Acquisitions and Dispositions (Details Textual) - USD ($)		9 Months Ended
	May 09, 2017	Sep. 30, 2018		Sep. 30, 2017		Dec. 31, 2017	Jan. 16, 2017
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total		$ 0				$ 26,269,000
Disposal Group, Including Discontinued Operation, Consideration	$ 23,000,000	23,000,000
Proceeds from Divestiture of Businesses, Net of Cash Divested		0		$ 69,528,000
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net		1,300,000
Discontinued Operation, Disposal of Discontinued Operation ,Transaction Costs		50,000		50,000
Payments to Acquire Businesses, Net of Cash Acquired		24,200,000
Joplin, Missouri and Victoria, Texas Television Stations [Member]
Business Acquisition [Line Items]
Disposal Group, Including Discontinued Operation, Consideration	66,600,000	66,600,000
Proceeds from Divestiture of Businesses, Net of Cash Divested	69,500,000	0	[1]	$ 69,528,000	[1]
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net		3,400,000
Discontinued Operation, Disposal of Discontinued Operation ,Transaction Costs	500,000	$ 500,000
Payments to Acquire Businesses, Net of Cash Acquired	3,400,000
Apex Real Property, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total	$ 23,000,000
Virginia Market [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total							$ 1,658,000
Business Acquisition, Transaction Costs							$ 8,000

[1] Net proceeds from the sale of the television stations reflect the sale price of $66.6 million, and the proceeds from sale of accounts receivable of approximately $3.4 million, offset by certain closing adjustments and transactional costs of approximately $500 thousand.