Acquisitions and Dispositions (Details Textual) - USD ($)		6 Months Ended	9 Months Ended
	May 09, 2017	Jun. 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
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
Proceeds from Divestiture of Businesses, Net of Cash Divested	69,500,000
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net		$ 1,300,000
Discontinued Operation, Disposal of Discontinued Operation ,Transaction Costs	500,000
Payments to Acquire Businesses, Net of Cash Acquired	24,200,000
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