred	$ 27,000

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